Ok guys, this may sound like a dumb question, but I have been fiddling around with datamaster settings on my 95' T/A w/OBD1 and was wondering about the dyno setup. I know this is not very accurate but what is the best way to get the most accurate est. from this dyno? In other words, when doing a recording and choosing the starting and ending points for the dyno should I stick with one gear (4th?) or just do a pull and then choose 2 points for one gear and adjust the trans gear ratio for the gear used in that section (IE: 1st - 2.66, 2nd - 1.78, 3rd - 1.30 or 4th - 1.00)? What steps should I take to get the most accurate hp/tq est? I know I should just get a dyno done but just jacking around and I figure this one is free. Let me know if you have any tips and your advise is much appreciated.

 

you should only use 4th since this is a straight 1:1 ratio and gear losses are at a minimum through the tranny. Further, the run should be as long as possible to get the most accuracy.

Good luck.

 

Thanks, what RPM do you think I should start and stop at, as what do typical Dyno techs do on a dyno?

 

I stumbled across the dyno feature also last week, I wonder how accurate it really is.

 

I've used this feature before and I've had some runs which were pretty similar to my dyno runs, however, it was not consistently accurate at all. It is easier to do with a 6speed rather than a manual.
As posted above, only examine the beginning and end points of the same gear. Know what gear you was in. Know that gear ratio. Use the default drag coefficient number, and if you have an auto use a drivetrain loss of 20%, and 15% for a manual. Also, when you start your "dyno pull," begin from a constant velocity. In other words, if you are picking data points from a 0-120mph run, and you pick your dyno start point at the beginning of 3rd gear in that run, your car is already accelerating at that point and increasing momentum. It seems this case gives you higher skewed results.

Starting a run at 2200rpm in 4th gear is going to take too much time on a road and put you way over the speed limit by redline. I'd use 2nd or 3rd gear and change the transmission ratio variable accordingly in the dyno calculator.

I haven't looked at datamaster in 2 years since my car has been down, so forgive me if i was not clear enough or said something in error.