JörgenK

I measured them today with a piece of 17mm hose. The short runner is just short of 300mm and the long runner is just short of 690mm!!!

ryoung

Two more bits of data that are not assumptions in my engine model.

JörgenK

Are you using engine analyzer pro? I use the standard version and I'm not sure that it get's the helmholtz tuning right. I only see inertia tuning effects and they fall off when the intake diameter goes up.

Can you simulate a 12" tapered runner for me? 1.75" dia at the head and 2" at the plenum.

ryoung

First pass using 3" intake and exhaust ports lengths, 1.189" intake valves, 1.047" exhaust valves, Bentley cam specs, tapered intake manifold runner per your specs, and lots of assumptions on port and runner flow coefficients etc etc:

315 hp @ 6000 rpm

Intake tuning pressure in psi @ rpm,

0.5 @ 3000
0.2 @ 3250
0.0 @ 3500
0.2 @ 3750
1.0 @ 4000
1.5 @ 4250
2.4 @ 4500
2.9 @ 4750
3.1 @ 5000
3.3 @ 5250
3.8 @ 5500
4.1 @ 5750
4.3 @ 6000
4.3 @ 6250
4.4 @ 6500

Volumetric efficiency peaks at 101% @ 5500 rpm

JörgenK

Thanks.