CincyScott

Ok, I'm interested in everyone's viewpoint on Billet Valve Covers. I have a set and I was going to use them, but Kevin talked me out of it. I think his logic is sound, in that the plastic ones don't absorb heat, and therefore the lifters don't get cooked like they do with the plastic.

I don't race my Turbo, and I don't plan on modding it much (400 hp in a car this light is scary enough to me), so I wonder if that would really affect me anyway.

Anybody else had this debate with themselves?

911PERVY

I have them fitted, I dont think Porsche designed them in plastic for the heat reason, more the ease of manufacture and price

I would like to know what the difference in heat really is between the two

I think the leak free covers is the way to go!

Quadcammer

the plastic ones are fine. I see no reason to switch.

They are a piece of plastic, they don't leak. If you install new gaskets and torque the bolts properly, there should be no leaks.

911PERVY

1000's wouldnt agree, they leak from the bolt hole inserts

Basal Skull

+1

Quadcammer

I simply can't agree. Could you provide some links where the leak is in the bolt insert?

Looking at the gaskets, it looks like the gasket goes around these inserts, so they shouldn't be causing any leaks.

perhaps they were over or under tightened.

CincyScott

I believe there is even a TSB from Porsche on the issue, where the metal grommets will pull through causing a leak. As has been mentioned, that could be from over tightening. I've replaced my gaskets once before on this car and still have a leak from the lower valve covers. I bought new bolts this time and am trying to decide which vc's to use.

I already own the billet ones new in a box, but am considering shelling out the $500 for the plastic ones. I think Kevin has a good point on the plastic ones, but I'll never run this car like most of UMWs clientele....just a fact of my driving style.

I think the 964Ts have metal ones, but they also don't have hydraulic litters either.

Kevin

A word of caution with the aluminum valve covers on the 993TT. The turbine housings sit right next the valve cover. At the end of the day, even the factory plastic cover take a beating. If you purchase the aluminum covers heat is absorbed. The component that takes the hit is the rocker and hydraulic lifter. It is really a concern for cylinder 1 and 4. The turbine housings can reach 1400 F. Plastic covers insulate the heat. These cars are getting miles on them. The plastic covers have worked for many years.

I don't have any horses in this race. Typically one should be able to reseal the stock plastic cover once or two times and then replace them with new. And BTW, the 930 or 964 Turbo that had the aluminum covers did NOT have a turbine housing sitting right next to them.

A good test is warming up you oven to 180 degrees. Put the plastic cover and aluminum cover on the rack. Pull them out after 10 minutes (use gloves). Let them sit for 3 to 5 minutes, then touch the two.

Turbodan

nothing productive to add to this thread except Kevin's point make sense and I find it hard to believe that Porsche changed from aluminum to plastic to save money on the flagship model.
on another note; Cincy: what inspired your avatar? my 23 month daughter loves peppa pig, she watches it on my iphone and it is quite funny. there is a good episode where there car is in the shop and they get a loaner...really funny

911PERVY

All 993 have the plastic covers from factory, just ask the guys working on these cars if the covers leak and where from

Good points raised on the temp issue, I will let you know if I have any troubles here

race.it

I was considering putting ali covers on mine but after a talk with kevin i got some of his new oil lines, as i could see them being a better investment for my car.

C4S993

In my case, the covers absorbed so much heat that they were bent and thus leaked; even leaked with new factory gaskets. The fix was new factory plastic covers and so far no leaks.

Patrick
1996 C4S

sonny1

Ceramic coat the covers and the turbine housings and shields.,cheers.