Quote:
Originally Posted by Ol' Ron
I like the 258ci engine because the port valve area can feed this to a higher RPM. WITH POWER. Having run a number of Dyno ests on Flatheads, they all seem to fall off after 45-4800 RPM. Sure they'll turn 55-6000 but the torque is gone. Very long cams with hi lift, and you can push this up abit, But the ports are th limiting factor. That's why Kong Jackson and Dick landy built their 16 port blocks. In Landys case the engines were supercharged and produced over 500 hp.
Back in the real world we have to use what Henry gave us. Porting and reliving work well at hi RPM, but offer little in the way of performance in a street engine.
I have a 3 3/8X3 5/8 crank assy and if I can find it , I'll sell it Cheep. Tell us how it works.
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Ron, the statement you're making about the Flatheads falling off at 4500 rpm is the exact reason why I think there is an inherent "dam" in the performance arena of the Flathead Ford. As you know at low engine speeds the Flathead's intake port/transfer area can easily cope with flow requirements. As engine speeds rise the port I feel either works pretty well or can be made to work pretty well. It's just that it's flipped on it's back and directing that airflow smack dab into the wall created by the cyl head. I'm convinced that by raising the dome over the cylinder significantly one could then significantly raise power due to less of a "flow dam" effect. I don't think trying to get the charge to make an abrupt turn like a stock or hi compression head does is the way to go at hi engine speeds.
I'm absolutely aching to test this theory. I realize that some racers of the past have done this with great succes but I would like to see what this can do on a street engine. I am seriously thinking of 3 5/16" x 4 1/4" or maybe even a 3 3/8" bore if my block checks out.