S engine 2.2 Port size

[Alan.UK]

Hi all,

Does anyone know the size of the head inlet port (manifold to head) on 2.2S engine.
Mine is approx 36mm and the size between stacks and manifold is approx 39mm. Does this sound correct.

I also saw another 2.2s engine recently and the head to manifold port was 33mm and the manifold had what felt like a step in the middle of it. The stack to manifold port was also smaller than mine.

Both engines are good engines I was just wondering why they are different
Any ideas.....

Alan.UK

71 S - Getting fresh coat of Signal Orange -

[jluetjen]

I've got some 2.2S heads and they have 36mm intake ports. This also matches BA's data in his 911 Performance Handbook.

I don't know of any early 911 heads that came from the factory with 33mm ports, but I have recently heard of some 2.4T heads which had smaller ports then the 32mm ports described by BA. So anything is possible. From gas flow calculations that I've done, I doubt that the 33mm ports came in factory S heads. They would have been too small for the 2.2 liter capacity and high rev'ing S cams and would have choked off the engine performance above 6500 RPM just where the S cams are pulling strong.

I suspect the second engine that you described has ported T/E heads. The 2.2 T/E heads supposedly came from the factory with 32mm ports. If they were ported, I don'k know why the were only ported by 1 mm unless the intention was to match the gaskets. Still, if the engine has S manifolds, they would have the step that you described which I can't believe it a very good thing. They can be ported out to S specs, it's just a question of time and $'s.

[Alan.UK]

Hi John

Thanks for your reply. Could I just confirm then that the 2.2 manifolds "should" have a step in them? The ones on my car are slightly tapered but are flat/straight with no step in them, is this correct.

Also the linkage arms on my manifolds are straight while on the other engine they are curved at the end. Does this shade any more light on the mystery?

Thanks
Alan.UK

[jluetjen]

I would be surprised if there was a step designed into the manifolds or that Porsche built them that way. But I've haven't inspected enough to know. If you put S manifolds on T/E heads, you would most likely wind up with a 2 mm step where the manifold and the heads meet. I'd never run a motor like that, but others have pointed out that lots of (non-Porsche?) motors have a mis-match similar to this as a result of assembly tolerances and they are none the worse. It would hardley constitute being "blueprinted" though.