I just got an 8 last week. I ordered the Gtech Pro RR and got it today. Nifty little thing. I need to go weigh my car to get acurate HP. any ways i was using it to test 0-60 times. I launched a few times and i was getting 6.8-6.9sec.. I was pissed. So I launched at about 5K and i got 6.1 something.. it was 97 out side with 2 ppl in my car and lil under 1/2 tank of fuel... Do I really need to launch at like 5K... what RPM have you guys gotten you best times at? I have 6spd with the Dunlop SP's. My car is stock not for long

 

5k seems right. Im amaized you pulled a 6.1 with two people in the car. Did you adjust for their weight when you made you pull. I think 6.1 pretty damn good concidering that 5.9 is the best I've seen and that was with the 250 HP ecu before they had to change it! Two ticks off aint bad at all.

 

1> Without a proper weight in the system the times can be off greatly even if you're wrong by only 100lbs or so. And you were probably off by more than that.

2> Yes, a 5000RPM launch is normal. In fact it's probably a bit low for "best" times. 7000+ is about the only way to break into the 5s. That's a byproduct of a car that's generating less torque than my buddies 1.8L Honda Civic on the low end of the tach.

 

But just my HP and TQ would be off if the weight is off right... How would the weight affect the computer 0-60 times. I dont think it would. If i said my car was 4200lb it shouldent matter to the computer because the car still rant to 60 in 6.1 right?? or am i missing something?

0-60 6.192
60ft 2.263
if it makes a diferance that run i set weight @ 3400.

 

Hah. I'm sorry, you're right. Late Night Brain-Fart. My bad.

 

Is it really bad for my clutch to launch at 7K. does the 8 have a good clutch?

 

Yes, it is really bad to launch at 7000; it wouldn't matter if the RX-8 had a great clutch. You should save that for rare occassions at the track. And if you're going to do it with any sort of regularity you definitely need to upgrade the clutch, but you'll never be able to make a habit out of those kind of clutch-drops.

 

i dont know how gtech's work, but i doubt it has some kind of sensor wire hooked up to your speedo to tell you how fast you're going right?

If that's the case then the way it calculates speed (in this case 0-60) would be based on weight, how many g-forces are pulled etc. So if your weight is off, then it would throw the 0-60 off because the g-force would think 60 is sooner then it is since it has no connection to your speedo.

 

The calculation of 0-60 would just need acceleration and time. HP would also require mass.

 

I hope your 8 that is a week old was used and you are not launching a brand new one without being broken in. Also what Car and Driver found was thier rx8 long term car got faster with miles. They were getting 5.9 0-60 after 40,000 miles. So depending on how many miles are on your car may cause a few tenths too.

 

I have 700 miles on it. Just wanted to see what it would do. It is a 2 yr lease(not that im going to trash it). Thanks for your imput guys.. The Gtech just plugs into my lighter. I have to calabrate RPMS and enter weight thats it. It goes off the electo pulses in the elec. system i think.

 

It processes the noise in the electrical system and looks for the pulses from the ignition system to get the engine rpm's. For 0-60 it integrates the acceleration over time. From this you can compute velocity and position at any instant of time.

The fundamental kinematic equations you get from integrating are these.
v(t)=v0+a*t
x(t)=v0*t+1/2a*t^2

Airplanes and Nasa both use this same technology to provide telemetry data to propogate their position.

For torque/hp runs the weight is needed.

 

You could be bsing me for all i know, but the fact that you wrote all that **** makes me think you know what you're talking about :D

 

not bs,

and it does not use rpm. 6.1 is damn good. best i have done is 6.45 to 60 but have got a 13.9 @ 94.5mph 1/4.

have fun be careful.

beers

 

The older gtech's don't use rpm, but the newer gtechs do. I have the gtech pro rr, it gives a nice full screen rpm gauge that synch's extremely well with the factory rpm gauge. It is pretty accurate except at idle it gets a little confused, but only on our car, I've tried it on four or five other cars and it works perfectly. I suspect its the negative timing split that confuses it. It uses the rpms to generate dyno plots and provides info on what rpm you launched at, where you shifted at, all kinds of good to know info.

 

learned something new, thanks for the info.

beers

 

Yea I have the G Tech RR.. Its awsome. PM me if you want a screen shot of my run.. Thanks

 

No one answer his question so I will try...

G is gyroscope... it measure the acceleration and speed of the car without any attachment and will be independent of what car you are travelling in.

If to measure the hp or torque.. it will be an estimated equation which need an input of mass... most people have said it.

It is a nice thing, but for $300 I would have the REVi or something like that :p

 

Thanks.

 

just checked my unit and the correct #s are. 6.1 to 60 and 14.45 for the 1/4 @94.5.

beers

 

we launch at 7500+ at Pro Solo events on DOT-R tires, 2.0x 60 ft times