Dyno Inconsistancies

[Lithium]

On a bit of a whim, I ran my car at a dyno day using a rolling road dyno (a Torque Performance one) to see how it went. All my other runs had been on a Dynapack hub dyno, but had been curious as to how the two would compare etc. The results were relatively interesting.

The only things that have changed is that when the hub dyno run happened, it was peaking at 11.3psi and it was dropping boost quite badly in the high revs - the rolling road run was peaking at 10.5psi.

During the first run on the rolling road, the rears lit up so I had to do another run with someone sitting in the boot to try and keep it stable - but the power curve looks quite different to the hub dyno curve. Could it have been been scuffing on the rollers? Tuning way out? Or just the way a different dyno reacts?

Hub dyno run:

And rolling road run is attached.

[Sydneykid]

Sorry the quality of the scanning is not good enough for me to read the data.

[N I B]

Safest thing is to only use shootout accredited dynos.

[Cubes]

Hub dyno's always read higher than rolling roads.

EDIT: Generally.. From what I've seen.

[Lithium]

Sorry the quality of the scanning is not good enough for me to read the data.

Are you talking about the rolling road dyno plot? That one for some reason seems to autoscale to the size of the window and comes out looking real crap - happens when I view it anyway. Try and maximize the window?!

And yeah - the peak power drop isn't what bothers me... its known the rolling roads can read 10-15% less at times than a hub dyno, its the shape of the curve which caught my attention.

[Cubes]

I thought the shape of the curve looked very similiar.. Both are rather linear.

[Lithium]

The main bit that caught my attention was between 90 and 110kph there is a "bump" which I didn't really see the same in the hub dyno plot, maybe its just me not being used to the different scale the plots are shown on :|