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miniman82
Samba Swamp Donkey
Joined: March 22, 2005
Posts: 9515
Location: Southern Maryland
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 Posted: Sun Jun 22, 2008 10:42 pm Post subject: Ignition systems |
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| Scott Novak wrote: |
| miniman82 wrote: |
| A large gap caused my engine to run like ass at idle, and get shitty economy. |
If a large spark plug gap caused your engine to run poorly, you've only got a weak ignition system to blame.
| miniman82 wrote: |
| Scott Novak wrote: |
| You may only achieve up to a 7% improvement in horsepower and torque, but it is an improvement over the entire RPM range, and there is NO performance penalty! The improvement in gas mileage alone will pay for the ignition system over time. |
Not unless you had an extremely fvcked up ignition system to begin with.  |
The stock Bosch ignition system is poor by design. It's output voltage drops as the RPM increases. It doesn't take much of a problem for the spark plugs to foul because the output current capability of the Bosch ignition coil is so small. Using a non-gapped core ignition coil, such as the Bosch ignition coil, is just plain stupid. It's one of those V8 moments that the design engineer has when they realize they were so stupid to not have added a gap to the core of the ignition coil. The technique has been around since the early days of radio. Back then they called them swinging chokes and used air gapped core inductors in power supply filters. Today, air gapped core inductors are commonly used in computer switching power supplies, like the computer that you are using now. Jacobs has been selling air gapped core ignition coils for over 10 years.
| miniman82 wrote: |
| Curing a carb problem by pumping more power through the plugs? How about fixing the carb problem first. |
An incorrect fuel mixture should not cause your ignition system to fail to ignite the fuel mixture. It's simply a sign of a weak ignition system. You shouldn't need to adjust your fuel mixture so your ignition system is able to ignite it. Your ignition system should ignite the fuel mixture regardless of your fuel mixture problems.
| miniman82 wrote: |
| Ignitions get the flak they do because people seldom know how to set them up properly, so they throw CDI boxes and high $$$ spark plugs at it untill they get the result they're looking for. |
A good ignition system doesn't need any special setup.
A Jacobs Mileage Master, as an example, is an high energy inductive switcher that will operate to 14,000 RPM. Jacobs also makes Capacitive Discharge ignition systems such as the Pro Street. However, the spacings in the Bosch and the small cap Mallory distributor are so small that you can't take advantage of the 65,000 volt capability that the Pro Street has. Any Jacobs ignition system will have great results with inexpensive copper core spark plugs.
| miniman82 wrote: |
| Then I saw the light, and set the spark plug gap to factory specs, and went to an OEM Ford stock computer controlled ignition. I push 10-12 lbs boost through my 1915, guess what plugs I've been running since day one? Yep, those $1.75 Champion lawn mower style copper plugs. |
Actually you are not only in the dark, but it's pitch black. You have obviously been doing something wrong if you have had poor results with wide spark plug gaps.
If you understood ignition systems, you'd realize that the fuel mixture density is what determines the ionization voltage of the spark plug gap.
Factory spark plug gap specifications are only applicable to factory compression ratios and fuel mixture densities with the factory ignition system.
Because the fuel mixture density inside a turbocharged combustion chamber is higher, the ionization required to jump the spark plug gap is also higher, and you need and ignition system that can keep up with that, as well as a distributor with a cap large enough to handle the higher voltages required to fire a turbocharged engine, such as a Mallory Comp 9000 distributor.
Scott Novak |
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Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747
| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
Welcome to the Samba. |
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miniman82
Samba Swamp Donkey
Joined: March 22, 2005
Posts: 9515
Location: Southern Maryland
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| Posted: Sun Jun 22, 2008 11:36 pm Post subject: |
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Scott, you sure do come in here and type a lot of words about a lot of things you hardly understand. I started this new thread to clear up some misconceptions, vice pollute the 1600 thread where it originated.
| Scott Novak wrote: |
| If a large spark plug gap caused your engine to run poorly, you've only got a weak ignition system to blame. |
This is wrong. This is exactly the kind of thinking I was referencing was I said this:
| miniman82 wrote: |
| Ignitions get the flak they do because people seldom know how to set them up properly, so they throw CDI boxes and high $$$ spark plugs at it untill they get the result they're looking for. |
If engine 'A' ran just fine with a .025" plug gap, why in the hell would you make it wider? Is it because you are one of those people who believe that by going to some plasma shooting CDI box, you're going to pick up that magic .5 horse in your 1600?
You're sorely mistaken, and there will be no fuel savings to be had to pay for it either, because the efficiency you would have picked up by igniting the fuel/air mixture 'better' would now get used to power that CDI box! They are large consumers of power, and if you don't believe me, look on a Jacobs/MSD/Mallory box. 15 amps or more isn't unheard of-those fat multiple sparks have a price.
| Scott Novak wrote: |
| An incorrect fuel mixture should not cause your ignition system to fail to ignite the fuel mixture. It's simply a sign of a weak ignition system. You shouldn't need to adjust your fuel mixture so your ignition system is able to ignite it. Your ignition system should ignite the fuel mixture regardless of your fuel mixture problems. |
..........
I'll just let this one speak for itself.
| Scott Novak wrote: |
| The stock Bosch ignition system is poor by design. <snip> |
It's what VW decided was good for it's engines, so are you smarter than a German engineer? Maybe you are. That being the case, would it make you happy if I fired my 1915 turbo with a Bosch Blue, just to prove you're wrong? Somehow I doubt it, as once people get these hairbrained notions that something 'has to be bad because someone told them so' in their heads, it's impossible to tell them otherwise-hence this thread. Wake up, Scott. You took too much Lunesta last night.
| Scott Novak wrote: |
| A Jacobs Mileage Master, as an example, is an high energy inductive switcher that will operate to 14,000 RPM. Jacobs also makes Capacitive Discharge ignition systems such as the Pro Street. However, the spacings in the Bosch and the small cap Mallory distributor are so small that you can't take advantage of the 65,000 volt capability that the Pro Street has. Any Jacobs ignition system will have great results with inexpensive copper core spark plugs. |
Are you a Jacobs dealer, or something?  You mention them more than Bush mentions Iraq in a speech.
First off, you were giving advice about making a 1600 better- show me a 1600 that is capable of turning 14,000 RPM, and I'll concede that it needs your ignition. As for not being able to use the 65,000 volts it has due to the distributor's design 'flaws'- you don't need it! Good God man, we're not talking about some Pro Stock car here!
| Scott Novak wrote: |
| If you understood ignition systems, you'd realize that the fuel mixture density is what determines the ionization voltage of the spark plug gap. |
 Congrats, first correct thing I've heard you say. Compression ratio also has an effect.
| Scott Novak wrote: |
| Because the fuel mixture density inside a turbocharged combustion chamber is higher, the ionization required to jump the spark plug gap is also higher, and you need and ignition system that can keep up with that, as well as a distributor with a cap large enough to handle the higher voltages required to fire a turbocharged engine, such as a Mallory Comp 9000 distributor. |
OK, well what if I were to tell you that at 10 lbs boost in my 'super speshul' turbo engine, I DON'T NEED any high voltage coil whatsoever? What if I told you I fire my 1915 with a coil from a bone stock Ford Tempo, and it runs pretty darned good? I have pictures of it in the build thread in my sigline, if you care to look. My coil is smaller than a Bosch Blue. Not only that, but I jump 2 plug gaps with a single coil (it's waste spark, which amounts to around .060" of total 'gappage'), not just one like a stock VW does. 
You're going down the wrong path with your thinking again, too. Just because you increased the cylinder pressures, doesn't automatically mean the stock coil becomes inferior. Again, throwing parts at the problem instead of understanding what's really going on.
You're not totally wrong, though. I'm sure there are engines that need a ridiculously high voltage to jump the plug gap, but I'm also sure you aren't going to find 90% of them driving down your street. Ignition systems are the #1 overengineered and over built system in engines these days, and I know I put the money I saved by NOT buying an MSD box to better use on my engine.
I bought more gas. 
