Newbie heads porting & heat exchanger question

[profblue]

Rebuilding a 2.4 engine, and I have the ports ported from 32/32 to 36/36mm. I am just pulling the trigger on new stainless heat exchanges, and only see essentially 2 models (MFI and carbs). My questions:
- What are the port sizes of the heat exchangers? are all 32mm, or are they larger?
- Is there a need to have these machined, or does it not significantly if these are not matched up, ie. 36mm from the heads into the 32mm of the heat exchanger?

Thanks,

[MST0118]

I think the normal SSI heat exchangers is 35mm inner diameter which is about 1 & 3/8 inches. Btw, your 36/36 port sizes are close to what was on the 73-76 MFI Carreras that had 36/35 ports. I’m not sure of the ID size of standard 2.4 heat exchanger though.

[stownsen914]

I’m not aware that Porsche built different diameter versions of the early heat exchangers for 2.2/2.4 models. You should be fine at 36 mm with stock ones.