A833 4-Speed on a 4-500hp 440: 18 or 23 Spline Necessary?

If your PP is a hi-clamp Borg & Beck with roller assist, it's going to hit pretty hard after a wot shift. Not the best thing for a 23 spl input.

An NA street/strip 440 probably puts out around 575ft/lbs. The 23 spl input should be good to 800ft/lbs +, but the torque output of the engine isn't a meaningful number for determining how much torque the transmission's input shaft will see in a wot drag race setting. The engine might have a 575ft/lb torque peak, but if the clutch has 800ft/lb capacity, the result of sidestepping the clutch is going to be 800ft/lbs being passed along to the transmission's input shaft. That's because even though the engine only makes a maximum of 575 ft/lbs of torque by itself, installing a clutch with 800ft/lbs of capacity behind it makes it possible for the clutch to borrow an additional 225ft/lbs of inertia energy from the rotating assy. Hitting the input shaft with an additional 225ft/lbs might sound like a good thing to get the car moving, but that borrowed inertia energy must then be paid back so the car doesn't actually gain anything from the extra hard hit.

Ideally, try to match your clutch's ultimate capacity as close to your engine's peak torque output as practically possible. Having a minimal amount of excess clutch capacity minimizes the hit on your transmission's input shaft, it also minimizes the amount of bog that you will see when you launch.

Grant