_________________
Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747
| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
Welcome to the Samba. |
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Scott Novak
Samba Member
Joined: October 12, 2004
Posts: 1586
Location: Minneapolis, Minnesota
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| Posted: Mon Jun 23, 2008 12:17 pm Post subject: |
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| miniman82 wrote: |
| Scott, you sure do come in here and type a lot of words about a lot of things you hardly understand. |
I'm an electronic technician by training. I've worked for two transformer companies testing both hardcore and ferroresonant transformers. I've spent 6 years as a product and development engineering technician developing switching power supplies and DC/DC convertors. I have tested many transformer and inductor designs with gapped cores and non-gapped cores, high frequency and low frequency transformers. I do type a lot of words about things that I actually understand.
| miniman82 wrote: |
| If engine 'A' ran just fine with a .025" plug gap, why in the hell would you make it wider? |
Who says that it is running fine with 0.025" spark plug gaps? Just because it is running, doesn't mean it is running as well as it could and should be running.
| miniman82 wrote: |
| You're sorely mistaken, and there will be no fuel savings to be had to pay for it either, because the efficiency you would have picked up by igniting the fuel/air mixture 'better' would now get used to power that CDI box! They are large consumers of power, and if you don't believe me, look on a Jacobs/MSD/Mallory box. 15 amps or more isn't unheard of-those fat multiple sparks have a price. |
If you actually understood the Jacobs ignition system, you'd realize that it only multi-sparks when it detects that fuel ignition has not taken place. The Jacobs ignitions reduce spark output energy when it is not needed.
A Jacobs ignition system is fused at 15 Amps. The current draw on a Pro Street at 10,000 RPM 8-cylinder or 20,000 RPM 4-cylinder is 10 amps. With a 4-cylinder at 10,000 RPM, the average current draw would be closer to 5 amps. I think you are talking about less than 75 watts to run a Jacobs ignition system on a typical engine. Much less than your headlights.
I'm not that familiar with MSD ignition systems. But I have not been impressed with the MSD schematics that I have seen.
I've known too many people that have had gas mileage improvements, after switching to a Jacobs ignition system. A Jacobs ignition system DOES improve gas mileage.
With the stock Bosch ignition system, you can only optimize it for one engine operating condition. At every other condition is is less than optimum. A Jacobs ignition system optimizes your spark at all engine conditions resulting in better overall gas mileage, and more horsepower under all engine conditions, not just at full throttle or part throttle, or when the engine is warmed up.
| Scott Novak wrote: |
| The stock Bosch ignition system is poor by design. <snip> |
| miniman82 wrote: |
| It's what VW decided was good for it's engines, so are you smarter than a German engineer? |
The VW engineers chose what was cheapest, not what was best. I'm sure the German engineers were well aware of their compromises. But it was a bonehead move by both German and American engineers to use non-air gapped core ignition coils. The air gap is free and dramatically improves performance of the ignition coil under load. The ignition coil is under a severe load as soon as the spark plug gap ionizes. Only a small portion of the ignition coil's voltage is even seen across the spark plug gap, once it ionizes, because of the high internal losses of the ignition coil
| miniman82 wrote: |
| That being the case, would it make you happy if I fired my 1915 turbo with a Bosch Blue, just to prove you're wrong? |
If you use a small enough spark plug gap you can certainly fire a turbocharged combustion chamber with a Bosch Blue coil. However, because of the poor characteristics of a Bosch ignition coil under load, your spark plugs can easily foul if your fuel mixture isn't near perfect. You will also need to use a hotter heat range spark plug and risk pre-ignition. And considering I'm one of the few people that has ever used a Comp 9000 distributor on a VW, and I strongly suspect that you have not, how could you possibly know how your engine would perform with very large spark plug gaps with a high energy adaptive spark ignition system?
| miniman82 wrote: |
| as once people get these hairbrained notions that something 'has to be bad because someone told them so' in their heads, it's impossible to tell them otherwise-hence this thread. |
I have actually done load testing with Bosch ignition coils and compared them with Jacobs and Mallory igniton coils. I KNOW how badly a Bosch ignition coil performs.
| miniman82 wrote: |
| Are you a Jacobs dealer, or something? |
I buy and sell used Jacobs ignition systems. I make no attempt to hide that fact. You could claim that I have a conflict of interest. However, I'm also happy to tell people which Jacobs ignition systems to buy, and I warn them that if they shop carefully, they can buy a Jacobs ignition system cheaper from someone else. But many people will still pay my higher prices because I road test the ignitions before selling them, and offer a 10 day warranty, and make sure that they get an ignition system that is right for their application. I'm impressed with the perfomance of Jacobs igniton systems, and I use them in my own vehicles. I've read the many Jacobs patents and understand why Jacobs igniton systems perform as well as they do.
I'm not that much different than Glenn and his cast iron Bosch distributors. He's found a product that he believes in, knows them inside out and out, rebuilds them and sells them. If he didn't believe that he had a superior product, he probably wouldn't sell them.
| miniman82 wrote: |
| First off, you were giving advice about making a 1600 better- show me a 1600 that is capable of turning 14,000 RPM, and I'll concede that it needs your ignition. |
The Bosch igniton system output starts dropping off like a rock at 3,000 RPM. It's not even capable of operating at full output over the range of a stock engine. And since we were talking about obtaining the maximum horsepower from a 1600, it's not inconceivable to run at 9,000 RPM. You'll also note that I have suggested using the Jacobs Ultra Torquer ignition coil, which is only capable of up you 8,800 RPM, but with a longer duration and higher energy spark, numerous times on Shop Talk forums and also on The Samba as well. Even if you don't rev your engine over 4,400 RPM you will benefit from a Jacobs ignition system.
| miniman82 wrote: |
| As for not being able to use the 65,000 volts it has due to the distributor's design 'flaws'- you don't need it! Good God man, we're not talking about some Pro Stock car here! |
I'd suggest that you actually do some research and read about the testing that as been done that proves the benefits of larger spark plug gaps. NASA has some interesting ignition research data on their website
| Scott Novak wrote: |
| If you understood ignition systems, you'd realize that the fuel mixture density is what determines the ionization voltage of the spark plug gap. |
| miniman82 wrote: |
| Congrats, first correct thing I've heard you say. Compression ratio also has an effect. |
Barometric pressure, humidity, cam profile, intake and exhaust port design, valve lift, valve shape, intake manifold design, carburetor size, exhaust systems, spark plug heat range, and even ignition timing will affect the fuel mixture density inside the spark plug gap.
Most people never think about the fact that as you approach TDC, the fuel mixture density increases and the ionization voltage of the spark plug gap also increases. With a weak ignition system, retarding your ignition timing could result in a misfire.
| Scott Novak wrote: |
| Because the fuel mixture density inside a turbocharged combustion chamber is higher, the ionization required to jump the spark plug gap is also higher, and you need and ignition system that can keep up with that, as well as a distributor with a cap large enough to handle the higher voltages required to fire a turbocharged engine, such as a Mallory Comp 9000 distributor. |
| miniman82 wrote: |
| OK, well what if I were to tell you that at 10 lbs boost in my 'super speshul' turbo engine, I DON'T NEED any high voltage coil whatsoever? What if I told you I fire my 1915 with a coil from a bone stock Ford Tempo, and it runs pretty darned good? I have pictures of it in the build thread in my sigline, if you care to look. My coil is smaller than a Bosch Blue. Not only that, but I jump 2 plug gaps with a single coil (it's waste spark, which amounts to around .060" of total 'gappage'), not just one like a stock VW does. |
If you understood the waste spark ignition system that you are using, you'd realize that the 0.030" gap, without any compression, only takes about 960 volts to jump that gap, so the ignition coil hardly notices that it is even there. Second, it's NOT a crappy Bosch coil. It may or may not have an air gapped core. It's only firing 1/2 as much as a single Bosch coil so it doesn't need to be a large to have the same output. However, the polarity of one of the spark plugs is reversed and ionization voltage is different. To optimize your system your spark plug gap on one of the spark plugs should be larger to compensate. It's not an optimum ignition system. Also, the isolated secondary winding is not as efficient as the auto-transformer design, of the typical ignition coil, where the primary and secondary windings are connected together. For the record, most ignition coils are actually transformers.
You only need a voltage high enough to jump the spark plug gap. What is more important is that you have more energy in the spark plug gap. That is where the Bosch ignition coil falls flat on it's face, and an air gapped core ignition coil shines.
