What really limits our engines to rev higher

[Aevus]

Since I'm rebuilding one of my engines, I was looking for ways to get higher RPM limits in order to get both the typical screaming sound of high rev engines and more horsepower (while keeping it N/A)...

Basically, the pushrod Viper engine is limited by:

- Valvetrain stability (it's a pushrod)
- Long stroke
- Oiling system (especially gen 1-2-3 and no dry sump for gen 4/5)
- Air flow (2-valves, heads limitations, etc..)

The ''theorical'' limit for mean piston speed is 25 m/s or 4900 ft per minute, but that's open for debate since some will say 4000 fpm is the maximum ''safe'' limit while others says a race engine can be pushed as far as 5500-6000 fpm. Many factors to consider here...

But basically a Viper's 3.96'' stroke would be at the 4900fpm limit around 7,400 rpm, which is already a lot. I've seen destroked Viper on youtube going to 8,000rpm and also few others in the 7,xxx range.

But other than destroking, what is the path to get that huge engine rev higher? Super lightweight and stable valvetrain is probably mandatory, then you need sufficient air flow (ported heads, high duration camshaft, excellent intake/exhaust systems, etc..) and obviously the oiling and cooling systems that will keep that high rev engine from blowing apart...

But what else?

Is super lightweight pistons/rods that important, or it's better to focus on parts strenght?
Same for push rods, is it better to have heavier oversized but very stiff and stable ones?
Extemely stiff valve springs? at the cost of losing efficiency


Some interesting stuff here on the subject:

https://www.motortrend.com/how-to/11...se-engine-rpm/

...but probably some tips do not apply for a 7-8000 rev engine.