Restoration of S2 Elan - EOK

[rgh0]

About 10% plus 10 hp gives the approximate adjustment I use for a twin cam in an Elan in the 120 to 150 hp range when done in an intermediate gear. This is based on some articles from puma race engines in the UK that you will find on the internet plus my own testing.
However the rolling losses are very specific to tire types and pressures and how well or otherwise they match the rollers. A friend of mine kept getting around a 15 hp difference with the same race engine in two different cars ( a twin cam europa and a seven) with the seven showing more power when it should be less with greater drive train losses. He finally tracked it down to how it was being set up on the rolling road dyno with the seven requiring to be strapped down harder to stop its rear wheels spinning due to drive shaft torque reaction on the dyno rollers at full power and this causing greater losses. The Europa was also being set up to sit on one roller rather than between two due to the suspension clearances and this was also reducing losses

cheers
Rohan

[Geoffers71]

Thank you Graeme and Rohan for your replies. Rohan I fully understand the conditions you list that would affect the figure, but your little formula, which I seem to recall something similar from way back, would give about 114 bp at the flywheel. I'm thinking that would seem reasonable with an SE cam and bigger valves ( or maybe that's still a bit low ) Anyway I think I WILL get the carbs properly cleaned......sometime........eventually .......