Comparing a Ford ignition coil to the Bosch VW ignition coil is like comparing apples to oranges. You will also note that American engines are often specified to use gaps of 0.054" or more. The average Ford ignition coil is far superior to the Bosch ignition coil.
| miniman82 wrote: |
| Just because you increased the cylinder pressures, doesn't automatically mean the stock coil becomes inferior. |
The stock Bosch coil is so weak that it barely operates up to 4,400 RPM. You need to reduce the spark plug gap to 0.025" just to compensate for the fact that the spark voltage is not constant throughout the RPM range. It's already inferior.
| miniman82 wrote: |
| Ignition systems are the #1 overengineered and over built system in engines these days, and I know I put the money I saved by NOT buying an MSD box to better use on my engine. I bought more gas. |
You bought more gas because your gas mileage was not as good as it could have been with a Jacobs ignition system. A Jacobs ignition system will pay for itself very quickly with today's gas prices. Ignition systems are one of the most underengineered systems on the automobile. The move to distributorless wasted spark ignition systems was a result of trying to reduce cost, not improving performance.
| miniman82 wrote: |
| I'm sure there are engines that need a ridiculously high voltage to jump the plug gap, but I'm also sure you aren't going to find 90% of them driving down your street. |
I'd suggest that you look at a Detroit ignition system. They have tried as large as 0.080" spark plug gaps. They also made the move to HEI High energy Ignition systems. Although their attempts were nowhere near as good as a Jacobs ignition system.
Scott Novak |
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Glenn 
Mr. 010
Joined: December 25, 2001
Posts: 76940
Location: Sneaking up behind you
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| Posted: Mon Jun 23, 2008 12:25 pm Post subject: |
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Wow, a lot of reading here. I'll have to print it off and take it with me the next time I hit the "dumper".
Seriously, there's some great info, let's keep this technical and run it as far as it will go.
thanks
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
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BrockGrimes
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Joined: September 18, 2006
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Location: Clovis, NM
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Hotrodvw
Samba Member
Joined: July 06, 2004
Posts: 6327
Location: Orygun
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| Posted: Mon Jun 23, 2008 10:57 pm Post subject: |
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owned
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'67 Sunroof
Eric
78x94 with IDA's....oober fun
Horsepower is an addiction........Addictions cost
lots of money!
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miniman82
Samba Swamp Donkey
Joined: March 22, 2005
Posts: 9515
Location: Southern Maryland
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Hotrodvw
Samba Member
Joined: July 06, 2004
Posts: 6327
Location: Orygun
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| Posted: Mon Jun 23, 2008 11:23 pm Post subject: |
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I think Scott owned ya on that one. I know jack squat about this stuff, so I'll just keep score. 
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'67 Sunroof
Eric
78x94 with IDA's....oober fun
Horsepower is an addiction........Addictions cost
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miniman82
Samba Swamp Donkey
Joined: March 22, 2005
Posts: 9515
Location: Southern Maryland
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| Posted: Mon Jun 23, 2008 11:30 pm Post subject: |
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I'm not done yet, I don't have time to respond-I'm at work.
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Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747
| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
Welcome to the Samba. |
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miniman82
Samba Swamp Donkey
Joined: March 22, 2005
Posts: 9515
Location: Southern Maryland
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| Posted: Tue Jun 24, 2008 3:30 am Post subject: |
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OK, at home now. Got off early, for once.
Superfluous postings from both of us omitted to keep this as 'short' as possible.
| Scott Novak wrote: |
| I'm an electronic technician by training.... |
That makes two of us, then.  Before I was formally trained, electronics had always been a favorite hobby of mine from very early on. I think I was 12 when I first picked up a soldering iron, but don't let ANY 12 y.o. mess with one.  Mostly tube-based audio amplifiers, but they are also quite sensitive to the iron used in them.
| Scott Novak wrote: |
| Who says that it is running fine with 0.025" spark plug gaps? Just because it is running, doesn't mean it is running as well as it could and should be running. The Bosch igniton system output starts dropping off like a rock at 3,000 RPM. |
It was just an example. My 1600 never had any issues running the recommended plug gap and stock points, and I assure you it most definitely runs well past 3,000 RPM. Would have been better with something other than the 009 it has, but I have moved on to better things.
I also have a 1972 Innocenti Mini, with a 1275cc A-series in it. It had electronic ignition when I got it, but I converted to an MSD box. I didn't notice any improvement in how it ran, but it was nice to have the rev limiter option. I didn't pick up any MPG, and since I never had it dyno'd, I can't say that any power increase ever occured either. Hence, a $250 waste of money. That $250 could have helped buy those ratio rockers I wanted, but instead I ended up waiting 2 more months to save up. If only I had learned sooner. 
I run .030" plug gap in the 1915; any more than that, and idle quality/boost onset starts to suffer. That doesn't mean I need a more powerful coil, it just means that with the coil I currently have, .030" gap is the gap it ionizes best. True, I could open the plug gap and get a more powerful coil, but as I said before, what's the point? I know you think there's something to gain in all this, but I just don't see the cost to benefit ratio ($340 for something that may not happen? ).
Here's another point of view for you to consider: I have absolutely no issues using the ignition setup I have, and I also have no intention of ever returning to an erratic distributor and all it's mechanical inaccuracies. Timing scatter is a thing of the past with crank fire; that alone is reason enough for me.
| Scott Novak wrote: |
| If you actually understood the Jacobs ignition system, you'd realize that it only multi-sparks when it detects that fuel ignition has not taken place. The Jacobs ignitions reduce spark output energy when it is not needed. |
I can't find that information anywhere on their site, do you have a reference?
| Scott Novak wrote: |
| A Jacobs ignition system is fused at 15 Amps. The current draw on a Pro Street at 10,000 RPM 8-cylinder or 20,000 RPM 4-cylinder is 10 amps. |
Fine. It's still probably more power than the stock coil draws, and that power is not free.
| Scott Novak wrote: |
| I'm not that familiar with MSD ignition systems. But I have not been impressed with the MSD schematics that I have seen. |
I have heard from a few random people that the electronics inside the 6 series boxes leaves a little to be desired, but I don't know for certain. I'm not willing to tear apart the one I bought to confirm, but if someone gave me one, maybe someday I'll find out.
| Scott Novak wrote: |
| I've known too many people that have had gas mileage improvements, after switching to a Jacobs ignition system. A Jacobs ignition system DOES improve gas mileage. |
Can you post a data sheet with back to back data? Was the ignition system in question properly maintained before the upgrade? We're just telling each other what we know at this point, because I'll tell you right now I don't have quantified data to back what I say. I only know there was no improvement with the MSD on the Mini, and there was an improvement by getting rid of the distributor with the VW.
| Scott Novak wrote: |
| A Jacobs ignition system optimizes your spark under all engine conditions. |
I'm sure it does, but remember-we were talking about a 1600. $340 is a chunk of change for an engine like that, especially if you only stand to gain maybe a HP or two vs a properly set up standard system.
| Scott Novak wrote: |
The VW engineers chose what was cheapest, not what was best. I'm sure the German engineers were well aware of their compromises. |
Maybe, but I'm also sure if they thought it was inadequate, it would not have been used. Make sense? I don't personally know any of the original engineers, do you? All I can do is speculate about what they were thinking at the time.
| Scott Novak wrote: |
| Only a small portion of the ignition coil's voltage is even seen across the spark plug gap once it ionizes, because of the high internal losses of the ignition coil |
Not sure what you're trying to say here?  When power is removed from the coil the magnetic field in it begins to collapse, and the secondary voltage begins to rise. Once that voltage hits the dielectric ionization point (not sure if that's accurate terminology) of the plug, that energy will be discharged all at once throught the direct short to ground that exists in between the plug's electrodes. Trust me, I understand there is a rise and fall time to it, but I'm unaware if it's possible to measure with a scope. If it is, I'm not risking an electrical shock to find out.
