That sounds suspiciously similiar to a sales pitch used by someone.....LOL! :P

 

High,
I knew u were b*** breaking Randall ,
call me a junk collector!

 

Hi Geo,

Yeah, I suppose I should have known you knew I was being sarcastic when you asked how much a new one is .

Hmmm .... three airboxes and a spare engine tray. That is serious pack-ratting. Suppose it's safe to say you don't live in a condo.

Have you considered making a coffee table out of the spare engine tray?

Actually, considering that you live in the northeast, it would probably make a pretty good snow-sled.

 

Mike & Brad,

I don't agree that removing the tray is benificial in any way. It MAY improve the cooling at high speeds but it is at the expense of your car's aerodynamics and downforce. In traffic, definitely not because, there is no air flowing through the engine.

Porsche engineers designed it for a purpose and that is for aerodynamics. The undertray is also called a diffuser. A diffuser is basically an inverted airfoil underneath the car. They work in the same manner as spoilers, ie to increase downforce. hence at high speeds, air is channeled underneath the car and exits via the diffusers thus providing ground effects, resulting in better road adhesion.

The under tray also keeps you engine cleaner.

993C4

 

These cars make minimal downforce. One of Porsche's intentions was to lower aero drag. If you notice that the front underside has been "cleaned up" over the years? Less aero drag = better fuel economy.

When Porsche creates new models with more power, they reduce engine noise, reduce engine emissions, and increase fuel economy. What other auto maker makes these kind of efforts. What an awesome engineering firm!

Chris

 

I would think that if this were true, the factory race cars (993 RSRs, 993 Cup cars, 993 GT-2s) would have left the engine cover in place. None of these cars use them and they are the only ones who go fast enough to even consider an aerodynamic advantage. Certainly it is not a diffuser, since diffusers look nothing like a flat tray under the car.

It is there for sound requirements. Sure it might clean up the air a little flowing out the back of the car, but it is certainly not a diffuser. None of us go fast enough (even DEs and club racing) to see any aerodynamic advantage.

From this website:



"A diffuser allows the air traveling underneath the car a place to expand and decelerate back to road speed as well as providing wake infill. As the air enters towards the front of the car it accelerates and reduces pressure. There is a second suction peak at the transition of the flat bottom and diffuser. The diffuser then eases this "high velocity" air back to normal velocity and also helps fill in the area behind the race car making the whole underbody a more efficient downforce producing device by reducing drag and increasing downforce."

E. J.

 

Hi everyone,
One other point in this debate: Having the tray off greatly simplifies the process of putting your car on jackstands.

 

I have to agree with EJ that there is nothing in the design of the tray to suggest that it would help create a vacuum under the car to aid downforce.

Dick, good point. With my lowered car, it's a pain to get it up on four jack stands without the benefit of that rear jack point.

 

Does anyone here have any training in aerodynamics?

My local mechanic (not the one that does my race setup) and I were talking about removing the rear cover (which I had already done) and he made a suggestion and I am curious if it would make any difference in cooling or eliminating some lift. His suggestion was to build a small air dam on the bottom of the floor pan right before the engine compartment.Maybe an inch or so tall and the width of the underbody. He suggested that the dam would cause a change in the air flow that would help draw out hot air from the engine compartment.
The only reason I give any weight to this is that I have seen several guys in Corvettes add these lips to the front fender wells to disturb the airflow and displace hot air from within the wheel well. Or at least that is what they are claiming.

Any ideas if this would help?

Greg

 

Anir,

What rear jacking point???

 

There is no rear jack point under the engine tray, however many do use the crank case beneath the engine to jack up the car, and hence refer to this as a rear jack point.

 

Not me ...

On the other hand, I do remember seeing how scuffed up my old tray used to look--does make one think it's protecting the engine from something.

Regardless, an awful lot of Porsche "authorities" recommend removing the tray, and have for many years. You would think they would have seen any gross side effects (e.g., engine damage) and changed their recommendation by now.

 

Randall:

What did you do to get those darned scuffs out?? I've got two trays that I'd bring out of the closet if I could JUST get those darned scuffs out. Tha.

 

Mike,

As Rob suggested, I was referring to the engine crankcase, as shown in the pic "lifted" from Robin's site.

 

We'll let Geo figure this out ... when he turns his spare tray into a coffee table. Can you imagine making a coffee table out of a scuffed up tray? That would be unsightly.