2.2 T pistons

[Mick G]

Newbie here, Got this 1970 911T, was given to me 15 years ago, Drove the car 2 weeks after it was new, went are separate ways, doesn't it come back to me years later, free, engine in a box, car a mess, sad to see, took the freebie and stuck it in the barn, been there since, other projects ahead of it, Well now Its turn has come, engine was seized from disuse, the PO decided to dismantle it to free it up, the main tool that was used was a hammer, cylinders beaten off, pistons mangled, most everything else appears OK, missing exhaust, heat exchangers, Let me get to the point. P&C's what CR can I put on a T without problems, the motor is going back stock, no other mods, actually low miles on it, not that it makes a difference, numbers all match want to keep it that way, Thanks

[Walt Fricke]

I don't follow - if you are going to make it stock, use stock stuff. You might find used but within spec Ps and Cs. The T is not the most desirable motor, so guys who hopped one up may have the stock stuff lying around.

[Mick G]

Walt, thanks for that,

[Flat6pac]

I have a 6000 mile long block, 71 2.2 T, for less than you can build for.
Bruce

[jpnovak]

This is one of the downsides of steel rings rusting firmly to cast iron cylinders. I have had to cut some off before. At least I only damaged the cylinders, not the pistons.

911T PC sets are usually easy to obtain.

[Heinz911]

Original Mahle 2.2 T pistons are not available anymore. I used Mahle S pistons as a replacement for them in new Mahle iron T cylinders, but had an issue with the P to C clearance. Piston nr. 4 seized and had to get it replaced and all my cylinders honed to increase the clearance. Knowing this I would have better honed my old cylinders to oversize and bought some custom JE or Woesner pistons to match. This leaves you also the opportunity to get the CR you want.
In my current set up with S-pistons I have a theoretical CR of 9.6:1 and it is running fine with standard T cams.

[Mick G]

Thanks for the responses, I was thinking if I have to replace the P&C's, that bumping up the CR wont cost me anything extra, and maybe gain a increase in HP, CR being the most significant gain versus other mods, just didn't want to go too far,

[doswald]

Mick, I'm in the process of rebuilding my '71 T. I had the stock iron cylinders bored 1 mm to 85 mm; and I'm installing JE pistons with 9.5 compression. I also had my cam reground to the Solex profile. To answer your specific question, my understanding is that 9.5 is about as high as you can go without dual spark plugs.

dho

[Matt Monson]

I'll be doing something similar to doswald, but on a 2.4.

[Mick G]

Thanks, that's what I was looking for, I think 9.5 sounds reasonable, but a Solex profile? not familiar with that, got to get some reading done on 911 engines before I get going on this

[Matt Monson]

It refers to the cam profile used on the first 911s made that ran Solex carbs, before they split to T,E and S models. Good all around performance grind.

[Walt Fricke]

I would suggest that a displacement increase is more valuable than compression bumping, and less tricky. You could have your case bored for 90mm cylinders. Lots of those in good used condition (or reconditionable) around. CIS pistons ought to be inexpensive also, if you don't want to spring for new ones. That would give you 2.519 liters. Boring cylinders you don't have to 85mm only bumps your motor to 2.3 (actually, 2.247) liters, and there are no stock pistons in that size if you want to economize on those parts.