Head ports to big? Performance proplems?
 

I have 40mm intake ports on my 2.5MFI motor with 38mm MFI throttle bodies. Will this cause any big problems in performance? I can not afford to have my extra 2.2S heads ported to 38mm intake right now so I want to try the 40mm ones. They are already twin pluged but big ports. The engine is a 66 X 90, 11:1 comp, GE-60 cams, 2.2S pump with RS space cam. Headers are 1 5/8. Should I go for it?

Mark:

JMHO, but those ports (and headers) are too big for a 2.5 w/GE60 cams and while it should run well, you are giving up a lot of torque between idle and 6K. Muffler system choices are also critical here, as well.

I would suggest rethinking this combination, especially if this is going to used on the street.

I hope you have a good, close-ratio gear stack. :)

Can't you just press in an aluminum collar to choke down the port diameter?

Thanks Steve. I was kinda hoping that the 38mm throttle bodies would be the main choke and the larger head port would be just a wasted port size.
Kenik, I have not heard of aluminum collars. The port job would have to be a perfect round bore for that to work I'm thinking. But thanks.
Sounds like I send out my extra 2.2S heads for the proper job.
When does the $$$$$$ slow down on these projects?
Thanks again.