baxdatass

Well I finally got my gtech pro. I have only used it once and so far I don't think that I know exactly how to use it yet. I have clicked of times of 5.84sec 0-60mph 3 different times, so I think it would be safe to say that that is what my car is doing, however my tires are near their wear indicatirs so I would expect better times with new tires, plus I wasa little rushed seeing as how everyone was coming in from work, so the normally quiet street was busy with people coming home. HP rating ranged from 176hp to 187hp. I KNOW that this can be better. Does anybody know what gear is best to test HP in? and how far up the RPMS I should go before stopping? New Wheels wider tires, and a VAFC are all underway and should be hear within two weeks. We shall see then what Gtech tells us.... muhuhuahahaha

TurboVtk

[QUOTE]Originally posted by baxdatass
[B]Well I finally got my gtech pro. I have only used it once and so far I don't think that I know exactly how to use it yet. I have clicked of times of 5.84sec

schwett

for 1/4 mile times, the front to back squat issue is minimal. there simply isn't enough suspension travel to significantly affect the numbers. our wheelbase is 94.5 inches. i don't know how much suspension travel we have, but looking at the wheelwells i doubt it's more than 4 or 5 inches. we're talking about 2 degrees of tilt. that will affect the numbers but not by much. someone who remembers their physics better can calculate it.

as for the roads not being flat, obviously this is important. if you want accurate results, find a nice flattish road in the middle of nowhere and do a half dozen runs in BOTH directions. throw away the best and worst in each direction and average the rest.

for horsepower, you really need to weigh the car with you in it. i've been very surprised at the actual weight in every honda i've weighed.

TurboVtk

[QUOTE]Originally posted by schwett
[B]for 1/4 mile times, the front to back squat issue is minimal. there simply isn't enough suspension travel to significantly affect the numbers.

schwett

the scale i go to is free unless you need a certificate, which is like 10 bucks or somethign.

xviper

Go to your local dump (landfill). They weigh every vehicle that goes in. My last weight with 1/2 tank of gas and me in it (at 3500 ft. elevation, if that makes a diff.) was 3003 #s.

TurboVtk

[QUOTE]Originally posted by xviper
[B]
Go to your local dump (landfill).

xviper

Oops, left out the slash. Meant 1/2 tank.

Russ

I dare say there are few individuals on the planet short of those working at Tesla themselves that have used the GTech pro unit more than I have over the past four years. I have logbooks dedicated to the unit which includes results from five automobiles and more than 300 runs. Not a whole lot with the S2000 (under 30) because frankly speaking, there hasn't been a whole lot I've done to it that would warrant so much testing. No high RPM clutch dumps, etc either. My results have always been garnered with 4-4500 rpm starts with a featured clutch release which for me, after all these years of practice, seems to be the most effective way to maximize power and traction. More importantly though, like most testing standards, for accuracy, there has to be a set of rules. Running the GTech in one direction pretty much voids everything for the day. Running in winds above 6 or 7mph will throw off the results. I don't measure g-forces (not interested) so I won't comment on that side of things but the above boldfaced quote from Pimp is a good example of misinformation (though honorably intended) with regards to the GTech. He states any downward slope during a run would give noticeably better results. This is Incorrect. Let me explain why:
Think about what it feels like when you are parked facing down a steep hill. You are pulled towards the front of the car by gravity, much like you would be if you were in the car while it was braking. Therefore, the acceleration figures the GTech reads are the actual acceleration minus the "apparent deceleration" of going downhill. So even though you are accelerating to 60mph, the GTech doesn't realize you're there yet because it hasn't been reading the same amount of acceleration
In other words, the time the GTech shows on the unit will actually be HIGHER than the car's correct 0-60 time. This is why running the car in both directions (to alleviate the statistical differences garnered by small elevation changes on what your eye may perceive to be a flat surface) is literally mandatory if accuracy is your primary goal.
I could write a small book on this unit but like most other things having to do with man and machine, garbage in equals garbage out. You can't tack it on your windshield and go out to make one run and claim your car is a 13.4 S2000.
Following the last nine or ten runs en route to modifying my PRM, my average 1/4-mile times have been in the 13.74-13.85 range. Could I duplicate this at a track? God only knows but we'll see in the spring. The only mods to the car have been the Tanabe Racing Medallion exhaust and the PRM, plus about 75-lbs weight loss from removing some items and changing others. The average STOCK times I charted with my car before doing any mods were averaging around 13.97 so the PRM/Tanabe/Weight loss has pretty much resulted in a drop in 1/4-mile times of .18 seconds which seems about right. The only gauge I have to measure whether or not I think my times are accurate is the success I've had against my dad's Lexus GS400 which has been taken to the track many times ( he averages 13.9 and change). We've raced three times with me behind the wheel of my S2000 and once with him behind the wheel and me in the GS400. Not once did the Lexus win (1/4-mile race). 'Been close though...each time, which leaves me to believe at worst, my GTech times are fairly accurate considering the closeness of our races and his verified track performance. The S2000, each time, finished about one to 1 1/2 car lengths ahead. (run on a deserted airport clearly marked at the end of the measured 1/4).
One more thing...the GTech is affected by drag, so your horsepower runs will not be as optimistic as a dyno pull. Best thing to do is before you actually begin to modify your car, put it on a real dyno and then roll it out on your best test surface and do some GTech HP runs. From that point on, drag should remain constant (say, redline in 3rd or 4th gear).
I did this with my Contour SVT and found out the difference between a GTech HP measurement and a stock dyno pull (stock) was 6hp worth of drag (remember though you have to be in the same gear and same top speed to compare since drag increases with top end). Bear in mind, especially with the S2K, you don't have to redline in 5th or above to get your HP reading. Hell, even 9K in 3rd should be fine. Also, FWIW, this type of measurement ALSO requires runs in the both directions. Like all others, preferably six (three in each direction), throw out the best and worst and average the other four.

E30M3

If you like the GTech you'll LOVE more capable meters. I have about 8-9 different performance meters and the only readily available unit I don't have is the old GTech - it's too much of a toy IMO. The GTech Pro Competition has potential but the software is not yet there. Race Technology's AP-22 and DL90 blow the GTechs away. They both datalog, the DL90 adds GPS and multichannel datalogging of nearly anything you want. With those two units you can take away the launch and shift related errors that are part of the old GTech approach. This makes tuning and testing efforts much more accurate and repeatable and easier on your machine. You can also use them to gain insight into driver limitations. The Vericom is also good but the datalogging versions are pretty pricey.

Stan