FastRX8

I have the G-Tech Pro RR.
Haven't used it much because I haven't gone to an autoX event since I bought it.
Anyways, I decided to do some HP/Torque runs this morning.
Either I did something wrong, or I have the slowest 8 ever made.

Here's the best results -
126.6 HP @ 8542 RPM
92.1 ft-lbs @ 5922 RPM

I had my car weighed w/ half a tank. Today I had a full tank so I added some weight for the extra fuel and me. Even if I was off by +/- 40lbs, would the numbers be that bad?

I did the runs just as the book recommends. My redline on the G-Tech is set at 9000, so I shifted into 2nd at 4000.

I'm posting my graph with the 4 runs I did. Also posting the instructions from the manual in case someone is not familiar with them.

Any input would be appreciated.

BTW - The only mods I have that would impact the HP are an ACT Prolite Flywheel, and Unorthodox pulleys.



- Cesar -

maikelnait

In the event you are NOT trying to get big laughs out of responses like mine, here's my advice:

I take it you actually shifted into second gear at 4000 rpm. Try shifting at 8500.

You may get different results

FastRX8

In the event that you DIDN'T bother to read the directions for the G-tech (which I posted), it says to "shift into 2nd gear before you are halfway to your vehicle's redline".
And,
"Don't worry about the fact that you aren't in the "sweet spot" of your power band when you first shift into 2nd gear. That's the point: we're measuring the power over the whole RPM range."

If I shift at 8500, I will get different results, but will they be accurate?
According to the instructions, no.
If there is G-Tech exception w/ rotaries, then please let me know.
But, I think I did this correctly.

I've never dyno'd a car either, but I think when you get to the gear you want to do the dyno in, you shift early, and accelerate through to the top end of the RPM's.
Similar to what the G-Tech recommends.
If you where doing dyno pulls in 4th gear, you wouldn't run 3rd gear to 8500 and shift, you want to see the hp throughout the entire range.

Besides, going to 8500 in 1st and shifting into 2nd gear, wouldn't give me more HP when I reach 8500 while in 2nd gear.

- Cesar -

maikelnait

Cesar (I take it you speak spanish, like I do, but I'll post in english, so everyone can understand and give you better advidce )

I was just thinking you were trying to make fun of a response. I see you are not.

Some of my fellow forum members in Spain also own a G-tech and have gotten 220 Hp consistent results, with a 240 Hp peak.

I believe they shifted gears at 8500 rpm and that's how they got their figures. That's all I'm saying.

I understood G-Tech used a G sensor to measure acceleration with given a known mass. That's how it can "estimate" hp. If you shift at 4000 you won't get all the acceleration needed to get an accurate reading. Again, I don't own one and I could be wrong.

maikelnait

When I dynoed my car, the guy did the whole pull in 5th gear (1:1), from 0 rpm to the redline.

FastRX8

Tell you what, because it won't hurt to try anyways, I'll do a couple of runs shifting at 8500.
I'll post those too. I just don't see how it would help.

BTW - I do speak/read spanish. but I've in California since I was 2, and never received any formal training in grammer. My written spanish would probably hurt your eyes.

rkostolni

You did the procedure correctly. The Gtech is measuring the acceleration of the car and computing horsepower. So there are other factors that it takes into consideration that a dyno doesn't like aerodynamic drag. It will always read lower, but I am surprised by how much lower yours reads. I would have expected something like 150whp. I can't remember what myne used to read when I was stock though.

maikelnait

No te preocupes, siempre hay tiempo para aprender!!

Sólo quería poder ayudarte con tu RX-8. Estoy seguro que tiene más de 220 HP (En el motor, no en las ruedas)

Pensé que estabas riéndote de la gente con los números que enseñabas, nada más (No offence).

Ahora me voy de vacaciones, pero a la vuelta preguntaré en el foro español a la gente que tiene Gtech para que te cuenten como hacen.

Saludos,

Miguel

rkostolni

Your friends Gtech's are off then. The Gtech doesn't make any correction for drivetrain losses, so it cannot read the flywheel hp. A stock rx8 will only put down 180whp on a dyno and that is before drag is even accounted for.

maikelnait

Thank you rkostolni, I did not know that (I don't own one) I'll ask them what they did to get such figures.

r0tor

iTrader: (1)

make sure the gtec is sitting level and your driving on a level surface... you may want to take a run in both directions of the strip your driving on and average the results

freebird_78

Just bought a GTech Pro RR and performed the procedure in the manual (the same on in the first post) and my results are similar. For three runs I got 133, 132, and 130 HP. Only mod is the AP pulley. Haven't had a chance to do 1/4 or 0-60 yet.

Anyone else have any results?

TeamRX8

iTrader: (25)

EDITED: agree with Charles below, not sure WTF I was thinking at the time I wrote that

freebird_78

CRH, would you mind doing a second gear pull and posting results? Now there are two of us with similar results, I'd like to see yours. I agree that it SHOULD read 170-180, but it doesn't. As far as level, the manual lists a procedure to automaticall level the unit.

I do think that maybe the DSC killed a bit, so I'll try it off.

