Using 993 Piston/Cylinders on 964 Heads?

[964Play]

Hello,

Is there any modification required to early 91' heads if I wanted to use 993 Cylinders with the gasket?
I currently have the old style 964 cylinders without the gasket groove.

Thank you for your help!

[MBruns]

Most 911 engine machine shops can cut the seal surface to update to the later style, what part of the country are you ?
Mike Bruns

[targa72e]

The 964 heads need to be modified to use the 993 cylinders as they are supported different at the head. This procedure is documented in a Porsche technical service bulletin 9404 . Most shops that work on 911 heads can do the update it is relatively inexpensive. more info below.

Understanding 964 Head Gasket Modification


thanks,

john

[964Play]

Originally Posted by MBruns

Most 911 engine machine shops can cut the seal surface to update to the later style, what part of the country are you ?
Mike Bruns

i'm located in the northeast. I already have 993 rods, pistons & cylinders I will just have to machine the 964 heads.
Thanks!

[964Play]

Originally Posted by targa72e

The 964 heads need to be modified to use the 993 cylinders as they are supported different at the head. This procedure is documented in a Porsche technical service bulletin 9404 . Most shops that work on 911 heads can do the update it is relatively inexpensive. more info below.

Understanding 964 Head Gasket Modification


thanks,

john

Hi John,

Thank you for the confirmation, I will have to machine the 964 heads to accept the 993 cylinders.

Thanks!

[Henry Schmidt]

If you're planning on using 993 pistons on a 964 engine you will encounter a rod to piston clearance issue.
The 993 rods are quite a bit narrower than 964 rods. 25mm vs 19.75mm?.
The pistons are similarly different.

[targa72e]

You will also need a 993 crank. As Henry pointed our the 993 rods are narrower than 964 which are the same as 3.2 and 3.3 engines. If the clearances work out you can run 964 pistons in 993 cylinders.

Thanks,

john