FLYWHEEL HP TO RWHP - FINALLY A FORMULA!!!

[Torquemonster]

This is the best i can find.... quote from website

"Converting wheel bhp to flywheel bhp and vice versa
To reflect the fact that % losses are high for low powered cars and vice versa I use the following equations which have been found to correlate well with real world transmission losses.

FWD cars - add 10 bhp to the wheel figure and divide the result by 0.9

RWD cars - add 10 bhp to the wheel figure and divide the result by 0.88

4WD cars - add 10bhp to the wheel figure and divide the result by 0.84

To estimate the expected wheel bhp from a known flywheel bhp just reverse the equations

FWD - multiply flywheel power by 0.9 and then deduct a further 10 bhp

RWD - multiply flywheel power by 0.88 and then deduct a further 10 bhp

4WD - multiply flywheel power by 0.84 and then deduct a further 10 bhp

Remember, these percentages are not "gospel" - they are good realistic averages."

The rest of article is at http://www.pumaracing.co.uk/power3.htm

 

[Jack B]

That is a great article.

 

[Gerald]

just say a little less that what the motor has...

 

[CMilViper]

I agree..great article!

 

[KenH]

There are a number of interesting articles on the main website at http://www.pumaracing.co.uk

Transmission losses are covered in a little more detail at http://www.pumaracing.co.uk/trans.htm

--- Ken

 

[TomMiriViper]

Good reading

Tom

 

[Detlef]

So all those making 430rwhp with Exhaust and HF CATS should be making around 500 hp at the crank.

 

[SUN RA KAT]

I think I need more power now...

 

[Supra]

Don't know if I like this formula as I lose 22 HP with it Just kidding, very interesting......

This is the best i can find.... quote from website

"Converting wheel bhp to flywheel bhp and vice versa
To reflect the fact that % losses are high for low powered cars and vice versa I use the following equations which have been found to correlate well with real world transmission losses.

FWD cars - add 10 bhp to the wheel figure and divide the result by 0.9

RWD cars - add 10 bhp to the wheel figure and divide the result by 0.88

4WD cars - add 10bhp to the wheel figure and divide the result by 0.84

To estimate the expected wheel bhp from a known flywheel bhp just reverse the equations

FWD - multiply flywheel power by 0.9 and then deduct a further 10 bhp

RWD - multiply flywheel power by 0.88 and then deduct a further 10 bhp

4WD - multiply flywheel power by 0.84 and then deduct a further 10 bhp

Remember, these percentages are not "gospel" - they are good realistic averages."

The rest of article is at http://www.pumaracing.co.uk/power3.htm

 

[Russ M]

Problem is that no formula can be used on a broad spectrum of cars. The hp measured at the wheels are affected by every drive line variable.

Half shafts
U joints
Wheel size
wheel weight
gearing
etc...

You can get close by using say 15-20% for a rear wheel drive car. And say 10-15% for a front wheel drive car.

But to be accurate, you must engine dyno and then wheel dyno. And you will know without a doubt what the % loss is.

 

[1TONY1]

Someone with a fresh Arrow rebuild needs to get back to back dyno numbers. Arrow runs the engines on an engine dyno....as soon as the owner gets the car back they could go to a chassis dyno. That would equal our true Viper driveline loss.

 

[Andy 98 RT/10]

Thanks for the write up, but remember, it probably really varies for each car.

 

[Russ M]

Thanks for the write up, but remember, it probably really varies for each car.

No,

Unless the cars have aftermarket components in the driveline past the fly wheel, drive train loss should remain the same for a 500hp or a 1000hp car.

 

[99 R/T 10]

Thanks for the write up, but remember, it probably really varies for each car.

No,

Unless the cars have aftermarket components in the driveline past the fly wheel, drive train loss should remain the same for a 500hp or a 1000hp car.

As a percentage or just the number. For example, loss of 15% regardless of how much HP or 70HP loss regardless if the car has 400HP or 1000HP?