15 HP for the mid-pipe? Wow (not doubting you). Might have to get one if someone can figure out a way to eliminate the CEL.

Brettus

iTrader: (2)

Hi Charles . 15 hp with the flywheel is pretty impressive as well . So you get 210hp with the catback+the flywheel ?
I've heard you talk about your N/A gains before & always wondered what you were doing that is different to anyone else . The 3" exhaust system you have seems to be the key . If I'm not mistaken - most people fit a 2.5" midpipe & catback - is that right ?

Brettus

iTrader: (2)

ceasar & freebird - have you tried doing 1/4 mile runs to see if you get a different result ?
The fact that Charles gets a figure that seems closer to the mark going the full 1/4 would suggest this is worth a crack .

FastRX8

How would a 1/4 mile run give you the HP curve over an entire gear? It wouldn't.
If I was actually measuring my 1/4 mile, I'd shift at around 8500+ rpms.
That would give me data from idle to 8500 in 1st gear.
The rest of the gears would only show from 6000 and above.

If someone can explain to me how to do a HP run using the 1/4 mile, I'd be willing to try it, but when I think 1/4 mile, I think "finish the 1/4 mile as fast as possible", and that means shifting at higher rpms.

BTW - I think Charles' car is an expection to the norm.
I have the flywheel, pullies, exhaust, and Racing Beat Flash and I'm willing to bet all of those combined might have only given me 15hp.
15hp from the flywheel alone is awesome, but I'd have to see it.
Me and two other local guys did flywheels/pulleys and none of us noticed any decent gains.
If he gained 30hp from a flywheel and midpipe, I'm jealous beyond words.

Brettus

iTrader: (2)

I think with the FW the you would not see the 15hp on a dyno but G-tech will give a real world representation of its effect in hp terms.
As far as the 1/4 mile run goes - it is worth doing even if it just validates results you already have .

spooledUP7

I have an early G-Tech pro and I just did two runs shifting at the beep up to 94 mph. Six hundred miles on the car.
1st run - 167
2nd run - 169
Looks like about 30% drivetrain loss. I'll have to try shifting lower and see if it makes any difference.

Lots of wheel spin on the first run, and lots of wheel spin at the 1/2 shift on the second run.

Other factors are 18" aftermarket wheels that feel about the same weight as stock (never put them on a scale), but are 9.5 in front and 10.5 in the rear. The rear tires are 265-35-18

olddragger

iTrader: (3)

witness for the pull Charles car has. It's there. w/o the nitrous. Plus Charle's is really an honest guy--if he sees something--you can believe it. Look at it this way--he is running in the high 13's without the bottle. Last I know he doesnt have light wheels/tires either. Nor a reflash. I dont think his car has been on any diet either.
Olddragger

olddragger

iTrader: (3)

glad to hear it Charles. That was a good feeling. Recently went for a little demo ride with Chars in his 300+hp ls1 rx7 and although that Ls1 pulls harder than ours----- that 1-2 sec pull from the start was about the same. I grin! Ah the memories.
OD

mysql101

at idle, does your g-tech pro ss/rr show accurate rpm numbers? mine only shows correct rpm when I'm somewhere over 2,000 rpm or decelerating down to idle. Once i'm at idle, the rpm reading sits at 4,000 for some reason. Any idea how it's measured?

shaunv74

When I've done my Gtech runs I've generally done 2nd gear pulls and shifted around 3000-3500 rpms so I get a pull from 2000 all the way up to 8500. Let me ask one dumb question to make sure you're doing it right. Did you push the accelerator all the way to the floor the entire run? Not trying to make fun. Just remember seeing the same thing when one of us on the last dyno day didn't floor it the entire dyno run.

I generally got 185-190 net hp on my Gtech Pro. Which is pretty accurate when you consider I recently got 195rwhp on a dyno and the difference would account for the aerodynamic drag.

From my experience here's what you need to make a good run:

1) Gtech needs to be mounted steady, doesn't need to be flat and level but needs to be securely mount so it doesn't move around at all.

2)you need to make sure your weight is accurate. If not it throws off the calculations

3)you need to make sure you have a straight flat road that is fairly smooth. Any big expansion joints or divots in the road will mess with it.

4) It will start recording once it senses a large acceleration so gradually take off in 1st and then shift early into 2nd and floor it through the entire run until redline.

5)also check out the Gtech forums they usually have folks you can send you data to that will help answer your questions. hmmm, just tried getting to the forum on their website and it didn't work. I wonder if they still have it up? www.gtechpro.com

shaunv74

My understanding on how the RPM is measured is through the electrical pulses in your cigarette lighter. It can pick up the variation in the power cycles based on your alternator rpm. If there a lot of interference in the signal (dirty power) it may not pick up reliable data at lower RPM due to the power pulses being weaker when you are idling.

Do you have an aftermarket stereo or modified your ignition system? That may be creating noise in your electrical circuit.

mysql101

nope. but my alternator fan at high setting can cause the car's idle to drop so low the engine sometimes stalls. Just trying to narrow it down so I can fix it. I have a grounding kit installed to a few ground points... would a faulty battery cause this issue with the g-tech?