I'll leave that to you, if you're so inclined.
| Scott Novak wrote: |
| If you use a small enough spark plug gap you can certainly fire a turbocharged combustion chamber with a Bosch Blue coil. However, because of the poor characteristics of a Bosch ignition coil under load, your spark plugs can easily foul if your fuel mixture isn't near perfect. |
Right, so you're basically confirming what I've been trying to tell you? If it works with the setup I have now, I doubt I stand to gain anything by going to a hotter coil. It doesn't backfire, misfire, or ping. Soon, I'll go to the dyno, so I'll know what I'm working with. If you're still interested, I'll put a distributor and MSD on it, and see what happens, but I already know for a fact the timing scatter caused by the distributor limits the timing curves I can run before bad things start to happen. Scatter happens on the BTDC and ATDC side of the house (which is visible with a timing light), so there is a limit to how much timing I can run before that few degrees of scatter causes ping. This doesn't occur with programmable crank fire (at least not that I can measure with the light), so I can run a more tailored and otimum curve. The result is more power.
| Scott Novak wrote: |
| You will also need to use a hotter heat range spark plug and risk pre-ignition. |
What does heat range have to do with this? Heat range is heat range, you can put the same gap on any range plug?
| Scott Novak wrote: |
| And considering I'm one of the few people that has ever used a Comp 9000 distributor on a VW, and I strongly suspect that you have not, how could you possibly know how your engine would perform with very large spark plug gaps with a high energy adaptive spark ignition system? |
I have not, and most likely will not use a setup like that, because as I've said, I know I don't need it. I'd rather have more accurate timing control.
| Scott Novak wrote: |
| I have actually done load testing with Bosch ignition coils and compared them with Jacobs and Mallory igniton coils. I KNOW how badly a Bosch ignition coil performs. |
I believe you. Truely. But a mildly hopped up 1600 isn't going to need something that extreme.
| Scott Novak wrote: |
| miniman82 wrote: |
| Are you a Jacobs dealer, or something? |
I buy and sell used Jacobs ignition systems. I make no attempt to hide that fact. You could claim that I have a conflict of interest. I'm not that much different than Glenn and his cast iron Bosch distributors. He's found a product that he believes in, knows them inside and out, rebuilds them and sells them. |
I don't know about a conflict of interest, but it does mean you at least have some knowledge of the product you sell, which is good. Oh, I'm so glad you used Glenn as an example! True, he does sell distributors, but we're having a discussion about coils (or their driver for the most part). Since that's the case, guess which coil he uses on his 2180 with IDA's?
Here's a hint: BOSCH BLUE!
Surely someone you'd use as an example know's what he's doing? I personally wouldn't put it past him; I've never seen him give bad advice, and I'd generally trust what he says without question.
BTW Glenn, if you have any objections to us using you as an example, just say the word, and I'll edit.
| Scott Novak wrote: |
| I'm also happy to tell people which Jacobs ignition systems to buy, and I use them in my own vehicles. I've read the many Jacobs patents and understand why Jacobs igniton systems perform as well as they do. |
I guess we'll have to agree to disagree then. I know what works for me, as do you.
| Scott Novak wrote: |
| NASA has some interesting ignition research data on their website. |
Now we're using NASA data to make a 1600 go fast??? Rocket Science? OK, OK....I'm sure they do ahve some good data, but the average hot 1600 won't make use of it.
| Scott Novak wrote: |
| Because the fuel mixture density inside a turbocharged combustion chamber is higher, the ionization required to jump the spark plug gap is also higher, and you need and ignition system that can keep up with that, as well as a distributor with a cap large enough to handle the higher voltages required to fire a turbocharged engine, such as a Mallory Comp 9000 distributor. |
Well, I don't need it; you've obviously seen someone who has? I have no dizzy cap, so moot point for me. A Mallory 9000 is probably extreme overkill for a lot of engines.
| Scott Novak wrote: |
| If you understood the waste spark ignition system that you are using, you'd realize that the 0.030" gap, without any compression, only takes about 960 volts to jump that gap, so the ignition coil hardly notices that it is even there. |
I clearly stated that I have 2 .030" gaps to jump, perhaps I was misquoted?
| Scott Novak wrote: |
| you are NOT using a crappy Bosch coil. It may or may not have an air gapped core. It's only firing 1/2 as much as a single Bosch coil so it doesn't need to be a large to have the same output. |
That much is true. I'm pretty sure my coil is of the encapsulated stamped layered steel gapless design; much like most AC household transorfers are, but I can't find anything to substantiate that. Maybe saw one apart?
| Scott Novak wrote: |
| You only need a voltage high enough to jump the spark plug gap. What is more important is that you have more energy in the spark plug gap. |
I know what you're trying to say; that the current in the spark causing it to be 'fatter' is what's leading to the improvements aftermarket people claim, and that the voltage is merely what ionizes the gap for the current to flow. Fair enough. But a spark is a spark, is a spark. If a single solitary spark jumps in the plug at the right time, it's going to fire the mixture (assuming that mixture is correct). As you so aptly stated, the mixture can cause fowling; well, fix the mixture problem, not the ignition for chrissakes!
| Scott Novak wrote: |
| Comparing a Ford ignition coil to the Bosch VW ignition coil is like comparing apples to oranges. |
So are Jacobs to Bosch comparisons, yet you persist to draw the conclusion that Bosch coils are somehow inferior?
| Scott Novak wrote: |
| The stock Bosch coil is so weak that it barely operates up to 4,400 RPM. You need to reduce the spark plug gap to 0.025" just to compensate for the fact that the spark voltage is not constant throughout the RPM range. |
I can personally assure you that this is most certainly not the case, and so can Glenn, and countless others. Where are you getting your data from, one person with a bad experience?
| Scott Novak wrote: |
| You bought more gas because your gas mileage was not as good as it could have been with a Jacobs ignition system. |
Whatever, man. I also have closed loop EFI and a dedicated wideband oxygen sensor, so the accuracy of the fuel system more than makes up for that miniscule ignition 'loss'.
| Scott Novak wrote: |
| I'd suggest that you look at a Detroit ignition system. They have tried as large as 0.080" spark plug gaps. |
WTF does that have to do with anything???? WE WERE TALKING ABOUT A 1600!!!! *^&(*#^)(*&$!!!!!!!
Can you still convince me to put an HEI, or even an MSD on a 1600? Probably not. I've still yet to hear a good arguement in favor of it. But I'm sure you will convince others to do it, because that's how sheep are. I think people just want to spend money on things they don't know they don't need. It's like you don't have bragging rights if you don't have certain parts or something.
BTW, I just found out tonight my VW with it's crappy ignition is only slightly faster than a Cadillac CTS with a V6! Guess I'd better move up to an MSD, and start beating those Lambo's.
_________________
Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747
| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
Welcome to the Samba. |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 76940
Location: Sneaking up behind you
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| Posted: Tue Jun 24, 2008 5:32 am Post subject: |
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| Hotrodvw wrote: |
| I think Scott owned ya on that one. I know jack squat about this stuff, so I'll just keep score. |
It's not a competition... I love to LEARN more.
And please... no wagering.
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
Member #1009
#BlueSquare |
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Jimmy111
Samba Member
Joined: October 05, 2006
Posts: 2643
Location: Wyoming
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| Posted: Tue Jun 24, 2008 6:11 am Post subject: |
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| The higher the compression and temperature, the more likely that the spark wont spark and it will just short circuit across the plug gap. That is the reason for wider plug gaps. The increase in energy is necessary to cross this larger gap and convert the energy to plasma. I dont really think that 65,000 volts is necessary or even practical in a ACVW. Mainly I think that it is just a marketing gimick for bragging rights. But on a turboed motor of any size I think that more than 30,000 volts is desireable and a other than points system helps quite a bit for the high RPM motors. |
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pupjoint
Samba Member
Joined: May 23, 2007
Posts: 1140
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| Posted: Tue Jun 24, 2008 6:23 am Post subject: |
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guys, sorry to butt in, but i would like to ask how about replacing these distributors, ignition boxes, blue coils with crank trigger unit with waste spark ignition, just like in modern cars today?
How would that compare with distributors? |
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Alexander_Monday
Samba Member
Joined: November 09, 2007
Posts: 306
Location: Springfield Missouri
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| Posted: Tue Jun 24, 2008 8:07 am Post subject: |
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| pupjoint wrote: |
guys, sorry to butt in, but i would like to ask how about replacing these distributors, ignition boxes, blue coils with crank trigger unit with waste spark ignition, just like in modern cars today?
How would that compare with distributors? |
My question also, as I am contemplating EDIS with MegaSquirt II.
Also, either of you know if the Accel EDIS coil is better than the stock?
_________________
Danth’s or Parker’s Law:
“If you have to insist that you've won an internet argument, you've probably lost badly.”
| andk5591 wrote: |
The original german engineers have attained sainthood and it is impossible to improve perfection.
