Sum, Scott is right. There is a simple mathematical relationship between torque, rpm, and horsepower. Horsepower is torque times rpm. Yeah, you divide it by 5252 to scale the result down to match what Watt's horse could do, but conceptually, you can think of horsepower as torque times rpm, i.e. the combination of the two. As I previously showed, torque and rpm are interchangeable entities that make equal contributions to performance, therefore they're weighted equally in the horsepower formula..............................
Ok I put the 5280 down because I was too lazy to go look up the 5252. Hey I was only off by 28 and that ain't bad when you are 63 and at least I know how long a mile is
, and I've seen the HP/Torque formula tons of times. Glen and I got to ride Watt's horse when we were younger in fact.
..................In any event, the important point is that the power peak rpm is always where the combination of torque and rpm are at their greatest. If you go to a higher rpm than the power peak, the torque will drop more than the rpm rises, hence you have less horsepower.......................
Ok so let's get down to the above statement. Here are some dyno numbers.
RPM HP Torque T + RPM T X RPM HP X RPM
2000 138 363 2363 726000 276000
2500 181 379 2879 947500 452500
3000 227 397 3397 1191000 681000
3500 278 418 3918 1463000 973000
4000 326 428 4428 1712000 1304000
4500 368 430 4930 1935000 1656000
5000 391 411 5411 2055000 1955000
5500 393 375 5875 2062500 2161500
6000 372 326 6326 1956000 2232000
6500 337 272 6772 1768000 2190500
You said to combine the rpm and torque and I wasn't sure from another post if you meant add them together or multiply them, so I did both. The adding together (4th column) didn't seem to work as the resulting number always got higher even when the torque was falling off at 6500. The multiplying method (5th column) seems to make sense and at 5500 you have the highest number and that is also the HP peak. Is this the method you use??
If I was gearing I would have probably picked about the same point based on the HP peaking there. The 6th column show HP X RPM and if you used that column 6000 rpm would be the peak and that is probably where I would shift on the drag strip, on the salt in the first couple gears for a high HP car short shifting seems to help as you can never get full throttle in these gears anyway.
Looking at all of this I think we are all coming to about the same conclusions just from slightly different perspectives and until you have some real world results on the salt or dirt it is hard to fine tune the gearing to achieve the maximum potential of the vehicle at any set HP/Torque level. Before you run you are doing a lot of guessing with the aero drag.
I'll add your torque/rpm to my data that I look at and also Sparky's Tractive Effort.