How does ported heads affect boost?

On my stock bottom end, I'm considering installing my old 9psi procharger. My motor didn't last long on the blower before but I'm wondering if the ported heads and 846 cam will help reduce some of the cylinder pressure.

I've heard of folks losing boost while making more power with ported heads. Is this true and how will the cam help or hurt me?

Will I be able to get away with lowering my boost to 6 psi and what, if any, gains should I expect to see?

I've heard of folks losing boost while making more power with ported heads. Is this true and how will the cam help or hurt me?
they're showing less boost on the gauge because more air is able to enter the cylinders, thus making more power... But, cylinder pressures are actually increasing.

The cam has more overlap, so it will actually help to relieve stress by bleeding off some boost while both valves are cracked open. I still wouldn't run past 6psi with stock pistons though.

Thanks for the info.

spray some alky that will help the bottom end last

I've heard of folks losing boost while making more power with ported heads. Is this true and how will the cam help or hurt me?


Think of boost (psi) as a measurement of restriction, not a measure of power. The more restriction you have between the blower and the valves, the more boost you'll make per given amount of airflow at any given rpm. The more boost you have, the higher the intake air temps will be, which will cause earlier detonation, less ignition timing allowed etc..

By porting the heads you'll lower the restriction (ie: lower boost levels at the gauge with everything else being equal), but you'll probably be flowing more air volume at any given rpm. Plus it'll be cooler air with less chance of detonation, more ignition timing available etc...

Mike