[Hcarraro]

John C. Thank for your inputs. Actually if you Google 87.5mm porsche pistons or any number of similar machinations, there are many 87.5mm pistons and cylinders out there. And Porsche did in fact use 87.5mm pistons in several of their engines but the high dome is what eliminates the 356 or 912s from consideration.

Here is a fact. Porsche did build 30 special S/T rally motors (Type 911/20) using a 2.0 liter and or a2.2 liter magnesium crankcase as a base that was then bored to 87.5mm. With a 70.4mm crank and the 87.5mm pistons you get 2381CC. John Starkey's book mentions these special engines on page 15 and I found blurbs elsewhere on the Internet.

Tom, I am almost positive the wrist pins on these pistons is 22mm but haven't had a chance to get to my shop to measure them. I was hoping Patrick would chime in. He is the fellow that removed an identical set of these pistons and cylinders from a 66 911 engine bored to 87.5mm.

My gut tells me that these are not Porsche S/T racing pistons but perhaps a knock off. According to Starkey's book Porsche built these race engines for the 1971 race season, and at 250hp a 2.381cc engine in a light weight 911 had to be a real potent race car.

It doesn't surprise me at all that an aftermarket supplier like EMPI or other would reverse engineer an original Mahle piston and Biral Cylinder in order to build a knock off of high compression piston and cylinder, especially when you consider the horsepower potential of a mixed and matched use of Porsche engine components.

Yep, the mystery continues. Thanks to all for the inputs.


Henry