engine lower cover

Have a 993 & read in Bruce Anderson's book that he believes alot of overheating problems can be alleviated by removing the lower engine cover. While it seems logical but will it effect the air flow characteristics in the engine compartment while driving?

George

yes it will, and not only for the engine.
the porsches where made a lot more aerodynamic by smoothing the underside, this also had a positive effect on the downforce.

i would suggest to leave it as-it-is.
the engine itself is such a airbuffer that in my opion it will not do a great deal of extra cooling without the cover..

i drive a 911sc 79 so i cannot give you more than my technical view on this...good luck

I think you need to address the use of the car before making any decisions. If your car is for street use and will see slow traffic and hot weather then removing the belly pan doesn't sound like a bad idea. How often are you going fast enough for downforce to be an issue? Also I would imagine all track 993s have no pan (also the heat issue). My vote is get rid of it. I've been trying to get my uncle to remove the pan from his '97 to no avail. His car is a garage queen which may be one use that can retain the pan with no ill effects.

Bruce Anderson has contacts to 'insiders,' both affiliated with Porsche, AG, and independent maintenance shops, so his position with respect to potential reliability problems because of overheating problems because of that shroud seem quite significant to me! He has written in Excellence of late in his technical advice column, indicating that the reasoning behind its' existence is strictly NOISE ABATEMENT, not aerodynamic, and that there are signs of shortened valve guide life and other heat-related problems NOT UNLIKE the 2.7's, so it would seem wise to me to heed his warnings if you are the least bit concerned about the longevity of your engine!!! If you have any doubts about the seriousness of his recommendation, you could email him at bruce1485@aol.com.

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Warren Hall
1973 911S Targa

joran,
I think the he should just remove it. When you say that "down force is lost" it should not be a factor.

FYI for some.

The nut shell theory of how lift is created.

If you take a given mass of air that hits the front of the car, lets say, at the bumper and half of it goes under the car (Short path because it is nearly flat) and the other half goes up the hood, over the roof, down the rear deck lid (long path) and meets the other half that it originally started at the front with, you will create lift.

The air that goes under the car is dense (high pressure). The air that goes over the car is less dense because it has had to speed up in order to get to the back end just as fast. When it speeds up the air streches and thins out becoming less dense (low pressure).

So the high pressure that is created under the car and the lower pressure that is created on top of the car actually work together (like an airplane wing) to raise the car at higher speeds.

Anything that can push air around the front of the car and not under it such as a(front air dam/spoiler) or disturb the airflow in the back (like a rear spoiler) will help "spoil" lift. Spoilers and air dams help counter act lift to allow you to go faster with more control.

Hope it helps someone,

s