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Fred Winterburn Samba Member
Joined: April 17, 2013 Posts: 423 Location: Ripley Ontario Canada
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Posted: Sat Aug 25, 2018 12:05 pm Post subject: Re: Upgraded ignition Spark Comparison (video included) |
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-I haven't ignored the misfire issue, because it should be common knowledge that kettering or cheap points replacement modules will have a high percentage of misfires because both are low energy and low power ignitions. When points are used to trigger a CDI, there are extremely few misfires because the points are only a trigger and have nothing to do with the spark quality.
-Testing sparks on my test rig is not theory, it is testing with real results that can only be obtained with an ignition off the car, so not quite theory really.
-I build a 6V model too. Those will provide a starting spark down to 3.2 volts.
-Plasma sounds interesting and I'll need to research it more. I'm more interested in what makes it a bad ignition, not so much what makes it a good one. Fred
Alstrup wrote: |
Fred Winterburn wrote: |
-None of my personal testing involves a dyno unfortunately, but I can test for spark quality quite easily which is something the dyno can't do. CDI has not really progressed much since 2009 from what I have seen. Most if not all of the multi-strike CDIs have the second spark event too long after the first and the first is usually short duration and sometimes weaker than it should be. I have never tested an MSD 7 series so I can't comment on them, nor have I tested the new digital MSD 6, or any of the Japanese offerings. All I can say is the old analogue MSD 6 is a poor performer and hardly a benchmark for CDI so I wouldn't be surprised if one of the plasma ignitions performed better. The MSD 6A multi-spark is not a controlled function and is entirely dependent on whether there can be enough current delivered to the two parallel power transistors which means a big fat red wire from the battery along with the switched red wire. The MSD power and output is entirely dependent of battery voltage. I'll bet the plasma ignitions are too.
-Of course no modern car would have points/condenser as it is a weak system, but in good condition it will outperform a cheap points replacement unit for a couple of reasons. The points/condenser system is an inductive system by the way. The role of the condenser does not turn it into an AC spark like some folks think. An inductive spark generated by opening an electronic switch or points produces a single polarity spark.
-Points make an excellent trigger for a CDI if done right and makes up for some shaft wobble and completely erases any effect from points bounce. It's a more reliable method than some of the cheap points replacement modules, although they will trigger a CDI well too, but no better. Fred
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You seem to keep ignoring the misfire percentage with points.
If your box will make 22 kv at 4,5 on the inside it sounds to be a very good solution for people that want to keep their cars 6volt.
apart from that I think its time to see some results from the other side of the pond. Otherwise this is turning into all theory, and theoy alone does´nt cut it.
Garrick, pm me.
T |
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clonebug Samba Member
Joined: January 29, 2005 Posts: 4027 Location: NW Washington
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Posted: Sat Aug 25, 2018 1:32 pm Post subject: Re: Upgraded ignition Spark Comparison (video included) |
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GARRICK.CLARK wrote: |
Sorry for this BUT. I have been reading this with interest and I'm now more confused than I was before. Crank trigger kits, CB Black box, MSD, to name a few, AND now plasma. For us guys trying to purchase a good ignition its now getting hard to choose the right thing.
I can I just ask .
What ignition on a blow through turbo that needs boost retard to survive IS a good purchase.
I need to light up the charge at high boost as the Standard points ignition i'm using is giving up under big boost conditions and is acting like a REV/POWER limiter.
Thanks Guys. |
Just bite the bullet and upgrade to Megasquirt crank fire ignition.....that way when you are ready you can move right into FI since it comes preinstalled.
Go ahead..........you know you want to........
No points......no nothing to worry about.....you don't even have to carry a spare anything with you because it always works. _________________
vwracerdave wrote: |
Take a good long look in the mirror and report back on what you see. |
Paul.H wrote: |
That one line on that chart is probably better info than you can get from this place in a month |
My Megasquirt Fuel Injection Turbo Buggy Build
Water/Alcohol Injection
Audi TT intercooler
Upgraded to MS3Pro-Evo
EcuMaster PMU16
ECUMaster ADU5 Digital Dash
http://www.shoptalkforums.com/viewtopic.php?f=3&t=127936 |
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brads Samba Member
Joined: June 15, 2017 Posts: 11
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Posted: Mon Aug 27, 2018 9:22 am Post subject: Re: Upgraded ignition Spark Comparison (video included) |
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Alstrup wrote: |
First, we have to keep it strtaight to not make misunderstandings. PCD is NOT plasma. It can be related to as a type of CDI. Plasma is a whole other game.
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Do you have any more details on your peaking cap design? I'm curious as to what you have put together. Is it similar to Nology plug wires? Is it something you are developing for sale?
Alstrup wrote: |
Second, I´m not saying that a MSD CDI is better as such I have just used it for comparison because most people can relate to it. Also, I do think that CDI´s have come some way even since 2009.
