what drivetrain losses?
Discussion
just got my 2.0 zetec remapped and I'm wondering what you guys would expect as a %age for drivetrain losses as I want to be sure I'm guessing the flywheel bhp right.
basically type9 box through english axle to 15" 195 tyres....
Tuner said you can expect 20% losses, what are your thoughts?
Thanks!
basically type9 box through english axle to 15" 195 tyres....
Tuner said you can expect 20% losses, what are your thoughts?
Thanks!
There is no percentage which will be accurate, and all at the wheels are completely subjective.
You will get different rates of loss depending on temperature/pressure/compound of tyres, gear ratios, diff ratio etc etc.
If your car was at a rolling road centre where the operator had any clue as to what they were doing, you would have done a run down test where the clutch is depressed and throttle released at max rpm at the end of the run. The rolling road is then able to measure the drivetrain losses alone. Aggregate the two scales and that gives an accurate estimate of power output on that rolling road.
Be certain however, that every rolling road is calibrated differently, i.e if you mate got more bhp at a different rolling orad, it does not necessarily mean he has more power.
Also simple things like new releases of control and measurment software algortithms for the rollers may also lead to unpredictable results. Always make a note of the software versiosn the rollers are running if you are going to compare runs over an extended period of time. This alone may save you huge amounts of money.
Also look at every dyno plot. The Torque and HP curves will ALWAYS intersect at 5252 RPM. That is not accident, it is where 1 Ft*lb of Torque is Equal to 1 HP. One is a measure of rotational force (ft*lbs), and the other is power (1 HP=745.7 Watts=745.7 N*m/s).
If the lines do not cross at exactly 5252rpm, the printout is only fit for the shredder.
You will get different rates of loss depending on temperature/pressure/compound of tyres, gear ratios, diff ratio etc etc.
If your car was at a rolling road centre where the operator had any clue as to what they were doing, you would have done a run down test where the clutch is depressed and throttle released at max rpm at the end of the run. The rolling road is then able to measure the drivetrain losses alone. Aggregate the two scales and that gives an accurate estimate of power output on that rolling road.
Be certain however, that every rolling road is calibrated differently, i.e if you mate got more bhp at a different rolling orad, it does not necessarily mean he has more power.
Also simple things like new releases of control and measurment software algortithms for the rollers may also lead to unpredictable results. Always make a note of the software versiosn the rollers are running if you are going to compare runs over an extended period of time. This alone may save you huge amounts of money.
Also look at every dyno plot. The Torque and HP curves will ALWAYS intersect at 5252 RPM. That is not accident, it is where 1 Ft*lb of Torque is Equal to 1 HP. One is a measure of rotational force (ft*lbs), and the other is power (1 HP=745.7 Watts=745.7 N*m/s).
If the lines do not cross at exactly 5252rpm, the printout is only fit for the shredder.
singlecoil said:
Auntieroll said:
singlecoil said:
Auntieroll said:
Why not read Pumaracings views on the subject,they make very interesting reading!
Any links?Edited by singlecoil on Saturday 17th July 18:49
http://www.pumaracing.co.uk/
tr7v8 said:
singlecoil said:
Auntieroll said:
singlecoil said:
Auntieroll said:
Why not read Pumaracings views on the subject,they make very interesting reading!
Any links?Edited by singlecoil on Saturday 17th July 18:49
http://www.pumaracing.co.uk/
from puma racing website:
"My own figures for transmission losses have been stated in previous articles but to recap they are usually no more than 15% of the flywheel power for FWD vehicles and no more than 17% for RWD ones. A good guide is to deduct 10% of the flywheel figure plus another 10 bhp for FWD and 12% plus 10 bhp for RWD. If you are starting from a wheel bhp figure then you have to apply those equations in reverse - add 10 bhp then divide by 0.9 for FWD or 0.88 for RWD to get back to a flywheel figure. Those figures were not just plucked out of thin air. They represent the culmination of many years of research and testing combined with the views of reputable companies like Bosch and VW. "
so my 198 at wheels = 236@ fly.
not bad for a 2.0 zetec!
"My own figures for transmission losses have been stated in previous articles but to recap they are usually no more than 15% of the flywheel power for FWD vehicles and no more than 17% for RWD ones. A good guide is to deduct 10% of the flywheel figure plus another 10 bhp for FWD and 12% plus 10 bhp for RWD. If you are starting from a wheel bhp figure then you have to apply those equations in reverse - add 10 bhp then divide by 0.9 for FWD or 0.88 for RWD to get back to a flywheel figure. Those figures were not just plucked out of thin air. They represent the culmination of many years of research and testing combined with the views of reputable companies like Bosch and VW. "
so my 198 at wheels = 236@ fly.
not bad for a 2.0 zetec!
s express said:
from puma racing website:
"My own figures for transmission losses have been stated in previous articles but to recap they are usually no more than 15% of the flywheel power for FWD vehicles and no more than 17% for RWD ones. A good guide is to deduct 10% of the flywheel figure plus another 10 bhp for FWD and 12% plus 10 bhp for RWD. If you are starting from a wheel bhp figure then you have to apply those equations in reverse - add 10 bhp then divide by 0.9 for FWD or 0.88 for RWD to get back to a flywheel figure. Those figures were not just plucked out of thin air. They represent the culmination of many years of research and testing combined with the views of reputable companies like Bosch and VW. "
so my 198 at wheels = 236@ fly.
not bad for a 2.0 zetec!
That's a lot for a Zetec, what's the spec, and what RPM is that figure at?"My own figures for transmission losses have been stated in previous articles but to recap they are usually no more than 15% of the flywheel power for FWD vehicles and no more than 17% for RWD ones. A good guide is to deduct 10% of the flywheel figure plus another 10 bhp for FWD and 12% plus 10 bhp for RWD. If you are starting from a wheel bhp figure then you have to apply those equations in reverse - add 10 bhp then divide by 0.9 for FWD or 0.88 for RWD to get back to a flywheel figure. Those figures were not just plucked out of thin air. They represent the culmination of many years of research and testing combined with the views of reputable companies like Bosch and VW. "
so my 198 at wheels = 236@ fly.
not bad for a 2.0 zetec!
dunnell black top on webber throttle bodies and dta ecu.
peak power was at my rpm limit of 7600 - it may have made more power higher up, i don't know as I wasn't going to risk a brand new engine (although Paul did say I could go to 9k rpm!).
engine spec is ported head, stnd valves, re-radiused seats, uprated springs, arp rod bolts, pocketed stnd pistons, dunnell cams, verniers, lightened flywheel etc etc.
car is very driveable (5th gear 1500rpm foot to floor and pulls cleanly) but i put that down to the guy who mapped it. cams don't come into their own until 5k+.
massive overlap on them!
peak power was at my rpm limit of 7600 - it may have made more power higher up, i don't know as I wasn't going to risk a brand new engine (although Paul did say I could go to 9k rpm!).
engine spec is ported head, stnd valves, re-radiused seats, uprated springs, arp rod bolts, pocketed stnd pistons, dunnell cams, verniers, lightened flywheel etc etc.
car is very driveable (5th gear 1500rpm foot to floor and pulls cleanly) but i put that down to the guy who mapped it. cams don't come into their own until 5k+.
massive overlap on them!
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