solsrch

Seems to me that I read somewhere that Porsche removed the cover for the cars they used in any kind of racing application. If they didn't worry about the aerodynamics (and certainly didn't care about decibel level) mine is staying off. Besides the general consensus, this is one topic where Viper Bob and Steve Weiner both agree. That by itself is good enough for me!

993tt

So most of you guys agrees that the cover sould be off. Seems like there should be reason enought to try it!

Just one question, I never experienced temp above 9 during street driving. No matter how hard I tried. On track I could reach 10 but I guess that could be expected. So, is it worth to remove the cover for street use if, as I said, I never go past 9 on the temp dial?

You guys say that it's just a matter of minutes to remove/install the cover but I need to jack the car up a couple of inches on one side to be able to pull it free. Is this because all of you are US spec ride hight and I have ROW or what?

/Erik

swftiii

993tt

As Greg Said:

The temp you are talking about is the oil temperature, which are not what we are directly concerned about. Yes, there is an indirect relationahip between the oil temp and the valve/valve guide temps.

Also, enjoy the increased sound of your engine while driving.

Skip

993tt

Ahh... yeah, right!


I just removed my mufflers and installed bypass pipes (home made) so I'm not sure I want even more increased sound!

/Erik

Mark in Baltimore

Erik,

Despite our affinity for SUV's and their all-terrain ride heights, I think most of us have had to jack the car up to facilitate access to the rear tray.

jford

Edward,
Well its been almost a day and nobody has come forward with tales of road kill or thrown tire treads being sucked up into their unprotected engines . I did hear a rumor that one 993 owner drove off a bridge and used the tray as a life raft but he or she has yet to chime in to substanciate. Mine will stay off unless street driving in bad weather, I once had to drive the car in the snow and was glad the tray was there to keep road salt from getting all up in the nooks and crannies.

Jamie

993tt

So, I'm a little bit safer now then!?

/Erik

Coleman

The biggest CON about removing the underside tray is trying to figure out what to do with it after it's off the car.. actually, that is the only CON about removing it.. (picnic table? skim-board? target practice? sled? yard sale?)


Coleman.

Flying Finn

Exactly! I just hit my leg to it yesterday.

For me, as Greg said, underside of the heads (where fan doesn't blow the air so effectively) will be cooler without it and if Porsche builds a car that's about to take 24 hours of abuse at Le Mans and decides it's better for that car not to have it, I need no further reassuring that it should stay on.

BTW, I took mine off the next day I got the car.

Kolbjorn S

Hi all, a thought from the desert. Here in Oman it gets quite hot, with a stable 40-50 degree C from mid-May till late September. I have had the undertray on/off for periods, but have not been able to notice differences on the gauge at all. It could be just me not noticing any differences, but if so they must be rather small. But I should mention that I am a rather sedate driver....
I recall a tread on the 964 board, where a guy put temp-sensors in the engine-bay, with/without tray, if memory serves me right, measured temp-differences were minute (if different at all?).
Today was a mere 40C in the shade, I have the tray on, car's running "cool" (at first mark, reaches level 9 o'clock in small 1st/2nd gear residential streets) - but then again, there's no traffic jam etc. here.

Best of regards!

max911

K2S, the gauge you are looking at is oil temperature, not cylinder head temperature. There is some oil flow through the head, so oil does absorb some of the heat, but it is the air flow that does most of the cooling of the heads.

The thread you refer to, if it the same one i am thinking of, was somewhat flawed from what i remember.
No cylinder head temperature gauges were used, just a hand held type of pyrometer. And, more importantly, the guy was out to prove that removing the tray had no effect on the engine cooling. Research should be done with an open mind!

stay cool,
max

mike cap

Guys,

I'll put in my $.02 from twenty years of flying single and twin engine piston aircraft with large displacement (360 to 550 CI), four and six cylinder opposed air cooled engines.

Absolutely nothing kills an air cooled engine faster than high cylinder head temperatures. It is so critical that most aircraft have very sophisticated cylinder head temperature (CHT) monitoring equipment. And many aircraft are equipped with "cowl flaps" to allow a pilot to manually control air flow over the cylinders and heads. Poor CHT temperature control can lead to cracked heads, cracked cylinders and a long list of valve problems. Its a lot harder to control CHT's with air than it is with water cooling.

As one of the top piston engine "blueprinting" guys once said to me, "Warm oil is good and hot CHT's are bad. And it's a hell of a juggling act to keep both where you want'em."

If you look at the way the cylinder and head cooling air flows on the 993 engine, you'll see that the engine tray creates a lot of back pressure and impedes the cooling air flow. Remove it if you want to maximize your engine life.

Mark in Baltimore

The guy on the 964 board who ran the test, IIRC, did the test on two different days with completely different ambient temperatures as the baseline. He also only measured the air, as opposed to internal engine temps. If I'm mistaken on this, someone please correct me.

It was a nice attempt but it could have been more tightly run.

kary993

I have had mine off for years. Take it off.

amfp

I keep mine off except in winter because of salt and sand that would kick up.