Hypothetically...

[SquareTone]

How much difference do you guys suppose it would make if all four of our injectors were timed to fire at the optimum time?
I know, I'm grabbing straws here. I just keep thinking that if my old 1.4L I-Mark got 80hp and 36mpg with a 1bbl carb, we must be missing out somewhere. A 1.6 with FI and tuned pipes should be head and shoulders above that 1.4.
Of course I also think that the FI 2.6L I4 in my Trooper should get either decent power or decent mileage, and it sucks at both.
Where do you suppose we're losing efficiency in these engines?
_________________
Tony
'70 Fastback AT/FI (daily driver (exept when the starter won't work, or it's out of gas, or I don't go anywhere, ...))

"...it is a well known fact, that those people who most want to rule people are, ipso facto, those least suited to it."
Help Improve TheSamba

[Mr. Bubblehead]

[blankmange]

I was also thinking that the sheer simplicity of the D-Jet may be its own worst enemy; it can't respond to any and all conditions efficiently. Don't get me wrong - it's a great FI system, but it must be less efficient than later, more complex designs...
_________________

[SquareTone]

[Tram]

D-Jet was developed for PERFORMANCE. Mercedes- Benz D-jet V8s get 10-12 mpg city, 15MPG highway IF YOU'RE VERY LUCKY. But they are rockets.
D-Jet 1600s deliver great performance and reliability. You have to look at the big picture. Are modern fuel injection systems better as far as MPG? YES. Are they therefore a better cost per mile bargain? NO. Why, you ask?
How many modern, sophisticated EFI systems can you fix at home with a volt- ohmmetre and a troubleshooting chart? How many of these modern systems can lose a ground in the wiring harness and NOT fry the ECU?
For 1960s technology, Digijet is decades ahead of its' time. It's tried and proven, and is about the only FI system that a reasonably knowledgeable shade- tree mechanic can actually REPAIR.
Emissions standards weren't as strict, and fuel was cheap. Plus, and this is critical: Air cooled engines were NOT designed to run lean!!! When I was at the dealer, if we had a customer brag about 40MPG on a Type 3 or 25MPG on a Bus, for example, we'd stick a sniffer on it and check the timing, because that fantastic MPG meant one thing: TOO LEAN, which equals a very short engine life. What good is 40MPG if you're doing a $1000 engine overhaul every 10 to 15.000 miles?
There are other ways to increase fuel economy. We recently went thru this in the General forum:
1. Correct tire pressure and alignment. Sorry, but lowering your car changes all of your alignment angles. If you like the lowered look, great. But don't expect your car to deliver stock performance or better with mods.
2. Maintenance. How long has it been since you repacked the wheel bearings? Are your brakes adjusted too tight? Are they releasing as they should? If you have an IRS rear end, when was the last time you repacked your CVs? What's in your transaxle? Coal and sludge? What's your charging system putting out? If it's low, FI efficiency and spark suffer, giving you lower MPG.
When was the last time you performed a full chassis lube?
When was the last time you serviced the air cleaner and inspected/ cleaned the crankcase ventilation system? Are you feeling guilty yet?
3. Proper Driving. Do you have an owner's manual? Do you even know what your shift points are? Do you drive around town (less than 35MPH) in third, or high? Do you know that lugging, or under revving the engine not only wears the engine, but sucks fuel?
4. Consider Synthetics! 30 to 35 MPG is certainly attainable on a stock Type 3 if all the BASIC settings are correct and the maintenance is up to snuff. I've had great results using synthetic motor oils, gear oils, ATFs, and chassis grease for years. It holds up well, doesn't break down, and reduces friction and therefore heat. Petroleum based oil is, well, a dinosaur (in more ways than one!!). If you're worried about cost, quit changing the frikkin' oil every 1500 or 2000 miles! Do it at the FACTORY RECCOMENDED intervals! Doing very frequent oil changes is all the rage now. It does no harm, but neither does it do any good. In fact, it's downright wasteful.
_________________
Give A Pal a Hand!
www.happytrailsfarm.org
May 4, 1970... Never Forget.

RIPRW

"Hell is- other people."- Jean- Paul Sartre

[urchin]

I just put 3,000 miles on my 66 sq bk and averaged 28 miles to the canadian gallon The carbs were out of sync and Envious set them for me in Oshawa and although it ran better it still has a real flat spot. I was really impressed with the fuel economy as I was loaded with stuff and driving 65 to 70 for 15 hours at a time with only fuel stops. My toyota van is only marginaly better on fuel and it is a high tech fuel injected pain in the ass.