Anything that anyone does to deviate from the original designs will be made to wrench on 20 year old Yugos with Harbor Freight tools in hell. |
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73stroker
Samba Member
Joined: June 24, 2004
Posts: 285
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| Posted: Tue Jun 24, 2008 10:16 am Post subject: |
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I bought a Jacobs box from Scott a little while back. Prior to that I was running a bosch blue and a 009 w\petronix. I can honestly say that when I went from the bosch to the Jacobs, it was night and day. I opened up my gap to .040 I believe. My car was more responsive and it certainly felt a heck of a lot stronger past 4k. Can't tell about the gas milage because of the foot attached to my right leg. But what I can tell you is that there was a massive improvement over the Bosch. Nothing else was changed other than switching from the Bosch coil to the Jacobs. I was looking for an MSD at the time but stumbled across Scotts ad. I did a little research on Dr Jacobs and spoke a guy that had run one in his Jeep. He said it was the best move he made, so I decided to buy the Jacobs and have been very happy with it. I have since upgraded the engine and the distributor, but have still kept the Jacobs. It runs great!
At the time I was running
1904
40x32 ported heads
44 IDF's
CR 9.0
w125
Just my .02
Love the topic guys, great stuff. |
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miniman82
Samba Swamp Donkey
Joined: March 22, 2005
Posts: 9515
Location: Southern Maryland
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| Posted: Tue Jun 24, 2008 4:28 pm Post subject: |
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| pupjoint wrote: |
guys, sorry to butt in, but i would like to ask how about replacing these distributors, ignition boxes, blue coils with crank trigger unit with waste spark ignition, just like in modern cars today?
How would that compare with distributors? |
If you look at my last post, I explained that the accuracy of EDIS crank fired ignition (what I have) outweighs the 'benefits' of a stronger coil.
| miniman82 wrote: |
| I already know for a fact the timing scatter caused by the distributor limits the timing curves I can run before bad things start to happen. Scatter happens on the BTDC and ATDC side of the house (which is visible with a timing light), so there is a limit to how much timing I can run before that few degrees of scatter causes ping. This doesn't occur with programmable crank fire (at least not that I can measure with the light), so I can run a more tailored and otimum curve. The result is more power. |
Distributors have a mechanical connection to the engine. In the case of a VW T1, this is through the distributor itself (which had has drive 'tang' mounted to it, and also the spring plate), to the drive gear, and from the drive gear via the brass gear to the crank itself. All these parts have tolerances, and do not form a perfect fit with each other. Since gearing has measurable amounts of backlash, this backlash is translated directly into measurable timing scatter. Say your engine needed 30* of timing, so that's where you set it. Now introduce 2* of scatter on the BTDC side. There is the possibility that you will run into detonation, because at times the timing will be 32*, and not 30.
With crank fire, this is impossible for obvious reasons. The other thing it has going for it, is being fully programmable. That means I can tell it to run whatever I feel like anywhere within the engine's operating envelope, instead of being confined to the mechanical restrictions of springs and weights like with the distributor. All these things are my arguement against using a distributor, because to me there are far more benfits over a distributor.
I don't know anything about the Accel EDIS coil, though I have seen it advertised. I don't see a need for it. Besides, the EDIS module is designed with the factory coil in mind, and I wouldn't want to affect the utter reliability of the standard setup by using aftermarket parts.
_________________
Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747
| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
Welcome to the Samba. |
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Scott Novak
Samba Member
Joined: October 12, 2004
Posts: 1586
Location: Minneapolis, Minnesota
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| Posted: Wed Jun 25, 2008 5:57 pm Post subject: |
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| Scott Novak wrote: |
| Only a small portion of the ignition coil's voltage is even seen across the spark plug gap once it ionizes, because of the high internal losses of the ignition coil |
| miniman82 wrote: |
| Not sure what you're trying to say here? When power is removed from the coil the magnetic field in it begins to collapse, and the secondary voltage begins to rise. Once that voltage hits the dielectric ionization point (not sure if that's accurate terminology) of the plug, that energy will be discharged all at once throught the direct short to ground that exists in between the plug's electrodes. Trust me, I understand there is a rise and fall time to it, but I'm unaware if it's possible to measure with a scope. |
Back to basics. As the spark plug gap ionizes, the voltage across the spark plug gap drops to only a couple of thousand volts. The rest of the voltage that the ignition coil generated is dropped across the internal losses of the ignition coil and the resistance of the rotor and ignition wire. When the fuel mixture begins to ignite and a plasma begins to form, the voltage across the spark plug gap drops even further. An air gapped core ignition coil, with a lower output impedance, will deliver more current into the spark and continue to aid the ignition of the fuel mixture until the plasma is large enough that the spark current no longer has any significant effect on the combustion. At that point the internal design of the combustion chamber has the predominant effect on flame travel. Whereas the Bosch ignition coil's output energy into the spark drops even further when the plasma begins to form and can increase the ignition lag time.
Also, the spark plug gap is a near constant voltage source dependant upon pressure and the width of the gap. When you open the spark plug gap, the voltage across the gap also increases. There is less voltage dropped across the ignition coil and ignition wires and more energy is transferred into the spark.
| Scott Novak wrote: |
| Who says that it is running fine with 0.025" spark plug gaps? Just because it is running, doesn't mean it is running as well as it could and should be running. The Bosch ignition system output starts dropping off like a rock at 3,000 RPM. |
| miniman82 wrote: |
| It was just an example. My 1600 never had any issues running the recommended plug gap and stock points, and I assure you it most definitely runs well past 3,000 RPM. Would have been better with something other than the 009 it has, but I have moved on to better things. |
I didn't say that your engine couldn't run above 3,000 RPM.
I should be more accurate and state that with a Bosch ignition coil, with breaker points, because the dwell time of the ignition coil reduces as the RPM increases, and once the dwell time is less than the time it takes to saturate the core of ignition coil, the output voltage drops like a rock as the RPM increases. This is a big problem with non-adaptive spark Kettering ignition systems. At very low RPM, A Bosch ignition coil can fire a large spark plug gap. However, as the RPM increases, the output voltage drops. At some RPM the voltage drops low enough that it won't fire the spark plug gap. You can make the spark plug gap small enough to fire at 5,000 RPM. But you have compromised your engine performance with such a small gap, just because your ignition coil's output drops as the RPM increases.
If you used an air gapped core ignition coil (such as a Jacobs) with an adaptive spark ignition system (such as a Jacobs) the output voltage remains nearly constant until it reaches it's RPM limit. You can use the same large spark plug gap at 500 RPM as you can at 17,000 RPM and it will still fire the spark plug gap. There is no need to compromise the ignition system with a small spark plug gap.
What I am implying is that you are unaware of the problems that a weak ignition system, using small spark plug gaps, causes. Which is mainly less than optimum ignition timing and misfires that you may not even realize are happening.
I do make a distinction between spark timing and ignition timing. Our timing lights only tell us when the spark occurs. We need to advance the spark timing enough so that the ignition takes place at the proper time.
In particular, smaller spark plug gaps with lower current sparks will result in greater ignition lag times, between the time that the spark is applied and when the fuel mixture has ignited to the point that the ignition current no longer has any effect over the combustion process. This ignition lag time is variable with different engine conditions. While you can set your spark timing to compensate for the ignition lag time at one particular engine condition, when the engine condition changes and the ignition lag time changes along with it, your ignition timing will not be optimum.
There is NO way to compensate for changes in ignition lag time with varying engine conditions. As you need to set your spark timing for the engine condition with the least amount of ignition lag time and highest combustion speed to prevent detonation, at all other engine conditions your ignition timing is retarded from optimum. This results in a loss of horsepower, gas mileage, and your engine may run hotter.
While a vacuum advance can compensate for the slower burn travel of a light load part throttle condition, it cannot compensate for ignition lag time variables.
While you can't compensate for changes in ignition lag time, you can reduce the ignition lag time itself, thereby reducing the effect of any lag times changes. A higher energy spark, along with a larger spark plug gap, substantially reduces the lag time between when the spark is applied and when the fuel mixtures has ignited to the point that the ignition system no longer has any effect on the combustion. This means that your ignition timing is closer to optimum under all engine conditions.
| Scott Novak wrote: |
| If you actually understood the Jacobs ignition system, you'd realize that it only multi-sparks when it detects that fuel ignition has not taken place. The Jacobs ignitions reduce spark output energy when it is not needed. |
| miniman82 wrote: |
| I can't find that information anywhere on their site, do you have a reference? |
Jacobs Electronics has been sold twice. You'd need to look at older Jacobs literature as well as the book Jacobs wrote about ignition systems and read the patents that Jacobs has received. You can search for the patents online.
