Hi
I am new here, this is my first post. I am doing a 914 project with a Subie WRX engine. Does anyone have any idea on which way the air flows through the engine bay? I am trying to optimize the top mount inter cooler flow. I am concerned there is a low pressure area at the engine lid which won't flow much air. I see 916-GT engine lids which I am assuming aid in airflow, but trying to get my thoughts around this. I wasn't planning on running engine tins with the Subie. Any help/thoughts are appreciated.
Ed

It flows down. Those little plastic tabs that are attached to the base of the engine firewall crate a low pressure area in the engine bay. I don't think it is a Hell of a lot but your inter-cooler will have the final say in this.
BTW,

Any thoughts of how to increase airflow through the engine bay (short of a snorkel)?

- Improve on the diverters under the firewall. There's lots of air going under the car at speed. Use it to suck more air through the engine compartment.

- You could also try side-scoops ala Boxster to try to force air into the engine bay.

- Cut off the windshield and remove the rear window and modify your engine lid into a scoop.

Many of us run air to water intercoolers. Some have air to air intercoolers in the rear trunk.

With all the engine heat you it will be hard to get the delta temperature air you need for an engine mounted intercooler.

I know you said no snorkle but this would be highly efficient for your application...it begs the question of intended use. Will your car see a road course or is it a hot rod?

I'd suggest pulling air from the undercarriage as Andy mentioned if you don't go up top - this is not without its challenges though either. I tried but it wasn't a clean install on my car.

Someone here (bellis?) went with side NACA ducts...

Welcome and best of luck.


Tony

The snorkel is challenging as it is a street car and will be driven with the top off most of the time. This is my first Subie so I am not too familiar with the intercooler airflow needs (but judging from the hood scoops on WRX's, I am assuming this will be a challenge)

Here is a picture of the MSDS build - maybe Marty would be kind enough to chime in on its effectiveness. This is probably a good route for you...

Tony

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Hey Ed,

Welcome!

I purchased a subie conversion that was done for a customer of Precision Chassis works
in Phoenix. It is driven with top off and mainly for pleasure and C&C events. Airflow does not seem to be an issue. Perhaps a call to Kent at PCW to ask-480-507-1865?

Have build pics in case you need some.

Good luck with build.

Thanks, I will call them immediately. They aren't too far away from my house. I would appreciate seeing your build pics.

PM me your email address. Also Renegade Hybryds in Las Vegas sells the subie conversion parts /kits. Steve is owner- tel. 866-498-2421. Can also advise on air flow question.

I agree with Mike, an air to water intercooler will be your friend. Sure its not the easiest to work with but it is the most efficient and compact way of getting what you want working.

I cut the rear bulkhead on my Suby conversion. This allowed me to position the IC in the stock subaru location relative to the engine. I then cut the trunk lid and the IC sits nearly flush.

This location is about the down turn point of the roof spill-over air. It seemed to work just fine.

We wrestled with exactly that same problem, how to make sure we got enough air cooled, especially at the extremes. The first iteration had the air-air intercooler in the engine compartment like this:



That one's larger than stock but didn't do as well as we wanted so we changed over to water-air with a small heat exchanger in front of the radiator, this:



And the water-air exchanger is in the engine compartment, this:



It works really well. I'm sure the air-air in the engine compartment would have been fine, we just wanted to make sure.

I thought of the water to air option, of course that creates a few challenges of its own. I live in the desert and would like to drive the car most of the year, so it will have AC. I have a concern if I have a radiator, a condenser, and the intercooler readiator I am going to have a problem with airflow through the entire system.

I have been toying with a couple of options, fans and ducting to the air-to-air, putting Boxster like air intakes in the fenders and mounting the water-air radiators there, or putting it all together stock, dyno'ing it and rethinking it from there.

That's pretty much how all new cars with front mounted intercoolers are set up, the Volvo S80 parked out front, for example, so I don't see why that would be a problem. I read somewhere that when they're layered there's a max 3 degree "shadow" from one exchanger to the next, and that's only in the overlap area. So it should be good, but you're right, it's easier to plumb an air-to-air all inside the engine compartment, for sure.

You can always put the intercooler radiator in the wheel well or under the trunk. Or you can remove your fog lights and put a couple of radiators/coolers there.

Lots of possibilities.