Rear Diffusor, Anyone ever think of doing this? Options

[TonyAKAVW]

While I was thinking about better ways to vent heated air from the radiator on a subaru conversion, I began thinking of adding a tray under the engine bay area to help isolate the bottom of the car from the top. This would be for the same purpose as the engine tin with a stock engine.

Anyway, when I got to thinking about having a tray under the engine bay I thought "why not extend it all the way back?" The rear valence on 914s traps air, why not put a rear diffuser there like the Lotus Elise has? If you have a continuous underbelly to the car that goes from front to back, it seems that this might work.

One potential source of problems is the exhaust heat from the headers, the pipes that go to the muffler, and the muffler itself. It seems like there might be a way to vent out that heat, maybe some grille material on the rear bumper? Bring in fresh air through the engine bay lid?

-Tony

[brant]

and another thought.....
when we used to run a -4 street car with no front cooler.
we lowered it extensively for track and used one of those rubber front spoilers on it. Very little air was flowing under the car, which was our intent.

but a side effect was that on the highway at constant high speed (80mph or so) the oil temp would slowly climb up into the red on our gauge and the only way to drop it was to slow down the car.

What we learned was going on was that the front spoiler was not allowing enough air under the car to make the turbulence flaps effective.

we changed the front spoiler to an LE style which was about 2inches further off the ground and problem solved... Race carst that have huge front spoilers always have front oil coolers and I think that is why you don't see them having this same problem.

the point is: your developing a cooling system that will be dependant upon cooling in the engine bay with no frontal ram air effect onto your cooler. Your going to want to be careful that you don't lower your car too much so as to choke off that air coming from underneath the chassis.

how low are the cars and spoilers on the existing/running subaru radiator in the engine bay cars?

brant

[kdfoust]

How about this? Looks cool and old skool hot roddy. I don't know if it does any real work...

Kevin

[kdfoust]

You can also check out this guy's website: Chuxter. He does some pretty interesting work trying to get airflow to his oil cooler mount in the rear of the car.

Kevin

[kdfoust]

Check out Clewett's solution for intercooling. Again one of the more interesting airflow solutions I've seen on '14s. I've seen the yellow car at the track. It is one fast 14.

Later,
Kevin

This post has been edited by kdfoust: Dec 11 2005, 02:54 PM

[Maltese Falcon]

...what Brant said , the diffuser is usually for ground effects (read : ground defects on ricers) (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif) .
For control of temps i.e. H20, oil, forced induction-- anywhere in the cold blowing wind will work. Where you put it is aesthetically and aerodynamically up to you.
A flat mounted H20 radiator above the rear trunk will create and trap air pockets in the coolant- not a good thing. However , that location works great on forced induction. The black car sees drops in boost temp (uses an 1,100 cfm intercooler) from 300f down to about 100f with the trunk location- as in the avatar.
Marty

[d914]

how about these side vents, looked pretty good.

[jd74914]

those look decorative and don't look like they go anywhere (IMG:http://www.914world.com/bbs2/html/emoticons/huh.gif)

[john rogers]

I have an air intake in my right side rear flare similar to the white car just posted. It is for the trans cooler and I found it let plenty of air in but there was some high pressure under the rear of the car just under the rear bumper and the air could not get out well. I had to make some additional ducting from the floor of the trunk with the opening at the rear so there would be a low pressure area and now the air flow is great. I think the air pressure under the rear is fairly high due to several factors: 1 - The outlet of the engine cooling air, 2 - the air sucked in by the rear wheels, 3 - the air that comes in from the area under the rocker panels after it passes the front wheels.

[dlo914]

flipped them:

[Crazyhippy]

v8 914's require roughly 1 sq ft of opening in the front of the car. (a lil more w/ a wild motor, lil motors still needed more than 90 sq in) And that is with a positive pressure airflow. Trying to pull air from the rockers or fenders is going to be tough. The pressure difference will not be as great, and 1 sq ft is reallly hard to do.

I think the best way will be to duct air from under the car, up the firewall (in front of the motor) to the radiator (maybe 45* from the top of the firewall down to the motor, fans on the top side pulling) and let the air go where it wants on the way out. It might go out the engine lid, it might go out the back.

BJH