Wheel BHP convert to flywheel BHP

**Nealevo** · Friday 2nd September 2011, 23:00

Does anyone know how to convert wheel bhp to flywheel bhp just want to test a theory out on my car but getting some wierd figures. Help please

**T5frankie** · Friday 2nd September 2011, 23:01

Originally Posted by Nealevo

Does anyone know how to convert wheel bhp to flywheel bhp just want to test a theory out on my car but getting some wierd figures. Help please

every car will be different mate

**t5_monkey** · Saturday 3rd September 2011, 08:13

That's basically like asking how good a band is!

can of worms. As a rule of thumb - add 20% on.

Other than that, you'll see endless threads about people arguing over it.. .there's no truly accurate way to measure losses apart from perhaps going on a MAHA dyno which are supposed to be pretty good.

**Yosser** · Saturday 3rd September 2011, 08:14

There is no formula, it's guesswork.

Good read on this topic here: http://www.pumaracing.co.uk/trans.htm

**cherry1809** · Sunday 4th September 2011, 18:01

If you want a not very acurate way...

Less WHP to FWHP 15% for FWD, 20% for RWD and 25% for 4X4. Usually completely wrong though.

**Wobbly Dave** · Monday 5th September 2011, 12:56

My losses are just 8% across 3 runs done at the end of July this year. I think 20% is wildly overated.

**t5_monkey** · Monday 5th September 2011, 13:50

Originally Posted by Wobbly Dave

My losses are just 8% across 3 runs done at the end of July this year. I think 20% is wildly overated.

I believe losses can also depend on if the dyno is a one roller, two roller, your geometry, tyre pressures blah blah...

Basically... don't bother calculating, just take your car on the 1/4 mile.

**p fandango** · Monday 5th September 2011, 13:54

Originally Posted by t5_monkey

Basically... don't bother calculating, just take your car on the 1/4 mile.

as you know, alot of things can vary your 1/4mile time so i've never been keen on using that for any sort of power comparison. Think i've got upto 2second differences between runs on the same day

**lance** · Monday 5th September 2011, 15:13

Well at 15% loss my car would have 265 BHP but according to HLMs dyno she has 230 whp and 248 BHP which seems bang on!

**antz** · Monday 5th September 2011, 15:29

I dont bother with flywheel powers due to transmission losses and such. Flywheel powers are just pub talk to make you sound awesome in front of your friends. What matters is the power you get at the wheels.

My Escort mk2 is 130bhp at the wheels with a bit more to come from a re-tune of the carbs. Ive had people say its anywhere from 143-150bhp at the flywheel but I dont care. I know Ive got 130bhp spinning up those rear wheels

**t5_monkey** · Monday 5th September 2011, 16:53

I don't really care about the power any more... it's like the Arab Israeli conflict, people argue about dynos now and will be doing the same in 1000 years... As long as it goes pretty fast and sounds EPIC that's the main thing.

**smithy** · Monday 5th September 2011, 17:23

the only thing im interested in is what the car goes like on the road ,my car goes on the rollers to check the afrs for boost and make sure i its running fine

**claymore** · Monday 5th September 2011, 17:56

Originally Posted by t5_monkey

I don't really care about the power any more... it's like the Arab Israeli conflict, people argue about dynos now and will be doing the same in 1000 years... As long as it goes pretty fast and sounds EPIC that's the main thing.

I agree, I don't care what hp I have, I just love the way it deliveres it

**T5frankie** · Monday 5th September 2011, 17:59

i disagree i want a zillion ponies, never gonna have enough lol

**t5_monkey** · Monday 5th September 2011, 18:44

As long as you can absolutely annihilate some tosspot in a 320d up a M-way slip-road - who thinks his diesel torque and an 'M' badge gives him super car slaying pace....

... it's all good

**Wobbly Dave** · Tuesday 6th September 2011, 00:37

Single roller dyno - 34 psi in the tyres. 14.613 sec quarter @ 102.99mph. 289 whp - 406 NM.

Peak figures are not the full story. Area under the torque curve, sustain & smoothness of that curve are also very important.

It is more also to stick to the same dyno where ever you go.

**t5_monkey** · Tuesday 6th September 2011, 01:40

My last dyno was 228whp - 375nm

14.77 @ 99.5 - alongside wobbly dave (until he hit 3rd gear that was!)

For Reference - Focus RS (with professional driver etc..)

1/4 Mile - 13.77s - Terminal Speed 105mph

As wobbly alluded to dyno is better for 'before' and 'after'

**Rnash2002** · Tuesday 6th September 2011, 10:09

All dynos will be different so no way to work out proper figure.

**Wobbly Dave** · Tuesday 6th September 2011, 16:29

Originally Posted by Rnash2002

All dynos will be different so no way to work out proper figure.

Exactly why you should pick one & stick with it.

**T5frankie** · Tuesday 6th September 2011, 17:06

Originally Posted by t5_monkey

My last dyno was 228whp - 375nm

14.77 @ 99.5 - alongside wobbly dave (until he hit 3rd gear that was!)

For Reference - Focus RS (with professional driver etc..)

1/4 Mile - 13.77s - Terminal Speed 105mph

As wobbly alluded to dyno is better for 'before' and 'after'

ford focus aint that quick mate (13.77)?

[ame]http://www.youtube.com/watch?v=DqNNU0Frfck[/ame]

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