Can I use forged pistons in cast-iron cylinders

[Heinz911]

I start this new topic because I want to get some fresh new attention to my engine problem.

I have rebuild my 2.2 T engine with new Mahle forged S pistons and original cast-iron cylinders. After only 50 miles the engine developed a ticking noise and after tear down I found a seizure on cylinder 4. My machinist now suggests that the combination of S pistons in T cylinders is the source of the problem. He measured the clearance (0,05 mm) between the P&C and says it is to narrow for forged pistons.

Does anyone have experience with this?
What would be the right clearance?
Can we solve this by honing the Cylinder to this bigger clearance?

Thanks for you responses!



Original thread:
Ticking noise after rebuild 70's 911T

[Turboman]

Originally Posted by Turboman

Heinz. Some years ago I asked Bruce Anderson if I could use JE forged pistons on a 914-6 iron sleeved cylinders. He strongly advice against using aluminum forged pistons on iron sleeved cylinders. He said that the expansion rate of the aluminum will cause problems with the iron cylinders. On the other hand I know a couple of 911 engines with cast iron cylinders and JE pistons running OK. I do have, JE forged aluminum pistons on iron cylinders on my 356, for over a decade without any problem. Wayne Dempsey's book, analyses and explain the different cylinders and pistons used by Porsche. You should read his book, and take your own conclusions. Tot ziens. Francisco

[tom1394racing]

Porsche used forged aluminum pistons in iron sleeved cylinders for all the 911S models up to 1974. The cylinders were iron sleeved with a finned aluminum outer shell. (Biral).