Piston ring end gap on 3.6L turbo build?
 

Currently building a 1994 3.6 liter M64/50 Turbo motor and plan on running 1 bar of boost. Here is a question I got from my builder today. Can anyone help. Thanks in advance.
"I would like to know if there might be a better head gasket to use. I have a Victor Reinz gasket set. The head gaskets look good, but is there something better that we should use.
If you can check on this also.
I need to know what is a good and safe piston ring end gap to run on the piston rings.
The old rings that I removed from your engine showed little wear, the gap on them is,
top ring .35mm
2nd ring .40mm
bottom ring .50mm

The new piston rings are Goetze rings 08-325100-00 the gap on these rings are.
Top .33mm
2nd .33mm
bottom .28mm

I think that the ring end gap should be this and maybe a little more.
top .40mm
2nd .40mm
bottom .30mm

This is going to be a lot higher boost engine then the stock one was so I would like to know what will be the best and the safest gap to run."

I didn't have to file my Goetze rings cuz they gapped out fine and yours look fine too, but I'm sure a pro builder will chime in and tell you for sure. Also, the sealing rings for the heads in the VR gasket kit should be the ones you need. My 3.3 didn't have any sealing rings at all so I had fire rings added.

What's a rebuild cost estimate run these days?

Henry? Steve? Can't anyone help with this info? Thanks

http://www.aa1car.com/library/ringendgap_wiseco.pdf

I used non standard rings in my build that had to be gapped, which were supplied by Chris Carroll at Turbokraft. Chris gave me the recommended end gap specs which lined up very much with the table I linked above.

I don't think there is anything particularly special about a turbo Porsche when it comes to piston ring end gap. The only thing I would say is, they run hot as hell. Given that, it seems to me that you want to err on the side of too large an end gap vs. too small.

But the Aluminum should expand more than the steel so I would say that you would want a tight ring gap cold since it will only get larger with either heat or mileage.

On Nikasil engines with hi compression I run these gaps if I can;

top ring .254
2nd .254 to .305
oil control .305 to .355

Never run less gap on the next ring down as problems like ring flutter could occur.


Stock engines can have as little as .15 @ the top ring with a max of .4

Anyone with a better head gasket idea? thanks

Any turbo engine builders have an opinion? Thanks in advance.

Aaron or "Burn-Bros" (see his post above) is a professional, so you are getting top notch info right there.

What did you decide to do?