Motor magazine's December 2005 issue had an interesting article in which they did a pretty serious comparo between HSV Clubbie R8, Scoobie MY06 STI and a Misterbitchy Evo IX. As well as doing the usual dragstrip and circuit runs, they also did power runs on a dyno, which is pretty unusual for a car mag - all they ususally quote is flywheel power figures. This has resulted in a fairly reasonable estimate of drivetrain losses that can be calculated. These are all factory stock cars, so (with a grain of salt) we'll accept the quoted power figures in this calculation - and all 3 cars were manuals, so this theory cannot be extrapolated to auto slushboxes . CLUBSPORT R8: 297kw @ flywheel; 235rwkw = 62kw difference = 20.9% loss. MY06 STI: 206kw @ flywheel; 157rwkw = 49kw difference = 23.8% loss. EVO IX: 206kw @ flywheel; 159rwkw = 47kw difference = 22.8% loss. CLUBSPORT R8: 5.53 0-100kmh; ¼ mile in 13.70 @ 174kmh; Oran Sth in 51.75 secs. MY06 STI: 5.43 0-100kmh; ¼ mile in 13.48 @ 166kmh; Oran Sth in 49.45 secs. EVO IX: 5.02 0-100kmh; ¼ mile in 13.32 @ 169kmh; Oran Sth in 49.75 secs. So if I now throw my Z into the comparison, everything seems to fit. My last dyno run was 207rwkw. If I apply a 23% drivetrain loss based on the magazines's results I get 269 flywheel kw, which slots in nicely. Comparing the drag strip times my best of 13.62 @ 170 seems to fit nicely and make sense of the figures. So, for the future, I will divide the rwkw figure by 0.77 to get an approximate calculation of flywheel kw, and I won't expect to beat a new STI or Evo IX until i'm running a bit more than 12lb boost! Aaaaaaah the things you have time to think about when you're away on holiday!
