motordyne M370 manifold - round 2

Jordo!

If the diameter is the same, but the runners are longer, you won't pick up power at higher RPM's, although you should gain some in the mid range. Looks like that's exactly what happened. With tuning, you should get back what you lost up top and break about even.

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esfourteen

You've stated this before, I don't know what makes you think you can just "tune" the power back here. Modifying timing and AFR any further than what has already been done are not going to get any more power out of this, with or without the manifold. Regardless, even if there was no top end loss, there are no gains to speak of (~5 tq for 600rpm)

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Jordo!

Because peak torque is basically fixed by diameter, but where you make it is determined by runner length.

Head flow and design is also an issue too, but the VVEL is going to make that much more variable.

Anyway, many transient modifiers may affect what the ECU is doing now that the airflow curve has changed, so you might be able to tweak timing or fueling to get back some or all of the lost power while maintianing the bump down lower.

At least in theory.

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