if my car makes 560hp to the rear wheels what is that
at the crank???

i was told to multiply it by 1.20 or 1.28

if i multiply by 1.20 == 672hp
if i multiply by 1.28 == 716hp
thanks in advance

boris

 

My car dynoed 553rwhp. Which equals about 640 to the crank. Hope this helps.

 

It depends on the dyno. It also depends on if you are talking awd vs 2wd.

On a 2wd car I would use 1.15 as an average for the different makes. The dynojet reading the highest (use 1.1)and the dyno dynamics reading the lowest (use 1.3). Mustang seems to be a good middle of the road.

 

On two wheel drive care, most people seem to estimate power train loss in the range of 15-20%, depending on whether the car is a manual or an automatic . . . AWD power train loss is greater.

Using a conservative 15% power train loss, you would multiply the RWHP by 1.18 in or to determine FWHP -- in this case, 560 RWHP equates to 661 FWHP.

Using a middle of the road 17.5% power train loss, you would multiply the RWHP by 1.21 to determine FWHP -- in this case, 560 RWHP equates to 678 FWHP.

Using a more liberal 20% power train loss, you would multiply the RWHP by 1.25 to determine FWHP -- in this case, 560 RWHP equates to 700 FWHP.

Given that you are a two-wheel drive with a manual transmission, I suspect you are some where in the vicinity of 675 FWHP.

http://www.musclecarclub.com/library...ne-terms.shtml
http://performanceunlimited.com/docu...wheelcalc.html
http://www.enjoythedrive.com/content/?ID=26050

Craig

 

not to step on your toes, but to get the accurate number you need to divide the rwhp by the remaining assumed drivtrain.

for example my car 627/0.85 = 737.6 crank hp

his car 560/0.85 = 658.8 crank hp

 

I have no idea why anyone cares what the at-the-crank
guessitmate is, because you only get what you get to
the tires. This is sort of bragging about how good your
wife is if you don't count the nagging or jewelry costs...
Joe

 

Joe, I would say to want the crank HP is so you can compare it to other cars. For example the enzo has 660 crank HP. If you have 560rwhp, it seems like the enzo has 100 hp advantage, but in reality it only has a 1.2 hp advantage. See where I'm going with this.

 

You are correct sir .75 for AWD and divide by .85 for 2WD

 

thank you for all your responces



boris

 

When you use a MAHA dyno,There is no guess work as to what it makes at the crank.

Neil

 

So Stephen my car made 586 all wheel hp on the GIAC 4wd dyno in California. You saying I am making 780 flywheel hp?

 

thank you for all your responces



boris

 

I doubt there is that much loss. I would say 20% at the absolute most. so 732 at the flywheel.

 

I was just taking his formula 586 awhp divided by .75 and came up with 780. I thought it was more like 700 to 725. Just multiplying by 1.20 or 1.22.

 

On mine and Garrett's Dyno yes. We have huge drag and loss.

You are correct Neil. The MAHA will allow a rollback calculation which gives actual drive train loss and calculates crank numbers