Jacobs ignition systems have a circuit that detects accelerating conditions and increases the energy output, and then reduces the output when the acceleration is over to increase spark plug life.
Jacobs ignition systems also increase the output energy by up to 380% while starting. Living in Minnesota with temperatures dropping as low as -30°F, this is a pretty important feature. Battery output is severely reduced in such cold weather. I can personally attest that Jacobs ignition systems start your engine MUCH faster in subzero weather than the stock Bosch ignition coil and breakerpoints.
| Scott Novak wrote: |
| You only need a voltage high enough to jump the spark plug gap. What is more important is that you have more energy in the spark plug gap. |
| miniman82 wrote: |
| I know what you're trying to say; that the current in the spark causing it to be 'fatter' is what's leading to the improvements aftermarket people claim, and that the voltage is merely what ionizes the gap for the current to flow. Fair enough. But a spark is a spark, is a spark. If a single solitary spark jumps in the plug at the right time, it's going to fire the mixture (assuming that mixture is correct). As you so aptly stated, the mixture can cause fowling; well, fix the mixture problem, not the ignition for chrissakes! |
The spark quality will affect how long it takes to ignite the fuel mixture and this will affect the ignition lag time, or even if the spark ignites the fuel mixture at all. Just having a spark is not a guaranty that the fuel mixture will ignite.
There are any number of things that can cause fuel mixture problems. Quite frankly, I'd prefer an ignition system that will ignite the fuel mixture under adverse conditions and get me home where I can fix the problem in my garage.
A perfect example is a leaky float valve. I had one that would allow the fuel to flood the engine while the fuel system was heat soaking after I parked my car. 10 minutes later, the engine would not start with the Bosch ignition system. The economy version Jacobs Omni-Pak would start the engine right up, flooding and all. I tested this many times switching back and forth between the Jacobs ignition and the Bosch ignition coil. The result was always the same. The Bosch ignition wouldn't start the engine and the Jacobs would start the engine every time!
A Jacobs ignition system will get you home when a Bosch ignition coil will leave you stranded. A Jacobs ignition system is CHEAP insurance.
Likewise, the Jacobs ignition system will keep your spark plugs from fouling while you are jetting a new carburetor.
A Jacobs ignition system will eliminate the interactive effects of a weak ignition system from the equation, so you can concentrate on getting everything else correct.
| Scott Novak wrote: |
| A Jacobs ignition system optimizes your spark under all engine conditions. |
| miniman82 wrote: |
| I'm sure it does, but remember-we were talking about a 1600. $340 is a chunk of change for an engine like that, especially if you only stand to gain maybe a HP or two vs a properly set up standard system. |
The whole point of the discussion was ideas to extract as much power from a 1600 as possible. Careful shopping can get you a brand new Jacobs ignition system and ignition coil for $100. I've purchased used Jacobs ignition systems with ignition coil for as little as $31, and other for $36, and another last week for $40. I've seen Jacobs Omni-Paks sell new for as little as $26. I know of one guy that bought a Jacobs Omni-Pak for $8 at a swap meet. I buy and resell used Jacobs ignition systems that I test and warranty for $100 including the ignition coil. The improvement in gas mileage alone pays for itself.
You also need to consider that as you modify the engine, the ignition requirements become more extreme. Anything that you do that increases the fuel mixture density, such as increasing the compression ratio, improving the volumetric efficiency, or retarding the ignition timing, also raises the ionization voltage of the spark plug gap. Either your ignition system must produce this higher voltage, or you must compromise the performance by reducing the size of the spark plug gap.
As the output voltage of the stock ignition system drops as the RPM increases, if you try to operate at higher RPM than the stock ignition was designed for, you must reduce the size of the spark plug gap in order to fire the spark plug.
| Scott Novak wrote: |
| The VW engineers chose what was cheapest, not what was best. I'm sure the German engineers were well aware of their compromises. |
| miniman82 wrote: |
| Maybe, but I'm also sure if they thought it was inadequate, it would not have been used. |
Bullshit. Companies make compromises all the time. Sometimes they even compromise your safety for their profits! VW was selling an economy car, not a high performance car. The stock ignition system will get you by, but it's NOT a high performance ignition system.
| Scott Novak wrote: |
| A Jacobs ignition system is fused at 15 Amps. The current draw on a Pro Street at 10,000 RPM 8-cylinder or 20,000 RPM 4-cylinder is 10 amps. |
| miniman82 wrote: |
| Fine. It's still probably more power than the stock coil draws, and that power is not free. |
The power to run the ignition system isn't free, but the efficiency improvement of the engine far outweighs the losses.
| Scott Novak wrote: |
| I've known too many people that have had gas mileage improvements, after switching to a Jacobs ignition system. A Jacobs ignition system DOES improve gas mileage. |
| miniman82 wrote: |
| Can you post a data sheet with back to back data? Was the ignition system in question properly maintained before the upgrade? We're just telling each other what we know at this point, because I'll tell you right now I don't have quantified data to back what I say. I only know there was no improvement with the MSD on the Mini, and there was an improvement by getting rid of the distributor with the VW. |
In many cases the Jacobs ignitions were used with well tuned engines and the owners noticed immediate improvements in acceleration, driveability and later gas mileage improvements. Sorry, but I don't have their data.
But when changing to a Jacobs ignition system, on a poorly tuned engine, results in a substantial improvement in performance, it only underscores how much better the Jacobs ignition system will perform under adverse conditions, and give you better overall performance between tuneups.
Installing a Jacobs ignition system on an engine with severely worn spark plugs will perform better than the stock Bosch ignition system performed with new spark plugs. The wider gap of the worn spark plug will improve performance if you can fire it, as the Jacobs ignition system can. The Bosch ignition system will begin to miss when the spark plug electrodes become rounded and the gap increases.
Note that I said worn spark plugs, not damaged. I don't advocate using worn spark plugs. As cheap as copper core spark plugs are, I recommend changing them instead of regapping them when they are worn.
In my case I have switched back and forth between the Bosch ignition system and the Jacobs ignition system with an immediate loss of performance whenever I switched back to the Bosch ignition system.
After I finish installing the dual Weber 40 IDFs and optimize the fuel mixture and spark timing curve of the distributor, I plan to switch back to the Bosch ignition system and see what kind of performance and gas mileage differences there are. I have an Innovate LMA-3 Multi-Sensor input device with an accelerometer built in, so I can log my acceleration and have some legitimate data. That will happen later this summer.
Your Mini's ignition system is probably a lot better than the stock Bosch ignition system, so improvement gains would likely be less. And if you didn't also increase the spark plug gaps, you may not have realized the MSDs full potential.
| Scott Novak wrote: |
| If you use a small enough spark plug gap you can certainly fire a turbocharged combustion chamber with a Bosch Blue coil. However, because of the poor characteristics of a Bosch ignition coil under load, your spark plugs can easily foul if your fuel mixture isn't near perfect. You will also need to use a hotter heat range spark plug and risk pre-ignition. |
| miniman82 wrote: |
| What does heat range have to do with this? Heat range is heat range, you can put the same gap on any range plug? |
I never made a direct connection between spark plug gap and heat range. Read more carefully next time. A Jacobs ignition system, with an air gapped core ignition coil, can operate with a colder heat range spark plug and still keep it clean. If you replaced that with a weak Bosch ignition system, you would need to use a hotter heat range spark plug to keep the spark plug from fouling, and the hotter heat range spark plug makes you more susceptible to pre-ignition.
| Scott Novak wrote: |
| I have actually done load testing with Bosch ignition coils and compared them with Jacobs and Mallory igniton coils. I KNOW how badly a Bosch ignition coil performs. |
| miniman82 wrote: |
| I believe you. Truely. But a mildly hopped up 1600 isn't going to need something that extreme. |
What is extreme about using an ignition coil with an air gapped core? It was sheer stupidity or ignorance on the part of automotive engineers to have ever used non-air gapped ignition coils. It's beyond my comprehension why anyone would want to use an inferior non-air gapped ignition coil even on a bone stock engine. The exception being someone trying to be period correct with a vintage automobile.
