Norm Peterson
corner barstool sitter
I think you could start with an unusually high-mounted camshaft a la the Ilmor-Mercedes pushrod Indycar engine. That would give you shorter and lighter pushrods that won't be so ready to go all sine-wave in shape as the revs climb. Or need to be heavy in order to be stiff enough which would require extra spring pressure (which comes back and hints at needing still more pushrod stiffness - and weight).Yes, but also no. A NASCAR engine's lifespan is measured in events, or hours. Lol. The problem with revving the nuts off an OHV engine is that the reciprocating mass of the pushrods and lifters is substantial and produces extreme wear on the entire valvetrain. That's why OEM's won't do it, it just won't last. In a DOHC engine, the camshaft is directly acting on the valve spring. In an OHV engine, the camshaft is exerting mechanical leverage from afar through a lifter and a pushrod/rocker arm. Accelerating all those extra parts takes more time, and more force. High angular acceleration = bad for longevity. Unless I'm missing a particularly clever design that is high revving but also reliable, in which case feel free to make me look silly.
Then use that Mechadyne camshaft concept, and maybe a 4-valve arrangement.
Norm