G-Tech accuracy and info?

[DanielM3]

A friend of mine just got a G-Tech the other day so I wanted to test it out on my car. I have a 95 M3 that has the 3.5" intake system from ECIS. Other than that it is pretty much stock.

My results seemed really good (too good?):

5.3 sec 0 - 60
246 hp ??

I made many runs to test repeatability and results were all very close. The hp # should be at the wheel right? So doesn't this seem high for my mods?

For comparison, we did the same tests in a 98 M sedan and the results were:

5.8 sec
207hp

His mods were only intake and fan delete.

Do these #'s seem right?

Thanks

Daniel

[qwickm3]

I have a gtech and i've always found it to pretty reliable as far as times. it calulates crank not wheel horsepower though. When comparing times on the Gtech to time at the drag strip its always been either +/- .1 sec. The only thing thats really different is trap speed because the gtech uses actual speed at the end of the 1/4 while a drag strip uses an average speed over 60ft.

[RenaissanceMan]

Don't you have to enter the precise weight of the car + driver for the hp readings? My understanding is that if the weight is off, your hp numbers will be way off.

[Jim O.]

If you're looking for HP numbers, this is pretty cool:

http://www.charm.net/~mchaney/roaddyno/index.html

I played around with one some - seemed to be pretty accurate, with reproducible results.

Jim

[DanielM3]

Hey guys thanks for the info

[paul e]

>>I have a gtech and i've always found it to pretty reliable as far as times. it calulates crank not wheel horsepower though<<

Sorry, Quick. This is wrong. I quote from the pamphlet:

"Gtech Pro also measures delivered horesepower, sometimes also called Rear Wheel Horsepower. This horsepower includes the loss of power through the drivetrain which is usually 10-15% (about 18% in our cars pe). Rear Wheel HOrsepower is what most people are instested in because that is what they experience ehen driving.."

[DanielM3]

thanks paul e

I was really going to be wondering why my car was down on power...and my friends M at 207 would have been in really bad shape.

thanks

daniel

[endonuky]

Maybe you guys, especially Jim O. can help me out with this. About 6 or 7 months ago, I bought and returned 2 g-techs from BMP. I don't know if they sent me defectives or what. The first one I couldn't get to function properly at all. The second one worked, and I entered all the specs. i.e. weight etc. properly, but I just got readings all over the place. I used it several times, always figuriing maybe I did something wrong. But I did my runs in the same place, the same way. I am careful and meticulous and do all my own work and mods on my cars, so I am not a mechanical moron, but the g-techs I had just seemed like junk. So, my question is, where to get one that may work?

PHIL

[Jim O.]

What are you trying to measure? Maybe there's something out there that's better for what you want to do. Things like the AC-22 or the Road Dyno might be better choices than the G--Tech.

Other than that, unfortunately I can't help you with your G-Tech problem - I haven't used the G-Tech myself.

Jim