Just took the car out on the G-Tech for the first time. Road was bumpy as hell but at least it was a long enough strip.
I tried riding the clutch from off idle to 3500, but 4000 came and I just blew the tires off. I stayed in it and powered through 2nd, but spun again and the car slid, but still stayed in it. First run was 13.08@122.8MPH.

Second run I tried riding the clutch all through 1st but the car spun through 2nd and went sideways again.....13.28@120.5MPH.

Third run, I thought to turn the boost setting to "low"(11pds) and try again. Launch "felt" terrible, spun through first, caught traction in 2nd, then spun and went sideways again till I hit 3rd.....13.08@123.5MPH.

You know what this means...spinning sucks!
These were with radial tires(Yokohama Avid S306) and trying to launch sucks with radials. I have a hard time believing that Drag Radials would help on the street, but maybe. Keeping the boost at a low setting is actually quicker on this car for the street. That's insane! With that MPH, shouldn't this car should go mid 11's with traction?

My question is this...going from my stock non-sequential twins to a T-78 would not make much difference, would it? I want to do it, but I am afraid of slowing the car down because I would cause even more tirespin? Does anyone have any comments or suggestions?

 

yeah man, no traction is killing you

your trap speed is great!!

 

you gotta make sure your on 100% level ground, even a 1 degree deviation will throw off yoru results. going up hill, i can get over 600hp hahaha

 

wow, how did you manage such a high trap speed??

 

I would take the G-tech's mph reading with a grain of salt. They don't measure mph in the same way as the timing lights at a 1/4 mile track, so the figures will almost always be 5-6% higher than real life.
For example, I consistantly get around 13.0 @ 116 on the G-tech, but I don't even get close to a 116 trap at the track.

 

I know it's not the most accurate, but, I use it to see consistency. For example, let's say a change in tire size drops 2/10's of a sec, I know I am going the right way. And when all those right ways are at their quickest...I go to the track. Saves major money this way.

 

The GTECH trap speed is always high because it gives you actual MPH at the end of the run. At the track, your MPH over the last 50 ft or so is averaged.

As you mentioned, the GTECH's real strength is that the results are repeatable. If you use the same stretch of road and try to always have the conditions be the same, it can be a good tool to see relative change.

One of my old cars would consistently trap 107 mph on the GTECH, but it would never break 102 mph at the track.

Sonny

 

Definitely. It's a great tool for comparing launch methods, tire changes, etc. Sustained G's is a very cool feature, and (believe it or not) the ET is actually very close (+- one tenth) to what you'll get at the track, with a similar launch.
But, like sonny said, the mph is not good for real world comparisons due to differences in mph measuring methods.

 

LOL, 600 hp by driving up a hill. Thats a great way to impress some one. "yeah, it's got 600 hp at the wheels, watch"

 

Uh, so you've gained 5 mph in 50 ft? I don't think so. Do a conversion to ft./sec. and tell us how you think that is possible when you're only trapping 107 mph. How do you think the GTech gadget is determining your speed? It is estimating your speed based upon a set of mathematical algorithms using data from a two-axis accelerometer-- which is a form of "averaging" in itself, because it lacks any real distance measuring data. While the figures attained by accelerometers are somewhat accurate for not actually being able to "see" anything, when you're talking about measuring speed at the end of 1320 ft, the only thing more accurate than the timing lights at the strip would be some of the latest GPS equipment that gathers axis positioning data from 8-10 satellites.

This is like the BS where they say that the NHRA start beam 18-inch "rollout" is good for 3-5 mph and "up to 0.5 sec." in 0-60 and quarter-mile measurements. Maybe for a Pro Stock/Funny Car/Top Fuel dragster running wrinkle-wall drag slicks, but a regular car running street tires? Yeah right....

For comparative purposes is the only thing that gadget is good for.

 

Drop that flag off of the staff. It is actually the last '66 feet ( http://www.partytimeracing.20megsfree.com/custom3.html ) and yes it does make that much of a difference. G-Tech has recognized this problem and will be providing a firmware update possibly to current products but most likely it will just be fixed in their next product offering.

The 18" rollout is also that big of a difference if the car is launched properly. It actually makes much less of an ET difference on something like a Top Fuel or Funny Car(its really hard to take 0.5 sec off of a 4.5-4.8 second run).

 

Gaining 5 mph in the last 66 ft (sorry, I was thinking along the lines of "last 5% of the quarter-mile") when you're only trapping 107 mph? I don't think so. That would be one hell of a top-end rush, or perhaps a blown run on a 500+ hp car.

And why are they "updating" the firmware for this "problem" when they are saying that the GTech measures the "actual speed at the end of the strip" in the first place?

I meant taking 0.5 seconds off a 0-60 mph run, or gaining 3-5 mph at the lights....sorry, should of been more specific...

