Bhp At The Flywheel

[mAltezza]

Hi all, few weeks back i got my apexi filter fitted and the camcon sorted, then had the car dyno'd it was 163.7bhp at the rear hubs, anyone know how much this would be at the flywheel?

Not the best of pics

[boddamloon]

is it manual?

[mAltezza]

no its tiptronic,

[Noel]

would the company that done the dyno not be the best to ask this of?

I was told that accurate results from auto's are very difficult, how did ye manage to stop it kicking down?

[mAltezza]

second gear, :D

[boddamloon]

As Noel said its not good to be accurate but if i remember right i think you take off 20-25% from fly wheel to get hubs so you could do the sum but this is just a bit of a shot in the dark mate

[loggyboy]

As above, 20-25% is general rule.. You could also do some maths If you know the manufacturers figures for fly and wheel power.

But there is no 100% accurate way without removing the engine and connecting that to the dyno!

[mAltezza]

when i got it all done the guy made a rough calculation which is the same for every car that he does, he worked it out as 196bhp,

But when IRLRs200 took his on the rolling road he got 138.1 bhp at the wheels and 196.8 bhp at the fly, these readings can from the printout he was given, 58.7 bhp was lost through transmission

on the same day 'lee Iceman' got 153.5bhp at the wheels and 213.3 bhp at the flywheel, 59.8 bhp was lost through transmission,

so not sure how he worked mine out, doesnt seem very correct ,

[sparkystav]

At the Tdi day we took it as 30% trannie losses and so times th figure from the wheel by 1.3 to get the fly.

Stav

[Bazza]

the closest method of calculating the losses are:

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

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

but you can not generalise, as every car has different losses, even the exact same car/model can be different

the losses even change depending on what speed the car is running at, so they are pretty much guesswork, most dynos work it out by adding the coastdown losses, which is far from accurate

at 163.7hp by estimation you should see 197.3hp at the fly

there will also be differences between wheel measurements and hub measurements

[mAltezza]

stav that seems more realistic, but if you use bazzas method, the figures are quite far off,

Stav is this the calculation that the guys at TDi gave you,

[sparkystav]

Yeah it was, but it was just a general rule of thumb i believe.

stav

[Noel]

second gear, :D

seriously? you dyno-ed the car in second gear? did your dyno guy know the ratio? 4th is ideal

[sparkystav]

5th on an IS.

Stav

[boddamloon]

did he not mean 2nd on the auto box?

[mAltezza]

ya i meant 2nd on auto box, if i use TDis method it comes to 212.8bhp, if i use Bazzas it comes to 197.3,

[TigerFish]

I think the only way you are going to get the figures is to go and have another dyno which gives you both (even then it will depend how they work it out). Either that or take the method that gives you the highest figure and be happy

[mAltezza]

really cant afford to take the ferry back to uk to have it done again,

[loggyboy]

Another thing to bare in mind when comparing dyno results is that every dyno will produce different answers as its very difficult to calibrate them. Even one done at the same place with a good time between each test could end up with a different/inaccurate result.

[mAltezza]

ya i know, i'll never get an accurate result, but i thought i could get a slightly more accurate result than 197.3BHP - 212.8BHP,

which result do i chose?

[boddamloon]

the highest offcourse

[mAltezza]

lets say 210bhp then?

[Moffet]

At the Tdi day we took it as 30% trannie losses and so times th figure from the wheel by 1.3 to get the fly.

Stav

We used 20% on the dyno day mate, with 30% my car would have 243.62 at the fly and Lee's even more than that!

[sparkystav]

lol ok 20% then.

doh.

so 196.44 for mAltezza then.

[mAltezza]

see thats where i dont understand,

But when IRLRs200 took his on the rolling road he got 138.1 bhp at the wheels and 196.8 bhp at the fly, these readings can from the printout he was given, 58.7 bhp was lost through transmission

on the same day 'lee Iceman' got 153.5bhp at the wheels and 213.3 bhp at the flywheel, 59.8 bhp was lost through transmission,

so with mine 163.7bhp at wheels, 196.4bhp at fly?

Doesnt seem anywhere near to their figures

:duh: :duh: :duh: :duh: :duh: :duh: