How do you convert RWHP ?

[VOI9 ASP]

How would you convert 437 RWHP to HP at the engine? Same question on Torque - 484 RW Torque to Engine Torque?

Edelbrock Headers, Borla Exhaust, Catbacks, K&N Filters, Smooth Tubes.

 

[GTzViper]

The most simple way is 437x.15 (15%)=65.55+437=502.55HP Very nice!

 

[Makara]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by GTzViper:
The most simple way is 437x.15 (15%)=65.55+437=502.55HP Very nice!

<HR></BLOCKQUOTE>

Assuming that parasitic drag is 15% of the flywheel horsepower wouldn't you have to multiply the rwhp by about 1.177 to the correct power figure. 15% of the rwhp is only 12.75% of the flywheel horsepower.

 

[BlackSnake]

The correct way to get it is do divide by the percentage of flywheel HP. If you are assuming a 15% drivetrain loss, then you are saying that rwhp is 85% of fwhp. That means in your case, you're looking at 514.12 HP at the crank.

Here's the math:

x * .085 = 437
x = 437 / 0.85
x = 514.12

 

[jgfurr]

BlackSnake is correct. You do not multiply RWHP by 1.15, but divide it by .85 instead.

 

[VOI9 ASP]

I've heard a few people say the number is 20%. Is 15% the correct number or at least a more accurate number?

 

[Kid97GTS]

Makara and Black Snake are both correct. rwhp/.85 is the same as rwhp(1.177).

The use of a 20% loss would probably be too high, given that the Viper is a manual transmission car, even with the presence of half shafts. I've heard empirical results of between 15 and 12 percent driveline loss.