engine redline

[MOPAR-or-NoCar73]

Hi everyone,
     I am still learning about engine building and such. I was just wondering, how is the redline of an engine is determined? How do engine builders know where the redline of an engine without blowing it up.

Thanks

[moper]

redline is a term for gage manufacturers.  The rpm at which the engine cannot hold itself together again is very individualistic. If it breaks, you went too far. You can engineer the engine to rev higher if you want/need it to. The point syou want to concern yourself with are the horsepower peak and torque peak. You want to launch just under peak torque and shift just at peak hp... basically anyway. And build it good enough to be safe operating at those rpms.

[Chryco Psycho]

the operating powerband is built into an engine , parts are all chosen to meet the demands of the RPM , typically valavtrain is the limiting factor so cam profile & valve springs are selected to match to pwoerband desired , generally speaking most builds are past there peak powerband well before the limits of what the engine will take are reached so it comes down to abuse if the engine blows , for example a typical build may have peak power at 5600 RPM * & a desired shift point of 6200 rpm ro keep the engine in its peak power range , with the correct parts this engine should live at 7000 rpm but why take it up there if your power is way down

[Roppa440]

Ideal shift point is always past peak power. You want the highest AVERAGE power between gears. You will find that the best rpm is different in each gear too.

The rpm where peak power occurs is mainly down to the size of the engine and the duration of the camshaft. But above 6500rpm you start getting into the territory where stock rods, rod bolts, main caps etc (even in top condition) want to wave the white flag and part company from you.

Then you also have problems with valve bounce and valve float starting. The rpms where that starts to happen are down to the quality (and matching) of these parts too.

[sadil340]

You may also want to consider the transmission characteristics. On my 340 car the shifting was fastest at 5300 RPM even though the engine was still pulling strong and could go all the way to 6500. Best ET's at the strip were gained by shifting at 5300.

[MOPAR-or-NoCar73]

Thanks for the help