Thoughts on g-timers for acceleration, etc?

I had a G-Timer. Turns out it wouldn't read the signal from the cigarette lighter of my M3, so I returned it. It uses the signal to plot RPM, shift lights, etc. The timing functions seemed to work well.

Before buying another, I would make sure from the company that it works with your particular vehicle (the folks at G-Timer said the issue was only with new BMW's, but I think they weren't completely forthcoming).

 

Nope--never did any of those calculations. But I have a friend who has one, has done it, and they are relatively consistent.

The big deciding factor is whether the accelerometer is a two axis or three axis. Three axis costs more, but can give you lateral acceleration and/or compensate for changes in car 'levelness" during acceleration. As your car tilts back during an acceleration run (nose rises) it can falsely increase the estimate of acceleration.

But, in any case, I think they are a great idea. Wish it had worked on my M3.

 

I should clarify what I mean by consistent.

First, assuming the testing is done by the same driver, on the same road, with the same air temp, with the same relative humidty, with the same tire temp, with the same engine temp (you get the picture), the results from run to run will be very close.

Also, the horsepower estimates will be consistent--but not necessarily accurate. So, the G-timer may say your horsepower is 300. A dyno may say 270. So you now know it tends to read about 11% high. You can use this correction factor to figure out what you real gains are from mods.

Not a substitute for a dyno, but good for ballpark estimates, especially if you are playing with distributor advance, etc. and can't run to the dyno to check every little change.

 

Apex'i makes a Rev/Speed meter and has an optional G sensor. the good thing about the G sensor and acceleration/cornering/decelration is that when accelerating, it takes it signal from the G sensor, not from the RPM or speed signals to begin timing. This takes care of any kind of wheelspin to give you an accurate reading. No horsepower ratings are available though.

Pricing on the base unit is ~$250 and the G sensor is about $75.

 

I have an AP22 Performance meter, and have found it to be quite sensitive to proper mounting. I once managed to get a 0-60 time of 6.0 secs from a car that is supposed to do it in 8.5ish.