MyE28.com

We did 3 runs with the gtech at about 10psi. The first run (red) the car was running wayyyyyyy too rich. Around 5000rpm the car started buckling. So I turned the FMU down.

The second run (green) -- The car was still running too rich -- the car didn't buckle, but started to REALLY lose power at boost. So I turned the FMU down.

The third run (black) - I had the FMU completely backed out and tuned down -- And it still felt like power was dropping off around 5000rpms on.

Whats cool about the gtech stuff is that they give you power readings at the wheels -- not crank. And it knows which gear you're in and calculates HP/Torque accordingly. Interesting technology.
The only thing I didn't like was how it didn't really show hp/torque until about 3200rpms.

Anyway -- Enjoy!

The GTech is a neat tool. You can get it to give results over the full RPM range, you just have to adjust your driving style for a full power graph. The basic method is to launch soft and shift very short, then smoothly roll into the throttle at low RPM and let it pull all the way through the lowest gear that can handle the power. It will calculate the torque and HP from the cleanest and broadest rev range it sees, so a balls to the wall drag strip style run will just give you the upper power band. You can't combine a good quarter mile run and a wide power graph run into one. It will give very consistant results, but it is only as good as what you feed it.

GTech graph

I believe the results are consistant -- these results are from adjusting from the FMU each run.

Is this the Gtech you see advertised on Speed Channel? I've wanted to look into one but never have. Where'd you get it ?

The numbers seem about right. Any 1/4 mile numbers from it? The 1/4 times on those things are pretty accurate (if you find level ground and do runs in both directions to average any slope). I know people that have gone to a drag strip with one and the numbers are usually within .1 or so of each other. The trap speed is higher though, since it's averaged at the drag strip but not with the G-Tech.

Maybe you don't need the FMU?


[Edit by Craig -535i- Seattle on [TIME]1108686755[/TIME]]

Sorry, I didn't mean to sound critical, your results look good to me. I just wanted to give you the pointer on getting wide rpm band results. However, another benefit of that technique is also improved consistancy, as long as you always use the same gear for the full powerband pull. It keeps the device from possibly choosing different gears for results you are comparing, which could introduce an error from the different amounts of wind resistance.

It wasn't my gtech -- it was my buddy's. Go here:
http://www.gtechpro.com/prod.html It's the 2001 one.

I really want to do the 1/4 mile test. But there's nowhere here in Boone that is completely flat and car-free.

Perfectly flat isn't that important, as long as you run in both directions to average it out. It won't be a perfect number, but it will be somewhat accurate.

Keeping in mind that a quarter mile run is pretty damn illegal so be careful.

Has anyone done a Gtech measurement and then backed it up on a dyno or at the track? Just curious to know how accurate the numbers actually are.
TIA
Justin

Nope -- I'd rather get some real dyno numbers. But this gives me a really good idea on where I stand.

On the way down to havelock (by the NC coast) I noticed my running rich problem went away. I'm almost convinced that it's a problem with elevation. The car was a ROCKET tonight -- more powerful than it's ever been -- I wish I had that little gtech thing then...

[QUOTE="BMWJustin"]Has anyone done a Gtech measurement and then backed it up on a dyno or at the track? Just curious to know how accurate the numbers actually are.
TIA
Justin[/QUOTE]

[QUOTE="Craig -535i- Seattle"] I know people that have gone to a drag strip with one and the numbers are usually within .1 or so of each other. The trap speed is higher though, since it's averaged at the drag strip but not with the G-Tech.[/QUOTE]

:p


[Edit by Craig -535i- Seattle on [TIME]1108833363[/TIME]]

Whups, I really need to read these posts a little better... sorry

[Edit by BMWJustin on [TIME]1108839959[/TIME]]