ok, i read that i should remove the under engine (black) tray, and i did. there is also one under the trans, do i leave it off too? its off the car now, but not sure if that one stays on or goes in the attic ;-)

 

Are you taking it off because of excess heat on the engine?

 

don't have excess heat now, but the shop that did my PPI recommended leaving it off and i read on that fellows post about high oil temps everyone agreed they were bad, just not sure if its only the rear one under the engine or both of them

 

"Off like a prom dress IMHO ! ! !"

Scott

 

Most here would recommend removing the engine tray to reduce heat buildup. Not much heat in the trans area, so no real gain from removing that one, so most leave it on.

Removing the engine tray was one of the first things I did after I got my car home.

 

I was told the tray offers some aero dynamic properties ... I have not yet removed it, and since doing the high-speed fan over-ride, I have no reason to run above 9pm on the temp gauge or 8pm if I want to use the over-ride earlier.

 

there is also one under the trans, do i leave it off too?
no, leave the one under the trans on (although do take the one under the engine off).

 

It's for noise laws, not for aerodynamics.

Porsche 993 race cars running in Le Mans' didn't have the tray so if not speeds in Mulsanne straight aren't high enough for factory race cars to run with the tray, I don't think many of us will do better than that.

Remowing the tray is more for the exessive heat on heads which even if the oil temp. is low can happen. No matter whan kind of fan set-up you run (I have the same thing) it is highly recommended to remove the tray.

Transmissing tray is usually left (some people remove it when they go to track) since there hasn't been problems that would come from exessive heat.

Bottom line, remove the engine tray.

 

you know, i knew that this a topic....but didnt realize how definitive the recommendation was to remove it....thought that this was another divided issue

i have never removed mine since the day i bought it.... i have put about 9k miles on my car since then, and no problems over-heating.... sounds like it is a good piece of insurance though.... doesnt the tray protect the underside a bit?

 

Well, I have a different opinion:

1. Heat rises... may be more advantageous to open the engine lid.
2. Tray protects the underside of the engine from debris.
3. Porsche builds aircraft engines and they are cowled to ensure even cooling.
4. 993's post date the certification of aircraft engines, so me thinks they learned a few tricks during the process.

The above opinion is shared with Adrian FWIW.

 

ohhh.... ADRIAN says it ok to keep my engine tray on....

SWEEEEET.... (Cartman voice)...

 

Heat radiates in all sorts of directions (its a 964 but...)



I'm going along with Bruce Anderson who warned us 10+ years ago about premature exhaust valve guide failures (which 993 owners are now starting to see in droves) caused by excess heat from the undertray. I would love to see PAG's engineering notes justifying the cooling air ducts bolted onto the bottom of each cylinder. Porsche was definitely concerned with airflow below the engine or they wouldn't have added them. Hopefully we'll know more with Adrian's 993 book.

 

I removed the engine tray...because...

1. The fan blows the cool air down into the hot engine and the hot air escapes freely...the hot air is not trapped inside. Like Flying Finn said, it's not the oil temp it's the head temp.
2. No debris issues for me so far (knock on wood)...but it's hard to imagine how anything can actually kick anything in there.....and it's clean even after 10K - I don't drive in the rain.
3. I can visually check for oil leaks etc
4. Better sound.
5. Better view - visually more pleasing than some plastic cover. BTW, I've cleaned the brown cosmoline stuff so it's actually beautiful to look at IMO.
6. I had not experienced my rearend flying in high speed so it's not an aerodynamic thing.
7. My car is probably a little faster now without it because it's lighter.
8. One less thing to remove & replace during an oil change DIY.
9. The most of the Rennlisters have it off - can't be wrong with that
10. Maybe I can sell it in ebay and make money for other mods.

 

Mine is off. There are lots of threads about this and Steve Wiener has posted on each one indicating what others have said - take it off! As to underside damage, I have somehow ripped the air box control hose twice. I assume from debris of some kind jumping up there and tearing it. Interesting that it is always on the right side. Perhaps it's not debris and just the part failing as I don't have any recollection of any "thunks" under there. Anyway, the tray is still off - how many cars can you think of that have them? Me neither.

 

This seems to be a never-ending story.

Tray is on for aerodynamics: Why is it that none of the racing versions have a tray on?

Tray is there to protect the engine: The 911 for most of its life time never came with a tray.

Tray is there for noise suppression: Yes, am sure this is the main reason.

My tray is off and stays off. If you need a placebo in thinking your engine is more protected, then keep it on...