Way back in the early 20teens we actually tested a 6AL for spark discharge in a 4 cylinder set up, with an average of 13,5 V which is generally where the average vintage car is voltage wise. That showed multistrike to about 3300 rpm. Whether 1 volt more on the supply would do so much of a difference I don´t know. We did not test that. So if I say approx 3000 rpm I´m sortof on the safe side.
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Your numbers are pretty spot on. On most CD ignitions, the multispark rate and max RPM is determined by how long it takes to fully charge the firing capacitor, which is related to the input voltage. 1-1.1mS is about right for a MSD at 13.5V. They state 20 degrees of crank rotation for their multispark window. If you take that ratio(1ms per 20 degrees) to a full rev, you get 18mS for 1 revolution, which is 3300 RPM.
Fred mentioned that he tested it to 4000 on a 8 cyl, which would equal 8000 on a 4. Most boxes would shut the multispark off at the same RPM, whether it is a 4 cylinder or 8. The box calculates that spark window to 20 degrees, based on the user selected # of cylinders. |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7210 Location: Videbaek Denmark
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Posted: Mon Aug 27, 2018 3:14 pm Post subject: Re: Upgraded ignition Spark Comparison (video included) |
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Hello Brad.
First, cool that someone with an elkectrical background can actually ewxplain what I/we see. I lack on that account.
Second, with the pcd. Yes it is along the same line as Nology, only IMHO they make one little mistake which reduces efficiency a good deal. The Nology still works nice, but we can make it better.
Third, my way is directly hijacked from the internet. I have been playing with how much or how little depending on how you look at it. At some point the plugs life takes a dive, but I do not know where that is yet. This has been around for quite a while, I for one, have just been so busy with other stuff that I did not notice it until last year. Since then I have read and tested extensively to try to get a better understanding of it. I have come some way, but I still have a lot to learn. Right now I have almost set on the road on anything from mild to super street and on one older GM car and one Lotus Super Seven. The experiences from the owners is everything from "why did I invest in this" to "WOW!" Regardless it is definitely a step in the right direction emission wise on vintage engines. It also seems that aircooled engines (VW´s) runs a tad cooler, but I´m not really suree about that. Theoreticly it does make sense if the burn is more precise and intense at the right time. There is definitely a fuel efficiency gain just about all claim 3-500m. more per Liter fuel.
Whether I´m going to put something in production. - Well, the thought has crossed my mind, but I do not know at this time. If I do, it has to be better than say Nology. I can do that, but not nessessarily cheaper.
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Fred Winterburn Samba Member
Joined: April 17, 2013 Posts: 423 Location: Ripley Ontario Canada
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Posted: Mon Aug 27, 2018 5:58 pm Post subject: Re: Upgraded ignition Spark Comparison (video included) |
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There seems to be two peaking cap designs. The original was in production at least as early as the 1920s and put a capacitor in series with the HT lead from the coil to the distributor. These were often sold at autumn fairs in North America right into the 1950s. A demonstration on an engine with fouled plugs would show a smooth idle, but would give poor performance as rpm increased as the energy transfer would drop accordingly. The cap in series idea is still being sold today which proves good snake oil has no shelf life. Nology wires appear to have the capacitor in parallel with the spark plug gap which seems a better idea, and more efficient but has similar drawbacks. If one is going to use a peaking capacitor it makes sense to use an inductive system with a big fat spark to feed it with enough energy that it could be useful. Driving it with a CDI would result in a much weaker spark. If one is after duration and power it is much easier to do on the primary side of the coil, not piggybacked onto the secondary and potentially buggering up the primary ignition source in the process. As far as plasma systems go, I cannot find the term defined properly, and in reality all sparks are 'plasma' so the term is used so loosely that it becomes meaningless. Some plasma systems claim to make no spark at all, some claim short duration, some very long. The discussion needs to be done brand by brand, rather than by name for the discussion to be coherent. Some so called plasma companies have disappeared already with one Canadian manufacturer amongst the casualties. That system claimed a very long duration spark. Fred
Alstrup wrote: |
Hello Brad.
First, cool that someone with an elkectrical background can actually ewxplain what I/we see. I lack on that account.
Second, with the pcd. Yes it is along the same line as Nology, only IMHO they make one little mistake which reduces efficiency a good deal. The Nology still works nice, but we can make it better.
