Its been a while since I posted, but a good subject.

Before all of the computer programs, we found on max effort tunnelram, Carbureted NA engines, that a 278 degree @ 0.050" intake was pretty much optimum starting point. Didn't seem to matter who's name was on the heads if they were decent. Dyno time to move the centerline around a bit. Very aggressive ramps only gave minuscule gains at the cost of quick VT destruction. Bigger bullets liked the cam timing retarded. Even now, some of the best grinds in our day when put into the program predict the most torque area over the RPM band. you could test 25 cams all around that VT and maybe chance 10HP.

As a side note, taking old racing heads and putting them into street service; I put a tiny HR in the engine and still make great power in the upper RPM ranges of the valve springs.

0.02.

Thanks Polyshpheric!

I'd love to have a copy I'll PM you my E-mail.

Hysteric: Yes I was very early follower of Harold at Ultradyne with his asymmetric lobes as 102 Intake centerlines, I learned a lot about camming stroker from a compilation of cam theory and lots of experimentation.

Also, BTW there is a GREAT youtube presentation where they interview 93 year old (and still working) Ed Pink talking about the 427 Cammer and the struggles with adapting it to Top fuel racing.

I'm sure you've watched these videos, but in case you haven't.

https://www.youtube.com/@darinmorgan3520/videos

Covers a lot, I watch them every six month or so

Sometimes we take air for granted because it is the environment we live in, and we forget that it has mass, density, and inertia when moving.
David Visard has a way he calculates port energy (I think that is what it is called?) which I think is flow and velocity combined.
I still don't understand how McFarland uses 1/2 Mach speed (around 563 feet per second) to estimate peak torque RPM?

I've always found that because a stroker (particularly one with a shorter rod) makes more average torque when I run a proportionally bigger intake lobe combined with an earlier (say 102 vs 106-108 ) ICL. because when you stroke the motor the amount of "give back" past BDC per degree of intake duration consumes a proportionally higher amount of effective displacement.

I think this is of dual benefit if you are seeking highest average torque (primarily a street strip or a torque monster bracket motor) because #1 the added stroke initially draws a bit harder on the intake port so the added duration (say 8 degrees vs a standard stroke) doesn't upset the drivability and the early opening gives you the same intake closing event as a +8 degree cam going in at 106. When you stroke a typical wedge engine it's hard to even get enough port on the motor to begin with and since you are generally RPM limited (due to higher net piston speed for a given rpm) the "supercharging" effect of packing the cylinder above its effective displacement is going to occur sooner in the RPM range anyway.

Above the torque peak (Peak VE) many people don't understand that the main reason the HP curve goes up but the torque moves down is because past peak VE the internal friction within the motor is increasingly becoming a "brake" (rising levels of piston ring drag, valvetrain spring rate loads, etc) and the port flow/velocity is trying it's best to overcome those parasitic losses. I think/believe this is why for most strokers the torque and HP peaks tend to be closer together and the HP falls off proportionally quicker. I think this is readily apparent with small block wedge strokers when people accidently discover that short shifting (say at 6400 vs 6800) has a lot less effect on the ET than a similar standard stroke motor....because the shorter stroke would have a proportionally less "Brake effect" per 100 RPM gain above the torque peak.

Of course this is a bit of an over-simplification, with some of the bigger race heads (like the CHI Ford heads) they can keep 'packing the holes' way up in the RPM range....even with very long strokes.

I think for any given/desired combo there is a "sweet spot" and I think understanding the cause and effect of the Intake closing plays a huge part in getting it optimized for whatever you are asking the motor to do.