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BGTV8 · 04-09-2012, 06:26 PM

The flow limit is actually the OEM inlet manifold. Without replacing the manifold, we are air-limited to around 420hp.

I have some VQ30 heads (primarily because the CR with these heads is 12.05:1 with std pistons) and 33mm dia inlets and these flow 288cfm @ 12.7mm lift on our flow-bench. According to my rough rule-of-thumb, this equates to circa 445hp and that assumes that the inlet manifold constraints have been resolved.

If we can get to 15mm of lift, we get 300cfm, which gets us to 460hp, but getting beyond 460 without going larger in valve diameter seems impossible (and 600 thou life is a stretch as we need bigger valve pockes in the pistons, and that drops the CR so I'm beginning to believe that half-inch lift is about it - and that means ~440/450 hp.

Getting to 500hp will require head-work - a lot of expensive flow-bench time, together with a bespoke inlet manifold (and 52mm throttle bodies such on manifold). I've already had some aluminium plates machined up to suit my heads and making a manifold out of 51mm tube is relatively simple, but still lots of work and research to go ... with the objective of getting to ~325 cfm which will go very close to supporting 500hp.

This will be a balls-out race engine and not for a road-able car ... for that, it will be 1/10th the cost by going s/c or tt.

RB

04-09-2012, 06:26 PM	#180 (permalink)
BGTV8 A True Z Fanatic Join Date: Dec 2009 Location: 03350 Australia Posts: 1,503 Drives: 09 Nissan 370Z M6 Rep Power: 29907	The flow limit is actually the OEM inlet manifold. Without replacing the manifold, we are air-limited to around 420hp. I have some VQ30 heads (primarily because the CR with these heads is 12.05:1 with std pistons) and 33mm dia inlets and these flow 288cfm @ 12.7mm lift on our flow-bench. According to my rough rule-of-thumb, this equates to circa 445hp and that assumes that the inlet manifold constraints have been resolved. If we can get to 15mm of lift, we get 300cfm, which gets us to 460hp, but getting beyond 460 without going larger in valve diameter seems impossible (and 600 thou life is a stretch as we need bigger valve pockes in the pistons, and that drops the CR so I'm beginning to believe that half-inch lift is about it - and that means ~440/450 hp. Getting to 500hp will require head-work - a lot of expensive flow-bench time, together with a bespoke inlet manifold (and 52mm throttle bodies such on manifold). I've already had some aluminium plates machined up to suit my heads and making a manifold out of 51mm tube is relatively simple, but still lots of work and research to go ... with the objective of getting to ~325 cfm which will go very close to supporting 500hp. This will be a balls-out race engine and not for a road-able car ... for that, it will be 1/10th the cost by going s/c or tt. RB Last edited by BGTV8; 04-09-2012 at 06:31 PM.