Juha G

Hey guys,

I thought I'd post this here since I believe many of you turbo folks have fiddled with your engines and have deeper knowledge/experience about them.
As a background I have an extensively modified 993 C2 with an Eaton supercharger. This is the first season with the SC and I am having problems with too high IAT's. I have a water/air intercooler which works fine on the street but at the track it is not up to the task.
I see IAT's rise past 50-degrees and sometimes even in the low 60s (celsius).
Motec is pulling back the ignition (4dgr past 50*C and 6dgr more past 60*C), since the max advance is 17dgr (high CR and SC) it is obvious that I am cutting the torque dramatically when the IAT exceeds 60 degrees.

The question is; What kind of IAT's do you see with your turbos at track?

I just bought a GT2 evo tailbase, hoping to get more cool air into the engine bay and I am also thinking about ditching the water/air intercooler for a larger air to air unit. But even with those, will I be able to keep the IAT's in check? Or should I look into water/alcohol injection etc.?

The car is a bliss to drive with all that torque but after 2-3 laps I am seriously down on power and it is not fun anymore...

Thanks in advance for any help!

Cheers!

Juha

pete95zhn

Here you go...

Basal Skull

Hi I'm traveling and using my iPhone... If you search under my username and DIY intercoolers you'll find some numbers/graphs on the track.

wagongotya

this is a tough issue and unfortunately this is an apples to oranges discussion since the cooling setup on each motor is so vastly different. oil capacity, oil cooling, air intake, air cooling, engine cooling, aero, engine boost, engine ignition timing, etc all play significant factors in the heat equation.

Basal has some great data to use as a baseline for the turbo motor, you'll likely need to address each area of the equation and will be making small gains in each area which will hopefully result in a significant gain overall.

Juha G

Thanks Pete!

Thanks, that was a lot of good reading! Thumbs up for the DIY job!!


I agree with you when we talk about engine cooling but that is not the issue I have. The engine stays cool enough all the time. It is just the intake air that gets too hot. The current system works fine on the street but it is not adequate for track duty. What ends up happening is the coolant gets hot and the small cooler up front is not able to cool it down enough.
There is no room for a bigger cooler and the current location is about ideal (next to the factory oil cooler), with regards to the best flow trough the cooler.

I think the GT2RS cooler setup might be a good approach.
Also, I read somewhere that the 993turbo stock ecu pulls back the timing only 6dgr when the IAT gets over 70.5dgr.
My IAT never goes that high (max. is about 63dgr) so maybe I am being too conservative with my IAT correction.
The Motec is now pulling 4 degrees when the IAT hits 50*C and an additional 6 degreees when it reaches 60*C. Maybe I should make it 4dgr at 60*C and 10dgr more at 70*C instead!?

BIG 928

my old gt2 racer used to get to 50 deg c and the power and boost would drop off, this was with a secan intercooler in the rear window with a duct from the roof, that exited under the car. it couldnt be in the standard place as i run multi throttles with high carbon plenums so theres no room. my point being it dropped to 30 deg c when i re routed the ducting in through the rear quarters and out through the rear window. so if you get a good size intercooler make sure theres plenty of air to cool it, as i found crap air flow, crap charge temps even with a quality cooler. id keep the aquamist as well i use mine on the gt2 evo engine. 50/50 water methanol. the more cooling the better in the inlet tract!

BIG 928

sorry just re read your post, id go air to air on the ic. a standard 993 turbo 1 is good for low boost?

regards mark

Juha G

Ok, I just purchased a set of 997 GT2RS intercoolers. I will follow rennlister Basal Skull's footsteps and fab my own intercooler using the GT2RS cores.

Out with the water and in with the air! (the water didn't really even belong to an aircooled car IMHO...)

Basal Skull

Cool!