John..

I am in the process of rebuilding my 81 Callaway 928. I hae two IHI RHB-6 turbos that bolt up to the hand made manifolds. Here is the issue: I have no gaskets between the manifold and turbos. I beleive the turbos were serviced sometime after the car was made, so I'm not sure if Callaway had installed gaskets or not. IHI no longer carries gaskets for those turbos.

I have access to a laser shop. What is the best material for such a gasket? I have heard copper works, but also may leak over time. Is stainless steel a good choice, and if so on either of these, how thick? 0.030"?? Can I run without?

Thanks

Danno

Does the turbo or manifold flanges have a groove? The 944 Turbo uses compression-rings instead of a normal gasket. This creates a small surface area of contact. The rings are hollow steel that compress for the seal.

If both mating surfaces are flat, I'd recommend taking the manifold to a machine shop and having them cut a groove for the compression rings.

dand86951

I would agree with Danno that if possible cut the grooves for the factory 951 steel rings. They seem to work for a long time.

John..

Both suraces are machined flat and the IHI turbo is more of a rectangular flange rather than a square flange.

dand86951

The trick is to see if the steel ring would fit over the rectangular flange, a circle over the rectangle. If there is room on the turbo flange, then machine the groove into the exhaust flange and you would have a good seal.

Danno

The exhaust flange on the KKK turbo is rectangular too, but the opening is round. The groove is actually on the manifold flange. I would carve the groove on the flange that's thicker with more meat on it.

Also the smaller contact area of the compression rings results in higher pressure, thus better sealing.

John..

I am probably going to go naked here. These things sealed well for 20+ years, so no reason they wont now.

You guys would have to see my manifolds to know exactly how tight they are. There isn't much meat around the mounting surfaces to do machining.

If I lose a gasket on the pass side I am up **** creek, as the motor will have to be lifted to gain access.

UGH! It is never an easy decision, especially when you are a perfectionist.

nine-44

I'd really hate to get flamed for this, but. What about copper gasket spray? I read on the can that it is meant for HG and turbo flanges to fill minor irregularities in the mating surfaces.

Steve Lavigne

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by nine-44:
<strong>I'd really hate to get flamed for this, but. What about copper gasket spray? I read on the can that it is meant for HG and turbo flanges to fill minor irregularities in the mating surfaces.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I was just thinking the exact same thing.

The Permatex Copper gasket maker that comes in a tube would probably be a good solution. I've had good experiences using this on my gearbox kart, but I had the thing apart so often that I couldn't gauge the longevity.

jdog

You could also use an anerobic gasket maker such as one made by permatex that is designed to be used when two metal surfaces are to be put together with out using a paper gasket.

John.

Callaway recommended high temp silicone....I also thought about the copper spray route. Whatever I use will need to be okay to 1000+ F, so I'll investigate and let you know.

I'm not sure it tha aneorobic sealants are good at those kind of temperatures.

Callaway advised against gaskets, for longevity reasons, but this is the only car I have ever seen without gaskets between the turbos and manifolds.

jdog

Yes, i believe that they are only good to temps. around 700.

Danno

If you can get the mating surfaces flat to within 0.1mm, then the coppercoat sealant should work OK. Easy way to test this is lay down a thin layer of prussian-blue on one surface and tighten the bolts. The gaps will show up easily.