if a qtr of ur power is lost in ur drivetrain then i think u need a new drivetrain most estimates i've seen are about 10% or thereabouts
unfortunately power is not power, any given engine with greater displacement would (generally) have a greater nett area of torque, ie more low down. etc etc etc the blanket 24% rule (of thumb) holds true for engine hps from 300-450, this may be because (depending on gear mass,r^2,friction etc) most engine and driveline arrangements in this range loose about 75-90hp through them (driveline) thus 75/300=0.25 and 90/450=0.2 now this is a basic summation of what occurs, an AD55 truck produces hardly any power but still seems to loose only 20 or so hp... why, because the loss in transmission is TORQUE, not power.... so the above 300-450 rule is based on a generalised power range that came from a torque value at 'x' rpm. basically transmission power loss is pure ambiguity, its a loss of torque not power, and that torque will vary from driveline to driveline, much the same that various PD s/chargers consume a certain amount of power over a rev range, but this is an actual torque value represented graphically as a power curve. ...blah blah blah......you get the jist rant over :bash:
Although, greater displacement engines tend to have a lower rev range, which balances out their greater torque. So a lower torque, higher revving engine (ie. Rotory's) will produce similar power to a high torque, lower revving ebgine (any commonwhore engine). I found this interesting:
...(more so in reponse to the quote, and last few lines esp.) thats pretty close to the idea, but people get hung up on this number thing - POWER. If you have light switch 'power' deliver and hence it would be a torque curve that suddenly increases and then quickly peaks and falls then it will not be useable. however an engine of equivalent (or even slightly lesser) power but with a greater nett T.avg will out perform the previously mentioned (light swith delivery power) enngine in a similar chassis, for the obvious reason that a)power can be feathered more accurately b)mid cornering (sudden) unsettling of the chassis is far less likely c)full/near full throttle applications are less likely to cause mid gear whell spin on the strip (1/4mile) d)etc..... again the truth is that its all about having a higher nett average torque than having '321'kW@whels/engine etc and to achieve this higher nett average torque you will need more cubes or/and a turbo/SC that increases the torque cure without making it too peaky. This peaky natue occurs in (NA) engines that are "highly" cammed, high CR, etc and ALSO on engines with excessively large match turbochargers/SC. there comes a point (less so on the 1/4mile because the use of lauch control and low PSI slicks etc) where the engine with a peaky deliver will be out performed by the engine with lesser power delivery but a higher nett T.avg most curcuit (and rally) engines are "tuned" (<-- i hate that use of the word) for this T.avg rather than power, becuase its all about "useable power" ....is this making sense, or am i just talking s#*t?
