GTech pro RR measurements

[biggie_]

Hi,

as somebody know, i live in an island (very little island), and here there isn't any rolling road to know the horsepower is giving my Q4, i bought two or three weeks ago a G-Tech Pro RR.

it has revealed to me like a great tool to know how much i'm improving the performances of my car, and i have to say that i'm very impressed with the consistence on the results.

at the moment i only have a K&N air filter (in the original box) and custom made chiptuning from a friend of mine who has a lot of knowledge about integrale's engine. I would like to share the graphics that I got with you ;-)

here is the results with OEM chip:



and now the results with chiptuning (I made two attempts because I realized that i have not reved enough the engine in the first attempt):

[wrinx]

Am I missing something...?

111.3Kw = 149bhp

137.8Kw = 185bhp

Are you adding estimated transmission losses, so they are around 185 & 220?

2sec off the 0-60 is impressive, although the standard is supposed to be around 7sec.

wrinx

[WhizzMan]

I see a lot of wheel/clutch slipping action in first gear, that would account for the 1 second lost on the 1-100 km/h runs. It is kind of hard to compare the two graphs since they have different time line resolutions.

It is hard to tell if both runs use 3rd gear for the power rating calculations? Different gears have different transmission losses so you'll have to make certain you are working in the same circumstances, measuring the same thing, to be able to compare.

What cW value, frontal surface and weights are you using for the calculation? What temperature, altitude and humidity are you making the runs? These can all be of influence on your final figures. Those combined could easily account for these power figures. The actual weight of your car, with you in it, tank filled, stereo and all fitted, can easiliy be 200 Kg more than the weight on paper. Temperature and humidity can also easily alter power as much as 10%.

You could try and do a run in 3rd gear only, starting at 1200 rpm. That would give you figures for 1200 to 4000 rpm as well.

The Gtech, when properly used, is indeed a very accurate device that will give you good power figures at WOT runs. It is less useful for doing actual tuning, since you really want a dyno that will brake your engine so you can do each load cell individually without having to worry about acceleration enrichment and other dynamic factors. Once you have those properly set up, you can fix your acceleration enrichment either on the bench or with a Gtech. For pure horesepower/torque contests, the gtech is great and will tell you immediately who had his car rolled at an "optimistic" rolling road outfit.

[biggie_]

Am I missing something...?

111.3Kw = 149bhp

137.8Kw = 185bhp

Are you adding estimated transmission losses, so they are around 185 & 220?

2sec off the 0-60 is impressive, although the standard is supposed to be around 7sec.

wrinx

Hi wrinx,

yes, the results are power on wheels, you have to add the transmision losses and aerodinamic losses too, my chiptuner estimated about 10 hp aerodynamic losses in second gear which is where Gtech has calculated the power, and he estimated about 195 hp with standard eprom and about 235 hp with the chip

About the bad 0-60 measurement that i done with the OEM eprom it was because i didn't reved enough the second gear and get the 60 mph in third gear, after that i saw that it was posible to get 60 mph in second gear, i'm sure that 7,5 sec are posible with OEM eprom

I see a lot of wheel/clutch slipping action in first gear, that would account for the 1 second lost on the 1-100 km/h runs. It is kind of hard to compare the two graphs since they have different time line resolutions.

Yes, you're right, that may be because I do not usually do this kind of acceleration from a standing and doubted about the time of final release the clutch.

About compare the two graphs i made some screenshots now that i hope can help you to compare better than before:

It is hard to tell if both runs use 3rd gear for the power rating calculations? Different gears have different transmission losses so you'll have to make certain you are working in the same circumstances, measuring the same thing, to be able to compare.

Both runs use 2nd gear for the power rating calculations

What cW value, frontal surface and weights are you using for the calculation? What temperature, altitude and humidity are you making the runs? These can all be of influence on your final figures. Those combined could easily account for these power figures. The actual weight of your car, with you in it, tank filled, stereo and all fitted, can easiliy be 200 Kg more than the weight on paper. Temperature and humidity can also easily alter power as much as 10%.

Ummm about cW value and frontal surface... that's the pitch factor that appears on the Gtech? if it is, i have fixed 2.0. About the weight of my car, it was weighed in running order with half a tank of fuel and me in the car in a precision scale in a few days before making measurements, the results was 1.585 kgs (i added the pdf file on this post). About the temperature my chiptuner advertised of that, and i was carefull to do the measurements in similar conditions, on the first attemp with Oem eprom it was 19 ?C and on the second attemp with Chiptuning it was 18 ?C

[WhizzMan]

Pitch factor is how much the Gtech is off-horizontally mounted in your car I think?

It doesn't correct for air resistance probably, which is why only the weight is entered. At least you measured right for the weight. If these are "at the wheel" powers, your calculation/estimation for transmission losses is probably less than 5 percent off. That is actually very good, considering most rolling roads don't come that close without calibrating for the specific car.

Officially, power figures are given "at 20 degrees Celsius" and yet another correction factor is applied. By doing tests at 20 or very close to that, you can prevent another figure that can be "tricked around with" appearing in your correction formula. Your tests at 18 and 19 are perfect for that.

[Steve Webb]

Hi Biggie, did you get the g-tech in Europe or did you get it shipped from the USA?

[biggie_]

Hi Biggie, did you get the g-tech in Europe or did you get it shipped from the USA?

Hi Steve, i have bought it from Uk from an ebay particular seller (second hand)


P.S. have you received my last e-mail with pics of my Q4?

[Steve Webb]

HI Biggie,

yep got your pics, I'm gonna get on and get them in the register in the next day or so.

I was checking the prices of the g-tech online and over here in Europe they are really expensive, I might see if my sis in the US can get a better deal.

Steve

[biggie_]

Hi,

today i take new performance measurements with the new "chip" that have sent my chiptuner last week.

i'm very happy with the results, in a few words...

- 10 bhp plus, now we are very close to 245 bhp at the clutch
- 5,85 seg on 0-100 km/h acceleration
- 26.27 seg at 1000 mts from standing.