[Russ Wolfe]

Ditto to what Tram said








Did I really say that?
_________________
Society is like stew. If you don't keep it stirred up, you end up with a lot of scum on the top!--Edward Abbey

Gary: OK. Ima poop.

[blankmange]

[SquareTone]

Tram, I'm totally with you on the mileage part. Plus, by modern standards, these cars are seriously overweight for their size. The I-Mark tips the scale almost 700lb less than a Square so I'm not terribly surprised by the mpg difference. If you could trim 700lb off of a T3 it would probably get around 30.
But your first sentence is back to my main question. Where's the performance? My 1.6 puts out 1/3 less hp than a 1.4, and the 1.4 was by no means a high-tech engine.
Now don't get me wrong - I'm not complaining. I think these are great little cars or I wouldn't be here in the first place. Like the title says, this is just hypothetical stuff. Just sort of random brain farting going on. I'm looking for a good discussion on where the potential for this engine gets lost.
When people talk performance for an ACVW it almost always starts with a CC increase, and I think there could be significant hp available before you go that route. Unfortunately, my total lack of automotive engineering knowledge makes it hard for me to figure out how one would get there.
_________________
Tony
'70 Fastback AT/FI (daily driver (exept when the starter won't work, or it's out of gas, or I don't go anywhere, ...))

"...it is a well known fact, that those people who most want to rule people are, ipso facto, those least suited to it."
Help Improve TheSamba

[Josie_Aus]

I've wondered the same thing often... could some tech-whiz pleas enlighten us?

[krusher]

VW were very good at keeping there engines reliable by basically strangling them. Instead of a rev limiter they just made the engine breath badly so it could not do high revs.
This is why for example why you de-strangle it with a header and quiet pack you get some extra power.
I would say the whole loss of power is in the desinge for relability against high power.
Also there are 3 sort of engines, short stroke, square and long stroke.
The vw engine is a short stroke engine this isnt great for power this is what race cars and motor bikes use. the short stroke does give a low feet per minute speed, which is back to relability.
for a 1600 to become a square engine it would have to be stroked to 85.5mm the same as the piston bore.

Its all realy in the combo, if vw had gone for longer stroke/smaller bore(squarer engine) better breathing: more air flow in , through heads, and out through exhaust. and a differant cam grind. The the power would be up. But I think due to the magnesium case relibability would have suffered.

[Bobnotch]

From what I've read, by converting to CIS injection (stolen from a mid to late 80's rabbit/golf), you can up the fuel mileage to about 30, and pick up some more useable horse power. Most likely this done by optimizing the given amount of fuel being supplied. Cam changes effect D-jet the most (ask bubbles ), because the fuel injection system is designed to monitor vacuum, and respond to those changes (richen or lean the system). If I remember correctly, the first poster asked about "batch"firing the injectors, well, the D-jet is already half way there, as it fires the injectors in pairs.

People just seem to forget that these cars are 30+ years old, were cheap cars when they were originally built, and got better fuel economy compared to the cars Detroit was selling. Advancements in technology, and the changes to today's fuel, have evened up today's cars, so that even midsize pickup trucks get almost as good, or even better fuel mileage. The thing is, most of today's auto manufacture's are going retro with their styling, to get new buyers, but we get to drive the original.

I do agree with Tram, basic maintenance will go a long way to picking up a few mpg's, along with making your car that much safer on the road.
_________________
Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here; http://www.thesamba.com/vw/forum/viewtopic.php?t=240540 -tear down
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120

[Bugman_Jeff]

[Air_Cooled_Nut]

[SquareTone]

[Air_Cooled_Nut]

[Tram]

[SquareTone]

[stvwguy]

I might be wrong... but i was under the impression that air cooled vw's don't make the same power because they have to run at a lower compression rate than more modern water sucking vehicles. I know the higher performance air cooled engines can run around 12:1 but they most likely will not last long. Im running around 8.5:1 on my 1835 in my type 3. I don't know what kind of compression is standard for newer watercooled cars is, but im pretty sure its more than 8:1

Also the overhead cams and lower rotating mass of a timing chain are just a couple of many small things that add up to less power consuption from the engine itself. As mentioned above.

As a reminder these are not large engines we are working with here. The best efforts of auto makers with a 1.6 - 1.8 is pretty good hp wise... but often these engines have to be reved very high to produce much torque.

Just my thoughts Im open to any new understanding

[raygreenwood]