to stroke or not to stroke?

crackedback said

HP in a vacuum, as if it's the only thing that matters, will make you a loser in many situations.

Slap an 18000-20000 rpm f1 engine in a 3500# car with a street converter and 3.55's, 28" tires... Yeah it makes 800hp, it won't accelerate for crap until way up in the band. Meanwhile the lower HP, more torque, 6K rpm grunter is going to run away from it out to the 1/8 mile point. Now put 8:1 rear gears, 8 speed trans and 14K rpm converter, suddenly the F1 engine will work better... but only HP matters. :)

What do the gear and trans ratios do? They multiply something, what is it? LOL

HP is a derivative of observed torque. Without TQ, you don't have HP.

Any build decisions should be based upon the desired goals.

Click to expand...

QUOTE "HP is a derivative of observed torque. Without TQ, you don't have HP."


EXACTLY. Well almost. You are close but yet so far away. Let me get you there.


HP is derived from torque...that is correct. So, you can have HP with less torque or you can have HP with more torque and that was the whole point of my post. HP is what counts because when you get a time slip it is broken down by TIME. That is T-I-M-E- for those who read a little slower.


If you have a long stroke, crap rod/stroke ratio and small bore, and then limit RPM by any number of ways, you will skew the numbers on the torque side (torque is higher than it should be) at the expense of HP. If you go the other way, with a shorter stroke, higher rod/stroke ratio and a big bore so you can get bigger valves in the port and make the port right, and then put the RPM's where you think they should be (depends on weight/gearing/tire diameter/clutch settings or converter stall) and the HP will be up and the TQ number will go down.

It's all simple math, except you keyboard warriors never add in TIME. TIME. TIME.

If you do the work faster you did it with HP. It's that simple.