HP based on Trap Speed and Weight
#1
10-13-2015, 04:10 PM
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HP based on Trap Speed and Weight
Hi Guys,
By using the following formula
Net HP = Weight in pounds* (Speed in MPH/228.4)^3
My car weight =3692 lbs
Driver = 175 lbs
Other crap (techart bodykit etc) = 50 lbs
Total Weight =3917 lbs
Trap = 129.54
Net HP = 714 HP
Based on this formula my cab is generating 714 HP?
By using the following formula
Net HP = Weight in pounds* (Speed in MPH/228.4)^3
My car weight =3692 lbs
Driver = 175 lbs
Other crap (techart bodykit etc) = 50 lbs
Total Weight =3917 lbs
Trap = 129.54
Net HP = 714 HP
Based on this formula my cab is generating 714 HP?
#3
10-13-2015, 05:34 PM
Where do you get 30% loss? But no, those formulas give all sorts of different numbers. HP is ephemeral as we can see. Dynos give different numbers. By that formula my car with the FVD doing 135.4 trap speed was 772 at the crank and we know it measured 493 on the Dynojet with the FVD module which is a staggering 37% loss, don't think so.
Dan McNiff at Dinan gave me this one.
Physics of HP and ET……wheelHP=Weight/(ET/5.825)3
based on the FVD runs at SAR I get 453 hp which is closer to what we measured but still lower.
Dan McNiff at Dinan gave me this one.
Physics of HP and ET……wheelHP=Weight/(ET/5.825)3
based on the FVD runs at SAR I get 453 hp which is closer to what we measured but still lower.
Last edited by wrs; 10-13-2015 at 05:39 PM.
#4
10-13-2015, 08:14 PM
Former Vendor
If you've ever been on a MAHA dyno or any dyno where parasitic losses can be measured/accounted for you'd see that drivetrain losses aren't a fixed number. They vary with RPM and wheel speed and are an exponentially rising curve, the higher the RPM and wheel speed the higher the drivetrain loss.
Dzenno@PTF
Dzenno@PTF
#6
10-15-2015, 06:59 PM
Former Vendor
Dzenno@PTF
#7
10-16-2015, 08:55 PM
I can't quite appreciate all of this calculation of peak HP based on total work done to get a weight to a speed within a distance.
Two very different curves within the used RPM could have the same trap speed and have pretty significantly different peak HP.
You might as well be guessing the price of a wine based on the smell.
Two very different curves within the used RPM could have the same trap speed and have pretty significantly different peak HP.
You might as well be guessing the price of a wine based on the smell.
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#8
10-17-2015, 03:31 PM
this is a strange conversation. i use the calculators on my friends cl65 and the # are almost spot on with what he actually dyno's and what he runs at the track. use the exact same formulas for my 996 turbo and the #'s are way off. we have never figured this out
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