Accurate HP calculator -- by Trap Speed and/or E.T.

[Oldschool]

Here is the best calculator I have found to determine horsepower by MPH through the traps or E.T.  Very user friendly and it seems to be very accurate.  I have many friends that have known horsepower and these numbers are very close.  This calculator indicates rear wheel horsepower.      

Also, place your cursor on the graph line in the bottom chart and slide along the line to see how much HP you need to run a certain MPH at the weight you entered.


http://www.ajdesigner.com/fl_horsepower_trap_speed/horsepower_trap_speed.php   

[firefighter3931]

I like to use the Moroso slide rule but i just compared it to your on-line calculator and it was very close. I would say that this tool is accurate. Drag 2003 is very good as well.

Thanks for the link ! 



Ron

[71chally416]

It's close but that's ENGINE HP, not RWHP. 

[Oldschool]

It's close but that's ENGINE HP, not RWHP. 

It is RWHP according to the three vehicles that I calculated.  I used 3 cars/engines that we put together and dynoed the engines.  This calculator registers about 15% lower than what the engines dynoed.  That is about right for automatic cars.       

[71chally416]

"Engine Motor Horsepower Estimate Calculator - Trap Speed
Automobile Car Truck Motorcycle
Quarter Mile Run Or Drag Race
Note: This is a rough estimate of engine horsepower."

It seems to be the same as the one I use>
http://users.erols.com/srweiss/calchpm.htm

A whole bunch of them for different things>
http://users.erols.com/srweiss/index.html

[Oldschool]

It is weird though.  I used several cars that engine dynoed about 15% higher than what this calculator shows. 

I used a 500" Mopar that we dynoed at 512 HP.  The calc shows 425.xx hp using the trap speed indicator.

I also used a blown SBC stroker that dynoed at 526 HP.  The calc showed 432.xx hp using the trap speed indicator.

Last but not least, I used the Beast.  The engine dynoed at 813 HP.  The calc showed 681.xx using the trap speed indicator.

Who knows what the truth is??    ...   lol   


Also, there are several folks using this calculator, (or ones similar), that get almost the exact same HP numbers with the calculator and the chassis dyno, which measures RWHP.        No biggie.....       Either way, these calculators are pretty neat if you like fiddling with numbers....      

[71chally416]

People are usually disappointed when they strap their cars to chassis dynos. The typical tranny/drivetrain sucks more HP than you think.
A dyno is only as accurate as the operator. Just a low rear tire can throw a chassis dyno off, and changing the air temp a few degrees can make a 450 hp motor have 500. These are just rough calculators (as they all state) and any figures you get on a accurate engine or chassis dyno by a competent operator are probably way closer to reality. 

[Oldschool]

Here is one that shows kinda what I am saying.  It shows the same number as the first calc as RWHP.   It also shows corresponding crank HP.  Lots of variables between dynoes, conditions, operators, etc...  Like I said, go figger....              Still fun to play with these things tho...      


http://www.fastcoolcars.com/hp_calculator.htm

[71chally416]

It'll be interesting to get my car to the track and run it this year. I'll get an accurate weight with my fat ass in the car and I already have the engine dyno sheet that I know is accurate so we'll see how it all shakes out on these calcs with my MPH. It'll be the first time I have all the things needed all together. The only variable will be the atmospheric conditions the day I run it, but they can be compensated for and Atco is a sea level track so that won't be a factor. 

[71chally416]

I was curious so I plugged some info into my Boss' Quarter Jr program tonight and it came out about the same as the first calculator you linked for FWHP. Within 5 hp~ 

[nivvy]

moparts formula is the exact same..... once you get rwhp go to the bottom and put in numbers then its easy to convert to engine hp
 

http://www.moparts.org/Tech/tech/index.html


everything 

http://www.wallaceracing.com/Calculators.htm

[wagesofsin]

try this, its very accurate providing you know what you have.

http://www.richmondgear.com/112901.html

i use this as a baseline test for all my cars, and i can match data almost perfectly.

[Chryco Psycho]

so by that my Duster was making 1hp / CI with 441 RWHP 

[StRoKeR]

 

[StRoKeR]