Porting 2V heads

[928s]

Guys just had some 2V heads ported, some of you may be interested in the procedure as many think they cannot be improved enough to justify the effort, I had that conversation with some of the regulars in the last 6 months. The thread includes some testing on my custom intake manifold.

Engine is going into my manual car but I am building bigger engine currently so this engine which is rebuilt will also be for sale next year. Should make 100 hp over the standard engine when used with my headers.

The thread is a typical internet forum thread, some crap in it but mainly facts.

The first page or start,Porsche 928 heads

Porsche 928 heads

The finish and results. Porsche 928 heads - Page 7

Porsche 928 heads - Page 7

This is a live thread and we will be adding the larger valved heads in the next couple of weeks. Those heads are going on a 104 mm bore, the capacity will be 5.35 litres, both engine run the compression at just over 11 to 1 and the engines have be finessed in quite a few ares. It should be interesting. Looking for around 440 to 450 HP for the bigger engine.

[Arizona_928]

Nice work. Post 93 looks like you hit a water passage?!
what block route are you going??

[928s]

Originally Posted by AZ_porschekid

Nice work. Post 93 looks like you hit a water passage?!
what block route are you going??

That port that hit water was on a sacrificial development head not the heads we were ever going to use. These heads are going on a 5.0 litre block.

[Danglerb]

I recall one of the issues with porting is shifting in the original casting so some spots may have less metal in some places. Sure would be nice if we could get CNC setup to make early or 944 heads into something better than Euro S.

[928s]

Originally Posted by Danglerb

I recall one of the issues with porting is shifting in the original casting so some spots may have less metal in some places. Sure would be nice if we could get CNC setup to make early or 944 heads into something better than Euro S.

We will be CNCing the big heads, i.e for the stroker, these are oval port heads that I got the valves from for the 5.0 litre engine. My cylinder head guy has tools per the thread and other tools like x-ray to see how thick the casting is. The reason we kept pushing was that the flow kept getting better and we just wanted to see how far we could push it.

I will be using a 55.9 mm intake valve and we will be looking for flow around a hundred cfm more than these heads. It will be interesting to see if we can get 270 cfm from the 104 mm bore engine. We set 250 cfm as the goal for these heads but only achieved 243 cfm albeit with a fat curve which was very good. The heads had been ported before as such you can't put that material back! This is what I suspect lead to our shortfall.