I have cross sectioned a Jacobs ignition coil and actually measured a 0.030" gap in the center leg of the core.
"Air Gapped Core Ignition Coils. A No Brainer!" http://www.shoptalkforums.com/viewtopic.php?t=119175
It is also foolish to try to use a Bosch ignition coil, with a built in ballast resistor, with a Capacitive Discharge ignition system. The additional ballast resistance in the primary circuit will cause additional losses because you are driving the primary winding with one high current pulse. The resistive losses are quite substantial, and there is additional heating of the ignition coil.
| Scott Novak wrote: |
| The stock Bosch coil is so weak that it barely operates up to 4,400 RPM. You need to reduce the spark plug gap to 0.025" just to compensate for the fact that the spark voltage is not constant throughout the RPM range. |
| miniman82 wrote: |
| I can personally assure you that this is most certainly not the case, and so can Glenn, and countless others. Where are you getting your data from, one person with a bad experience? |
As I have already said, you can make the Bosch ignition system operate at higher RPM if you compromise the engine performance by sufficiently reducing the spark plug gap.
A Jacobs adaptive spark high energy ignition system with an air gapped core ignition coil may not be the only ignition system out there that works really well. I'm just familiar with Jacobs and I know they work well and that they can be purchased for reasonable prices. I have taken Jacobs ignitions apart and I know that they are well constructed and potted for extreme vibration resistance.
A stock Bosch ignition coil is probably only capable of handling about 8 Gs of vibrational force. A Jacobs ignition system and ignition coil can handle over 70 Gs of vibrational force. If I was racing with solid transaxle mounts or driving off road, a Jacobs ignition system would be good insurance.
| Scott Novak wrote: |
| NASA has some interesting ignition research data on their website. |
| miniman82 wrote: |
| Now we're using NASA data to make a 1600 go fast??? Rocket Science? OK, OK....I'm sure they do ahve some good data, but the average hot 1600 won't make use of it. |
You'd be well advised to read the wealth of information in the NASA archives. It is quite applicable to bone stock ignition systems.
| miniman82 wrote: |
| Oh, I'm so glad you used Glenn as an example! True, he does sell distributors, but we're having a discussion about coils (or their driver for the most part). Since that's the case, guess which coil he uses on his 2180 with IDA's? |
I'm well aware of Glenn's use of the Bosch blue coil. Hopefully he'll see the light someday and use an ignition coil with an air gapped core. Actually, I'm tempted to send Glenn a Jacobs 60:1 turns ratio Ultra coil to try on his engine.
Scott Novak |
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Scott Novak
Samba Member
Joined: October 12, 2004
Posts: 1586
Location: Minneapolis, Minnesota
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| Posted: Wed Jun 25, 2008 5:58 pm Post subject: |
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The following has little to do with the original discussion of maximizing the performance of a 1600 cc engine.
| miniman82 wrote: |
| I also have a 1972 Innocenti Mini, with a 1275cc A-series in it. It had electronic ignition when I got it, but I converted to an MSD box. I didn't notice any improvement in how it ran, but it was nice to have the rev limiter option. I didn't pick up any MPG, and since I never had it dyno'd, I can't say that any power increase ever occured either. |
It's very likely that you never increased your spark plug gaps sufficiently to take advantage of what I presume would be the MSDs higher energy output. "Electronic ignition" doesn't tell us very much unless we know whether or not it was an adaptive spark ignition system. You also didn't tell us if you were using an air gapped core ignition coil. There is insufficient information to draw ANY conclusions from this.
| miniman82 wrote: |
| Hence, a $250 waste of money. |
You may have wasted your money because you failed to open your spark plug gaps wide enough.
| miniman82 wrote: |
| I run .030" plug gap in the 1915; any more than that, and idle quality/boost onset starts to suffer. That doesn't mean I need a more powerful coil, it just means that with the coil I currently have, .030" gap is the gap it ionizes best. True, I could open the plug gap and get a more powerful coil, but as I said before, what's the point? |
The reason using larger spark plug gaps improves your performance has previously been explained. There is plenty of research available that show the improvements of larger spark plug gaps, if you want to do some researching online. Detroit has been convinced that larger spark plug gaps are better, and has used spark plug gaps as large as 0.080".
| Scott Novak wrote: |
| I'd suggest that you look at a Detroit ignition system. They have tried as large as 0.080" spark plug gaps. |
| miniman82 wrote: |
| WTF does that have to do with anything???? WE WERE TALKING ABOUT A 1600!!!! *^&(*#^)(*&$!!!!!!! |
Ignition principles don't change just because you water cool an engine. In some respects an air cooled VW engine is more extreme as the temperatures vary more than a water cooled engine. And we were also talking about maximizing the horsepower of a 1600 cc engine, which will likely mean an increase in the compression ratio as well as increasing the volumetric efficiency which will increase the fuel mixture density and increase the voltage requirements of the spark plug gap.
| miniman82 wrote: |
| Can you still convince me to put an HEI, or even an MSD on a 1600? Probably not. I've still yet to hear a good arguement in favor of it. |
Whether it's a high performance 1600 cc or a 2600 cc engine, if the compression ratio and the volumetric efficiency are the same, they will both have more stringent ignition requirements than a stock 1600.
If you mean an HEI ignition system like the ones that Chevy uses, I wouldn't use one of those either. And I think that Jacobs makes a better ignition than many or most of the MSD ignition systems. But in all fairness to MSD, I'm not so familiar with the newer MSD ignition systems and what kind of performance improvements that they have made.
| miniman82 wrote: |
| Here's another point of view for you to consider: I have absolutely no issues using the ignition setup I have, |
Your wasted spark ignition system is very likely to have a higher energy output than the Bosch ignition system. But as your ignition system is not capable of firing larger spark plug gaps, you have no idea what the performance that you are not realizing would be.
| miniman82 wrote: |
I also have no intention of ever returning to an erratic distributor and all it's mechanical inaccuracies. Timing scatter is a thing of the past with crank fire; that alone is reason enough for me
but I already know for a fact the timing scatter caused by the distributor limits the timing curves I can run before bad things start to happen. |
That sounds more like you may have had a bad distributor with lots of radial side play in the distributor shaft, or excessive axial play in the distributor shaft, or excessive axial play in the distributor drive gear, or perhaps a worn brass gear on the crankshaft, or excessive crankshaft end play.
The original discussion was about improving a 1600 CC engine. You have already made improvements to your ignition system, and this doesn't really relate to the Bosch ignition system in the context of what we were talking about. Although for all of your efforts, you aren't taking full advantage of your system. As you don't have a distributor cap to worry about over-voltaging, you can increase your spark plug gaps much larger, as long as you have an ignition system that is adequate for the task.
Although to be quite honest, the series connected spark plugs of your wasted spark system leaves a lot to be desired. There are additional losses using an ignition coil with isolated secondary windings instead of the traditional autotransformer connection that most ignition coils use. The gaps of two of your spark plugs will fire at a higher voltage than the other pair because of the reversed polarity of the spark current. Even if you use different spark plug gaps to try to better optimize the ignition system, the energy in sparks in one pair of spark plugs will be higher than the energy in the sparks of the other pair of spark plugs. Also, to increase your spark plug life, you should rotate your spark plugs like they do on aircraft engines using wasted spark ignitions systems. Of course, copper core spark plugs are cheap and may not be worth the effort.
| Scott Novak wrote: |
| And considering I'm one of the few people that has ever used a Comp 9000 distributor on a VW, and I strongly suspect that you have not, how could you possibly know how your engine would perform with very large spark plug gaps with a high energy adaptive spark ignition system? |
| miniman82 wrote: |
| I have not, and most likely will not use a setup like that, because as I've said, I know I don't need it. I'd rather have more accurate timing control. |
The point was that you haven't even tried a large spark plug gap with an ignition system that was capable of firing it. Whether you use a distributor with huge internal spacings to be able to use higher spark voltage or if you go distributorless is irrelevant.
As far as the crank trigger and electronic ignition timing control, there are times when it pays to use more complex electronics and other times when it can cause more problems than it cures. A good quality distributor handles the spark timing quite effectively with very little reliability problems.
