3.3 heads on a 3.2 SS?
 

I'm converting my 3.0 to a 3.2 Short Stroke. I'm also going to turbocharge it. Can I use 3.3 930 heads without machining anything?


Thank you for any help with this.

Chris

I would not do anything like what you are doing without consulting a Porsche engine designer...

Not sure what the advantage of using 930 heads over SC heads. But it depends on a number of factors.

The alloy is different for one; the turbo heads are RR350, high temp alloy. The NA cars used alloy "Y." The RR350 alloy is good for an extra 100 degrees of CHT, IIRC.

Short answer is yes, they will bolt on to the head studs and cam towers. Intake stud lengths etc. are different and the big difference is port size. The alloy is better but ultimately power potential might not be as good given the smaller ports on 930 heads stock for stock.

For reference, I am using 930 casting heads for the better alloy in my Short Stroke 3.3L Normally Aspirated build…….. but they have been extensively ported with 4mm oversize valves and new seats by xtreme and a little welding to get rid of the CIS injector notch to match up with TurboKraft’s EFI injector blocks and 3.6L intake manifold. If I were to do it again, the cost difference to just get fully new xtreme casting heads is small enough, I’d just do that.

None of the 3.0 930 turbo heads had RR350 marked on them, they had Y.
3.3 turbos got the heads made from RR350 during MY 1978.

My 1978 turbo has been made autumn 1977 and letter Y is casted on the heads. 930 heads made January 1978 have RR350 on them. I don't know the exact month when did the change happen.

http://forums.pelicanparts.com/uploa...1692340557.jpg

edit: or maybe Porsche decided that they have to mark RR350 on the head and this was the reason for changing from 930.104.341.2R to 930.104.341.3R but they both could be from excatly same RR350 material.

edit2: I started new thread in here 930 3.0 and 3.3 heads

934 & 935 had letter Y on their heads, at least the earlier ones.
Actually the 935 heads on the link below has the exact same cast number as on my 930 heads 930.104.341.2R and that 935 head has been casted July 1979.

935-twin-plug-heads-imsa-champions-john-fitzpatrick

The simple answer to your question is yes. The 930 heads will work.
The bigger question is, what's your performance goal, and how do you plan to attain that goal. They have very small ports so you can configure the ports the way you want. You're not locked into a big port that may not suit your design parameters.
The 930 heads are a great place to start if your goal is <350hp. Of course they can accommodate more but then you're talking about reducing detonation propensities.