Third, my way is directly hijacked from the internet. I have been playing with how much or how little depending on how you look at it. At some point the plugs life takes a dive, but I do not know where that is yet. This has been around for quite a while, I for one, have just been so busy with other stuff that I did not notice it until last year. Since then I have read and tested extensively to try to get a better understanding of it. I have come some way, but I still have a lot to learn. Right now I have almost set on the road on anything from mild to super street and on one older GM car and one Lotus Super Seven. The experiences from the owners is everything from "why did I invest in this" to "WOW!" Regardless it is definitely a step in the right direction emission wise on vintage engines. It also seems that aircooled engines (VW´s) runs a tad cooler, but I´m not really suree about that. Theoreticly it does make sense if the burn is more precise and intense at the right time. There is definitely a fuel efficiency gain just about all claim 3-500m. more per Liter fuel.
Whether I´m going to put something in production. - Well, the thought has crossed my mind, but I do not know at this time. If I do, it has to be better than say Nology. I can do that, but not nessessarily cheaper.
T |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7210 Location: Videbaek Denmark
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Posted: Tue Aug 28, 2018 8:06 am Post subject: Re: Upgraded ignition Spark Comparison (video included) |
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Well, let me turn the question upside down.
- If I´m wrong, and I just might be, how do you explain:
Better power,
better torque,
engine wanting more fuel and at the same time,
better burn (cleaner emissions)
a tad better fuel efficiency and finally,
tendency to engine running cooler?
T |
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Fred Winterburn Samba Member
Joined: April 17, 2013 Posts: 423 Location: Ripley Ontario Canada
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Posted: Tue Aug 28, 2018 10:14 am Post subject: Re: Upgraded ignition Spark Comparison (video included) |
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What brand (manufacturer) plasma ignition are you testing? Fred
Alstrup wrote: |
Well, let me turn the question upside down.
- If I´m wrong, and I just might be, how do you explain:
Better power,
better torque,
engine wanting more fuel and at the same time,
better burn (cleaner emissions)
a tad better fuel efficiency and finally,
tendency to engine running cooler?
T |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7210 Location: Videbaek Denmark
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Posted: Tue Aug 28, 2018 1:24 pm Post subject: Re: Upgraded ignition Spark Comparison (video included) |
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Not plasma on that one. As described Mallory Unilite with pcd upgrade. 3 x 15kv681pf.
T |
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Fred Winterburn Samba Member
Joined: April 17, 2013 Posts: 423 Location: Ripley Ontario Canada
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Posted: Tue Aug 28, 2018 3:59 pm Post subject: Re: Upgraded ignition Spark Comparison (video included) |
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Alstrup, Thank-you. So I ran a peaking capacitor experiment. I daisy chained 4 10kV 2000pF caps in series for a total of about 500pF total and put this in parallel with the spherical electrodes on my test machine. This is more than what you used for the peaking capacitor, but told me enough to figure out how it might be beneficial in some cases. For starters, when viewing electric arcs one should be wearing glasses to limit the UV damage to eyes. The light from the spark gap with the peaking cap was so bright (and louder which is rather telling) that I could only look at it for short periods of time. With points/condenser driving it at 15volts applied, the available voltage was only 15kV so small plug gaps are the order of the day when using a peaking cap unless it is driven by a very high voltage and high energy ignition. Using a smaller peaking cap would maintain more of the available voltage but result in a less intense arc. With the points/condenser at 15V applied the total duration was 40µS with a single negative polarity spark. So basically the peaking cap shortened the total duration from approximately 1.5 milliseconds down to 40µS. Next, I drove it with my CDI test mule that has a switch for 12V and 6V. When selected to 12V and run at 15V, the available voltage to the spark dropped even further which is what I thought would happen. The waveform changed when driven by the CDI in 12V mode but the total spark duration remained short at 40µS. When I switched the CDI to 6V mode and drove it at 15V, the available voltage went up and the CDI was able to produce another spark of opposing polarity after the initial 40µS spark. So, the bottom line is that if the peaking capacitor is being supplied by an inductive ignition, that in some cases and mostly at low rpm (but with a 4 cylinder might go higher) the spark will probably light fuel better but requires a small plug gap to maintain rpm. Chances are that opening up the plug gap without the peaking capacitor would be just as good or nearly depending on the fuel mixture. Driving a peaking capacitor with an MSD ignition that already has a short duration spark of about 40µS would be silly and give a weaker spark with very low available voltage so misfires would be quite likely. Driving the peaking capacitor with a Ford TFI or some other means to provide high voltage and current would make the peaking capacitor idea more favourable. The major problem that I can see on the scope is the extremely long voltage rise time. Only testing would tell for sure, but it is quite likely that the peaking capacitor connected in parallel with the spark gap would be worse at firing through fouled spark plugs. (In series a peaking cap makes the plug fire better through fouling as long as there is enough ignition energy to feed the cap before it discharges) There is only one way to find out, and that is to test it. Perhaps in the next month or so when I have time, Fred
Edit: I forgot to mention that even with the very intense spark with the peaking capacitor, there were no extra stray sparks from molten metal being shed from the soft iron electrodes on the test machine, so the heating of the electrodes is no worse.
quote="Alstrup"]Not plasma on that one. As described Mallory Unilite with pcd upgrade. 3 x 15kv681pf.
