Re: Just a few RPMs from total destruction
Posted by Tim Cole On 2013/8/3 11:53:27
Here is what my handbook says: "Multiple valve springs are used where large lifts are required and a single spring does not have enough strength to control the valve." Call it what you want, but a single spring has one frequency and a second spring has another.
Suppose an engine is turning 5000 rpm. Each valve is then closing 2500 times per minute or 41.66666 hertz. Next suppose the degrees of rotation for closure is 30 then the closing time is 2 milli seconds. Suppose the spring can close no faster than 3 milli seconds, then the valve remains motionless for 1 milli second. In the time the valve is motionless the piston has moved approximately 1/4 inch. In an interference engine this is huge because the piston is moving toward a fully extended valve. A spring that requires less than 2 mill seconds to close is thus higher frequency because it can cycle more times per second. The old BSA motorcycles would rev high enough for valve smash with commensurate problems.
I think if the motor was converted to computer control it could be adjusted to produce around 500 horsepower (600 with nitrous). A modern Ford will tolerate that, but a lesser motor will explode. So that would be a good test of the unit.
Attached is a cutaway of a modern oil system. The old practices have been discarded. These old motors aren't engineered for those kind of results.
I like the engine for normal service. Once the basic problems are sorted out they drive very well. Even with the Ultramatic. I wouldn't be caught dead in a 50's Cadillac, superior engine and transmission notwithstanding.
But gee willikers, my cheap modern car will cruise comfortably at 100 mph, although if a deer jumped in front of me I would be a dead duck, so I don't that. I have a crack in my right front parking light from swerving to avoid a turkey buzzard at less than 55mph.
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Suppose an engine is turning 5000 rpm. Each valve is then closing 2500 times per minute or 41.66666 hertz. Next suppose the degrees of rotation for closure is 30 then the closing time is 2 milli seconds. Suppose the spring can close no faster than 3 milli seconds, then the valve remains motionless for 1 milli second. In the time the valve is motionless the piston has moved approximately 1/4 inch. In an interference engine this is huge because the piston is moving toward a fully extended valve. A spring that requires less than 2 mill seconds to close is thus higher frequency because it can cycle more times per second. The old BSA motorcycles would rev high enough for valve smash with commensurate problems.
I think if the motor was converted to computer control it could be adjusted to produce around 500 horsepower (600 with nitrous). A modern Ford will tolerate that, but a lesser motor will explode. So that would be a good test of the unit.
Attached is a cutaway of a modern oil system. The old practices have been discarded. These old motors aren't engineered for those kind of results.
I like the engine for normal service. Once the basic problems are sorted out they drive very well. Even with the Ultramatic. I wouldn't be caught dead in a 50's Cadillac, superior engine and transmission notwithstanding.
But gee willikers, my cheap modern car will cruise comfortably at 100 mph, although if a deer jumped in front of me I would be a dead duck, so I don't that. I have a crack in my right front parking light from swerving to avoid a turkey buzzard at less than 55mph.
Attach file:
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