December 13, 2004
Rolling road shootout!
Chris Rome and myself went along to Surrey Rolling Road at the weekend to try our cars back to back on the rollers. My car has always appeared 'faster' than others down the straights and so the expectation was that my car would show power at the upper end of the Rover claims.
I know very little about rolling road accuracy or otherwise, but the cars were strapped down onto the rollers. Although I wasn't paying particular attention, there seemed to be very little movement when the power runs on my car were being done. The at the flywheel graph is below.
Now the headline figure (115 bhp) looks fine although the power dies away more sharply than I'd expect above 6K. There is a large dip in the torque curve lower down as well.
So, Chris' car was put on the rollers and during the power runs the back end seemed to be moving a lot more, implying that it was wasn't as 'tied down' as mine. Anyway, the headline figure is 120 bhp and a slightly unusual looking set of curves given the Rover claims. Here's the two traces overlaid (my car - red, Chris' - blue):
As a point of reference - Caterham quote a max power of 115 bhp @ 6K and max torque of 107 lb/ft @ 3K. My car showed 115 bhp @ 6K and 112 lb/ft at 5K rpm (!) [and around 107 lb/ft at 3K rpm]. Chris' showed 122 bhp @ 6.6K through to the redline and 108 lb/ft at 3K rpm [with only 105 lb/ft at 5K rpm when my car was showing peak].
Interesting that I seem to have a sudden torque surge at about 5K rpm. Basically, the comparison seems 'wrong' due to some factor (such as the way the cars were strapped down). I'll also be doing a compression test now to narrow down whether I've suffered from the curse of the cracked number 3 piston.....
Posted by charles at December 13, 2004 1:40 PM