Guess The BHP & Torque ? (Updated)

[beach]

the difference between wheel and fly bhp is not right. tyre pressure/weather/fuel have nothing to do do with that discrepency.

if your just looking at the fly and torque figures you could say that seems a reasonable output for the modifications. but something is not right with the results you got, because of the wheel figures...

Edited August 11, 2006 by beach

[Phantom Photon]

The figure at the fly is only an estimated guess as best so the wheel figure will be the more accurate. Unless you actually remove your engine from the car and put it on a proper dyno you will not get an accurate flywheel figure.

[beach]

the normal figure for front wheel drive car to lose in transmission is 15%. 99bhp at wheels would give you about 116.5bhp@fly which is bad.

my result was 107.5@wheels with a panel filter. my RR calculated it to be 130bhp@fly through the coast down loss calculation which would be 17.5% loss.

99bhp@wheels with a 17.5% loss would be 120bhp. so still down on factory power.

there must be a mistake somewhere.

The figure at the fly is only an estimated guess as best so the wheel figure will be the more accurate. Unless you actually remove your engine from the car and put it on a proper dyno you will not get an accurate flywheel figure.

i agree. so if the 99@wheels is correct then something is badly wrong with the engine setup. as said above 105@wheels is about right for a standard gti?

[Tigz™]

the normal figure for front wheel drive car to lose in transmission is 15%

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Who told you that?

And of course tyre pressure would affect the wheel reading, if his pressures were low the reading will be lower.

[beach]

yes i agree the reading will be different from expected if the tyre pressures lower etc. what i'm saying is that wont make any difference from the claimed fly output based on wheel output.

15% is the world accepted average loss of fwd cars. its an average, but its very close to what you can expect in most cars. as said the loss calculated on the RR i went to was 17.5%. but there should not be a case where over 20% losses occur in a normal fwd car.

the result we are looking at here shows a 30% loss through transmission. i dont go with that. but then we coould ignore the fly figures anyway.

would be good if we had a table of lupo members wheel figures and mods done.

i dont know how to create one though.

Edited August 11, 2006 by beach

[Tigz™]

30% is pretty much what I've seen in results from Lupos over the past few years.

Its been well descussed, why the Lupo seems to suffer it more than the Polo.

On the same rollers in Northampton, Ive seen some standard GTIs under 100bhp and some quite a bit over.

We really cant take figures too seriously.

The rollers are not designed for that!

[beach]

i dont belive thats correct though. in that case i have 153.5bhp in my standard gti with just a cotton panel filter replacement. 107.5 with 30% loss.

do you think wheel figures should not be taken seriously aswell. i think they have a bit more weight to them, compared to fly figures anyway.

Edited August 11, 2006 by beach

[Grapo]

i dont belive thats correct though. in that case i have 153.5bhp in my standard gti with just a cotton panel filter replacement. 107.5 with 30% loss.

do you think wheel figures should not be taken seriously aswell. i think they have a bit more weight to them, compared to fly figures anyway.

Well judging by your 112lb/ft quote. Mine at Northampton RR made 123.3bhp at the fly with 111lb/ft. Surely your torque should be higher if you have 130bhp. I'm guessing the calculation they have made ffor your fly wheel figure is wrong.

[beach]

torque and bhp dont go up by the same %. you can gain more bhp but actually lose torque. so that doesnt really relate.

but still, lets say i had 15% loss which is only 2.5 % different from what they did i would have 126.5bhp. and i wouldnt have a problem with that. these variances are no where near the 30% loss some results are claiming.

[A9XSJ]

Graphs Added PAGE 1

At the end of the day it was a bit of fun, but its iteresting to hear your views style="vertical-align:middle" emoid=";)" border="0" alt="wink.gif" />

[Tigz™]

do you think wheel figures should not be taken seriously aswell. i think they have a bit more weight to them, compared to fly figures anyway.

I do, but it depends which way you look at it.

Against diffrent cars, or the same car on diffrent rollers, then no, I dont take them too seriously.

I have an artical by a well respected engine tuner/rolling road operator in a book at home.

Ive been meaning to 'borrow' it for a good few thread over the past year, I'll to and write it up this weekend.

[Jez]

polo/lupos that run 085 gear boxes seem to lose about 25% from various different RR graphs ive seen,

[beach]

polo/lupos that run 085 gear boxes seem to lose about 25% from various different RR graphs ive seen,

but i think its more likely to be really 15-17% otherwise how can a standard engine put out about 150bhp at the fly?

[Tigz™]

Roller opertators know that if some chap in his modded car gets a lower reading than the rollers down the road, they wont come back again.

125bhp at the fly, 99bhp at the wheels seems to be about right.

140 at the fly, 99 at the wheels is just the operator not taking everything into account correctly imo.

[beach]

it can get a lot of things confused when we talk fly figures. we should talk wheel as much as possible. even then it doesnt clear up the issue that i got 107 at wheels with a panel filter, compared to 99 wheels with manifold/aftermarket exhaust and a bmc kit. but then again it could, it might prove that those mods are not got for the vw engine.

[beach]

A9XSJ i'm not having a go at you for your results, it just makes an interesting discussion. its good to get as many people as possible to take their cars on the dyno to see how it goes etc.

my dyno graph

as promised i have posted my graph on my dyno thread. above is a link to the graph.

[T5POL]

http://www.pumaracing.co.uk/coastdwn.htm

This is what I go by. Very good explanation and I have proof in 4 RR printouts to prove Dave @ Puma Racings theory.

I agree with Beach, although what Andi is saying is that Rolling Roads are only useful when you go with a standard car, then go to the same RR but with a few mods, to see what improvement has been made.

Edited August 11, 2006 by T5POL

[Tigz™]

it can get a lot of things confused when we talk fly figures. we should talk wheel as much as possible. even then it doesnt clear up the issue that i got 107 at wheels with a panel filter, compared to 99 wheels with manifold/aftermarket exhaust and a bmc kit. but then again it could, it might prove that those mods are not got for the vw engine.

Just because its the same make of car, doesn't mean its going to have the same readings.

For ll you know, if your engine was in his car, on those rollers it may have only got 95bhp at the wheel and vice versa.

You may make sure your tyre pressures are up before hand, you may use 98 RON fuel and not 95RON fuel, theres so many variables its impossable to compair one car to the next.

[beach]

it would be nice to have another gti owner who lives in cornwall go on the rollers with me sometime. that would be a fair comparison. if we as said checked tyre psi, and fuel etc to be the same.

the day before my run i filled up with optimax and did my tyre pressures.

Edited August 11, 2006 by beach

[Tigz™]

If the tyre pressures, tread (yes Im being anal) fuel ect were perfect, you could do a comparison on which car was running better, but against mod and mod on diffrent cars I dont think its possable.