Phil

these cars should not be droven. They should stay in an air conditioned garage.
They are cars!!!.........thats it.....they break down, they have problems. SO WHAT every car has problems. If something is broken, or worn out.......fix it........get over it.......but with a 993 what ever you do......DO NOT DROVE IT. Droving could cause problems............sheesh..........

Rob993

Ok pcar964. What do you know?

Rob

sww914

When I was a tech at a Porsche shop, we took them all off and left them off because we didn't like putting them back on. I think that most of us agree that there may be higher temps at very low speeds.
I think most of us agree that there may be more stability at extremely high speeds.
I think that several of you are being unreasonably hard on one another.
I have been very impressed, generally, with the gentlemanlike behavior on this board, and the great courtesy that members show each other.
I've seen the products of Mr Ruf's career,and I've met him, and I'd have to say, he's not full of sh*t. He builds awe-inspiring cars. I wish that I could achieve what he has.

Bull

"What I heard" is good enough for me because I heard it from Porsche Engineers at Porsche AG during a visit to Germany. So, thanks for the permission to continue to believe the guys who created the stupid thing. BTW, what they said, which is what I have posted in the past, was that the tray was put in place due to the need to meet noise regs in several counties. The same regs that played a major part in the death of the air-cooled engine altogether.

Enjoy your tray.

TheOtherEric

FWIW, my measurements agree with tj90's findings that the tray doesn't affect head temp when driving. I recently hooked up my engine cylinder head temp sensor to my data logger and did some runs. I didn't test idling.

Buckeye19

Bob, I do not believe that anybody is arguing that a Porsche engineer did in fact make those statements. Was that engineer in charge of underbody air management for the 993? I am an engineer at a large R&D firm, but I am certainly not qualified to make statements on the inner workings of every single project we have here.

This thread was started regarding the tray’s relevance to high speed stability on a stock 993. The 993 underbody also has trays covering the center tunnel and under the front suspension/steering rack area. Were those also added strictly for engine noise? Of course not. So the fact that those exist shows that the Porsche engineers did in fact pay consideration to air management under the car for reasons other then engine noise.

It is entirely possible that a part designed primarily for one purpose (engine noise) can in fact serve a secondary purpose as well (improvement in high speed stability). Removing that part may improve one condition, but be detrimental to another condition unintentionally. There are still unknowns in every production car when it leaves the factory since the development costs have to be kept in check.

Bull

All very possible, and I appreciate your comments.

The comments were made by a group of engineers during a brief meeting. I didn't check the credentials of every one of them, nor their resume'. The y went as far as to say that the tray wouldn't be on the cars if it were not for the noise regs. I have simply been trying to point those comments out as a possible, even likely indication that it wasn't put in place for any other reason. I never mentioned anything about engine temps, etc., nor do i care if anyone keeps the damn tray on or off.

Apparently saying so represents "listening to demagogues", "parroting" and being "sheeple"! All by someone who is confusing some numbers with "science". The only "parrote" I have heard is saying "where is your data, where is your data, I thought so, I thought so...."

tj90

Calm down Bob your going to have a stroke!!!

Bull

Not likely. It would take something that I took seriously and mattered to do such a thing!

Coleman

Okay, Point taken.. I was not aware of your thermocouple experiment thread.. I'll search the topic.. Where was the thermocouple reading taken from? I wonder if some of the "reported" exhaust valve guide wear could also be from the headers heat and the adjacent surrounding head area? These would (I suspect) have a different outside and inside temp then other parts of the head? I dunno much 'bout thermodynamics..

COleman..

Anatol

It comes as a surprise that slow driving US gets so heated about high speeds.

Me and my friends, all with 964 RS in clubsport configuration, drive with the pan as it is regarded as a major factor in reducing the drag coefficient as compared to previous 911 models, including the Turbos.

Of course, nothing is absolute - something a few posters seem to forget. Their may be a trade off for the pan - increased heat. But for the na models this seems to be less of an issue whereas for the turbos this appears to be more of a problem - hence no pan.

But if you really go fast, like 180 mph in an 964 (on the autobahn ), you notice a lot of instability on a stock car (with engine mods), even with the pan. Only with a rear wing, front splitter and stiffer suspension do you stabilize the car enough to be comfortable. But due to the pan you can go that fast, even with modest power. A stronger but wider and less aero efficient 965 Turbo does not achieve such speeds.

I might burn a valve every once in a while but I certainly do not kill my engine with carbon build up like all those down town crawlers - even with their pan off.

jnnking

Ya, thanks for rubbing the Autobahn in our US faces.

R993TBO

I hit 150mph+ at several times a week here in Germany on some stretches of the Autobahn. These speeds are quite normal here so I think the tray does serbve a stability purpose. Also keeps all of the crud off that will prematurely rot away your turbos and oil resevoirs.

2ndof2

I don't know anything about stability at sustained high speeds in my car but I have noticed that w/out the tray on the car seems to radiate less heat out the top grill once I park the car. I assume that means any heat that was trapped with the engine tray on is no longer being trapped. Hey Coleman, if the verdict is putting my tray back on, where was it you said the empty field is that you threw yours away in again? LOL

Bull

I'm collecting them all and selling them at the beach....they make good skim boards.