Does anyone know why the unworked exhaust ports of cylinder 2 and 3 are narrower than cylinder 1 and 4's exhaust ports in the B series vtec heads (specifically the B18C1, especially in the bowl area)? Cylinders 2 and 3 exhaust ports are also directional left and right. I'm hand porting my first head and am concerned about enlarging the exhaust ports in cylinder 2 and 3 to match cylinder 1 and 4's thinking i might break into the coolant area. Anyone have experience with this? Thanks for any help.

 

If you are enlarging the port walls/mouth at ALL, you are most likely doing it wrong.

Blend the bowls, clean up any casting flaws, do a final pass with ~300 grit, and call it a day.

Any more than that, and you better have a flow bench, or at the very least, individual EGT's when tuning...

 

If you really feel the need to start grinding away, at least read this first.

The Old One - Energy Dynamics : Articles

The Old One - Energy Dynamics : Articles

"The most important areas to work for flow are all in the valve seat area. You can make damned near any port flow 90-95% of a fully worked configuration, by doing only the chamber, the seats and 3/4" into the ports. The ports' entries and exits may be the easiest stuff to reach and slick-up, but those parts really don't mean anything when it comes to flow."

 

Thanks for the reply, I've actually read those very informative articles SOOO many times. I've been told by a professional porter with a flow bench that the left and right directional runners basically need to be treated as their own and not try to match them just because they are so different from the others. I brought the head to him Saturday and we took some measurements of the runners and started making a adapter for my bore size because he only works with domestic stuff. So hopefully next Saturday we'll see how it's flowing and where improvements can be made.

 

That's cool you have access to a flowbench. Curious to see what does what when it comes to posting and cfm.
Are you gonna deshroud the valves on the combustion chambers too?

 

I read those articles, and it has inspired me to try mild porting when the time comes. Looking for more knowledge, does anyone else have any great articles they'd like to post up?