[PonyBoy1574]

So what determains when a engine redlines? If I storke her up will that change the red line or will it still stay the same??

[Twister]

it is a combination of things, but with a pushrod engine, the #1 factor is the lifters...but what really dictates redline is piston speed, the longer the stroke, the more torque, and less RPM's.......because the piston with a 3.25 inch stroke will travel faster and further than a 3 inch stroke at 5000RPM.....

[mm.racing]

Not just lifters but the entire valvetrain in pushrod engines.

Also, many people will rev the crap out of their engine just because it will do it. Getting your combination right and in perfect tune on a dyno will ensure you know what your engines capabilities are. Just because you can spin it to 6500RPM doesn't mean you are making any more power than you were at 6000. Most street engines aren't revvers anyway. High end torque and horsepower aren't real friendly on light to light jaunts around town.