Just wondering, planning to trim the tin at the red line here and leave the front tin off altogether, also like in this picture.

Is the gap near the cooler OK or is that going to be a problem. Not sure what the alternator side will look like when it is cut back.

Anyone BTDT?

thanks,
dr

I don't get it... Why would you choose to "trim" your tin? Do you want your engine to overheat??? Ever notice how the rubber seals around the engine compartment seal off expelled hot air??? This design keeps the hot air out & allows the fan to ingest "fresh" air. Trim the engine tin and you have effectively defeated engine cooling. I wouldn't do it. Looks like a BIG mistake.

, why? i have seen this done before on race cars..but why? what is the benefit?

done all the time on race cars, ask brad. I think all of his race cars are cut back.

easier access, easier to R&R motor, etc.

just want to do the job right.

dr

Have you ever noticed that a race car is not a street car? If your car is going to spend 90% of its life at full throttle, within 500 RPM of redline, moving at speeds over 70 MPH, then "race car" stuff is appropriate to it. If you have to sit in stop-and-go traffic, if you aren't pulling the motor every other month (and rebuilding it every year!), if you spend much time at street-legal speeds, then a lot of "race-car" stuff is not appropraite.

It's a Bad Idea to try to cool the engine with air that has already been heated. Air that goes through the cooling fins (and comes out the bottom of the motor) has been heated up quite nicely. Air that is dumped out of the heat exchangers is even hotter. Most of the race 914s that I remember that have had the engine tin cut away were actually getting their cooling air from the headlight buckets, through a "sewer pipe" (large aluminum duct) running through the engine bay. The cooling air didn't come from the engine bay at all!

I wouldn't cut the tin off unless you were doing that sort of heavy-duty ducting. And if you are, then go ahead and trim it off to the bend where it flattens out.

--DD

have never seen the "sewer pipe"

does the duct run from the front of the car all the way thru the cabin into the motor compartment?

dr

don't cut that tin!!! i'll swap you for some bent stuff you can whittle away at. 2.0 or 1.7/1.8.

kevin

Sounds like you may be building a real race car--in which case I'll just extract my foot from my mouth and go over there...

Anyway, that's the only way to get the air from the headlight buckets to the cooling fan. You might find some pics of it on the High Performance House website (http://www.highperformancehouse.com), in pics of Rich's yellow FP race car.

--DD

I'm cutting mine as well.....to help with the radiant heat, my headers are ceramic coated........

street/auto-x car.........

let's look at the logic that some of you experts are dishing out

With all of the stock tin on, sure you are not sucking up heat from under the car, but instead, you are sucking up much more heat from inside the engine compartment, it's even worse with the rain tray still installed....where is this "magical" cool air coming from with all the tin and rubber installed????

from above.
through the engine lid and little side vents ...

it'll be warmer than outside but still MUCH cooler than from "down there",
Andy

Ceramic coated headers actually radiate less heat.

The rain tray isn't sealing up the engine compartment, air still gets through.

Heat rises, so the engine compartment will be hotter with the cut tin.

Think about why the fuel pump vapor-locks while near the engine, you want the engine to suck that heat back in when you are going slow or sitting in traffic?

Well if Dr. Porsche was still alive we could ask him. It was him and his engineers at VW that figured this out over many months and many kilometers of testing back in the late 30s, followed by years of experience producing all those air-cooled VW cars. It may not seem like the engine compartment is all that cool, but I'm guessing that it is cooler than the underside of the engine. I've heard lot's of VW folks say that they've noticed a drop in engine temps on street cars when they made sure that this seal was back in place.

It seems a lot of people misunderstand the purpose of the sheetmetal. It's purpose is to create a plenum or separation between high and low pressure air. It's supposed to create a high pressure area above and low pressure below. It's aircraft cooling 101. It just seems these principals are somehow missed in the aircooled auto engine crowd.

I'm sure in racing applications some folks know what they can get away with, but the better you can seal between the area above the sheetmetal and the area below, the better and more even the cooling air distribution will be.

synthesisdv's car is a racecar his set-up will work fine.

On any daily driver leave the tin alone and don't try to out think the factory.