2.7L Pistons and Cylinders
 

I have a 1976 2.7L 911S that I am in the process of rebuilding. Engine was rebuilt at 34,000 miles ( I dont know what was done just that there was a rebuild. Upgrades are present). Car now has 64,000 miles and has been sitting for 15 years. Upon teardown I have discovered that I have 5 cylinders that are Mahle Allusil Cylinders and one that is a Mahle Nikasil. One of the allusil pistons and cylinders are scored so that one needs replaced either way. So I am trying to decide what I should do.

Options as I see it are:
1. Replace all cylinders and pistons with pistons, rings and Nikasil Cylinders, Mahle. Most expensive.
2 Replace all five piston and cylinder sets with Nikasil and rering the 6th.
3. Replate the Allusils with Nikasil via US Chrome. Replace Pistons and rings with JE or Mahle.
JE does sell a piston kit for these however the compression ratio is 9:5 not 8:5. I would have to figure out how that would affect the CIS calibration.
4. Replate the Allusils with Nikasil via US chrome and reuse the pistons. Replace rings. So this appears to be the less expensive option however I seem to recall in Wayne's book Allusil pistons are not compatible with Nikasil coating?? So probably the least desireable option.
5. Consider a JE piston kit with new Nikasil Cylinders but this puts me back into the calibration issue going from 8:5 to 9:5 compression ratio.

Looking for some feedback on these options and what you feel is a reliable solution at a reasonable cost comparatively speaking. Probably the easy answer is go all new it just is the most expensive. Thanks for your input.

So you have one odd nikasil and one scored alusil (how badly?)

Personally I'd start fresh with new machine-fit P&Cs. Have you considered JE pistons and Nickies Cylinders? About $1k cheaper than mahle

http://lnengineering.com/products/aircooled-cylinders-pistons/porsche-911-1965-77.html?p=3


Other than that, option 3 with JE pistons would be cost effective and you'd have nice new pistons to boot.

You could buy a good used set of Mahle Nikasil P&C's for about the same price as having you Alusils replated in Nkasil. PM me if you would like to explore that option.

You might ask JE if they could give you lower compression pistons.