Rear wheel horsepower

[1948man]

While we're on the subject, have bike manufacturers started stating the rear wheel horsepower on their specs? The 1200 bandit states about the same HP as the old specs for the gs 1100gl. Surely it's got considerably more. I know it's got more low and mid torque. If they have changed the way they claim HP does anybody know about when the change occurred?

[Graham]

and yours is showing,


it is unbelievable how you twisted that argument around.

Hp and torque are functions of RPM. Gear ratio or load doesn't matter.

What is even worse is your completely avoiding the data

Gear ratio or load does matter, load is part of hp. You are using incomplete data. Didn't get that in my last post?

[posplayr]

Gear ratio or load does matter, load is part of hp. You are using incomplete data. Didn't get that in my last post?

If you have an alternate formula and can provide an example calculation of how to relate:

Rated Power to Dyno Power for chain v.s. shaft drive

it would be amusing to see it.

[Graham]

If you have an alternate formula and can provide an example calculation of how to relate:

Rated Power to Dyno Power for chain v.s. shaft drive

it would be amusing to see it.

Rated new bike Power to Dyno 30year old bike Power for chain v.s. shaft drive with unknown ratio and tires and possible mismatch.

Sorry, part of your formula was missing.

Use two motorcycles, one chain and the other shaft. Matching final drive ratio and rear tires. Dyno transmission output HP, dyno rear wheel HP.

Transmission HP minus the rear wheel Hp of same motorcycle will equal final drive HP loss of that motorcycle.

If comparing final drive types the ratio and tire load (size) must match. If they don’t match then you will end up comparing the final ratio or tire load and not final drive type.

[posplayr]

Rated new bike Power to Dyno 30year old bike Power for chain v.s. shaft drive with unknown ratio and tires and possible mismatch.

Sorry, part of your formula was missing.

Use two motorcycles, one chain and the other shaft. Matching final drive ratio and rear tires. Dyno transmission output HP, dyno rear wheel HP.

Transmission HP minus the rear wheel Hp of same motorcycle will equal final drive HP loss of that motorcycle.

If comparing final drive types the ratio and tire load (size) must match. If they don’t match then you will end up comparing the final ratio or tire load and not final drive type.

I dont see a formula, I only see arm waving

Sorry for putting you on the spot,

If you want to understand how gear ratios affect power transfer look it up. The formulas are pretty easy to find. .

Here is a simple reference

http://www.lira.dist.unige.it/IIT_school/CICLOXXIII/courses/slides/MECH_LECTURES/MECH_LECTURES_02.pdf

In “real world” every transmission has an overall efficency.

The transmission efficency is the ratio between the input and the output power.

t= Wout/Win= Tout / Tin

[Flyboy]

Just to side track for a second;

Typical drive line loss is 15% with a driveshaft.
Typical loss with chain and sprockets is 5-10%.

All good and well, but this assumes a new chain and sprocket set with no wear, as the chain wears, it will consume more power, to the point where a very badly worn chain and sprockets will have a greater loss than the shaft drive.
Seeing as a chain starts wearing from the time it is first installed, it would be logical that the rear wheel HP is decreacing steadily with every ride.

Just thought I would mention it....ok back to topic.....

[posplayr]

Just to side track for a second;



All good and well, but this assumes a new chain and sprocket set with no wear, as the chain wears, it will consume more power, to the point where a very badly worn chain and sprockets will have a greater loss than the shaft drive.
Seeing as a chain starts wearing from the time it is first installed, it would be logical that the rear wheel HP is decreacing steadily with every ride.

Just thought I would mention it....ok back to topic.....

I would agree that any drive shaft will probably tend to improve efficency as it wears (bearings loosen) and any chain will eventually start to lose efficency if it wears or is in need of lubrication.

But, assuming "normal" (or typical) wear patterns and the fact that the drive shaft has about twice the losses of a chain (nominally) it is doubtful they would ever cross over (chain worse than drive shaft) unless we are talking bout a chain that gets very hot from just ridding around.

[Nessism]

This info seems about right based on what I've read over the years...

GS1100E - rated hp = 108, measured rear wheel hp = 94

GS1100G - rated hp = 94(?), measured rear wheel hp = 72

Where the shaft drive system burns up hp is when the power takes a 90 degree turn - once in the secondary reduction gears, and then again at the final drive. Each of those turns consumes something like 2.5% of the available power which makes a total of roughly 5% extra power consumption beyond a chain drive system.

Even with that extra power consumption built into the system it seems unlikely that the 1100G engine makes 94 hp at the crank. If the rwhp = 72, then the crank hp is most likely in the mid/upper 80's.

