Transmission power loss ?
12-21-2010, 12:56 AM
#22
Member
There's a simple answer to this, one which I alway like to bring up..... do not use flywheel bhp figures as they are subject to more inaccuracy.
Use whp only.
Flywheel figures are for the pub.
And, the way Dyno Dynamics does it is by calculation on coast down IIRC, not by entering a fixed value.
Finally, careful when your IT and AT exceeds about 5 degrees differential, as it starts to really screw the readings up...
Use whp only.
Flywheel figures are for the pub.
And, the way Dyno Dynamics does it is by calculation on coast down IIRC, not by entering a fixed value.
Finally, careful when your IT and AT exceeds about 5 degrees differential, as it starts to really screw the readings up...
12-21-2010, 01:24 AM
#24
Member
Originally Posted by Irvatron,Dec 21 2010, 08:21 AM
Oh and cars don't really loose much power nowadays well strong blocks like the S.
12-21-2010, 02:23 AM
#25
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Figures are just figures and don't mean *that* much on their own. Where they are useful is when tuning and doing a before/after comparison to see if tuning has worked.
The same engine can produce different stats on two different rolling roads. The car is still producing the same power, just the figures (or yardstick for example) are different. One may say 230bhp, the other 220 etc. the actual power of the engine is still the same, just not the "figure" that the RR gives you.
So on RR *A* for example, it produces 230bhp however without knowing the figure from THAT RR and in the same conditions (o/s temp, air etc.) from when the car was NEW, there's no way of telling whether it's lost any over the years. i.e. RR *A* may have indicated 230bhp (if tested) when it was new, in which case, no loss over the years.
The same engine can produce different stats on two different rolling roads. The car is still producing the same power, just the figures (or yardstick for example) are different. One may say 230bhp, the other 220 etc. the actual power of the engine is still the same, just not the "figure" that the RR gives you.
So on RR *A* for example, it produces 230bhp however without knowing the figure from THAT RR and in the same conditions (o/s temp, air etc.) from when the car was NEW, there's no way of telling whether it's lost any over the years. i.e. RR *A* may have indicated 230bhp (if tested) when it was new, in which case, no loss over the years.
12-21-2010, 03:42 AM
#28
Member
Originally Posted by gbduo,Dec 21 2010, 11:57 AM
I was always told mechanical efficiency of a gearbox was about 85-88% depending on the gear design largely and factors to reduce friction.
12-21-2010, 03:50 AM
#29
Registered User
Originally Posted by richmc,Dec 21 2010, 01:27 AM
This one was done by MASE. 
It's still a RR, which means any figure it produces is as truthful as the average Politician.
AFR originally was V high, especially at the top end.
Ususal AFR is in the mid 12s, but dips to mid 11s in the top end.
Anything rotational is going to cost you power because it has to be given kinetic energy, thus taking away the kintetic energy that COULD be given to the car.
Clutch, gearbox, propshaft, diff, driveshaft, hubs, brake discs, wheels all have to be spun, thus absorbing power.
Reducing the mass of any of these items will net you effective power.
12-21-2010, 04:39 AM
#30
Just a thought and nowt to do with the thread really but more about rolling roads, how often do these guys have them recalibrated and to what standard are they calibrated ? That is if they do at all,
And if they do not have them done, and not to a traceable standard every bit of kit is likely to be all over the place, so only figures off of a single machine should be compared and even as some one said only before and afterwards compared when done in a short space of time.
And if they do not have them done, and not to a traceable standard every bit of kit is likely to be all over the place, so only figures off of a single machine should be compared and even as some one said only before and afterwards compared when done in a short space of time.