testing for proven BHP prior to buying...

[sprinterVR6 0]

Just wondering what's the most common way of proving bhp on a used car your about to purchase.

 

Does the AA or RAC 'Car Check' test cover this?

 

I've heard stories of some VR's showing figures a good bit lower then 190.

[millerman 0]

poss the only way would be to rolling road it

i did mine a couple of weeks ago and it was down 12 bhp to 178 (vr6) it also depends on the rolling road some give better figures and some worse

so i have been told and where i got mine done the figures are normally a lower

[dr_mat 0]

No-one can know what the power output of a specific car is unless they've recently dyno-ed the engine. You can get a rough idea from a rolling road run.

If the car is "significantly" down on power then it's faulty and you can bring it back to normal by repairing it ... Any VR should be somewhere between 180 and 200 bhp, but there's no way you can guarantee any specific numbers within that range, it depends on far too many factors (the weather, even).

[millerman 0]

yer when i did mine it was really hot about 28 degs i bet the numbers would be different if the temp was around 10-15 degs lower

[VR6 0]

... and no the AA/RAC check won't include a dyno run.

[davidwort 0]

in gear acceleration times will give you a pretty good idea, just compare with VW driver figures for a standard car, doesn't even need to be a VR, you'll need to use the full rev range though. Might have to do a few simple sums and preferably using something other than the speedo to get an accurate speed reading, they underread by a fair wedge.

It's wheel hp that counts anyway, not some calculated, transmission loss, temperature corrected fiddle factor, so driving on the road will tell you the truth :)

[sprinterVR6 0]

Cheers guys - i guess my fear was that I'll be half way back to Ireland with a VR punching way below it's weight :scratch:

But as you guys said - it should be pretty obvious if it's way off the mark

 

:salute:

[millerman 0]

to be honest i cant really tell if the powers down or not !! :D

[sprinterVR6 0]

suppose at the end of the day, if your happy with the power you've got then no worries.

 

Side note: I do remember many years ago a feature in a car mag, not sure which one, and it showed a whole load of Corrado's being rolling roaded and gave the expected bhp figure, the actual fig on the day and the car's owners thoughts on his/her result.

of the 15/20 cars done, standard non-moded VR's mainly, quite a few showed figures of just a itty bitty over 200bhp.

This was, according to the writer at the time, to do with the engines been 'nicely run in' or 'very well looked after' etc etc.

This is all very subjective obviously, but nice to know that some of the Corrado's out there may be showing improved figures. :D

[coullstar 0]

To be honest VW are generally quite conservative with there figures. Any car Ive had done has always been more than factory quote. Just pub talk anyway.

[aide 0]

i may be well off the mark here, but i read somewhere you could approximate bhp/ torque through a gps recorder and running some maths, both from a standing start and in gear rolling

 

now, feel free to shoot me down :D

[Tempest 0]

i may be well off the mark here, but i read somewhere you could approximate bhp/ torque through a gps recorder and running some maths, both from a standing start and in gear rolling

 

now, feel free to shoot me down :D

 

Indeed, that´s the principle that´s used by devices like Race Technologies' AP22.

 

Force is acceleration times mass. So you need to measure acceleration, which this device does (micro-machined accelerometer, eg. as developed at Coventry University, parallel research group to mine, when I was still there). You need to supply the mass (weight) of your car to the device software.

 

Energy or work is Force times distance. The distance you travel is determined by the device from the acceleration (integrated twice by time gives you distance) and the time elapsed.

 

Power is energy or work divided by time.

 

That´s the simple version, but effectively describes what this device does. To then determine the losses in the drive train, it also requires you to do an acceleration to a certian speed, then let the vehicle roll to a standstill, which is measured by the device, from which it can work out the drive train losses. All stored intenally, download into a PC and using Excel or whatever evaluate your runs.

 

Tempest

[dr_mat 0]

(though massively inaccurate since you can't take into account wind resistance and coefficient of drag..)

[CazzaVR 0]

VAGCOM can calculate BHP- think it's block 120. Should work with a VR, but not totally sure :?

 

Shame they don't make a liquid gauge for the C :(