Originally Posted by
Burnzybubbles
Do you also take the reading from OBD? I'm guessing ignition signal is best as it will be real time reading, is there too much lag from OBD and that's why it's not the best method or is refresh rate no good?
I'm guessing older stuff before OBD you have no other choice.
OBD refresh rate is rubbish. We can do if need be, but the resolution is poor as the dyno graph can only be drawn with the same resolution as its RPM input because.
Because HP = Torque x RPM ÷ 5252, if you only got say, 20 RPM readings over a 10 second power run, you would then only have 20 torque data entries.
The power would then be interplated between those columns, giving a very smooth, but unrepresentative account of the power curve.
On some newer cars, the OBD refresh rate is great and can be used, but those seem to be pretty few and far between.
Probably due more to an incompatability with my dyno and newer protocols though admittedly.