Using an old copy of an automobile magazine, these are the cars with hp and lb ft I am trying to work out the RPM for:
2007 Honda Accord 2.4 sedan, 2.4-liter 187hp 4-cylinder, 164 lb ft pulling power
The math I did to work out RPM:
187 x 5252/164 = 5,988.56 (rounded up to 6000rpm, how far should i round up in significant figures or decimal places)?
2007 Peugeot 207 1.6 HDi 110 GT, 1.6-liter 110hp 4-cylinder, 177 lb ft pulling power
110 x 5252/177 = 3,263.95 (rounded up to 3,264 rpm, or should it be 3000 rpm?)
I used these formulas:
Torque and horsepower relations: T = HP * 5252 / RPM
HP = T * RPM / 5252
RPM = HP * 5252 / T
In my two examples, have I got the math correct for car engines? With RPM, when do I need to round up correctly and what significant figure level do I need?