Calculating HP Numbers
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From: Virginia Beach, VA
Calculating HP Numbers
I posted this but I figured I would make it a thread. Just see everyone going crazy over DYNO numbers.. A DYNO whether Dyno Jet or Mustang Dyno.. two very different ways of calculating #'s are GREAT GREAT tunining tools but leave them at that.. u can manipulate them to give them any numbers u want. Try this to get your REAL power to the wheels at that givin time.. good luck.
The best way to get true #'s on what your car is putting down is take it down the local dragway once or twice usually cost 15 bucks... dont launch the car hard to make sure u dont break anything (very sticky starting line, IRS tends to really hop, remember u r not going for time, but MPH so u dont want to spin at all) but dont bog it either.. slip the clutch keep the RPM's up, Autos.. u guys can probably just mash it once the car starts rolling. These cars stock once u get rolling u can put it to the floor the rest of the way. I suggest power shifting to get the most MPH.
Most dragways have a scale as well, if not take your car through a truck stop and have it weighed with you in it, use this formula...
hp = weight * (speed / 234)3
For you non math majors
lets say my car weighs 3400 pounds with me in it.. and i run 98 MPH in the 1/4 well take 98 divided by 234 that equals .419 rounded off... take that to the 3rd power (times itself 3 times .419x.419.x419= 0.074) rememer dont x's it by 3 or u will come out wrong. now take your weight 3400x.0.074 and the number you get is the power your putting to the ground on that run. which i get 250 RWHP. Try to note the weather conditions, note if you get a head wind or a tail wind, get the DA (Density Altitude) ask any major drag racer at the track and he can tell you, especially bracket racers, And you can correct to SAE HP.. (seal level) If u want to know how Weather affects your car look up Density Altitude.. Humidity, temperature and track elevation from sea level (the closer to seal level the better your car will perform take your car to denver and u will see what im talkin bout.) all play a HUGE factor in performance.
Hope this might help some of you guys out.
The best way to get true #'s on what your car is putting down is take it down the local dragway once or twice usually cost 15 bucks... dont launch the car hard to make sure u dont break anything (very sticky starting line, IRS tends to really hop, remember u r not going for time, but MPH so u dont want to spin at all) but dont bog it either.. slip the clutch keep the RPM's up, Autos.. u guys can probably just mash it once the car starts rolling. These cars stock once u get rolling u can put it to the floor the rest of the way. I suggest power shifting to get the most MPH.
Most dragways have a scale as well, if not take your car through a truck stop and have it weighed with you in it, use this formula...
hp = weight * (speed / 234)3
For you non math majors
lets say my car weighs 3400 pounds with me in it.. and i run 98 MPH in the 1/4 well take 98 divided by 234 that equals .419 rounded off... take that to the 3rd power (times itself 3 times .419x.419.x419= 0.074) rememer dont x's it by 3 or u will come out wrong. now take your weight 3400x.0.074 and the number you get is the power your putting to the ground on that run. which i get 250 RWHP. Try to note the weather conditions, note if you get a head wind or a tail wind, get the DA (Density Altitude) ask any major drag racer at the track and he can tell you, especially bracket racers, And you can correct to SAE HP.. (seal level) If u want to know how Weather affects your car look up Density Altitude.. Humidity, temperature and track elevation from sea level (the closer to seal level the better your car will perform take your car to denver and u will see what im talkin bout.) all play a HUGE factor in performance.
Hope this might help some of you guys out.
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