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Hi:
Excuse my ignorance on car matters. I am trying to get an accurate figure of torque made by my car. The torque figures on dyno I am told are not correct as " other factors" have to be factored in. My question is there anyway of getting an accurate torque figure for my car from the dyno graph.

http://img818.imageshack.us/img818/1585/photomzd.jpg

Any help appreciated.

Cheers Novice1 aka Ron

Novice1 wrote:Hi:
Excuse my ignorance on car matters. I am trying to get an accurate figure of torque made by my car. The torque figures on dyno I am told are not correct as " other factors" have to be factored in. My question is there anyway of getting an accurate torque figure for my car from the dyno graph.

http://img818.imageshack.us/img818/1585/photomzd.jpg

Any help appreciated.

Cheers Novice1 aka Ron

Bottom line, no. There are far to many variables to work out an engine torque figure. Things like gearing (diff and trans), tyre and wheel diameter, dyno roller diameter, tyre pressure etc etc all come into play, and the calculations to get it are near impossible.

If however you are mapping it to do work and see if you've made the right mods, then the chassis dyno is still a useful tool.

The only way to do it is to dyno the car before and plot a graph (as you have done), then after the mods do it with EXACTLY the same dyno, gearing, tyres, pressures etc etc. This is the only way to do it unless you use an engine dyno, and even then you would still need to use the same one.

I am lucky enough to use a chassis dyno that is excellent for doing this sort of tuning, but they are few and far between. They require an excellent operator to ensure all the compensation figures etc are correct (eg: humidity readings, etc etc). The most important thing to do when developing an engine or a car is to USE THE SAME DYNO. I am forever seeing people do work, then use a completely different dyno to chase figures. In the end if you are doing this you are just kidding yourself, and not learning anything about your car.

Use the same dyno, map the figures and you'll get a pretty good idea whats going on.

Cheers
Woz

Thanks for the info wozzah. I do use the same tuner and have three different dyno graphs. Each time the power, torque figures go up. I am told not to go more than double standard torque which is the reason for my question.
Cheers Novice1 aka Ron

Novice1 wrote:Thanks for the info wozzah. I do use the same tuner and have three different dyno graphs. Each time the power, torque figures go up. I am told not to go more than double standard torque which is the reason for my question.
Cheers Novice1 aka Ron

Is that to avoid breaking anything?

Woz

wozzah1975 wrote:

Novice1 wrote:Thanks for the info wozzah. I do use the same tuner and have three different dyno graphs. Each time the power, torque figures go up. I am told not to go more than double standard torque which is the reason for my question.
Cheers Novice1 aka Ron

Is that to avoid breaking anything?

Woz

Sure is. Just had engine rebuild with wiseco forged pistons and crower rods. Not sure tho how much 5 speed gearbox can take power-wise.
Cheers Novice1 aka Ron

Latest data after Ls2 coil packs, new ignition high performance leads and new plugs.

Power 203.4 kw atw
Torque.......mind blowing.

Novice1

The solution is simple, use a hub dyno, than no need to worry about tyre size ,roller dia, tie down pressure etc.
Make sure the car is in a 1 to 1 gear in the gearbox, divide torque ratio given by diff ratio, that will give you an accurate torque figure.
Courtesy of Deckspeed Racing

Thanks for info re hub dyno. I do have a torque figure. Next time it goes on the dyno Iwill see its dynoed on hub dyno.
Cheers novice1