perfomance diesel information???

[Charlie Smith]

Earlier, Beatty, Robert wrote:
> 
> Anyone got any sources for diesel performance mods?  I have a co-worker that
> has a TDI motor to play with and is always tinkering with crap.  He's
> interested in any sort of things that make a diesel GO! :)

Boy, is this an excuse to ramble on while digesting the first and second
cup of coffee  :-)


First, the new fangled way - MTM makes chips for the TDI.

Second, I believe the main difference in the European higher power
TDI models is the turbo, with the variable vane hot side.

Then third, the old tried and true hot rod things:

Perhaps a little more injection timing advance before anything else.

Then more boost and fuel.  Then a better exhaust system.

He first needs to put a pyrometer in the exhaust, and probably use 1100F
as a redline if the pyrometer is downstream from the turbo.  Reason, is that
the injection pump injects a certain amount of fuel per increment of time.
So more fuel means an injection period lasts longer.  As you go to more
and more fuel, the injection period gets longer ...  until it's so long
that there is still fuel burning going on when the exhaust valve opens.
When you adjust the fuel injection amount upward that last time, you will 
see the exhaust temperature go way up.  Thus the need for the pyrometer.
When you get to this point, you have to balance advancing the timing
with increasing the injection amount - to keep the exhaust gas temperature
under about 1100F.

Raising the boost is primarily to get more air by weight into the engine.
All the usual stuff like intercoolers and different turbo cold sides 
applies here too.  With a diesel, you can raise the boost without any
more fuel, you just don't gain anything.  There isn't any mixture richness
you have to shoot for, as long as you have enough air to burn the fuel
you inject.  The whole key is burning more fuel and you get more power.

You can scientifically juggle raising the boost and increasing the
fuel injection amount.  First, increase the fuel injection amount.  
If you see black smoke at full throttle, raise the boost a bit.  
Repeat as necessary, while watching the exhaust temperature.

On the exhaust.  Years ago I had a VW 1500 diesel stuffed into a Sirocco,
with a Spearco turbo kit and a 5 speed tranny.  I was able to run a 2"
straight pipe from the turbo back without sounding like a Mack truck.
It just sounded deep and louder, just what you want for a home made
sporty car  :-)   Made a neat whistling noise when you shifted, and
helped power a bit too.  Don't know the HP, but it was quite a bit
quicker than gas powered Rabbits in those days.

I know this is the wrong list for this, but I've got 2 add on turbo setups
for the 1500/1600 VW diesel and also an Audi I5 2.0 diesel engine laying out
there in the garage I'd like to get sell.  I might even be able to find
a turbo that was close for the Audi diesel.  Back when I had the '86
5kCSTQ, I always figured when the gas engine wore out /  broke, I'd have 
the first Audi Quattro turbo diesel in town.  Alas, the MC engine proved
bullet proof and when I sold the car with 200K miles it still didn't even 
use much oil ...  as you can see from my signature below, I've moved on
to more serious diesel power  :-)

    - Charlie


  Charlie Smith   charlie at elektro.cmhnet.org  614-471-1418  
  http://elektro.cmhnet.org/~charlie   Columbus Ohio   USA

  95 S6 Quattro  -  24 PSI, RS2 6 speed, and other features  
  96 Dodge Ram   -  30 PSI, w/Cummins turbo diesel