Chain drive, manual gearbox, wet clutch drive train losses.

[stevo as b4]

Can we discuss the above, and with input from anyone with experience of having their bikes tested/tuned, and or from anyone who works in the bike industry or the tuning or racing industries?

If we can compare exact same set ups like bikes with chain primary drives, or helical gears, or straight cut etc, should we expect to see similar percentage losses between different bikes tested with as many of the variables controlled such as:

Oil types,
Make and model of rear tyre,
Tyre pressures,
Chain type,
Chain tension and lubricants

Etc etc?

Do people have any scientific evidence of the effects of internal friction levels inside engines and gearboxes, changing noticeably with rpm?

I used to think that any given set up would show a fairly fixed percentage loss, but as power and rpm increase then it's said the losses increase with it.

So a GSXR1000 say that makes 150bhp at the back wheel, will when tuned to say 175bhp and maybe 500-1000rpm higher peak power speed, will have higher transmission losses due to friction differences alone.

I know there's things like tyre growth at speed, tyre pressure differences with temperatures, and chain drive losses changing with rpm too, as they are forced to wrap around the sprockets etc.

Is it too much of a black art to guess, assume or calculate between std and modified examples of the same bike though?

[ZX-7R]

Beer + above post =
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Current Bike - 2000 ZX-7R

[Beehive Bedlam]

[stevo as b4]

I haven't really had enough beer though yet tonight to actually make any sense of it?

I guess what I'm after is, how laughable is it to pick a bike ( for example say a K8 GSXR 1000) and say that with the same hardware like tyres, chains, oil, sprockets, etc that they all have about xx% transmission loss from one example to another, and between one that's standard or one that's had tuning etc.

Also if there is was a fairly fixed transmission loss, then assume say a 2008 ZX10R had the same type of gearbox arrangement, primary drive, and similar gear ratios, would the transmission losses be near the same between different manufacturers of the same type of bike?

[chickenstrip]

[stevo as b4]

That's true, but if say a Fireblade uses a set of helical primary gears, then would it not be common for a GSXR to also use the same set up?

They are both IL4 wet clutch engines, and I'd assume there's only so many ways you can make such an engine?

Basically some people have said a typical chain drive bike engine will struggle to lose 5-6% in the transmission or from crank bhp figures to the rear wheel, but others say it's 12-15% with a fair variance factor.

Some people also confuse transmission losses with under or over stated manufacturers power claims. If for example BMW say the S1000RR is 200bhp and several bikes dyno at 194bhp r/w, then either one of the numbers are wrong, or the transmission losses are tiny compared to the norm etc.

[chickenstrip]

[almostthere]

my head hurts
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[RhynoCZ]

First, we need to identify what numbers are we actually getting from the manufactures. Most of the manufacturers will give you the power output at the crankshaft with auxilary cooling and battery charging. I've never heard of anyone measuring the powerout put with auxilary oil pump, but nothing is impossible, I guess.

Second, what units are manufacturers using. kW, PS, HP, ...

Third, when you go to a DYNO shop, do they have the DYNO calibrated?

Then, there's the internal friction of the engine. This is actually quite an interesting topic. You all might noticed that modern cars use more oil than cars from 15 and more years ago. Why is that? It's got a lot to do with efficiency = better fuel economy = less CO2. You see, instead of making the engine very precisely, maximazing each combustion cycle, the manufacturers make engines less precise = more oil goes around the rings and other bits of the engine, which reduces the internat friction, which leads to less fuel being transformed to heat.
Some manufacturers just use bigger oil sumps, others for some reason never bothered (for instance, Mazda is quite famous for their oil hungry engines).

Why don't you get the factory numbers from your bike?
1) Bearings (engine, gearbox, wheel)
2) Carbon deposits
3) Debris of all sorts flowing around in your oil
4) The DYNO you use is not calibrated
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[Teflon-Mike]

Brake-Horse-Power.. let me describe a very simple Brake-Force-Dynometer.... is a big brake disc; the brake caliper on a carrier that's free to rotate around the axle, and restrained not by a torque arm, but by a simple beam and weight. Apply brake, caliper is pulled round by the disc, lifts the beam; when beam hangs 'level' the weight on the beam times the beam length, gives you 'torque' being reacted, torque times the rpm of the disc gives you the power the brake is reacting; hence Brake-Horse-Power.

Commercial dyno's generally aren't quite so crude, and the brake disc is replaced by an electrical generator or a water-pump, so that they can absorb and dissipate more energy without over-heating, but that is the principle of a 'Brake-Force-Dynometer'

More usually direct driven off the crank-shaft, on a lab-rig, or 'bench- dyno' these are the type of Dynometer that 'standards' are based on, as they are very simple, and very accurate; measuring almost directly the Brake-Force the dyno, they are very accurate and measurements easily repeatable.

The more common 'Rolling Road' dynometer, or 'shop' Dyno, first measures power delivered not at the end of the crank-shaft, and NOT actually at the driven wheels, but delivered to the roller, an entire vehicle is strapped to. Then rather than measure the brake-force or delivered torque, the dyno measures only the 'speed' of a flywheel of known moment-of-inertia.. change of speed gives the rate of acceleration of the flywheel, then with a LOT of maths, the torque needed to cause that acceleration may be calculated, times the speed gives an 'instantaneous' indication of delivered 'power'.

From first principles; POWER, is an imaginary commodity, you cannot measure 'power' it doesn't actually exist at any actual moment of time. It is Defined as 'Rate of Work Done' so you may measure the work done, in a period of time, that's force x distance, but that is what you have what you can see, only after a period of time, can you retrospectively divide the work-done in that time period to derive the 'rate'..

