How important is the IC to hood seal?

steven c · 11-26-2009, 06:50 AM

Just going over details on my new to me 91 965 and found that the intercooler is about an 1/2" below the rubber seal on the right side. Looks like someone was adjusting for rattles maybe and even cut the right side mounting plate off shorter. It still rattles when cold but should I spend time making this fit better? Thanks

mark houghton · 11-26-2009, 07:06 AM

The laws of physics say that the air flow will take the path of least resistance, so some of the air will go through that gap as opposed to going through the IC. The real question, lacking any imperical data, is if it makes a substantial difference in air charge temperature.

Perhaps there are some forum lurkers who have some persoal experiences to share, but I would say fix it if you can. or just ignore it and don't be running your car real hard when the outside temperature is scorching hot (as it can get in Texas). Which - by the way - is probably a good rule of thumb anyway with or without a good seal.

MikeD930 · MikeD930's Garage

In my opinion, I'd say leave it open. I'd rather have cool air for the engine (air fan) rather than cool air for the intercooler. Who is going to be on full boost all the time?

A930Rocket · 11-26-2009, 08:18 AM

I noticed a +10* difference In oil temps with my shroud on. soon as u took it off, temps went down.

Having said that, you are defeating the purpose of the intercooler by not getting all the air through it you can. Hot air can create a climate for detonation.

DDDD · 11-26-2009, 09:09 AM

Quote:

Originally Posted by A930Rocket

I noticed a +10* difference In oil temps with my shroud on. soon as u took it off, temps went down.

Having said that, you are defeating the purpose of the intercooler by not getting all the air through it you can. Hot air can create a climate for detonation.

By shroud, you mean covering the entire engine bay right? You are not talking about just the rubber seal around the IC. Just want to make sure...

A930Rocket · 11-26-2009, 10:28 AM

Yes, what I had was a shroud that covered all but the intercooler (there was a small gap between it and the I/C).

Quote:

By shroud, you mean covering the entire engine bay right? You are not talking about just the rubber seal around the IC. Just want to make sure...

steven c · 11-26-2009, 05:48 PM

I am asking about the rubber seal to the IC. Yes, it gets hot here but the car is not a DD so it will not suffer the high temps much. Never the less I plan on installing a second oil cooler before next Summer. Looks like I need to buy one part and work on getting the back right corner of the IC up to the seal. Thanks

911nut · 911nut's Garage

Cool, dense air makes more power than hot air.
Anyone who has done back-to-back dyno pulls can attest to the fact that pull no. 2 will register a lower hp number than pull no.1 due to intercoorler heat soak.
If you want your car to be all that it can be, make sure that the seal is sealing.

RarlyL8 · RarlyL8's Garage

If air is allowed to go around the intercooler the intercooler becomes a heat sink. I tried this with my aftermarket intercooler and the difference was huge in terms of eliminating heat soak.
Fix it.

WPOZZZ · 11-27-2009, 07:08 AM

Steven - A bit off topic, but take a look at your ac lines. There is a bolt from the tail that rubs the aluminum line and will make a hole in it. Just tie wrap some fuel hose around it for protection.

steven c · 11-27-2009, 12:15 PM

Quote:

Originally Posted by WPOZZZ

Steven - A bit off topic, but take a look at your ac lines. There is a bolt from the tail that rubs the aluminum line and will make a hole in it. Just tie wrap some fuel hose around it for protection.

Thanks Bryan, I will give that a look also.

WPOZZZ · 11-27-2009, 01:40 PM

Quote:

Originally Posted by steven c

Thanks Bryan, I will give that a look also.

If you are looking at the engine, it is on the right side. You can see where I tie wrapped mine.

steven c · 11-27-2009, 05:27 PM

Ahhh That is why mine are tie wrapped together...must have been the factory approved method? Thanks!

drmatera · 11-29-2009, 01:43 PM

Quote:

Originally Posted by A930Rocket

I noticed a +10* difference In oil temps with my shroud on. soon as u took it off, temps went down.

hmmm, ever since doing my EFI conversion my car has run noticably cooler. And I removed the shroud when i did the double stack intercooler mod.... i think i'll take the drop in engine temp over the possible loss of a few degrees of intake air temp, besides my methanol kit will help with air temps.