T[/quote] |
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74 Thing Samba Member
Joined: September 02, 2004 Posts: 7389
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Posted: Wed Aug 29, 2018 10:16 am Post subject: Re: Upgraded ignition Spark Comparison + Plasma/PCD info |
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What about plugs with a capacitor in them like Pulstar or something like that? |
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jpaull Samba Member
Joined: February 22, 2005 Posts: 3461 Location: Paradise, Ca
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Posted: Wed Aug 29, 2018 10:35 am Post subject: Re: Upgraded ignition Spark Comparison + Plasma/PCD info |
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I added Plasma/PCD into the title, so that anyone searching for plasma can land in this thread. Its just to fun and interesting to learn about.
For anyone that does not have a Dyno at their disposal, please note one thing very "Telling" about ignition upgrades:
When combustion is improved through better ignition, your idle will increase. Why? Cause more gas is burned. When I changed from Bosch blue/resister over to Blaster SS non resister wires/plugs, the idle went up. Same with Peaking Cap and Plasma, this would be another step up in combustion efficiency.
As Alstrup noted in his Dyno comparison, the engine "wanted more fuel". Why did it want more fuel suddenly after the PCD upgrade? Cause it has the power to burn more! Note also that when a engine "Wants more fuel" that more horsepower is now available.
Imagine your jetting your engine, and you jet to a point that no more horsepower can be made out of your combo. Then, you upgrade your ignition, and suddenly your engine can take abit more fuel and makes more power.
This situation described above, is what made David Vizard a believer in Plasma ignition. When he built a 525 BBC to the point where he thought no more horsepower could be made, and dynod it with a Ionfire Plasma and gained 9 more horsepower, he then included it in his teachings. |
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Fred Winterburn Samba Member
Joined: April 17, 2013 Posts: 423 Location: Ripley Ontario Canada
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Posted: Wed Aug 29, 2018 3:14 pm Post subject: Re: Upgraded ignition Spark Comparison + Plasma/PCD info |
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They will be peaking capacitors, either in-series or in parallel with the spark gap.
74 Thing wrote: |
What about plugs with a capacitor in them like Pulstar or something like that? |
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Fred Winterburn Samba Member
Joined: April 17, 2013 Posts: 423 Location: Ripley Ontario Canada
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Posted: Wed Aug 29, 2018 3:41 pm Post subject: Re: Upgraded ignition Spark Comparison (video included) |
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I ran another experiment this evening after getting home from work. I tested the peaking capacitor to see how it would affect the primary ignition system's ability to fire fouled spark plugs. The shunt resistance I used in parallel with the spark gap on the test machine is 126kohm. I ran the test at 14 volts to make it a bit more realistic and 500 rpm to keep the dwell high for the comparison and to allow the points to open cleanly when in Kettering mode. This test was done with a standard brand coil with 3.5 ohms, so not a powerhouse but good for comparison testing and I have found that more efficient coils do not help with fouling any more than inefficient coils which came as a surprise to me when I tested that a few years ago. For this test I used HT leads with about 10 kohms total resistance.
-With the CDI alone (my CDI not MSD or another brand) without the shunt resistor, the maximum spark voltage= 30kV. With the shunt resistor=15kV
-With Kettering (points condenser) the maximum spark voltage= 31kV. With the shunt resistor=1500 volts (10 times less than with the CDI).
-With the peaking capacitor in parallel with the spark gap, the maximum spark voltage dropped to approximately 750 volts with the Kettering system driving it, and with the CDI, the the voltage rose to roughly 1200volts.
One of the major benefits of a higher powered ignition is the ability to fire fouled spark plugs, either because the insulators or the plug electrodes are wet or the plug is fouled by carbon and/or other electrically conductive deposits. With the peaking capacitor in parallel a more intense spark is make with a short duration. The downside is that the available gap voltage is approximately 2/3 (or 1/2 with the value I chose) of what it should be by design. That means a small plug gap to compensate. And the complete lack of ability to fire through wet or fouled plugs is yet another problem but a very important one unless the engine is already warm and the plugs are clean and the mixture perfect, etc.
