ABF power
in [Tuning]
|
From: Burgerman on 25 Jul 2007 13:14 "Clive George" <clive(a)xxxx-x.fsnet.co.uk> wrote in message news:46a779ae$0$1628$ed2619ec(a)ptn-nntp-reader02.plus.net... > "Burgerman" <burgerman(a)ntlworld.com> wrote in message > news:qrJpi.1207$ie3.245(a)newsfe3-gui.ntli.net... >> "Clive George" <clive(a)xxxx-x.fsnet.co.uk> wrote in message >> news:46a7570b$0$1589$ed2619ec(a)ptn-nntp-reader02.plus.net... >>> "SteveH" <steve(a)italiancar.co.uk> wrote in message >>> news:1i1t9m7.1rg54ui1qybbk2N%steve(a)italiancar.co.uk... >>>> Burgerman <burgerman(a)ntlworld.com> wrote: >>>> >>>>> Prey tell us how? >>>> >>>> 'Corrected' = 'fudged to say whatever the punter wants to hear' >>> >>> Ok, I've now heard two bits of this. So there are two sets of >>> corrections : one based on environmental conditions, set according to >>> known standards. >> >> Yes. >> >> And >>> the other which is the fudge factor to convert from wheel BHP to engine >>> BHP. >> >> No theres no such thing. > > Isn't there? I know you said there isn't on your dynos - but aren't other > dyno people somewhat notorious for being a bit generous in their > conversion from wheel to engine power? > > cheers, > clive Its simply not possible to give a flywheel power figure on a chassis dyno no matter what the manufacturer claims. The only valid data on any chassis dyno is rear wheel hp. All they give you is a measured bhp loss or a negative run down figure of the transmission while not under load.over the same speed range. It can be added to the power graph and give a good aproximation of flywheel power though but thats all. Its a valid measurement in its own right but it cant measure the increased losses that loading the helical gears and thrust bearing loads and subsequent oil heating that occurs..It may only be a small percentage of the total transmission loss but it cannot just be ignored. If any of them actually claim otherwise then they are breaking the law with false advertising claims. My own software is capable of doing it. But its locked out in the retail version. It was for our use only to measure the drums windage and bearing losses from 250mph down to 12mph while free running without a vehicle so that this could be removed from all subsequent runs and the dyno reads 0bhp while the drum naturally slows by itself. --
From: Burgerman on 25 Jul 2007 13:53 "Burgerman" <burgerman(a)ntlworld.com> wrote in message news:cyLpi.2868$vi3.2758(a)newsfe2-gui.ntli.net... > "Clive George" <clive(a)xxxx-x.fsnet.co.uk> wrote in message > news:46a779ae$0$1628$ed2619ec(a)ptn-nntp-reader02.plus.net... >> "Burgerman" <burgerman(a)ntlworld.com> wrote in message >> news:qrJpi.1207$ie3.245(a)newsfe3-gui.ntli.net... >>> "Clive George" <clive(a)xxxx-x.fsnet.co.uk> wrote in message >>> news:46a7570b$0$1589$ed2619ec(a)ptn-nntp-reader02.plus.net... >>>> "SteveH" <steve(a)italiancar.co.uk> wrote in message >>>> news:1i1t9m7.1rg54ui1qybbk2N%steve(a)italiancar.co.uk... >>>>> Burgerman <burgerman(a)ntlworld.com> wrote: >>>>> >>>>>> Prey tell us how? >>>>> >>>>> 'Corrected' = 'fudged to say whatever the punter wants to hear' >>>> >>>> Ok, I've now heard two bits of this. So there are two sets of >>>> corrections : one based on environmental conditions, set according to >>>> known standards. >>> >>> Yes. >>> >>> And >>>> the other which is the fudge factor to convert from wheel BHP to engine >>>> BHP. >>> >>> No theres no such thing. >> >> Isn't there? I know you said there isn't on your dynos - but aren't other >> dyno people somewhat notorious for being a bit generous in their >> conversion from wheel to engine power? >> >> cheers, >> clive > > > Its simply not possible to give a flywheel power figure on a chassis dyno > no matter what the manufacturer claims. The only valid data on any chassis > dyno is rear wheel hp. All they give you is a measured bhp loss or a > negative run down figure of the transmission while not under load.over the > same speed range. It can be added to the power graph and give a good > aproximation of flywheel power though but thats all. Its a valid > measurement in its own right but it cant measure the increased losses that > loading the helical gears and thrust bearing loads and subsequent oil > heating that occurs..It may only be a small percentage of the total > transmission loss but it cannot just be ignored. If any of them actually > claim otherwise then they are breaking the law with false advertising > claims. My own software is capable of doing it. But its locked out in the > retail version. It was for our use only to measure the drums windage and > bearing losses from 250mph down to 12mph while free running without a > vehicle so that this could be removed from all subsequent runs and the > dyno reads 0bhp while the drum naturally slows by itself. > > > > Added After re reading your post I have to add that the extra losses caused by the way chassis dynos measure run down losses are actually too low rather than too high because they actually dont measure the extra losses caused by the torque or load in the gearbox and therefore ignore this component of the total loss. So the negative transmission power curve they reverse and add to the rear wheel power curve is actually a little too small. In other words it is going to show a lower "flywheel" figure than the correct one.
From: Depresion on 25 Jul 2007 14:35 "Burgerman" <burgerman(a)ntlworld.com> wrote in message news:cyLpi.2868$vi3.2758(a)newsfe2-gui.ntli.net... > > Its simply not possible to give a flywheel power figure on a chassis dyno > no matter what the manufacturer claims. The only valid data on any chassis > dyno is rear wheel hp. What about front wheel hp? Or is that not valid? ;P
From: Douglas Payne on 25 Jul 2007 14:57 Depresion wrote: > "Burgerman" <burgerman(a)ntlworld.com> wrote in message > news:cyLpi.2868$vi3.2758(a)newsfe2-gui.ntli.net... >> Its simply not possible to give a flywheel power figure on a chassis dyno >> no matter what the manufacturer claims. The only valid data on any chassis >> dyno is rear wheel hp. > > What about front wheel hp? Or is that not valid? ;P Negligible on a motorbike anyway. (c: -- Douglas
From: Burgerman on 25 Jul 2007 15:16
"Depresion" <127.0.0.1> wrote in message news:46a79829$0$1620$ed2619ec(a)ptn-nntp-reader02.plus.net... > > "Burgerman" <burgerman(a)ntlworld.com> wrote in message > news:cyLpi.2868$vi3.2758(a)newsfe2-gui.ntli.net... >> >> Its simply not possible to give a flywheel power figure on a chassis dyno >> no matter what the manufacturer claims. The only valid data on any >> chassis dyno is rear wheel hp. > > What about front wheel hp? Or is that not valid? ;P > Well I sold 5 bike dynos to every car one. And I was mainly interested in bikes so my mobile unit was a bike dyno. And you dont get many front drive bikes! And I dismiss front drive as utilitarian shopping trollies! As long as they go at all who cares! |