a9x_hatch

im just wondering what sort of cfm increase i would get from getting my patriot ls6 stage 2 heads hand finished any ideas?

Steve Bryant

iTrader: (1)

I am guessing that you would get a 2 or 3% increase at the higher lifts. Hand finishing done properly is very esthetically pleasing to look at, but it does not help the air volume or velocity a bunch like you (and I) might like to believe. More importantly, most of the air and exhaust charge goes into and out of the cylinder at low to mid lifts. In this area, the hand finishing might not even help by 2 or 3%.

This is just my opinion. I'm not a head porting specialist, but I have hand ported my own heads with very respectable gains on a flow bench and I am an engineer with a Commercial Pilot's license and a flight instructor. I have done a lot of study in high velocity aerodynamics, but I'm still not as knowledgeable as somebody who's really savvy about this.

I ported my heads using the Joe Mondello approach on LS1 heads of enhancing the swirl ramp and the mixture dam but leaving both intact. TD's z at TEA's also gave me some good pointers too. Also, I mostly just cleaned up and smoothed the exhausts because I want to enhance torque for my truck in the mid range and I don't want to dump the combustion pressure too quickly. Had I been porting for top end HP, I would have worked the exhaust ports differently, but that was not my goal.

I'll bet Gunnar or someone at Patriot could tell you with a good bit of accuracy about hand finishing gains since they're his heads. I'm not saying that there is no power to be found, but its probably pretty elusive.

All my best,

Steve