Houdini

iTrader: (3)

Yes, the original version only had a single axis accelerometer which required you to be level before launch. Now, with the 3 axis competition, it self levels itself. In addition, you can angle it any way you wish. Once mounted, you take a practice launch and the system then determines the straight line direction using all 3 axis measurements. Then, by using them as vector components, it combines the 3 to determine the magnitude and direction of the combined forces. It should also be able to correct the fact that the car tilts on launch since it also measures acceleration orthogonal to the ground(this should always measure 1g for gravity). If the car tilts, then the downward force will be equal to 1g x COS(angle of the car). Lets say the car tilts 5 degrees, worst case scenario since that translates to over 8 inches of difference between the front and rear tires. COS(5 degrees) = 0.996. That means even if it doesn't correct for tilt, you're only off by 0.4%. Not really a big deal unless you like to nit pick since 0.4% translates to 1HP on a stock FD.

I would guess the RSM wouldn't be that accurate. Especially since, if I remember right, it runs of the vehicle speed sensor. If you spin the tires or they slip, you'll get a false reading. I think G-tech quotes out their accuracy as 5/100s of a second and repeatibility as 1/100 of a second. That's better than any of us will probably need. It's not dyno but it's probably the cheapest thing to it.

talljosh85

iTrader: (3)

Kento, its cool, sorry I got so defensive quickly.

Houdini; thanks for the advice. I'll have to try your suggestions out, and post the results when I get a good cool night to go out.

The Supra, by the way, has a random tech downpipe & high flow cat, 2nd gen TRD exhaust, titan cam gears, a 1st gen profec b, a greddy boost cut controller, and was running somewhere between like 14psi and maybe 17 or 18, I can't remember exactly. There were two of us in the car, the targa was off, a/c on, windows down, and it was set on low boost. My dad bogged the launch, forgot to disable traction control or even turn it off, and I accidentally entered the weight a little low for the car. ANYWAYS, the numbers were as follows: reaction:1.749s, ET 13.018, trap speed:124.04, 60': 2.326, 0-60mph: 5.635s, max hp: 402.1 @5637rpm, and max torque was 383.0 ft/lb @ 5127prm. The weight had been set to 3430lb, while the actual weight was closer to 3800lb. We will be messing around with it more in the coming days. The G-Tech Pro Comp claims accuracy to the 1/100 of a second, for whoever may be interested. Josh

greg schroeder

I have one of the old gtech meters. The trick to getting correct and accurate measurement from the older unit is setting up the device properly. It must be completely level and facing straight forward. It works. It is possible to get very inaccurate readings if you set the instrument up incorrectly. If these things are off they sure do a good job at being off exactly the same each time.

I've had three FDs now and a bad launch on a stock FD definitely gets you a 5.9 second 0-60. A good launch from about 3500 rpm with mild tire spin and no wheel hop gives you a 5.0 or so in stock trim on an 80F day. With my last FD I managed regular 4.2 0-60 times with 13lbs boost, PFS cat back, intercooler, intake and computer.

My buddy just got a 911 turbo X50. With the two of us in the car, full tank of gas, 112F day and 3500 rpm launch it was doing 5.18 to 5.3 in the 0-60. I know on a cool day with just the driver it will pull a 4.2 and with a higher RPM clutch dump it may dip into the 3s.

For HP testing weight of the vehicle must be entered. If you enter the weight higher than what your car actual weighs, your HP numbers will be higher. If you enter the weight to low, HP numbers will be lower.

I also have used Kart racing Aim units which similarly use accelerometers, but with a more complicated design. The last system I was using actually was able to map the track and then display it on a computer. This was done by simply driving around the track.