[1948man]

If the loss is 15% in the shaft drive setup (no consensus), well then 72hp divided by .85=84.7 hp at crank.
At any rate, I was trying to determine the general health of my engine and at 72 rwhp, it seems to at least be not particularly sickly so I guess I can justify continuing to add little things like a dynojet, rustless tank, coil relay mod etc. The Bandit search is stalled.

[posplayr]

I provided a summary of what I did in my head previously so that most of the steps are clear to even the most casual reader. As I noted , I did guess as some of my previous statments but was clear and explict about those assumptions. The rest that I was doing in my head is detailed here.

http://www.thegsresources.com/_forum/showthread.php?p=1330216#post1330216

And to Graham,

If you review the thread above you will note that I did not deal with variations due to load , RPM , different gear ratios or tire sizes. While the analysis could be extended to account for the second order effects of those parameters, the primary reason for not including them is the foundational law of physics "Conservation of Energy".

Since under this principle

A.) energy can be neither lost or created

and

B.) Power is time rate of change of energy

http://hyperphysics.phy-astr.gsu.edu/hbase/work.html

and

C.) since differentiation (time rate of change) is a linear operation, conservation of power also applies; so total power is also conserved.

Therefore we can conclude total power is invariant (with losses excepted)under power conversion operations due to mechanical advantage system (e.g. lever arms and gear ratios).I hope that makes it clearer why your previous assessment was fundamentally flawed. You will note that is teh reason that those parameters are absent in the loss equation I used.

Further, so it is made painfully clear to you, what I described at the other link is not an "opinion", it is detailed and rational analysis of fact and assumptions. In stark contrast, your statements which have no such basis and are shown in fact to be fallacious do in fact qualify as an opinion as there is no other polite way of characterizing it.

Merry Chrismas Everybody, it is time to enjoy the season

[Graham]

I provided a summary of what I did in my head previously so that most of the steps are clear to even the most casual reader. As I noted , I did guess as some of my previous statments but was clear and explict about those assumptions. The rest that I was doing in my head is detailed here.

http://www.thegsresources.com/_forum/showthread.php?p=1330216#post1330216

And to Graham,

If you review the thread above you will note that I did not deal with variations due to load , RPM , different gear ratios or tire sizes. While the analysis could be extended to account for the second order effects of those parameters, the primary reason for not including them is the foundational law of physics "Conservation of Energy".

Since under this principle

A.) energy can be neither lost or created

and

B.) Power is time rate of change of energy

http://hyperphysics.phy-astr.gsu.edu/hbase/work.html

and

C.) since differentiation (time rate of change) is a linear operation, conservation of power also applies; so total power is also conserved.

Therefore we can conclude total power is invariant (with losses excepted)under power conversion operations due to mechanical advantage system (e.g. lever arms and gear ratios).I hope that makes it clearer why your previous assessment was fundamentally flawed. You will note that is teh reason that those parameters are absent in the loss equation I used.

Further, so it is made painfully clear to you, what I described at the other link is not an "opinion", it is detailed and rational analysis of fact and assumptions. In stark contrast, your statements which have no such basis and are shown in fact to be fallacious do in fact qualify as an opinion as there is no other polite way of characterizing it.

Merry Chrismas Everybody, it is time to enjoy the season

So you are using horsepower figures from 2 different motorcycles of the same model, 30years apart for your formula? Are you trying to tell everyone that horsepower does not change on a motorcycle over 30years or from cycle to cycle of the same model? I will not believe in your formula because it assumes too much and you have no hands-on testing involved. Your math does not add up to a hill of beans.
And merry Christmas to you.

[whiterabbitt]

I would like to point out that while there are plenty of variables, dyno progams take into account things like tire size and gear ratio, besides all a dyno does is measure how much work is done over a period of time.

The people that can put their bikes on a dyno are most likely the people with well taken care of machines in excellent running condition, so these arguments about 30 year old bikes is pointless.

I kinda think that your just fighting the fact that chain is more efficient than shaft.

[Graham]

I would like to point out that while there are plenty of variables, dyno progams take into account things like tire size and gear ratio, besides all a dyno does is measure how much work is done over a period of time.

The people that can put their bikes on a dyno are most likely the people with well taken care of machines in excellent running condition, so these arguments about 30 year old bikes is pointless.

I kinda think that your just fighting the fact that chain is more efficient than shaft.

It really don't matter to me. Just too much assuming involved.

[Suzuki_Don]

It is not just the efficiency that a chain has over a shaft setup, but there is a huge weight saving to be considered as well. I believe that Suzuki upped the sizes of their motors by approx 100cc to account for the inefficiency, power loss of the convenience of a shaft drive. Roughly speaking the 550 to 650, the 750 to 850 and the 1000 to 1100.

[tas850g]

This is the spec sheet for my 1986 gsxr1100g

Max Power

125 hp @ 8500 rpm* ( rear tyre 115.2 hp @ 9000 rpm )