Need help understanding VW classifications

[BlueStreak]

Since my attempted threadjack elsewhere fell on deaf ears, I would like to know if anyone can help me understand the following:

Why are the following cars which will gain power from the ECU allowance classed at a lower weight per HP than similar cars that will NOT gain power from the ECU allowance?

The Golf IV is: 20.4 lbs/hp in STOCK form at spec weight
The Golf III is: 20.4 lbs/hp in STOCK form at spec weight
The Golf II is: 21.7 lbs/hp in STOCK form at spec weight
The Golf I is: 23.1 lbs/hp in STOCK form at spec weight

Doesn't the above seem bass ackwards?

If all of these cars were classed using the same process, how did the older/lower tech/fixed engine management cars end up with worse weight/hp numbers than the newer cross flow headed/ ECU enhanced cars?

Assuming CIS single side headed cars could make the same power as the later cars, is there a logical reason why, at a minimum, all of these cars are not spec'd at the same 23.1 lbs/hp?

Shouldn't the cars that can take advantage of the open ECU be xx percent heavier per stock hp than carb and CIS cars that can't?

The better I can understand the process, the fewer letters I'll have to write!

[Scirocco#28]

There's no way you'll get a Mk4 down to 2350 so its a moot point anyway.

[shwah]

I'll say the same thing here then.

I do think something doesn't fit in the classifications. However I also think you will see more gains on the Rabbit than you realize. Dump the toilet bowl exhaust manifold for a Techtonics header. Bump the compression to 9:1 (it is probably around 8ish now, despite a claimed 8.5), go to a dyno and get the fueling right.

Why will you see more gains?
.5 is a higher % increase in compression ratio, and increasing compression ratio has diminishing returns as the starting point gets higher. You will get more gain here than the other cars.

The exhaust manifold on your car was also on the early Golfs. Simply changing to a dual outlet gains 5hp. This means you may see up to an additional 5hp from a header than a Golf with dual outlet (that's more than 5% of stock right there).

Electronic fuel injection does not make extra hp magically appear. The newer two cars have a cleaner airflow path at the MAF, but with stock throttle bodies, intake manifolds and valves is that even a restriction? (I really don't know this). If you take steps to adjust the fueling of your CIS for optimum power on a dyno - this will make more improvement than almost anything else. More than once I have seen 15-20hp gains at high rpm points simply by fixing the factory lean setup (although this was on CIS-E cars - same pricipals apply, just a differnt method to adjust fuel).

If I can put together a 25% gain on my motor, I do expect that you could extract a 30% gain out of yours - however it is one thing to do the math on a keyboard, and another to acheive it, maybe I am off base.

I hope to have a better idea of what a well built A1 1.8 can do in the next month or so.

[BlueStreak]

Chris,

Comp is 8.9:1, Techtonics header, the cylinder head was prepped to the edge of IT rules (by Techtonics (they used to offer that service)), the cam is on the strong side of the mfr spec'd tolerances. Multiple exhaust approaches were dyno'd before the current one was settled on.

The engine is a top tier IT build, which adds to the frustration of seeing the later cars run away.

[Knestis]

If you'd send me dyno sheets with air/fuel data, it's more information for the ITAC to put into the mix as we try to grow our understanding of how the pieces all fit together.

K

[Beran]

I think you over estimate what the open ECU wil do.... Most of us have already reprogrammed chips and have been running them... So 95% of the gain that is avaible has already been taken advantage of.
The restriction for the newer cars is air flow related and not fuel. An open ECU will not gain you more air flow just better control of the amount of fuel added to optimize burn.... which you can already do with a re-programmed chip.
But getting an extra 5% is what some people will do.

Just my humble opinion - I am also not an expert at engine managment.

B

[BlueStreak]

If you'd send me dyno sheets with air/fuel data, it's more information for the ITAC to put into the mix as we try to grow our understanding of how the pieces all fit together.

K

I've lost them, but I will be going back for some tuning with a wideband, and once I've got a new sheet, I'll get it to you.

BTW - Thank you for your work in this matter.