I'll offer some further comfirmation of the cooling effectiveness of a
larger IC.  I recently added a moderately large IC to my Mercedes
OM603 (6 cyl turbodiesel) and bumped up the full load fuel quantity
screw in the injection pump--more fuel.  In theory, this modification
delivers close to 180hp, up from 148 stock horsepower.  My pre-turbo
EGTs never exceed 1050F, no matter how hard I flog it up hills or
during WOT runs @ ~110mph.  A friend of mine with a stock OM603
routinely runs over 1200F (pre-turbo) climbing hills and has seen
1450F during a hard 1/4 mile run at the dragstrip.  I bet if you could
locate those Vanagon tdi intercoolers into some serious airflow, or
add water/methanol injection to the intake stream, those EGTs would
decrease that much more.

My 2 pfennigs.

On 5/31/05, Martin Jagersand <jag@cs.ualberta.ca> wrote:
> Hi David,
>
> Your hi powered TDI observations are quite interesting. Especially
> that you can keep it cool enough despite the increased power.
>
> FYI: My 1.9TD has nearly the same EGT readings: around 400C
> at 100-110 km/h highway and up to 800C in long hard climbs.
>
> Jake Russell who was active on the Diesel list several years
> ago found that there was a direct coupling between EGT change
> and intercooler efficiency. Ie at 15psi boost the post turbo
> temp is often in the 100C range. Using an oversized intercooler
> (Jake found that the Audio 5000 one worked quite well, but it's
> a lot bigger than the TDI one), the post IC temp can be brought
> to almost ambient (e.g. 20C). Then measuting EGT with and without
> intercooler the EGT dropped nearly the same amount as the intake temp.
>
> I tried to put the big Audi 500 IC in my Vanagon setup, but it
> is a tight squeeze, and I never found a good reliable solution.
> (Same setup as yours with IC behind drivers side tail light).
>
> I was curious if you have before and after IC temps for different
> boost pressures and airflows through the IC?
>
> How do you wire your IC fan? Always on? Or temp controlled?
> At highway speeds does it need to be on? (I'm thinking there might
> be a pretty good airflow through the air channel anyway)

Casey
Biodiesel:
'87 300TD intercooler (205k)
'84 300D (201k)
Gasser:
'89 Vanagon Wolfsburg Edition (184k)
Olympia, WA