Pros and cons on 964 bottom motor cover?

[trader220]

Has anyone run their 964 with the bottom motor cover off for cooling? what are the pros and cons of doing this? Thanks

[Type961]

pros :
-less noise
-cleaner engine

cons :
-heat
-access for tuners

On my ex-964 I did remove it...

regards,
Luc

[Rot 911]

Isn't this a standard recomendation? I know Bruce Anderson and John Walker both recommend the removal for cooling purposes. The cover was only put there to reduce engine noise.

[trader220]

I was under the impression that it was also part of the areodynamics package to aid airflow under the car? I was thinking bout a ducktail on one of these and was concerned about cooling

[surflvr911sc]

Didn’t it also help the airflow under the engine in order to reduce rear end lift?

I would think that none of the reasons for it being there in the first place outweigh the main reason for taking it off – HEAT.

[304065]

Mine's on. As much as I respect Bruce's opinion I respect the factory's more.

[Rot 911]

While it may reduce lift, the main reason was that in order to sell the car in Switzerland Porsche needed to lower the decibel level of the engine. The best they could come up with was the engine cover.

[91C2wrencher]

Have a look see on this topic here.


http://forums.rennlist.com/rennforums/showthread.php?s=&threadid=82117

[91C2wrencher]

or here

http://forums.rennlist.com/rennforums/showthread.php?s=&threadid=81762

under tray ad nauseum........

[Planter91C2]

oh, and which oil should i use?.....

[JeremyD]

I have (had) followed this closely - seems like there was a much higher incidence of issues in warmer states - commutting areas where there was an opportunity to sit in traffic on hot days -

BTW - I took mine off - when I had my C2 Targa -

[Speedster94]

i think it was mainly for the Noisereduction ,as well as the sidecovers killing the Valvecovergaskets and Valveguides by overheating the valvecovers/ Towers . As for the Cooling with the Ducktail , check this out !


No problems at all with cooling ,it gets a little light over 150 Mph,
but you get used to it .
harald

[TMH]

The BIGGEST problem with this question (and the reason it will continue to be asked) is that there are excellent justifications for taking it off and for leaving it on. I have heard about the noise limitations before and that seems plausible. I have also heard about the improved aerodynamics with it on, but I am not normally running in the 140+ mph range where this is supposedly most effective. I have taken the stance that Porsche engineers are way smarter than me, but I agree they have made some well-publicized mistakes. Pretty much can't argue with the protection it provides to the engine, but it does mask some oil leaks and makes engine work more difficult.

I can't find the thread any more, but I have also read that it was effective in maintaining a level of consistency in engine cool-down which was said to be very important, but I never knew whether this was one man's opinion or whether it was based on sound engineering logic.

I have found that my 964 runs pretty cool, but I have never Auto-X'd the car so I don't know what the temps might do during runs, or while idling between runs. Might get hot then...

Bottom line, I asked my local wrench, and he said leave it on. I have so far. But that doesn't mean I am not going to ask another local wrench for his opinion, or stop reading the posts when this question is asked again in the future.

Tom

[maxnine11]

i modified an original tray for my 993. It offers some protection, some noise suppression, some cooling, and some aerodynamics.
When it is really hot out, I leave it off. If I have to do some cold Canadian driving, i will put the unaltered tray back on.






max

[Steve@Rennsport]

Take it off,..........

As someone in the Porsche business its a "pay me now, or pay me later" situation.

Speaking only for myself, I take no satisfaction in doing permature valve jobs/overhauls from worn guides and terminal oil leaks, and these undertrays are the leading cause here.

Porsche installed them for noise supression to comply with Swiss noise regulations. These REALLY restrict cooling airflow through the cylinders, heads, and case.

[KTL]

That is some darn nice craftsmanship there Max.

Well done!