Stroked 3.2 motor build?

[911TT33]

Hey guys,

Is it possible to use a 964 crank with 100mm P&Cs in a 3.2 Carrera motor to bring it up to 3.6L?

This is for a rebuild I’m considering in 2025 on my twin turbo 3.2, which currently uses 930 97mm P&Cs, thicker base cylinder shims, C2T head gaskets and 993 GT2 EVO CAMs.

Looking to run 8.0:1 C/R on the new build.

Also planning to hook up twin plugs and go with an aftermarket ECU such as Motec/Haltech. Undecided.

[Loxit001]

Nice! A stroked 3.2 motor build sounds awesome!

[icarp]

looks like someone is trying to up there post count

remember that name

[GG Allin]

I have a 3.6 that was built on a 3.2 crankcase. The 964 crank is a direct fit. It has early 964 Mahle cylinders that were modified to fit the case. The case was also opened up to 105mm to make the cylinders fit. A little off the cylinders, a little off the case. The stud spacing on them was also modified.

[911TT33]

Originally Posted by GG Allin

I have a 3.6 that was built on a 3.2 crankcase. The 964 crank is a direct fit. It has early 964 Mahle cylinders that were modified to fit the case. The case was also opened up to 105mm to make the cylinders fit. A little off the cylinders, a little off the case. The stud spacing on them was also modified.

Awesome build! Good to know it’s been done 😎👍🏼

My motor already has 964 piston squirters. I’m thinking I’ll also upgrade to a 930 engine oil scavenge pump.

[MoreGAS]

What you need also to address besides elongating the holes for stud spacing differences is the cylinder height difference . You'll have to make a spacer to press on after cutting the O ring groove out of the bottom of the 964 cylinder to make up the difference to a stock 3.2 3.3 cylinder, then you can adjust the deck Ht w traditional but special copper shims(we can provide) .. We have done this several times (on our own stuff as kind of left handed lol ) and even making a 3.6 L turbo in a 3.3 case as you aim. I'd advise to flame ring the top as that mating surface head to cylinder is still pretty dodgy and the weak link on that engine, even at 1 BAR.
LN sells some Billet cylinders for this 100 MM race dimension appl. but they are silly costly as most of their stuff tends to go.

It may be better to run 95 Bore(or find C2 Tbo cylinders fully finned 97 s and get rid of the finless 97 MM cylinders that crack on occasion) , put in a "stroker" crank, and keep the cylinders stronger and more round under high cylinder pressures you'll see w Boost. A couple more psi Boost can easily make up the difference in lost displacement.

beST

Kevin
GAS Motorsport

[911TT33]

Originally Posted by MoreGAS

What you need also to address besides elongating the holes for stud spacing differences is the cylinder height difference . You'll have to make a spacer to press on after cutting the O ring groove out of the bottom of the 964 cylinder to make up the difference to a stock 3.2 3.3 cylinder, then you can adjust the deck Ht w traditional but special copper shims(we can provide) .. We have done this several times (on our own stuff as kind of left handed lol ) and even making a 3.6 L turbo in a 3.3 case as you aim. I'd advise to flame ring the top as that mating surface head to cylinder is still pretty dodgy and the weak link on that engine, even at 1 BAR.
LN sells some Billet cylinders for this 100 MM race dimension appl. but they are silly costly as most of their stuff tends to go.

It may be better to run 95 Bore(or find C2 Tbo cylinders fully finned 97 s and get rid of the finless 97 MM cylinders that crack on occasion) , put in a "stroker" crank, and keep the cylinders stronger and more round under high cylinder pressures you'll see w Boost. A couple more psi Boost can easily make up the difference in lost displacement.

beST

Kevin
GAS Motorsport

Thanks for tuning in, Kevin.

Yep, I was definitely considering flame ringing the cylinder to head junction and running thicker cylinder base shims.

My current build has 0.5mm base shims with 0.5mm C2T head gaskets, and my 97mm cylinders were shaved down by 0.75mm to retain the desired C/R.

[PeteKz]

If you shortened the cylinders .75mm, be sure to check the clearances between the pistons and the heads.

[MoreGAS]

Ditch the stainless rinky dink c2 tbo gasket as that is not helping really and Porsche skipped that next engine version. You'll have to cut the heads additionally outside the mating surface (or it will hit and not seal) when you remove that gasket(ask me how I learned 20-25 yrs ago ;(
An MLS gasket would be great(not easily achievable w your bits) or flame ring it as noted so you don't have to do later when you Blow boost out which is probable if you have stock late 930 CIS at 1 BAR...
We all in The Porsche World fit the copper gaskets to adjust the deck, simple as that. VW guys don't even run them, dodgy to me as I don't want to do again for free when it leaks .
You have a darn near flat piston(even if an 8:1 aftermarket deal) so hitting the head is pretty impossible if deck is correct, .036" minimum. If you put a fairly big Tbo cam in, which I encourage, you may need valve pockets remember.

BooST on

Kevin
GAS Motorsport