Measured in the steady state, a brake-force dyometer reduces experimental accuracy by reducing he number of variables, specifically those that may change with time... and measuring base units, force, distance, time, the amount of calculation error is similarly reduced; hence 'Bench' dyno's can be very very much more accurate.

Measured in the dynamic state, an inertial dynometer, is subject to a huge degree of experimental accuracy then even more calculation error from taking only one measurement of speed, at usually incredibly short sampling periods, then any more added by the drive-train between the flywheel and the piston-tops.

Worth mentioning that DIN standards for quoted power include a 'back-motoring' factor; after running an engine up against the brake to get the delivered power, the dyno, which usually uses an electric generator to absorb delivered energy is 'back motored' to drive the engine to the same crank speed and measure the power needed to turn the crank, pistons, cam-shafts, valves, alternator etc etc etc... which is why DIN figures are often more flattering than ASA standard quoted power, and more so, the more cylinders and valves and stuff get back-driven...

Lets say we Dyno's a 100bhp bike engine.... if you measured that on an engine brake, you would probably get a figure of something in the order of 97bhp, at the crank, which would come 'up' to 100bhp after adding some 'correction' factors from measuring the lab conditions of air-temperature and barometric air-pressure, and 'correcting' to sea level and room temperature...

There we have a 3% discrepancy before we even start....

Oh-Kay.. now Correct to DIN, and back-motor the engine, and measure the power loses, driving the valve train, oil pump, and gerator and shit.....

Worth mentioning at this point that in the early 1970's the huge drop in quoted power for US muscle cars wasn't entirely due to detuning to meet emission controls, but 'standards' where to flatter muscle-motors they were often bench tested with the ignition powered from a bench supply, the motor bare of alternator, without a water-pump cooling water circulated off a mains tap or header tank, some-times even with the oil pump disconected and the sump 'dry' the motor lubed off an external oil supply! What had been sold as 300bhp cars the year before suddenly became 220bhp cars... around a 25% discrepancy.. without making any allowance for power-steering pups or air-con compressors in the vehicle 'as sold'!!!

This is the sort of discrepancy you can easily get from adding 'back-motoring' correction, and the more cylinders you have, the more cams and valves you have, the more complex the motor by way of water-cooling etc, the more those back-motoring 'losses' will be, so the more adding them will flatter quoted power figures.

NOW lets put something on a rolling road... that 100bhp motor, that actually delivered 97bhp to a brake, but possibly got quoted at as much as 108bhp with back-motoring losses added, now delivers probably something like 85bhp to the rollers.... inertial dyno's seldom have back-motoring capability to measure the driven loses, but, we now have a chunk load more possibly drive-line losses basically to just 'guess' at.....

As said, they are not the most accurate to begin with; and have an even larger scope for calculation error.... SO start adding corection figures for ambient conditions and presumd transmission and back-motoring losses, and you are int a HUGE arena of speculation....

What rolling roads are good for is NOT absolute power ratings, but comparative readings, setting up an engine, taking a base line figure running an engine up before making set-up changes, then after figures to compare gains or losses.. minimizing variables comparing the same road, same operator, same calcs and correction etc.

The typical 5-10% losses in a motorbike transmission, REALLY are pretty small potatoes in the grater scheme of measurement and calculation accuracy, or even the discrepancy that can me provided by different standards that include or exclude more or less back-motoring, BEFORE you get to the big set up and the effect of tyre temperature or the strap-down force and tyre pressure etc!

And when you get up to 150+bhp regions, driving a roller through a single tyre, the amount of experimental error, the degree of calculation error, the degree of variation provided by correcton to different standars is enormous, and the relatively small % of loss in the transmission, is essentially insignificant in that % ambiguity...

NOW... stick the bikes up the strip.... when the flag-drops the bullshit stops..... and what gets t the timing lights first will even then not be the bike with the most 'measured' power, but the one that, and has the rider that may, in the real world can put most to that into effect....

Which begs the question.. what REALLY is your question? If you want to argue dyno races, then, grab a beer, and add a lot of peanut salt to whatever any-one says.... if you want to know how 'quick' a bike is... take t to a track!
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[Polarbear]

Why are you interested in where and why a bike loses a few horses?

I ask because 99% of us cannot use a 600 supersport to it's maximum potential let alone a 1000cc+ bike.

I have a bike with about 125 BHP now, I had A Busa that was Dyno'd at 170+ and I doubt if I was much faster on that.

As a theoretical exercise, I don't have a clue except shaft drive is not an efficient way of transferring power compared to a chain (but cleaner )
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[stevo as b4]

Good question.

Im actually interested in much lower power output engines losses too. I just picked out some 1000's as commonly known bikes, and also because I think there's alot more dyno testing done on superbikes, and because they are raced there should be more known about the topic.

All I really wanted to know is in as controlled conditions as you can make it, does an XYZ1000 always have a fixed percentage power loss between the engine and rear tyre?
Does the percentage change as you increase horse power, and can this be calculated?

Many have made good points,but I want to forget about high mileage engine wear, bits in the oil, slipping clutches etc.

Let's say two new bikes, same tyres, same tyre pressure, and same dyno on any given day, will they say both have X transmission losses, and does it stay the same if you tune one of them?

[Kickstart]

Hi

Suspect there are slight differences. Differences in teeth on gears, probably a tiny amount from the number of sprocket teeth, etc.

While you could drive the engine from the rolling road, or just measure drag with the engine in neutral both these assume that the transmission is equally efficient driving in both directions (which with badly worn sprockets is very much not the case).

A good condition well lubed chain is a very efficient form of drive. Belt drive a bit less efficient but not bad (and doesn't get worse with wear until wear is terminal). Shaft drive even worse.

All the best

Katy
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