Opinions needed on /6 intake and exhaust port sizes Options

[tornik550]

My engine was originally a 2.2e however I rebuilt it as a 2.7l 9.5:1 compression. My heads are 2.2e heads with 32/32mm intake/exhaust ports and 46/40 valves.

Would there be a benefit/problem with enlarging the intake port to 35mm? Stock 2.7 heads have the same valve size and 35/35 ports. I would have the exhaust ports enlarged also however that appears to be a difficult job and I cannot find anyone to do it.

Also I have two sets of headers- 1 1/2" and 1 5/8"

Thoughts on the port size and header size?

[mepstein]

I plan on using 1 5/8" on my 3.2

[mepstein]

double post

[r_towle]

I was under the impression that the 2.7 motors are parts motors...
So, buy some 2.7 heads...

[screenguy914]

Yes, port size was enlarged to increase gas flow per their design specs. There are several Porsche machine specialists who can correctly increase the port dimensions. if possible, I would suggest a facility close to home. Where are you? If not a requirement, Rennsport Systems, Competition Engineering, Aase Bros., Supertec Performance, as well as other shops. Perform your due diligence in choosing a shop. There are borderline/unscrupulous/incompetent individuals/business out there.

Another option, depending on the condition of your 2.2 heads - since the shop may want to replace/regrind the valves and seats as part of the operation as well as other needed work (truing cylinder head-to-cylinder surface, replace valve guides, etc.), is to source a set of rebuilt 2.7 heads with the correct port sizes. The shop can perform the same above operations with the correct port size to begin with, and you'll have a set of 2.2 heads to sell to offset the cost of professional porting and flow bench testing, perhaps $1000-$1500. Many shops can perform the basic machine work. However, Porsche-specific machining jigs mark a shop who can perform these operations accurately with repeatability.

Knowledgeable tech people recommend 1 5/8 exh. tubes (1 1/2" ID) for engines around 3.2 and larger.

Large tubes on a smaller engine may sacrifice mid-range torque. Thus, 1 1/2" tubes would be recommended for engines <3 liters.

You could also ask for recommendations at 911-specific tech forums such as PelicanParts.com and/or Early911SRegistry.org.

Welcome to the slippery slope of engine rebuilding.

Sherwood

[tornik550]

Thank you for the info.

I should clarify my situation. I was not clear in my original post.

I have a completely rebuilt set of 2.2 heads. I contacted cgarr about increasing the port size. Apparently this is not a unusual modification. He opened up my intake ports to 35mm and cleaned up the exhaust port. I am not sure why but he doesn't do the exhaust port.

Since my heads are already rebuilt and have wider intake ports, I am not really interested in getting 2.7 heads.

I am glad to hear that I should be using the 1 1/2 headers. They are a nice new set of MSDS headers. The 1 5/8 is old and ugly.