G Graph

[DJones]

Has anyone else got any G Graphs from their GTech meters or similar..

Just intrested in how other setups have performed, i guess in many ways, putting BHP and torque to one side. The G graph demonstrates the true feel of the car i.e aggressive to timid..?

[Smiley]

Looks pretty much like one s2central.net posted recently about a not fully optimized 2871 application..
0.9G

[Rusty]

Sweet! That compares to about 0.5g peak (old GTech) in 2nd for mine Need a bigger turbo!

[EspenW]

True, the G-graph follows the torque graph, and that is how the car feels in gear.
This is why the butt dyno can be extremely deceptive: a car that pulls high G's for a short while will feel faster than a car that pulls less peak G's, but sustain them at a higher rpm. Short gearing will also make a car feel faster, but might very well actually slow it down once out of first gear.
I will scan and post some G-graphs later
Do you have G-graphs from pulls in just one gear? Shifts can cause the G's to spike once the clutch grabs.
BTW, your 12.3s 1/4 time will put you on par with a 996 GT2. A more aggressive start with 60' times closer to 1.6s should put you in the high 11's


Some 2nd gear peak G's that I have tested:

Audi 80 2.0E: 0.25G
Chipped S6+: 0.39G
Stock RS2: 0.50G
Chipped RS2: 0.56G
My RS2 on E85: 0.81G
Stock A4 1.8TQ: 0.34G
Chipped A4 1.8TQ: 0.44G
Mini Cooper S: 0.29G
My Golf 2: 0.43G

In the RS2 I don't dare to do a high rpm clutch dump, so it bogs from the start. I see approx. 0.95G in first gear at 34mph. A clutch dump would have seen far above 1G off the line, but I'm afraid some pieces of metal would suffer.
On a second gear only pull in the RS2 I see 0.81 G and on a third gear only pull I see 0.6+ G.
Test weight is 3590lbs.
Final drive is 4.11 second gear is 1.89 and third gear is 1.32. It does approx 68mph in second gear. 60-90mph in 2.77s in third gear.

[vcosmin]

My car is missfiring heavy under boost, but from anterior meassurments, i say about 0.4-0.42g, in second gear. Chipped audi 100 C4 S4 AAN,

[S2central.net]

Here's the one I was referring to... just shy of 0.9G actually but none too shabby for a big lump of UrS4 that clocked in on the weighbridge that day at 4320lbs. The car isn't finished yet (running too rich) - more live mapping should improve it, but it bodes well shall we say. Full spec on this car to come when its all fettled...

[DJones]

True, the G-graph follows the torque graph, and that is how the car feels in gear.
This is why the butt dyno can be extremely deceptive: a car that pulls high G's for a short while will feel faster than a car that pulls less peak G's, but sustain them at a higher rpm. Short gearing will also make a car feel faster, but might very well actually slow it down once out of first gear.
I will scan and post some G-graphs later
Do you have G-graphs from pulls in just one gear? Shifts can cause the G's to spike once the clutch grabs.
BTW, your 12.3s 1/4 time will put you on par with a 996 GT2. A more aggressive start with 60' times closer to 1.6s should put you in the high 11's


Some 2nd gear peak G's that I have tested:

Audi 80 2.0E: 0.25G
Chipped S6+: 0.39G
Stock RS2: 0.50G
Chipped RS2: 0.56G
My RS2 on E85: 0.81G
Stock A4 1.8TQ: 0.34G
Chipped A4 1.8TQ: 0.44G
Mini Cooper S: 0.29G
My Golf 2: 0.43G

In the RS2 I don't dare to do a high rpm clutch dump, so it bogs from the start. I see approx. 0.95G in first gear at 34mph. A clutch dump would have seen far above 1G off the line, but I'm afraid some pieces of metal would suffer.
On a second gear only pull in the RS2 I see 0.81 G and on a third gear only pull I see 0.6+ G.
Test weight is 3590lbs.
Final drive is 4.11 second gear is 1.89 and third gear is 1.32. It does approx 68mph in second gear. 60-90mph in 2.77s in third gear.

Thanks for the detailed response. I dont have a single gear pull but will do one when its back on the road. I to dont dare do a high rev aggressive take off for the reasons you say.

You can see the short gear changes in the graph attached it needs 3rd gear to get to 60, if i raise the rev limit and be more aggressive off the line together with faster gear changes it should.. be able to get to 60mph in circa 3.5secs. Another interesting point from the attached graph is that i was coasting prior to the 1/4 mile marker. All in all looks like better times could be achieved.

[DJones]

Here's the one I was referring to... just shy of 0.9G actually but none too shabby for a big lump of UrS4 that clocked in on the weighbridge that day at 4320lbs. The car isn't finished yet (running too rich) - more live mapping should improve it, but it bodes well shall we say. Full spec on this car to come when its all fettled...

Paul that does look strong for a heavy old girl.. nice work..

[Rusty]

Here's the one I was referring to... just shy of 0.9G actually but none too shabby for a big lump of UrS4 that clocked in on the weighbridge that day at 4320lbs. The car isn't finished yet (running too rich) - more live mapping should improve it, but it bodes well shall we say. Full spec on this car to come when its all fettled...

That peak in 2nd is about the same as I've measured on mine @ 0.5g

Shame that the old GTech only gives instantaneous and no data logging. It's like checking the boost on a WOT run in 3rd

[EspenW]

That peak in 2nd is about the same as I've measured on mine @ 0.5g

Shame that the old GTech only gives instantaneous and no data logging. It's like checking the boost on a WOT run in 3rd

That first peak is caused by the clutch grabbing after the gearchange. Do a pull from low to high rpm in gear to see real peak G's.
NB: The Mk1 G-tech will store max G's recorded.
However, get something with datalogging, it is so much more helpful than something that just reports peak values that are often caused by spikes.
I would look at the Racelogic Performance box if I were in the market for a performance meter.

[EspenW]

Attached are some 2nd gear graphs.
The RS2 on environmentally friendly biofuel pulls 0.84G peak
The (claimed) 400hp 4.2L V8 S6+ pulls 0.39G peak
The 2L 8v 80 Avant pulls 0.28G peak

I think I read somewhere that there is no replacement for displacement. The fool that wrote that lie must never have heard about a cunning invention called forced induction :mischeif:

[Jamo]

More displacement = more torque .I would say the guy who said it was a genius.

[EspenW]

More displacement = more torque .I would say the guy who said it was a genius.

Well, my 2.2l lays down 550+nm to the wheels while the 4.2L lays down 295nm at the wheels. I would say the turbo offers a pretty good replacement for those 2 liters of displacement.

[EspenW]

Interesting thread from BMW forum showing that the G-Tech RR is spot on with the GPS based Racelogic Performance box:

http://www.e90post.com/forums/showthread.php?t=90939

[S2central.net]

For the price I think G-Tech RR is damn fine piece of kit... Maybe not perfect but there's a few settings that can be altered / optimised on it when compared against more accurate equipment (at drag strip for example) so that it can be more accurate. However - for me - its absolute accuracy is not as important as how easy it is to get trustworthy, repeatable results on the same car when doing before/after type comparisons. The racelogic box is probably better - but is it *that* much better for the difference in £££$$$€€€ ?