Subaru WRX Forum banner
1 - 20 of 22 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
Hi,

I have been reading this forum for some time now and have finally joined so that I can post and do searches. I am looking at a WRX wagon to complement my V8 302 Miata (more seats but am aiming for the same level of insanity).

The concensus of opinion seems to be that the output temperature of the stock TMIC suffers when at idle due to heat soak from the engine. However, I have yet to hear of anyone using an intercooler fan. This approach has been used on MR2 and Celica turbos to good effect - so what am I missing?
thanks
Mike
 

·
Registered
Joined
·
424 Posts
I've been tossing idea's around about this same problem and have come up with a few different means to solve the heat soak problem.

The obvious one is the water spray kit to cool the intercooler off. cheap and easy to build yourself, but only works when your spraying.

My brother and I came up with the idea of using a fan but didn't know it was tried and true already. Also didn't know if pushing the air up (against the incomming air) - or down (where there isn't as much flow)- would be better.

The third idea that I have, I got from looking at a picture someone posted that appears to have freon tubes running back and forth across the top of the intercooler. I'm guessing that this is hooked into either the stock cooling system, or posiibly a stand-alone cooling system that pushes freon through the tubes to help freeze the air before it contacts the intercooler. This looks like a good idea, but would be a nightmare to implement.
 

·
Registered User
Joined
·
2,210 Posts
This relates to something I have going on, so I thought I would contribute:

Because of where I mounted the Nitrous fogger nozzles, I had to temporarily remove the hood scoop insert last night. I was worried that my EGTs would be higher than normal on my way to work this morning, but I wasn't prepared for what I observed.

Firstly, the EGTs climbed a little faster than usual, but not alarmingly so. However, at cruise they settled about 20-30 celcius lower than I usually see. When I floored the gas pedal from a cruise my EGTs climbed significantly faster than I'm used to, and reached a peak about 10 celcius higher than I normally see. I didn't rev it out very far, so I have a feeling that they would have risen much higher. Ok, nothing unexpected in any of this. Here's what I found interesting though; when coasting with my foot completely off the gas pedal, the EGTs dropped like a stone. I actually got the needle to settle below the minimum reading of 300 celcius. Normally I never see lower than 500C regardless, and my EGTs fall very gradually.

What I take from this is that I have less air flow past my IC, but the massively increased cooling of the turbocharger and over the motor in general is having a positive offsetting effect. Based on this observation, I would definitely retain the scoop for its cooling abilities if I went to a FMIC. It seems that setup would be optimal.

Anyway, I'll put the scoop insert back on in a few days when I have trimmed it to accomodate the fogger hoses. I might also increase the size of the opening that directs air to the turbocharger.

I wonder if it would be worth trying to rig up some ducting to route air from the wheel well onto the turbocharger...

-Pace
 

·
Registered
Joined
·
2,213 Posts
what if you just cut that side piece next to the scoop diverter out? the grid on that thing should do more harm than anything when it comes to airflow. if you open that up, you should be getting a lot more airflow to the turbo...
 

·
Registered
Joined
·
3,501 Posts
The thing is, the air is traveling down from the scoop. If you rigged something from the under the car, the air would be going up. You'd get mad turbulence, but no directed flow.

-Jim
 

·
Banned
Joined
·
7,636 Posts
PlatinumWRX said:
How about using the scoop just for the IC and putting a fan in to cool the turbo?

-Jim
that's certainly not a solution to air turbulance under the bonnet though. i kind of like the ducting from the fenderwall idea. especially if you have a shortram installed, it would be a piece of cake with a few feet of ganzflow. i don't think there'd be too much turbulance if it was aimed at the far passenger side of the blower.

pace, i'm really surprised at the EGT #'s you posted. i think the cooling wouldn't be as drastic with the ducting, but certainly significant.

dR
 

·
Registered User
Joined
·
2,210 Posts
PlatinumWRX said:
The thing is, the air is traveling down from the scoop. If you rigged something from the under the car, the air would be going up. You'd get mad turbulence, but no directed flow.

-Jim
Well I was thinking the ducting could route up from the wheel well, and then point down at the turbo. Would be a very contrived setup though.

Another option might be to have ducting that goes from the smaller opening in the insert and routes it directly down over the turbo. At the moment there is a significant gap between the turbo and that opening, so most of the air probably diffuses and has little cooling effect.

-Pace
 

·
Registered
Joined
·
3,501 Posts
I'll probably be upgrading my TMIC soon, so the intercooler will cover the whole hood scoop opening. I'm probably going to have to do the fan route to keep the hot side of the turbo at a reasonable temp.

-Jim
 

·
Banned
Joined
·
7,636 Posts
i think the best solution for cooling there is the old 2.5rs vents in the hood. pipe the one on the left to thte turbo, and the one on the right to the intake manifold. then your new TMIC can hog all the scoop exposure it wants.

plus they look sweet. ;)

dR
 

·
Registered
Joined
·
3,501 Posts
dark_rex said:
i think the best solution for cooling there is the old 2.5rs vents in the hood. pipe the one on the left to thte turbo, and the one on the right to the intake manifold. then your new TMIC can hog all the scoop exposure it wants.

plus they look sweet. ;)

dR
That's a great idea. Maybe I'll put a small scoop on my hood specifically for the turbo. Were those vents functional on the 2.5RS, because the hood scoop wasn't really.

-Jim
 

·
Registered
Joined
·
424 Posts
How about not only water spraying the intercooler but also spraying the Turbo itself off? This seems like it would bring the temp of that baby down quite a bit. Would there be any harm in doing so, such as cracking or anything?
 

·
Registered
Joined
·
2 Posts
Discussion Starter · #18 ·
Hi,

Does it actually make sense to cool the turbo down, except when you are about to turn off, or are out of boost. Cooling the Turbo will reduce the gas volume in the exhaust and in principle would reduce the `drive' to the exhaust turbine. Surely it only makes sense to cool the unit between or after `boosting' - i.e. when running slowly in traffic or stationary. Note this is exactly the same time you get heat soak issues...

What surprised me about this whole question of an intercooler fan was that from what I have heard/read etc., the TMIC works OK at speed, but suffers at low speed or stationary. I appreciate that the FMIC is a better solution, but it seems much more expensive than buying a better TMIC and addressing the heat soak issue with a fan.
Perhaps there is not enough room to put a fan in under the IC to such air down through the hood scoop - I don't know as I haven't got a car yet. A fan would also help to cool the rest of the engine when stationary.

In terms of keeping a good airflow through the engine bay, has anybody experimented with an air dam to stop air coming in underneath and bypassing the rad? I have found this very effective in a Miata where you can make most of the air go through the rad. It also helps to reduce the hood bulging with high air pressure at speed!
mike
 

·
Registered
Joined
·
170 Posts
One of the members, Gregwrx, has a fan mounted under his upgraded MRT intercooler. I hope he doesn't mind me throwing him into this thread, but he did post his mods here for all to see.
 

·
Registered
Joined
·
118 Posts
jmussetter said:
How about not only water spraying the intercooler but also spraying the Turbo itself off? This seems like it would bring the temp of that baby down quite a bit. Would there be any harm in doing so, such as cracking or anything?
Naw dude, you'll be sweeping up the pieces off the street in no time. :p
 
1 - 20 of 22 Posts
Top