Since almost everyone here is power hungry I would have figured someone has put the stock/modded heads/manifolds on a flow bench. It would be nice to get a flow rating on the VQ heads and intake manifold. This would make choosing a custom camshaft grind alot easier. Not to mention I wonder how well the heads flow compared to other nissan engines like the VG30DE, VG30E, SR20DE. If anyone cares here are the flow numbers of Z31 VG30E heads/manifolds. I should also point out that there have been claims that the VG30E in the maxima has slightly better flow heads than the Z31s did.
<snip from www.z31.com>
First, understand that power is directly proportional to airflow thru the entire intake system. If you know the CFM of airflow you can predict the POTENTIAL HP that particular engine can produce on gasoline, NO MATTER WHAT ELSE YOU DO. I did some testing for airflow on stock heads, stock plenum with stock throttle body, and a machined and polished plenum with the 60 MM throttle body (Spensor England). The tests were performed on a superflow 600 flowbench. The test pressure was 28" of water at 200 CFM. To economize the length of this post, I will present only peak power at .600 valve lift. The stock head and plenum are from my 85 ZX Turbo.

Stock Heads tested alone flowed 168 CFM
Stock plenum w/TB mounted to head 132 CFM
Modified plenum w/60TB mounted to head 148 CFM

At 28" of water the power coefficient is .26
.26 X 132 = 34.32 34.32 X 6(cylinders) = 205.92 Potential HP
.26 X 148 = 38.48 38.48 X 6(cylinders) = 230.88 Potential HP

This is a good estimate of what you can expect from a NA 300ZX
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i got the heads tested before and after to see what the port/polished heads flow at. I also had cams done but they are turbo cams which are different from NA cams.

 

I was wondering was there much to be gained from the headwork? I know that my VG30E heads flowed alot better after the porting just by comparing them to the oem heads I had. Actually if it wasn't for my bent valves (valve float) and cracked left cylinder head I could get them flow tested.

 

I have some 4th gen upper intake manifold that I can get it on a flow bench. Who has a flow bench?