I think I'll run a quick experiment with the peaking cap in series and see how it behaves. I had always believed that it helped with fouling at low rpm but now I am having doubts. Stay tuned, Fred
Fred Winterburn wrote: |
Alstrup, Thank-you. So I ran a peaking capacitor experiment. I daisy chained 4 10kV 2000pF caps in series for a total of about 500pF total and put this in parallel with the spherical electrodes on my test machine. This is more than what you used for the peaking capacitor, but told me enough to figure out how it might be beneficial in some cases. For starters, when viewing electric arcs one should be wearing glasses to limit the UV damage to eyes. The light from the spark gap with the peaking cap was so bright (and louder which is rather telling) that I could only look at it for short periods of time. With points/condenser driving it at 15volts applied, the available voltage was only 15kV so small plug gaps are the order of the day when using a peaking cap unless it is driven by a very high voltage and high energy ignition. Using a smaller peaking cap would maintain more of the available voltage but result in a less intense arc. With the points/condenser at 15V applied the total duration was 40µS with a single negative polarity spark. So basically the peaking cap shortened the total duration from approximately 1.5 milliseconds down to 40µS. Next, I drove it with my CDI test mule that has a switch for 12V and 6V. When selected to 12V and run at 15V, the available voltage to the spark dropped even further which is what I thought would happen. The waveform changed when driven by the CDI in 12V mode but the total spark duration remained short at 40µS. When I switched the CDI to 6V mode and drove it at 15V, the available voltage went up and the CDI was able to produce another spark of opposing polarity after the initial 40µS spark. So, the bottom line is that if the peaking capacitor is being supplied by an inductive ignition, that in some cases and mostly at low rpm (but with a 4 cylinder might go higher) the spark will probably light fuel better but requires a small plug gap to maintain rpm. Chances are that opening up the plug gap without the peaking capacitor would be just as good or nearly depending on the fuel mixture. Driving a peaking capacitor with an MSD ignition that already has a short duration spark of about 40µS would be silly and give a weaker spark with very low available voltage so misfires would be quite likely. Driving the peaking capacitor with a Ford TFI or some other means to provide high voltage and current would make the peaking capacitor idea more favourable. The major problem that I can see on the scope is the extremely long voltage rise time. Only testing would tell for sure, but it is quite likely that the peaking capacitor connected in parallel with the spark gap would be worse at firing through fouled spark plugs. (In series a peaking cap makes the plug fire better through fouling as long as there is enough ignition energy to feed the cap before it discharges) There is only one way to find out, and that is to test it. Perhaps in the next month or so when I have time, Fred
Edit: I forgot to mention that even with the very intense spark with the peaking capacitor, there were no extra stray sparks from molten metal being shed from the soft iron electrodes on the test machine, so the heating of the electrodes is no worse.
quote="Alstrup"]Not plasma on that one. As described Mallory Unilite with pcd upgrade. 3 x 15kv681pf.
T |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7210 Location: Videbaek Denmark
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Posted: Wed Aug 29, 2018 3:53 pm Post subject: Re: Upgraded ignition Spark Comparison + Plasma/PCD info |
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Fred, you are attacking this the wrong way. In fact you are way off. Spend a night or two with reading first before you go any further.
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Fred Winterburn Samba Member
Joined: April 17, 2013 Posts: 423 Location: Ripley Ontario Canada
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Posted: Wed Aug 29, 2018 4:10 pm Post subject: Re: Upgraded ignition Spark Comparison (video included) |
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This experiment was quick. No mega spark with the capacitor in series. Putting the peaking capacitor in series with the CDI knocked the available spark gap voltage down to 25kV from its usual 30kV so not nearly as bad as with the cap in parallel. The spark was weaker and had only two sparks, the first negative and the second positiive but no subsequent sparks as the energy simply wasn't there to make more. Also the CDI supply current dropped by about 250mA which makes sense as the output impedance increased with the capacitor added. The capacitor in series with the Kettering was more interesting. The available voltage dropped to 20kV but the spark changed into a bi-polarity spark. So instead of a single negative polarity spark that normally continues to drop voltage and current. the spark had a second strike of positive polarity roughly 150µS later. That makes the spark a little more like CDI on the scope except that having the capacitor in series made the ability to overcome fouling even worse. So why then, did the demonstrations at fall fairs where these in line capacitors were demonstrated actually smooth out a rough idle? If it couldn't overcome fouling any better (and actually worse) why did the idle improve with a spark having less energy and less overall duration. The only difference is the second spark of opposing polarity which would be more intense 150µS later than if the spark was allowed to burn naturally for a longer period of time. I cannot answer that question. Fred
Fred Winterburn wrote: |
I ran another experiment this evening after getting home from work. I tested the peaking capacitor to see how it would affect the primary ignition system's ability to fire fouled spark plugs. The shunt resistance I used in parallel with the spark gap on the test machine is 126kohm. I ran the test at 14 volts to make it a bit more realistic and 500 rpm to keep the dwell high for the comparison and to allow the points to open cleanly when in Kettering mode. This test was done with a standard brand coil with 3.5 ohms, so not a powerhouse but good for comparison testing and I have found that more efficient coils do not help with fouling any more than inefficient coils which came as a surprise to me when I tested that a few years ago. For this test I used HT leads with about 10 kohms total resistance.
