It was tested on pump gas.

Cam is big, peak is at 6400. The contest measures from 2500rpm but maybe it still favors a hard charger up top? I’d have to look at the calculation they use to figure that out. I’m thinking they used power and torque in it, which would doubly favor higher RPM power.

people focus on bore and stroke too much. It’s nearly irrelevant from a power/torque standpoint. Total displacement is what matters.

I think it’s still very relevant. People here build engines in this size range a lot. You could put this head, cam, and induction combo on a 530-572 and have an awesome boat motor.

That’s a race car build. All you would need is a chase boat full of drives and 100 octane. Nice combo for a bracket car though, and would put we’ll set up chassis in the 9’s.

I'm actually a little surprised it peaked at 6,400 in a 509 with 260 duration at .050. I understand the lsa differences in performance wider the broader and narrower the peakier but my question is duration vs lsa. I never really played with much do to majority of my builds have been for marine with 111-114 lsa.

https://www.hotrod.com/articles/cams...ted-explained/

i don’t agree. Displacement is displacement regardless of the bore stroke combo. The head only flows based on the pressure drop created below it. That pressure drop will on average be equivalent for the same displacement at the same engine speed. The only caveat is that the larger bore combo might create a better flowing chamber.

Id attribute the 6400 peak to the very tight lsa. Wider lsa’s can hang on up top better.

If I'm not mistaking MT is trying to say that the 4.5" stroke is bringing peak hp down with the said duration @.050. Without looking into it more I would guess with a 4" stroke 509 ci would likely make peak hp above 7k. That's a given.