GTech and my times!

[GreeceS13]

Hi,

My S13 has induction,exhaust first pipe+de cat all 2.5", elbow 2.75", chip stage1. Alone it go at 12 psi!

I think that it has 200bhp!

I try with gtech with very bad tyres..!

0-60 6.1sec
1/4 mile 14.8 with 99.8mph

Good times??
Gtech tells the truth??

[Vetal]

0-60 is very good. But I'd say mph is a bit too high for 200bhp

[ByReaL]

No G-Tech does not tell the exact truth, i have a G-Tech unit but i test it only to see the power incrase, do a test, do a mod, and again do a test, and this way i see how many ~HP i gained due to that mod.

if u know someone who have same g-tech like u try to use both devices when u do a run and u will notice diferent result (not big diference but it is, on same car same run 2 identical devices shows diferent resul...)

and about testing on 2 diferent cars there is no relation betwen the power figures

my car 200SX CA18DET 169HP when was stock the gtech showed ~154HP
my friend car Vento VR6 2.8L 174HP, the gtech showed 121-123 HP

400m race betwen us i was with about 3-4 meters in fron of him at the finish (the weight of the cars is almost the same ~20Kg diference, so in my belife it is no way that if that 30HP diference was true betwen us ,at the finish line be only 3-4 meter diference)

anyway i belife the G-Tech is good only to see the ~HP gain afther a mod, the time is irelevant.

when it showed ~154HP my best time was 7.17
when it showed ~174HP my best time was 6.69
when it showed ~204HP my best time was 6.6
i refer to 0-60 time
400m time never tested that

[Vetal]

I measured friends's old CRX with my GTech. After taking into account air resistance and converting whp to bhp using Pumaracing's formula, max bhp were within 1-2% of factory quoted ;) So my opinion is, it is very accurate, just pay attention to calibration, proper attachment, and study all the forces that are slowing your car down ;)

[voodoo_melon]

I managed 15.0 :o at 99.3mph at Santa pod running about 220bhp, so if you did *really* good gearchanges then 99.8 is possible, but not easy.

[omsking200sx]

i got with my mods on my gtech a 5.97 0-60 and a 14.99 1/4 both in the damp. was getting 6's and 15's for ages and took a few times to get those times.

[GreeceS13]

I don't understand how we can do very good 0-60 and bad 0-400..!
omsking200sx your time is near with mine..! No other car with so good 0-60 do a so bad 0-400!

[skyshack]

converting whp to bhp using Pumaracing's formulaThis one?
http://www.pumaracing.co.uk/trans.htm
That's nearly just as much rubbish as the dyno results he's complaing about in coastdown losses.
http://www.pumaracing.co.uk/coastdwn.htm

Applying his +10bhp and / 0.9 rule for FWD to the wheel power for the XR2 he tested.
3rd gear - 95 bhp at the wheels
4th gear - 92 bhp at the wheels
5th gear - 88 bhp at the wheels
Gives
3rd 116.7bhp, 4th 113.3bhp and 5th 108.9bhp. He has lost/gained 9bhp between 3rd and top and only top gear gives a good approximation to expected power. Anyone applying this to a test in 4th will get the wrong result. Anyone with a different top gear/diff ratio/wheel size to the XR2 will also get a wrong result.

Above 30mph RWD and FWD trans efficiency is proportional to speed
My best fit using the XR2's data is Engine power = wheel power / (0.971 - (0.00125 x mph)).
XR2 speed in gears at max power is 75, 101, 127mph.
Engine power using above is 3rd 108.4 bhp, 4th 109bhp, 5th 108.4bhp.
A variation of 0.6bhp and somewhat closer to the expected 108.5bhp than his forumla. I can get an exact fit using a formula with speed squared term but dyno results are not accurate enough to make it worthwhile.

Below 30mph the losses are not proportional to speed but won't drop below a limiting value set by gear meshing efficiency - 99% per spur gear. 98.5% for a helical diff. This only applies above 30mph as the biggest loss is due to the diff crown wheel flinging oil and it has a different oil fling mode at low speed - more like a paddle wheel and the level stays full. It may also go to pot above 150mph or whatever speeds it is when the oil level in gearbox and diff reach a lowest possible level and the oil is being flung at the case walls faster than it can drain back so there is no more reduction in wetted area of the gear.

4wd will be a bit more due to 2 diffs flinging oil (though they tend to be smaller) and a power splitter. I haven't done much analysis yet but losses are something like (0.96 - (0.0015 x mph)). The 2nd diff doesn't give a 2nd meshing loss as the loss is 2 * 1/2 power x effy = same as single diff. The only addititional meashing loss is in the transfer gear or chain.

[DavidRuston]

I dont know much about the G-Tech units but......

Rover 220 Coupe Turbo did 14.67 at Pod the G-Tech timed him at 14.8 for same run

Now thats not bad accuracy for £40 I reckon

[voodoo_melon]

I don't understand how we can do very good 0-60 and bad 0-400..!
omsking200sx your time is near with mine..! No other car with so good 0-60 do a so bad 0-400!
Shite off the line but quick through the gears I guess. 15.0 was pretty pants for me but I was pleased with the 99.3 terminal.

[IIvIIitch]

are they really that accurate?

ive got one but not had the chance to test it yet, little pointless with the turbo gasket blowing. soon to be sorted tho

[omsking200sx]

I don't understand how we can do very good 0-60 and bad 0-400..!
omsking200sx your time is near with mine..! No other car with so good 0-60 do a so bad 0-400!


like i said it was damp. road hadnt dryed out properly yet.

[Vetal]

Funny, yesterday I tested friends' slightly modified Supra TT. He had 244.34kW on rollers measured the day before. My GTech at the first run showed 244.1kW :cool: I know it's just a coincidence but still :rolleyes:

[Vetal]

skyshack: how did you get this formula you gave?

[GreeceS13]

[b]New times[b]

1/4 14.65sec
0-60 6sec
whp 196 :| :| :|
So bhp how much will be?!? :| :|
I have only 12psi!!