-With the CDI alone (my CDI not MSD or another brand) without the shunt resistor, the maximum spark voltage= 30kV. With the shunt resistor=15kV
-With Kettering (points condenser) the maximum spark voltage= 31kV. With the shunt resistor=1500 volts (10 times less than with the CDI).
-With the peaking capacitor in parallel with the spark gap, the maximum spark voltage dropped to approximately 750 volts with the Kettering system driving it, and with the CDI, the the voltage rose to roughly 1200volts.
One of the major benefits of a higher powered ignition is the ability to fire fouled spark plugs, either because the insulators or the plug electrodes are wet or the plug is fouled by carbon and/or other electrically conductive deposits. With the peaking capacitor in parallel a more intense spark is make with a short duration. The downside is that the available gap voltage is approximately 2/3 (or 1/2 with the value I chose) of what it should be by design. That means a small plug gap to compensate. And the complete lack of ability to fire through wet or fouled plugs is yet another problem but a very important one unless the engine is already warm and the plugs are clean and the mixture perfect, etc.
I think I'll run a quick experiment with the peaking cap in series and see how it behaves. I had always believed that it helped with fouling at low rpm but now I am having doubts. Stay tuned, Fred
Fred Winterburn wrote: |
Alstrup, Thank-you. So I ran a peaking capacitor experiment. I daisy chained 4 10kV 2000pF caps in series for a total of about 500pF total and put this in parallel with the spherical electrodes on my test machine. This is more than what you used for the peaking capacitor, but told me enough to figure out how it might be beneficial in some cases. For starters, when viewing electric arcs one should be wearing glasses to limit the UV damage to eyes. The light from the spark gap with the peaking cap was so bright (and louder which is rather telling) that I could only look at it for short periods of time. With points/condenser driving it at 15volts applied, the available voltage was only 15kV so small plug gaps are the order of the day when using a peaking cap unless it is driven by a very high voltage and high energy ignition. Using a smaller peaking cap would maintain more of the available voltage but result in a less intense arc. With the points/condenser at 15V applied the total duration was 40µS with a single negative polarity spark. So basically the peaking cap shortened the total duration from approximately 1.5 milliseconds down to 40µS. Next, I drove it with my CDI test mule that has a switch for 12V and 6V. When selected to 12V and run at 15V, the available voltage to the spark dropped even further which is what I thought would happen. The waveform changed when driven by the CDI in 12V mode but the total spark duration remained short at 40µS. When I switched the CDI to 6V mode and drove it at 15V, the available voltage went up and the CDI was able to produce another spark of opposing polarity after the initial 40µS spark. So, the bottom line is that if the peaking capacitor is being supplied by an inductive ignition, that in some cases and mostly at low rpm (but with a 4 cylinder might go higher) the spark will probably light fuel better but requires a small plug gap to maintain rpm. Chances are that opening up the plug gap without the peaking capacitor would be just as good or nearly depending on the fuel mixture. Driving a peaking capacitor with an MSD ignition that already has a short duration spark of about 40µS would be silly and give a weaker spark with very low available voltage so misfires would be quite likely. Driving the peaking capacitor with a Ford TFI or some other means to provide high voltage and current would make the peaking capacitor idea more favourable. The major problem that I can see on the scope is the extremely long voltage rise time. Only testing would tell for sure, but it is quite likely that the peaking capacitor connected in parallel with the spark gap would be worse at firing through fouled spark plugs. (In series a peaking cap makes the plug fire better through fouling as long as there is enough ignition energy to feed the cap before it discharges) There is only one way to find out, and that is to test it. Perhaps in the next month or so when I have time, Fred
Edit: I forgot to mention that even with the very intense spark with the peaking capacitor, there were no extra stray sparks from molten metal being shed from the soft iron electrodes on the test machine, so the heating of the electrodes is no worse.
quote="Alstrup"]Not plasma on that one. As described Mallory Unilite with pcd upgrade. 3 x 15kv681pf.
T |
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pupjoint Samba Member
Joined: May 23, 2007 Posts: 1140
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Posted: Fri Aug 31, 2018 10:33 am Post subject: Re: Upgraded ignition Spark Comparison + Plasma/PCD info |
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interesting thread, I do admit I am lost in the electrical technical terms and discussions.
I fitted Fred's CDi in Jan 2018 to my Bosch blue coil, Glenn Ring rebuilt 019, stock B5HS NGK plugs, stock 1600 with Dual Dellortos.
one of the better things I have ever done. the diff with and without CDI is quite obvious so much so I changed back to points only to see if I were imagining things.
almost 2500 miles now, yea car not driven much, points, and plugs look OK and I have not adjusted or changed anything.
