There is a whole load of misunderstanding floating about RE rolling rds.
Firstly, they are accurate, accurate being that they can repeatedly give you a similar figure. Inaccuracy is if you did it once and it gave 100bhp, then second time it gave you 150bhp with no changes.
The nature of a a RR means that it is hard not to be accurate, most measure a known torque input by which BHP is calculated and it cannot be a wrong or false number when calculated from torque. You cannot get an incorrect ATW figure since it is calibrated with KNOWN torque inputs. Now, variations may arise with teh use of different brand RRs, different measuring methods, ambient conditions. THe operator on the actual power run has no real imput as far as mashing the throttle goes. Gear choice also affects ATW outputs.
And in reality, you are not getting ATW figures, your getting the figure INCLUDING the losses from the rollers themselves.
The problems arise with fly figures which should always be taken witha pinch of salt. And the problem is that most people, even if they realise this and preach the fact that RRs fly figures are over calculated, will ALWAYS post and take their higest ever figure even if its from some backyard operator........just props the ego, no harm.
So weather the place you went to calibrated the machine correctly, or purposely decided they wanted it to over read a teeny bit is pot luck.
use a RR, any RR...........just use the same one, as long as you know your not getting duped, true figures dont really matter. So long as teh RR is accurate to difference in any power gain or loss is all that matters. If somebody says they have 150bhp, and you only have 120bhp...........if you beat them in pure acceleration, you can rest assured your horses are bigger. lol
