- #1
Rx7man
- 425
- 189
Well, I ran my truck down the 1/8th mile track over the weekend, and with a bunch of the online conversion calculators it told me that my truck is about 487hp.
So I plugged in the old kinematics formulas, and i got quite a discrepancy between them.. Did I do the math right?
Time = 10.055s
Speed (from trap speed) = 75 mph = 33.5 m/s
Distance =1/8th mile, 201.2m
Mass = 7370 lbs = 3350kg
Ke = 1/2 mv2 = 1883 KJ
P = 1883/10.055 = 187 KW
P = 187/.745 = 251 hp...
Yes, that's perfect world, no friction, wind resistance, and doesn't include Ke left in the drivetrain
that's pretty much half of what the online calculators come up with
Now if I shifted 3 gears (manual) and each shift takes .75 seconds (that's optimistic on a truck), would I be correct in deducting that time from the elapsed time?
so
P = 1883 / (10.055-(3*.75)) = 241KW = 323hp
So I plugged in the old kinematics formulas, and i got quite a discrepancy between them.. Did I do the math right?
Time = 10.055s
Speed (from trap speed) = 75 mph = 33.5 m/s
Distance =1/8th mile, 201.2m
Mass = 7370 lbs = 3350kg
Ke = 1/2 mv2 = 1883 KJ
P = 1883/10.055 = 187 KW
P = 187/.745 = 251 hp...
Yes, that's perfect world, no friction, wind resistance, and doesn't include Ke left in the drivetrain
that's pretty much half of what the online calculators come up with
Now if I shifted 3 gears (manual) and each shift takes .75 seconds (that's optimistic on a truck), would I be correct in deducting that time from the elapsed time?
so
P = 1883 / (10.055-(3*.75)) = 241KW = 323hp