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7210 Location: Videbaek Denmark
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Posted: Fri Aug 31, 2018 10:39 am Post subject: Re: Upgraded ignition Spark Comparison + Plasma/PCD info |
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I do not have the insight to spot what you are doing different exactly. But something aint right. Because if it was, how can you explain what I asked previusly:
Better power,
better torque,
engine wanting more fuel and at the same time,
better burn (cleaner emissions)
a tad better fuel efficiency and finally,
tendency to engine running cooler?
And also another thing. On one of the engines I installed it on we did another little test. This engine is a medium tune 2 liter Type 1 engine that makes 170 to 180 psi Bmep at peak torque. We tried to enlarge the plug gap to see just how much the kettering system could handle (Pertronix 3 Ohm coil, Ignitor module stock Bosch 1 K ohm wires and 50 ohm/foot wires.) Interestingly enough there was less difference than I would have thought. both wires handeled 1,1 mm plug gap on cruise. The Bosch wire set up started to have blow outs at about 3000 rpm when you asked for power and it just became worse and worse as rpm progressed. The copper core held up until about 4200 before the sparks began to fail, but it managed to survive and come back until just under peak hp. Then it was a lot of misfires until power dropped off above peak.
When I installed the PCD upgraded wires I kept the plug gap at 1,1 mm. and tested it to the limit both on the street and on the chassis dyno, and there was NO misfires, at all.
So if there is a voltage drop to the extend that you claim over the plug electrodes, why can it then handle more plug gap than without the PCD upgrade ?
T |
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Fred Winterburn Samba Member
Joined: April 17, 2013 Posts: 423 Location: Ripley Ontario Canada
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Posted: Fri Aug 31, 2018 11:23 am Post subject: Re: Upgraded ignition Spark Comparison + Plasma/PCD info |
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Alstrup,
The voltage deficit is huge with the value of peaking capacitor that I used. Is your peaking cap in parallel with the spark plug gap? You didn't say. In series the voltage drop isn't as large. However, whether in parallel or series, you are using a peaking capacitor that is smaller so the voltage deficit won't be as large as I tested. But it doesn't change the fact that the available voltage will be lower with a peaking capacitor.
I can offer a possible explanation to explain your success. That is, despite the voltage deficit, you are still able to make a spark because your plug gap is small enough that a spark forms every time all the way to your upper rpm limit with the peaking cap (and without). The higher power of the spark is allowing combustion more often when the low power of the Unilite by comparison can't do so even though a spark is still occurring. If you opened up the plug gaps far enough you will find that the Unilite will still make a spark while with the peaking cap connected, there won't be a spark.
I am not disputing your results, only pointing out the shortcomings of using a peaking capacitor in series or in parallel. Ideally if using a peaking cap in parallel, one would use an inductive driver that multisparked at 200µS intervals with a much higher voltage and current output than a conventional inductive ignition. That way you would have enough voltage for wider spark gaps and give the mixture a second spark if the first didn't ignite the fuel successfully. One drawback with the design is that it would still not fire fouled spark plugs well and would be a current hog. Also it would not be suitable for a distributor ignition system due to the higher voltage required. Fred
Alstrup wrote: |
I do not have the insight to spot what you are doing different exactly. But something aint right. Because if it was, how can you explain what I asked previusly:
Better power,
better torque,
engine wanting more fuel and at the same time,
better burn (cleaner emissions)
a tad better fuel efficiency and finally,
tendency to engine running cooler?
And also another thing. On one of the engines I installed it on we did another little test. This engine is a medium tune 2 liter Type 1 engine that makes 170 to 180 psi Bmep at peak torque. We tried to enlarge the plug gap to see just how much the kettering system could handle (Pertronix 3 Ohm coil, Ignitor module stock Bosch 1 K ohm wires and 50 ohm/foot wires.) Interestingly enough there was less difference than I would have thought. both wires handeled 1,1 mm plug gap on cruise. The Bosch wire set up started to have blow outs at about 3000 rpm when you asked for power and it just became worse and worse as rpm progressed. The copper core held up until about 4200 before the sparks began to fail, but it managed to survive and come back until just under peak hp. Then it was a lot of misfires until power dropped off above peak.
When I installed the PCD upgraded wires I kept the plug gap at 1,1 mm. and tested it to the limit both on the street and on the chassis dyno, and there was NO misfires, at all.
So if there is a voltage drop to the extend that you claim over the plug electrodes, why can it then handle more plug gap than without the PCD upgrade ?
T |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7210 Location: Videbaek Denmark
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Posted: Sun Sep 16, 2018 12:13 pm Post subject: Re: Upgraded ignition Spark Comparison + Plasma/PCD info |
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OK.
Had a chance to do a little more testing last night. I specificly adressed the postulate that the PCD hook up would actually reduce voltage over the plug gab. I did not really uinderstand why this could be true since I am able to run larger plug gap with PCD compared to without. So the exercise was to find out how and why.
