Hudsonator revs his hopped up 230 Plymouth 5000 RPM. Mind you, this is in tractor pulling so it is only a few minutes at a time.
I'm still working on the McCulloch blown 265. But this is not an all out horsepower project. I plan on keeping the pressure down to 5 pounds or so which should give me about a 1/3 HP increase over the stock 120, or 160HP total.
About the same as a stock 318 2 barrel or slightly less.
Hudsonator also claims that the limiting factor to flathead horsepower is the engine's ability to reject heat.
His engine after a run is practically red hot from head to oil pan while the rad is cool.
His competitors with newer OHV engines, finish a run with the engine cool and the radiator hot.
This indicates that the stock cooling passages etc are simply not designed for high horsepower levels.
One reason old timers used aluminum heads on hot flatheads, is that aluminum disperses heat better than iron giving a cooling advantage right where the engine is hottest.
