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Hey Thanks Harry for the Info! Good Info!
What were you using for Inches of wc for your testing? 28"WC?When I did my testing, I used 28"wc (Industry standard), and tested all the way up to 14mm, mainly just to get the additional data points.
My suspicions proved correct after spending considerable time testing, retesting, verifying and analyzing my data... (well over 250 hours in bench testing alone)
I noticed that once past CVL, both exhaust and intake port flows flattened out. Considering the design constraints within the head, Nissan did a pretty damn good job at both designing and executing the design of these heads. Thanks again Harry, for posting your numbers, very nice!
Humbly stated, (not bragging or boasting), I achieved a maximum of 270 cfm using stock size valves.
You can probably figure out where they maxed out at. However, I'll keep how I achieved those numbers close to my chest - for now.
Clues to how this was accomplised this (as in a previous post) are the cc'ing results:
All of the chambers came in at 50.0 cc's
All of the intake ports came in at 150.0 cc's
All of the exhaust ports (sans 1) came in at 86.0 cc's with the one loner coming in at 85.6 cc's.
All of the cc'ing was checked re-checked, then verified (tested 3 separate times). All of the flow testing was documented, tested, re-tested and verified, again, 3 separate times:
The flow results for each of the ports are less than 1 cfm spread throughout the entire valve cycle event, between all of the ports and Valve settings. (Which is why the one exhaust port is 0.4cc's less than the other 5 ports.) Yes, I am "Old School", Yes, I'm anal about modifying any set of heads, and Yes it is very time consuming to conduct testing and modifications this way. Finally, YES! I created, measured and analyzied Port Maps and equations (as previously posted). I do not consider however (at least up to this point), that these set of heads are finished, as I have a few more "tricks up my sleeve" that have yet to be incorporated.
Not sure I want to venture down that path however, as I'm happy with the results attained thus far.
Past experience has taught me that these tricks usually result in even better flows, however they start affecting reliability (hense my apprehension to incorporate the additional changes). I can't wait to get these heads on a built short block, and then doing some flogging on the dyno...
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