I have had this G-Tech sitting around for a couple of years now, so just for grins I attached it to both of my "fast" cars to attempt to measure chassis HP. G-Tech claims a +/- 3 HP accuracy, but I'm not sure I buy that number.
MTM claims my Audi makes 320 HP off the crankshaft with the RS2 turbo and manifold. It is a pretty healthy setup. So, I entered the vehicle's weight and did a few runs. The G-Tech returned 256 HP, which is supposed to be the rear wheel, or chasis HP. Considering the Quattro system sucks up more power than a simple rear driver, this seems to be a good number. I used 20% driveline loss making the MTM claim and the G-tech number right in line with each other. Maybe this thing is accurate?
Okay, off to the 928. I entered in 3550 for a vehicle weight (I was in it) and did a few hard 2nd and 3rd gear pulls. G-tech returned 310HP peak for a chassis HP. I am going to assume the drivleine on the car consumes somewhere between 50 and 60 HP (stock S4 dynos at about 265 at the wheel and makes 317 off the crankshaft). That makes for somewhere between 360 and 370 HP to the crankshaft on 8 lbs of boost....this also falls in line with voltage measurements from my MAF sensor (i.e. calibration chart), be it a tad bit on the low side. Manifold pressure was between 8 and 9 psig. Shift points were just below 6000 RPM.
Anybody else measured HP with these items? I would assume the internal algorithm is pretty good at taking into consideration the variables required to calculate the HP based on the vehicle weight. Of course a Dyno would be more accurate since wind resistance and the like are not there like on the road.
I just wanted a baseline on the old intake system before I move to the new unit this week.
I have recently dialed 5 degrees out of the ignition advance (under manifold pressure) on my car in anticipation of adding a few lbs. of boost once my new air cooler arrives. In addition, the state of tune right now is crude. I still have a lot of work to do.
MTM claims my Audi makes 320 HP off the crankshaft with the RS2 turbo and manifold. It is a pretty healthy setup. So, I entered the vehicle's weight and did a few runs. The G-Tech returned 256 HP, which is supposed to be the rear wheel, or chasis HP. Considering the Quattro system sucks up more power than a simple rear driver, this seems to be a good number. I used 20% driveline loss making the MTM claim and the G-tech number right in line with each other. Maybe this thing is accurate?
Okay, off to the 928. I entered in 3550 for a vehicle weight (I was in it) and did a few hard 2nd and 3rd gear pulls. G-tech returned 310HP peak for a chassis HP. I am going to assume the drivleine on the car consumes somewhere between 50 and 60 HP (stock S4 dynos at about 265 at the wheel and makes 317 off the crankshaft). That makes for somewhere between 360 and 370 HP to the crankshaft on 8 lbs of boost....this also falls in line with voltage measurements from my MAF sensor (i.e. calibration chart), be it a tad bit on the low side. Manifold pressure was between 8 and 9 psig. Shift points were just below 6000 RPM.
Anybody else measured HP with these items? I would assume the internal algorithm is pretty good at taking into consideration the variables required to calculate the HP based on the vehicle weight. Of course a Dyno would be more accurate since wind resistance and the like are not there like on the road.
I just wanted a baseline on the old intake system before I move to the new unit this week.
I have recently dialed 5 degrees out of the ignition advance (under manifold pressure) on my car in anticipation of adding a few lbs. of boost once my new air cooler arrives. In addition, the state of tune right now is crude. I still have a lot of work to do.
The way i see it..
Everything has to be accurate for accurate results. The wgt should be exact as you can get it. I drove my car to a local rock landscaping place and asked if i can drive on there scales. After weighing myself and seeing spot on 180 on the scales i drove the car on. Got the weight and then i jumped off the scales and the wgt dropped by 180lbs. I was amazed at the accuracy. The gtech has to be securely mounted. Anytime you tip the device, one direction or another it will measure accleration along that plane and will influence the result.
Ive heard if your car has a "soft" suspension that the car will squat more leading to a false indication of greater accleration when the Gtech (attached to the car) tips back with it.
I dont reley on the results...its a nice to have tool, but go to a dyno for more accurate result and one you can compare with others.
Just my experience with one, the older cheap GTECH.
Anyone chime in with the the new one GTECH-PRO??
Everything has to be accurate for accurate results. The wgt should be exact as you can get it. I drove my car to a local rock landscaping place and asked if i can drive on there scales. After weighing myself and seeing spot on 180 on the scales i drove the car on. Got the weight and then i jumped off the scales and the wgt dropped by 180lbs. I was amazed at the accuracy. The gtech has to be securely mounted. Anytime you tip the device, one direction or another it will measure accleration along that plane and will influence the result.
Ive heard if your car has a "soft" suspension that the car will squat more leading to a false indication of greater accleration when the Gtech (attached to the car) tips back with it.
I dont reley on the results...its a nice to have tool, but go to a dyno for more accurate result and one you can compare with others.
Just my experience with one, the older cheap GTECH.
Anyone chime in with the the new one GTECH-PRO??
I don't have any experience with the G-Tech but here in the UK there is a similar device from Race Technology. I have an AC22, and a friend has an AP22 (this one you can download the captured data to a PC).
We use them set up to the same "tilt factor", weight and CD factors, just to compare 928s - our own cars and also others that we get to see.
The figures seem reasonably accurate in absolute terms. My Euro S2 auto comes out at 259bhp rwp. My friend's CS with a newly rebuilt motor just under 300 (manual of course).
Have a look at the Race Tech website at www.race-tecnology.com
We use them set up to the same "tilt factor", weight and CD factors, just to compare 928s - our own cars and also others that we get to see.
The figures seem reasonably accurate in absolute terms. My Euro S2 auto comes out at 259bhp rwp. My friend's CS with a newly rebuilt motor just under 300 (manual of course).
Have a look at the Race Tech website at www.race-tecnology.com
Three Wheelin'
I would agree with the comments on the squatting or tipping of the device, but all in all I think it provides a good baseline from which to compare numbers. Under accelleratio I could see high accellerations between shifts, but flat out full throttle up towards the redline the car isn't squatting that much.
The fact that the results fall in line with the voltage measurements off of my MAF also leads me to beleive it is well within the ballpark for comparison purposes.
Who knows what the real world accuracy really is, but I am sure this thing is repeatable for its designed purpose.
I had actually made a circuit years ago to attempt to measure accelleration, but quickly realized I could just buy one for a whole lot less money and time.
The fact that the results fall in line with the voltage measurements off of my MAF also leads me to beleive it is well within the ballpark for comparison purposes.
Who knows what the real world accuracy really is, but I am sure this thing is repeatable for its designed purpose.
I had actually made a circuit years ago to attempt to measure accelleration, but quickly realized I could just buy one for a whole lot less money and time.
Three Wheelin'
Nice to have some numbers from both the G-Tech and the Dyno. Now, that is really impressive. Fundamantally, the equations have to work, I guess it is all in the way the unit is mounted and with minimizing vibrations.
I have my baseline now, so that is great.
I have my baseline now, so that is great.