2.7s 1974 engine upgrade....

[st sulpice]

Am i in the right direction!!!!!

i want to get more power from my 2.7s 1974.
after hours and hours of research i took all the tread i read and went to this conclusion:
(I really want to keep my cis system)
what i have on the bench so far is:
real 2.7rs 90mm piston/cylinder
964 cams
fresh 2.7s head
Webb Machine Design Stainless Porsche 911 CIS Airbox
ssi headers
Carrera OIL FED Chain Tensioner Update Kit
front carrera cooler
BMC Sport Air Filter

Can you help me with my choice

how many horse power do you think im gonna get?
Thanks

[Henry Schmidt]

Originally Posted by st sulpice

Am i in the right direction!!!!!

i want to get more power from my 2.7s 1974.
after hours and hours of research i took all the tread i read and went to this conclusion:
(I really want to keep my cis system)
what i have on the bench so far is:
real 2.7rs 90mm piston/cylinder
964 cams
fresh 2.7s head
Webb Machine Design Stainless Porsche 911 CIS Airbox
ssi headers
Carrera OIL FED Chain Tensioner Update Kit
front carrera cooler
BMC Sport Air Filter

Can you help me with my choice

how many horse power do you think im gonna get?
Thanks

The biggest restriction to performance in your proposed build is your piston choice. Although they claim to be 8.5:1 they really aren't. They are closer to 8:1.
By running a higher compression piston (9.0 or 9.5 to 1) you will get the most out of your CIS. The SSIs and air box have zero affect on horse power.
If your cams are truly 964 factory cams and not 964 regrinds they won't fit in 2.7 cam towers.
964 cams are 49mm and 2.7 cam towers are 47mm.
My favorite cam for early CIS engines is the Webcam 20/21 or some version of that spec from another grinder.

[Walt Fricke]

As Henry notes, your '74S came (most likely) with the same header design as the SSIs. Those don't rust, and look better, but don't function better. A better functioning header costs a lot more.