 

You can sit here and throw theories all you want. I was just stating my experience with the device and the fact that at the track, your speed is averaged at the end.

As we've all said, it's good for measuring relative change. I've never taken its absolute numbers seriously.

Sonny

 

I got a 113 mph trap speed while running a 13.6 on the G-tech which is BS, fastest trap speed I ever got was 107.5. I dont think the G-tech is very accurate at all...

 

Kento is right. I use the Geez! chassis datalogging system and the sensor iteself is very similar to the G-Tech. The sensors are merely accelerometers. They do not measure speed directly like a wheel speed sensor can and they cannot measure position directly like a GPS for instance. All the accelerometer knows is that it accelerated this hard in this direction for this amount of time. Things like uneven ground, body roll, yaw or wheel spin can cause errors in the readings. Geez! has the ability for the user to largely correct for this; to my knowledge the G-Tech products do not. In order for the data to be "perfect" you would need to add wheel speed, yaw, pitch and roll sensors at least and GPS would help too.

Geez! plots and discussion

 

yeah your trap is about 10-15mph too high get real man
yeah non seq twins (nice move) and t78 are real similar you wont notice any power gains dont bother doing it

 

I'm very surprised no one has commented on his tires. Yoko Avid S306s? Those, sir, are shitty tires for a sports car.

My advice would be to get some real tires.

 

Because people on forums all over the place are complaining about the accuracy of their product since it measures actual top speed and not the 66' average like people see on their time slips.

 

What?????
Are you high on grass son??
Don't tell me I am getting 123mph on the G-Tech and that it is 15mph to high! There's no way this car will only pull 108Mph through the traps. Maybe off by 5 would make sense but 15? Go exagerate somewhere else!
And you're also telling me that the T-78 won't make any more power gains than stock twins??
Come on man, by listening to you I would be going slower.

 

DUDE ..

First of all, Throw that Piece of **** G tech away.
and all the #'s you got from it is JUNK.. DOn't even
consider it..

To have trap speeds of 125mph give or take a MPH
You would be running 10 and 11's. .
To put t hings in perspective.. at that MPH
11.23 @ 123mph, and thats on a ZX7. With a so so launch.

and to answer your other question.
DUDE no matter what you do to your stock TWINS.
Most HP you can squeeze at its LIMITS is 350.
Thats at THEEEEEE MOST.
a T78 Single turbo can up out 450RWHP @15psi.
The t78 will make your TWINs look like a Windchime.

Forget the Gtech. Get a STOP watch.. Mark off 1/4mile
Start stop watch, as you past marked spot, Stop stop watch. and Look at MPH.. That guessamate is better
that that Gtech.

Sorry to burst your bubble.. BUT haha its funny.
running mid to high 13's at 125mph.. LOL hilarious.

 

what do a 400hp, 600hp and an 800hp supra have in common?

13 time slips

with traps exceeding 120mph

it is possible you know

in his case, prob not

 

Yeah whatever

Using 2950lbs for car+driver weight:

fastrx7man: 11.7042 @ 117.28 (2/18/04) stock twins, stock ports, 15 psi - 364hp (estimate based on the ET), 371hp (estimate based on trap speed)

BOOSTEDRX7: 10.98 @ ?? (I can't find the website about it) - 440hp (estimate based on ET)

94RXse7en: Put down 331.4hp on a Mustang Dyno at 4,300' elevation (non-SAE corrected). I think that would put him well into the 370hp+ range on a Dynojet w/ SAE corrected.

 

Tracey..

are you talking Fly WHEEL HP?? or
REAR WHEEL HORSEPOWER???

and if you talking FLYWHEEL.. Take 15% off those #'s
and Whaaala... Less than 350 RWHP..

and the guy that had 400+ HP on stock TWINS..
I WOULD have to say BUUUULLLLLLL SHIIEETT ,
on that one..

 

You are wrong. There's a few on the forum who have gotten well over 350 rwhp on the stock twins, and have the trap speeds to prove it. It's true that 350 rwhp is certainly the practical limit....

And on a high boosted turbo-car with poor low-end torque, it is very common to have poor ETs with high trap speeds on street tires. It's entirely possible he's running a 13.0 at 115-117 mph, if he has enough mods.

As I brought up before -- he's running extremely shitty tires. I'm surprised he could get out of the high 13s on those things.

 

Well that makes a lot sense, doesn't it? A product that is claimed to be so accurate being made less so, just for the purpose of sales...

I guess I'll have to say it once again for the cheap seats....

An accelerometer only estimates speed based upon set of parameters that even then must be tightly controlled for anywhere near "accurate"-- and I use that term loosely-- results. It has no real method of positively gauging actual speed or distance.

For those who want to use this gadget for comparative purposes, more power to ya. It's when you start saying this is a highly accurate measurement that I have major disagreements.