Power outputs at the wheels

[sydeos]

The following link shows independently tested figures for power outputs at the wheels vs Manufactures quoted figures.

It would appear the VW usually under quotes it power outputs.

It also shows the power loss from AWD systems

http://www.rri.se/

[Golfer]

Awesome link sydeos!!!

Kudos
John

[gpk_gti]

great find sydeos!!:) suprising no one found it before!!
worthy of a sticky??

[Oneofthegreats]

I'm a sceptic. Someone clear this up for me

This topic has been talked about before but I'll dribble it again.

Those figure's to me look like they've taken drive train losses into consideration cause no car has 0% drivetrain loss.

I know on some, if not most brand dyno's (Haven't played on them for quite awhile now) they can run a program that can take drivetrain losses into consideration so all you see is the crank power.

But.
I've seen standard M3's spit out 185-190rwkw's. This work's out to be 252kw at the engine (M3 standard spec.) with 30% drivetrain loss.

XR6T's turning out 180-185rwkw's with 30% loss through the drivetrain it work's out to be 235-245kw's @ the engine. Standard spec XR6T.

My standard GTI spat out a mind blowing, gut churning 66fwkw's which, with 30% power loss work's out to make 88kw(117hp) @ the engine. Alittle bit more than standard. All 3hp Whoopy Do!

My two bob.

[gpk_gti]

u dribbling again golfworx?? hehe

I thought fwd loose much more than rwd.

check here-
http://www.pumaracing.co.uk/POWER3.htm

[SoVeReIgN]

Rough figures

FWD : 15% - Fairly direct output to wheels, no change in direction if engine is mounted east -> west
RWD : 20% - Extra change in direction in diffs and weight of driveshafts
4WD : 30% - Same as above + weight of extra set of driveshafts and wheels

Figures will vary so much between cars because different manufacturers usually use different ways of getting engine power (DIN Engine Dyno etc) or just plainly lie about their figures (Think japanese sports cars under 206kw "gentlemens agreement") and obviously tired engines or engines not run in properly or even just engines from Friday/Monday will not being making as much power. :)

[Oneofthegreats]

Thanks Fuzion.

This backs up my 30% power loss to the wheels theory.

Doesn't a standard Mk4 GTI make 150hp?




Stock FWKW 88-92
Chipped FWKW 105-118
Chipped Modified FWKW 115-130



So a 30% loss of power to the wheel's would be approx 85 FWKW's. How about that.

It doesn't matter if it's FWD or RWD. AWD are different & there power loss is much more.

But the power still has to go through bearing's, seal's, gear's, syncro's, clutch's, flywheels, (torque convertor's & flexplates if auto).

It's when they say with a FWD the power doesn't have to make a 90 degree turn at the diff., but what they forget is even if a FWD is in 4 or any gear 1:1, it still has to go through 2 sometimes 3 main shaft's before it gets to the pinion gear.
With a RWD in 4th 1:1 the drive it direct to the diff. & only has to make a 90 degree turn.

So it's 6 of one, half a dozen of the other.

[sydeos]

I'm a sceptic. Someone clear this up for me

This topic has been talked about before but I'll dribble it again.

Those figure's to me look like they've taken drive train losses into consideration cause no car has 0% drivetrain loss.

I know on some, if not most brand dyno's (Haven't played on them for quite awhile now) they can run a program that can take drivetrain losses into consideration so all you see is the crank power.

But.
I've seen standard M3's spit out 185-190rwkw's. This work's out to be 252kw at the engine (M3 standard spec.) with 30% drivetrain loss.

XR6T's turning out 180-185rwkw's with 30% loss through the drivetrain it work's out to be 235-245kw's @ the engine. Standard spec XR6T.

My standard GTI spat out a mind blowing, gut churning 66fwkw's which, with 30% power loss work's out to make 88kw(117hp) @ the engine. Alittle bit more than standard. All 3hp Whoopy Do!

My two bob.


Did you actually read the information on the test procedures?

This test is at the wheels. Check the following URL -

http://www.rri.se/index.php?DN=28

There is not zero drive line loss the test figures would indicate that some manufactures understate the engines power output. That is the whole point of the post.

The link came from an Autocar article expressing the same conclusion.

[Lima]

This would indicate that VW understimates their figures as well. j:

My wife's GTI is stock.

http://www.vwwatercooled.com.au/forums/images/imported/2007/07/YCM811_dyno_300607-1.jpg

Haha, not that I'm placing too much faith in this result, but it's all good fodder for fun and games.

[evorobin]

If the dyno guy had told you they were flywheel figures they would have been more accurate LOL

[Oneofthegreats]

I did read through the info in the link & I'm still not a believer sorry.

I'm not here to cause an argument or a s#%t fight.

My reasoning is simple. A car that weigh's so much, make's so much power, can only go so fast & that's it.

You take a standard Golf GTI which weigh's approx 3100 pound's with a driver, fuel etc.
This car makes 147kw's (200hp).
The best recorded 1/4 mile by most magazines is approx 14.7 -15.0 ET with DSG. No MPH recorded.
Update: The lastest Motor Mag recorded a 14.6@97MPH

This work's out to be 98% spot on. The car is making a tiny bit more hp than indicated by the manufacturer by only approx. 15hp.

I'm not saying that all manufacturer's figure's are the be all & end all, as most German & Japanese car company's do underestimate there power figure's.

Also, that dyno graph indicates it's in shootut mode which can have a controlled drivetrain loss built into it, so it would be indicating the crank power/kw's.

If you go off the result's in the link, the GTI would be able to run very low 14's to high 13's.

[shaneth]

Rough figures

FWD : 15% - Fairly direct output to wheels, no change in direction if engine is mounted east -> west
RWD : 20% - Extra change in direction in diffs and weight of driveshafts
4WD : 30% - Same as above + weight of extra set of driveshafts and wheels


This is exactly what i thought as well. Then i confirmed it with a mate of mine who is a dyno operator up here. And as Sovereign said thats a rough guide as not all cars are the same but in general you are pretty safe with those figures.

[sydeos]

I think you are missing the point here.

Dyno testing results under common test conditions by independent testing body.

The results are only valid for the vehicles they have tested for output at the wheels on their dyno.

The only conclusions I and Autocar have made are that the VW/Audi group along with various other manufacturers appear to be understating there power outputs when looking over all the data that has been collected.

Not trying to start any fights that is all I am saying :D

[shaneth]

Leigh who are you addressing mate

And that site is interetsing yes but afaik rolling roads/ chassis dynos are ment for a tuning purpose mainly. Yes they do give you an indication of power especially when you do before and after results around a Mod. But they dont take all the loses into consideration. But once again afaik car manufacturers use flywheel dynos. And are much more accurate when it comes to power readings.

[Spyda]

Does it all realy matter?

I would have thought the only power that matters is the one that you put to the road. If i had 200hp and only 150hp at the wheels doesnt that mean i can only use 150hp...so isnt that the only one that realy matters?

Ive heard the veyron produces a great deal more then the 9 hundred whatever bhp its rated at but depends from car to car.