The biggest advantage of a distributorless ignition system is the elimination of the distributor cap and it's associated voltage limitations. But using a distributorless system with a series spark plug connected wasted spark ignition system is taking two steps forward and one step backward. Jacobs made an 8-cylinder series connected wasted spark ignition system that can probably be adapted to use 4 separate autotransformer configured ignition coils, one per cylinder, that would all use the same negative spark polarity. You would also likely have improvements in your ignition system if you simply replaced your ignition coil paks with Jacobs coil paks.
| Scott Novak wrote: |
| If you use a small enough spark plug gap you can certainly fire a turbocharged combustion chamber with a Bosch Blue coil. |
| miniman82 wrote: |
| Right, so you're basically confirming what I've been trying to tell you? |
Hell no! What I'm saying is that you can compromise the performance of any engine by making the spark plug gaps small enough to fire with a weak ignition system and make the engine run. The engine just won't run at it's maximum potential.
| miniman82 wrote: |
| It doesn't backfire, misfire, or ping. |
I'll buy that you are capable of hearing pinging and backfires and that you don't hear any. But people often don't hear when the engine misses occasionally. I wouldn't bet money that I could hear every miss.
| miniman82 wrote: |
| Soon, I'll go to the dyno, so I'll know what I'm working with. If you're still interested, I'll put a distributor and MSD on it, and see what happens, |
I'm not particularly interested in the results of an MSD ignition system. And until you fix the timing scatter problem that you appear to have with a distributor, the results would be questionable.
| Scott Novak wrote: |
| Because the fuel mixture density inside a turbocharged combustion chamber is higher, the ionization required to jump the spark plug gap is also higher, and you need an ignition system that can keep up with that, as well as a distributor with a cap large enough to handle the higher voltages required to fire a turbocharged engine, such as a Mallory Comp 9000 distributor. |
| miniman82 wrote: |
| Well, I don't need it; you've obviously seen someone who has? I have no dizzy cap, so moot point for me. A Mallory 9000 is probably extreme overkill for a lot of engines. |
A Mallory Comp 9000 isn't at all overkill for even a bone stock engine. It's just very expensive and may not be worth the performance improvement for some people. You can also use a distributorless system to overcome the voltage limitations of a small distributor cap.
And with your turbocharger, you in particular need a high energy ignition system that is capable of firing larger spark plugs gaps. But I can't force you to make full use of your engine's potential. But you have already made a step in the right direction. Because your turbocharged engine has a higher volumetric efficiency than a stock engine, the fuel mixture density is likely to be significantly higher than a stock engine. The voltage across your 0.030" spark plug gaps is higher than the voltage across 0.030" spark plug gaps in a stock engine would be. That is a good indication that your ignition system is better than the stock Bosch Kettering ignition system. It is also very likely that your spark currents are higher than a stock Bosch ignition system.
| Scott Novak wrote: |
| If you understood the waste spark ignition system that you are using, you'd realize that the 0.030" gap, without any compression, only takes about 960 volts to jump that gap, so the ignition coil hardly notices that it is even there. |
| miniman82 wrote: |
I clearly stated that I have 2 .030" gaps to jump, perhaps I was misquoted?
My coil is smaller than a Bosch Blue. Not only that, but I jump 2 plug gaps with a single coil (it's waste spark, which amounts to around .060" of total 'gappage'), not just one like a stock VW does. |
You weren't misquoted. You're implication was that your ignition coil was working hard to drive the equivalent of a 0.060" gap. My point was that one of the spark plug gaps is not under any compression, while the other spark plug is under compression. The spark plug not under compression takes very little voltage to fire and only uses a very small portion of the ignition coil's output. It's not like your ignition system is firing the equivalent of a 0.060" gap under compression. Firing both spark plug gaps at once, in your wasted spark setup, is more equivalent to firing one 0.032" spark plug gap under full compression.
| Scott Novak wrote: |
| You bought more gas because your gas mileage was not as good as it could have been with a Jacobs ignition system. |
| miniman82 wrote: |
| Whatever, man. I also have closed loop EFI and a dedicated wideband oxygen sensor, so the accuracy of the fuel system more than makes up for that miniscule ignition 'loss'. |
It's not an ignition loss that we're talking about. It's less than optimum ignition timing that cannot be compensated for by any closed loop system.
For that matter, closed loop systems have a nasty tendency to hunt and have less than optimum performance while they are trying to settle down. For that reason alone an adaptive spark ignition system could benefit your closed loop EFI system while it is hunting. A carefully set up open loop system will often out perform a closed loop system. But it takes a lot more time and effort to optimize.
You didn't mention if your ignition timing control was closed loop or open loop. Again, an adaptive spark ignition system can help compensate for many variations in engine conditions. In particular, during sudden accelerations the fuel mixture can go suddenly lean. Research has shown that large spark plug gaps are beneficial when trying to ignite lean fuel mixtures. An adaptive spark ignition system with an air gapped ignition coil could be beneficial in this situation.
But your ignition system is probably a big improvement over the Bosch ignition coil and breakerpoints that we were referring to. You wouldn't see as much improvement by switching to a Jacobs ignition system, as you would see if you were switching to a Jacobs ignition system from a Bosch ignition system. But again, you haven't indicated if you have an adaptive spark ignition system or if your ignition coil has an air gapped core.
| Scott Novak wrote: |
| you are NOT using a crappy Bosch coil. It may or may not have an air gapped core. It's only firing 1/2 as much as a single Bosch coil so it doesn't need to be a large to have the same output. |
| miniman82 wrote: |
| That much is true. I'm pretty sure my coil is of the encapsulated stamped layered steel gapless design; much like most AC household transorfers are, but I can't find anything to substantiate that. Maybe saw one apart? |
You can't tell by looking if an ignition coil has an air gapped core, as the gap is inside the coil where you can't see it. You can do a load test on the ignition coil and get a pretty good idea if the ignition coil has an air gap or not. I have cross sectioned a Jacobs ignition coil and actually measured a 0.030" gap in the center leg of the core.
"Air Gapped Core Ignition Coils. A No Brainer!" http://www.shoptalkforums.com/viewtopic.php?t=119175
| miniman82 wrote: |
| I know what works for me, as do you. |
Actually, by your own admission you haven't tried using huge spark plug gaps with an ignition system capable of driving them. So how could you possibly know if you have unrealized performance?
| Scott Novak wrote: |
| Comparing a Ford ignition coil to the Bosch VW ignition coil is like comparing apples to oranges. |
| miniman82 wrote: |
| So are Jacobs to Bosch comparisons, yet you persist to draw the conclusion that Bosch coils are somehow inferior? |
I wasn't clear enough. The comment was in reference to the autotransformer connected Bosch ignition coil being compared to the isolated secondary series connected wasted spark ignition coil setup. The size reference was not particularly relevant because of the completely different application. I wasn't suggesting that it wasn't a viable improvement over a Bosch ignition system.
And yes, the Bosch ignition coil is definitely inferior to the Jacobs ignition coils by any possible measurement that I can think of.
Scott Novak |
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ocdbeetle
Samba Optimist
Joined: March 18, 2008
Posts: 1176
Location: South Carolina
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| Posted: Wed Jun 25, 2008 6:20 pm Post subject: |
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1967 Lotus White Beetle |
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Scott Novak
Samba Member
Joined: October 12, 2004
Posts: 1586
Location: Minneapolis, Minnesota
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| Posted: Wed Jun 25, 2008 6:52 pm Post subject: |
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| pupjoint wrote: |
guys, sorry to butt in, but i would like to ask how about replacing these distributors, ignition boxes, blue coils with crank trigger unit with waste spark ignition, just like in modern cars today?
How would that compare with distributors? |
The series connected waste spark system used in many of todays cars was done to reduce costs. It is NOT, and I repeat, NOT a performance improvement per se.
Going distributorless does have advantages. But you don't need to compromise the ignition system with a series connected waste spark system.
If you want the ultimate in performance, a distributorless ignition system using one adaptive spark ignition system and one air gapped core ignition coil per cylinder would be the ticket.
You can also run this as a waste spark system, but I doubt that it would improve performance significantly. But I could be wrong. Maybe there is a performance advantage to sparking the exhaust gases. It may reduce hydrocarbon exhaust emissions. But the extra energy required may also reduce the gas mileage and increase the emissions per mile.
It does sometimes simply the ignition control by using two crank sensors to trigger four cylinders. There are a number of different ways to accomplish the task of triggering the ignition systems on each cylinder.
Scott Novak |
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