Christer

I think there is some confusion here (maybe on my part).

Removing your undertray will not reduce the temperature of the oil in your engine - well no more than wrapping a cool wet towel around a boiling kettle. Removing ones undertray will arguably help keep parts of the engine cooler which is a good thing.

I don't think it likely that rocks will damage your engine, or that your engine will ground before other bodywork does.


Cupcar, I also had concerns over my HT leads, as not only do I not have an undertray I also do not have heatshields either. So far, no problems (I inspect them every 3 months) and I have had the current exhaust on for 6 months or so.

Arjan, if you were at 10 o'clock last time then this is not something that will damage your engine in any case. I suppose you have checked that your low speed fan works?

Arjan B.

Christer,

Yes,I checked my low speed fan, I check it every few months when I look after my oil level manuel [normal I watch the gauge].
It starts running at 9:30 on the gauge, and the gauge drops very fast after the fan starts running.

Arjan
964 C2C 1992 Black

Adrian

Dear Arjan,
I am also still waiting for the documented evidence that the rear tray causes premature valve guide wear. Everythingon this board is pure heresay and opinion based. Valve guides wear. The valve moving up and down in the valve guide causes the wear. Now what are premature wear rates? What are normal wear rates? You have to have normal wear rates before you claim premature wear rates. Where is the data. This would be easy to do for some of these engine repair shops. They could record the engine specifics such as mileage, with or without underside engine cover and provide the individual valve guide original size and measured wear. None of this data has ever appeared anywhere. I would like to know the effect of heat on the valves themselves. I believe our valves are sodium filled at the bottom. To get more valve guide wear the valve would have to expand. What is the expansion rate of the valves. Now the cooling system both air and oil operates within certain operating ranges. If the oil cooler thermostat opens at the correct temperature, engine operating temperature is reduced. This is the same for all 964s. People are saying their engine is running cooler, with the cover removed, under what circumstances?
The simple fact as already stated that there is only heresay, second and third hand data.
You often hear the comment "why were the cup cars not fitted with rear covers". The Carrera Cup is a racing car not and never was a road car. The ones on the road now are converted race cars. Very different from a standard 964 road car. I do not consider the Cup and its engine as being any form of guideline for engine wear issues.
Under FIA rules at least the rear engine cover was considered "ground effects" back in the early 90s. I might also add that many LeMans cars from the early 90s were allowed to run rear covers and did so purely for underside protection.
I do know that in the UK premature engine rebuilds have been required on the Carrera RS. Again the M64/03 engine, again built for club sport racing. Premature valve guide wear came up here to but figures and measurements were never produced nor was it proven that the valve guide wear caused the problem which required the engine build. You also see this premature valve guide wear issue appearing on other models including the 993. I await some evidence to show this. Until then I recommend that the rear engine cover be left in place for normal road use. If you are a competitive racer then premature valve guide wear is the least of your problems and I would prepare the car to race and win. This would include the removal of all excess weight. Then I would remove the rear cover, insulation etc.
Ciao,
Adrian
964C4

Arjan B.

Adrian,

The answer you gave, is the one I most like to do.

I think I remove the insulation, so the heat can go away more easy.

Thanks for your time!

Arjan
964 C2C 1992 Black

Bill Gregory

Adrian,

964 engines incorporate a ceramic port liner for the exhaust valve, which provides sufficient head temperature reductions that the factory deleted sodium-filled valves from our engines.

Arjan B.

O.k. Adrian [and the rest],

I removed the unsulation material during my lunchbreak.
Also the ones on the valve cover sides and rear end.

WHAT A JUNK.... al the material was in bad condition.

Now I will see was is does, I agree it will be a little better for cooling the engine.

Have fun,

Arjan B
964 C2C 1992 Black

91C2wrencher

Way to go Arjan! Chalk one up for the heresey boys! I to removed the pan and the connected sheilds and baffles (there was a lot of deterioration and oil soaked in to the insulation) years and years ago with no detrimental effects to date.

Arjan B.

91C2wrecher,

Is this a American way of humor or what??
The way I read this reply, I do'nt understand your comment completely, but what I think you're saying that we all are fooling around, right.

The way you act comes to me as you're thinking that you're the best.

Correct me if I am wrong, so that I can excuse me.

Arjan
964 C2C 1992 Black

John Boggiano

I think you misread him, Arjan.

He just gave you a pat on the back and is pleased you have done the job.

Short of coming round and buying you a drink and lending you his girlfriend - that's about as much as he can do to say, 'Nice one, mate'. As we say here!

91C2wrencher

Arjan, Yes we are all joking around. Sorry if you thought otherwise. On this board are many people with many opinions, including myself, and sometimes we get a little carried away with ourselves. And no, I'm not the "best", but I have been working on my car for nine years and have the benefit of a local shop that is very talented, sharing and experienced. Like you, I come to this board looking for answers and have to filter out the good and the bad replies. Glad to see you removed the tray and such, probably a good decision, I've never looked back from tossing mine. Peace, Love, Out.......

Thanks JB, very well put.

Schwabe

Hi all,

the question " remove it or not" engaged me also a lot of time.
In respect to many threads in this forum regarding this question I asked a local porsche dealer here in Stuttgart what to do.
He said: "Don't remove the undertray. It is designed to give the car a plain ground floor like a formular one car. If it is removed you will run risk to crash your car at higher speed, because the car gets swingup (I hope swingup is the correct word)"
I asked him further if this panel will produce more heat in the engine, which itself will destroy the valve guides.
He said: "This is nonsense. At normal usage the engine will not reache that hight temperature which destroys the valve guides."
So I decided for me and my car, to leave the undertray where it is and where Porsche has it designed for.

Arjan B.

John,

I told already before, If it was not fooling me, I would say "excuse me".
Probably difference in continental understandings.

Arjan
964C2C 1992 Black

Arjan B.

91C2Wrencher............

Sorry!!!!!


I did'nt understand it as I told before.

I hope Randall Granaas will learn me more of this kind of humor next month when I visit them in California, so this way of talking will be clear to me.

Sorry that I tought the wrong things, but I meet to many people during the days in my job as a Service Manager that Know everyting, Bin everywhere and know always a better way to do things. That pisses me off once in a while.

Again...SORRY

Arjan
964 C2C 1992 Black

johnfm

Andy

you can search the oft visited oil temp threads. Randall G wrote a good DIY - you just splice a switch in -line with one of the wires that goes into the CCU - so when you operate the switcgh the CCU gets a 'no circuit' . This switches on the fan. I cannot remeber if the wire is G22 or G18, but the job takes minutes.

LouZ

I'm an engineer, so I want a scientific (or at the least, a logical) explanation for every action!

Six months ago, I took off the pan, inspected the underside, and put the pan back on.

Three weeks ago, I took off the pan and stuck it in the corner of the garage.

Reason? - FULL MOON!

Argan - This is just "so-called American humor" If I see 91C2Wrencher at Sunday's auto-cross, I'll yell "OFF COURSE" just for you.