Understanding Dyno figures

[JUS CRU-ZN]

Hey all,

i've had numerous arguments with various enthusiasts re dyno figures. People try to compare performances to determine which tuner seems to be better. All of this is really dependant on yr definition of better.

But wat I really wanna determine is the ffg so people can compare apples with apples.

Power figures on a dyno : Flywheel or At the Wheels(ATW)?

Torque : Fly or ATW or independent?

Gear : 3rd or 4th? Why?

Of course above are irrespective of measuring units.

Thanks in advance for yr learned input

 

[GREY 225]

Oh yeh,dyno results are always good for an argument,personally i would say at the wheels results are the ones that count,after all thats were it is needed.Most dynos only use run down to calculate engine power anyway which is open to many variables,unless you are using a bench dyno with the engine attatched then the most accurate results/figures i think is at the wheels,gives you a true idea of how powerfull it is on the road.For example you may get mr subaru sti man quoting 300+ hp @ flywheel which sounds like it will be super fast on the road,and he will go and say "mines got more power than yours blah blah" and so on,but after you factor in trans losses then this may fall to around 250hp @ the wheels.You come along with a 2wd car and make 270 hp at flywheel but also make 250hp @ wheels,so on the road there is nothing in it power wise.

 

[JUS CRU-ZN]

So would I be correct in saying that Torque figures remain the same whether you measure power at flywheel or at the wheels??

thx

 

[ibizacupra]

*they should* but dyno's process the information very differently.

 

[JUS CRU-ZN]

Thx... atleast that settles it. There's no conversion needed so it should be more or less the same.
I was beginning to to think my understanding had a big gap!!