I tested with a regular quality blue Bosch, a 3 ohm Pertronix, a 06 ohm Bosch and a 0,6 ohm Pertronix coil. Now, if we take the differences in usable voltage out of the equation the bottom line is, that when you do this right, you will have anything from 10 to 50% higher voltage over the electrodes compared to normal kettering, points or electronic points. With a set of new Bosch points the increase in voltage with the PCD upgrade is 3-5% less. The variation in spark strength comes from the use of different capacitors. I was previusly a little worried about making the PCD too powerfull so the plug life would take a dive. Now I am more courageous. As long as the correct plugs are used and as long as one does not overdo it with wild plug gaps the plug life will remain about normal. Plug gaps in the 1 to 1,2 mm range (0,040 to 0,050) dependant on set up seems to be the sweet spot.
I deliberately drowned an almost stock 1600 engine (except from 8,2-1 CR and a free flow muffler) and started it with normal ignition and normal plug gap. Then switched system and drowned it again. With the blue Bosch coil I could start the engine just as good (or slow if you will) with 1 mm plug gap. At 1,2 mm it really struggeled to overcome the flooded plugs. With the 3 ohm Pertronix it started almost immediately with 1,1 mm plug gap. So I naturally opened the plug gap a little more to find the limit. That seemed to be somewhere between 1,25 and 1,3 mm. Also, with the 3 ohm Pertronix and 1,2 mm plug gap the engine drives great. No cut outs or anything. With the blue Bosch you get noticeable misfires at peak torque and around peak hp. Reduce the gap to 1 mm and the Bosch has no trouble.
Bear in mind, this was on an almost stock engine. On a high compression large cam duration engine this will not be the same. But the pattern will be equal. I do know that with a Bmep of about 170 psi at peak a 3 ohm Pertronix and 1,1 mm plug gap works well in a good set up. With most average set ups I would recommend 1 mm. to be on the safe side.
Now, where does this extra spark power come from you most likely ask. - It comes from being accumlated. The coil delivers the same power, but with the normal kettering system you slowly build up a voltage difference between the electrodes and the spark will begin at a relatively slow rate, go to its peak and burn out in an average of 15-17 Ns. in total. With the PCD system you use the capacitors to "suck up" the initial part of the voltage delivery from the coil. Then when the capacitors are full and the coil is on its max delivery the plug gap will be ionized and the entire load will be dumped in one fat spark in about 10-12 Ns. (In my case it is actually 3 sparks that come almost simultaniusly, only about 2 Ns. apart. If you look at the spark through a magnifier you can actually see that there are three sparks at one time. And that is part of why the spark is "fat"
It is difficult to put numbers to something that you can´t really measure. But if we look at it this way, we can say that in a good std 12V igntion system we (I) have 0,85 mm plug gap. With a good PCD system I use say 1,1 mm plug gap. The increase in plug gap alone makes for a 29% increase in surface touch to the ambient mix. And that is without taking the fatter spark into consideration. If we could find a way to determine that we could easily be talking around a 50-60% increase.
I have menthioned it before and will do it again. This is NOT a subsitute for a good CDI system. It is sort of a step on the way, but a good step.
Several people and companies that I have talked to about this keep saying that they want a good long duration spark to ignite most possible. I don´t exactly disaggree with them, but I am more and more convinced that a big fat spark, at the right time, in the beginning of the burn cycle, is just as, if not more efficient for the burn. That way you get the burn to evolve faster and be more complete before the piston passes 15 degrees ATDC. And THAT´s where the increased power comes from.
I have to test more IRL, but I´m posive that I´m on the right track. I just need to understand it better.
T |
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jpaull Samba Member
Joined: February 22, 2005 Posts: 3461 Location: Paradise, Ca
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Posted: Tue Sep 18, 2018 10:55 am Post subject: Re: Upgraded ignition Spark Comparison + Plasma/PCD info |
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I am just guessing, but there might be a few that feel they are reading Greek.
Alstrup is showing that using 3 capacitors gives a more powerful short spark, and actually in groups of 3.
Alstrup, along with Aaron Murakami, David Vizard, everyone at Ionfire ignition, Aquapulser Ignition, and many others have found that a more intense spark (even if shorter) can ignite more of the available fuel then a less powerful(even if its longer duration) spark. More available fuel burned, means less emissions, and more power. A more intense spark is needed to "reach" all of the air fuel mixture in the chamber.
With the same amount of energy available, it can be given in a shorter and more intense way, or less intense and over more time. The Capacitors give it more intensely, and in a group of 3.
It lets us also run leaner Air/fuel ratio's. People have been capable of running 19:1 air/fuel with Plasma based ignitions. Why throw away so much gas running 14.7-16?
This subject is interesting to the people that want to maximize what they have available. |
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