3.2L heads on 3.0L motor?

[cstreit]

Gang,

Was thinking of putting a set of 3.2L heads on my new motor... 3.0L SC motor with Cams and 10.5:1 Mahle pistons, carbs, etc...

3.2L heads obviously had bigger ports 40/38 than the 3.0L SC US model of 34/35... So this would be an advantage and save some machine work opening up my heads, BUT...

What would this do to the compression ratio? WHat about dome compatibility? Anyone know?

[cstreit]

Noooobahdee knowsss, the trouble I've seen... er.. question I've asked...

Bump.

[A Quiet Boom]

Chris, if the heads cc the same and have the same shape then compression won't be altered. I've been thinking of this myself since I have access to some 3.2 heads but until I know the cc's of both heads I can't be sure. So...let's help each other, if you cc your 3.0 heads, I can cc the 3.2 heads and we can compare. It's even possible (but unlikely) that compression might go up. My brother in Michigan has a 3.2 core that I've been trying to buy the heads from. If your unfamilar with cc'ing heads have a machine shop do it or buy a kit from Summit Racing or Jegs.

[cstreit]

Thing is 3.2L cylinder/heads are gasket-less aren't they? I'm beginning to wonder if these could work on 3.0L cylinders...I'm pretty sure it would drop the compression slightly... If I recall, they may have a bigger dome pocket, but I can look that up.

I gotta find out if they are even compatible before thinking about ccing them... But if they are, it's a deal...

[Bill Verburg]

Except for port size, I believe that the SC and Carrera heads are the same. They definitely both use the same .25mm thick head gasket(gasket less was only for the early 964s)

[john walker's workshop]

don't forget that they're shorter on the intake to compensate for a phenolic spacer between head and intake. i've never CC'd them to see if the chamber size is the same, but i believe it is.

[pbs911]

I thought the 78 - 79 heads were the ones with the larger ports.

[82SC]

i bought my set of 3.2L head because I was told from andial and rennsport systems that they are better then the SC's I had.

this was for a 3.5L MFI engine that Steve W had helped me plan...

I think the advantages are bigger ports and a better "shaped" comb chamber...whatever that means.

I will look in my email archive3s and see if I can dig up Steve W's email about them

MJ

[82SC]

this is what Steve W at rennsport systems said about the heads





I am thinking if buying his heads is a good addition to my current project?

The heads should get new guides and a total valve job. As indicated, these must
be mated up to the intake legs.

> Do they flow better?

Heck yes!

> are the ports bigger?

Yessir, and better shaped internally.

> would these be compatible with my SC?

With some work.


MJ

[CamB]

Steve's site has info on the differences between the heads.

"The first 3.0 SC engines, 78-79, employed larger ports and intake manifolds than the later, 80-83 models. These early heads are a little more suitable for modifications and have more airflow than the later ones. For applications requiring major camshaft and compression upgrades, both types of SC heads should be opened up and flowed for maximum airflow at all valve lifts.

The 3.2 Carrera heads used on the 83-89 engines represented a major increase in airflow. These are excellent heads for street engine as well as mild race engines, just as they come, from Porsche. Additional airflow improvements can improve these even more for racing applications.

We have been able to make these 3.2 heads flow as well as the Factory 935 heads, a benchmark of performance. For racing and/or high RPM use, we recommend using better valve springs to help control the large, heavy valves and help prevent valve float which can occur as low as 6800 RPM with older, stock valve springs."

http://users.easystreet.com/porsche/2f.html

[Sicklyscott]

This is a VERY old thread but I was wondering if the OP got this working. I'm currently beginning to plan (3 years out maybe) my 3.2SS build and was looking into twin plugging a set of 3.2 heads instead of reusing the 3.0 heads I have.

Any thoughts? Any lessons learned?

[toddu]

Have 3.2 heads on my 3.2SS. Also have 3.2 cylinders (no gasket ring). Makes about 299 fwhp.

Todd

[911S_1975]

Originally Posted by Sicklyscott

This is a VERY old thread but I was wondering if the OP got this working. I'm currently beginning to plan (3 years out maybe) my 3.2SS build and was looking into twin plugging a set of 3.2 heads instead of reusing the 3.0 heads I have.

Any thoughts? Any lessons learned?

Hi, sorry to bring this all thread back.
Any update on this topic?

I´ve got a 1980 3.0 SC small ports engine which I´m about to rebuild it.
Just wondering if replacing the small ports heads with 3.2 heads would make any sense?

I´m not planing to build a race engine but if I can be close to ROW late 200hp Sc I would be happy! I don´t want to lose low end torque as it has to be streetable.

Any suggestion would be welcome!