How good are dyno charts and peak HP claims?

[paturoa]

I was googling around the place and found this

http://www.mcnews.com.au/Testing/Hon...no/Comparo.htm

I looked at the first chart and thought well the old GSX14 looks a bit sad at the top end.

Then I looked at the second and thought that the XJR13 has some real world roll on advantage for overtaking.

Then I looked at the 3rd and went shit look at that.

Then I looked at the last and now I'm just confused

[TLDV8]

I think the thing to look at.

The GSX1400's max HP at 7000rpm (Quite low compared to the CB/8k and XJR/8.5k )

Then look what it is doing torque wise from 3000 to 6000 rpm.

One guess what my next bike is going to be.

[nudemetalz]

At the end of the day low end and mid-range torque is what counts in real world situations and I think you got nothin' to worry about there with your '14 !!!
Seriously considering one of those being my next bike too

[paturoa]

yeah, for single gear roll ons between 75 kmh thru to 140 the torque advantage of the GSX is huge.

But a quick look at the std power vs rpm graph would indicate that the others would have the advantage.

[beyond]

I bought the 14 based on the fact that it's fuel injected and has heaps more useable torque for on road situations. That and it really handles.

Low and mid range torque is awesome out of corners and it's got great pulling power. Horsepower isn't everything when you have gobs of torque on hand and as the old adage goes, there's no substitute for cubic capapacity.

Oh, normally a GSX1400 is 106bhp.

I love my 14.

[idleidolidyll]

I was googling around the place and found this

http://www.mcnews.com.au/Testing/Hon...no/Comparo.htm

I looked at the first chart and thought well the old GSX14 looks a bit sad at the top end.

Then I looked at the second and thought that the XJR13 has some real world roll on advantage for overtaking.

Then I looked at the 3rd and went shit look at that.

Then I looked at the last and now I'm just confused

I was lucky to have worked in a bike shop with a dyno for a while and i can tell you that most manufacturers claims are bullshit.

Triumph is one of the worst. From someone who worked for them in Pomgolia, they measure the power by taking off the starter, alternator and anything else that might help pump up the rating. They also weigh them with no water or oil and without even oil in the bloody forks.
The japanese are almost as bad and the italians are liars.

my XJR1300Sp made 95 BHP in standard form but for $200 and some labour we managed to get 127bhp pretty easily.

gruntiest bike i saw was an old GSXR1100 with a turbo! It made 190 bhp but the power rushed in so suddenly iot must have been almost unridable.

Most Harleys make about 55 bhp but obviously have torque to spare.

A late model R1 made about 135 and was peaky compared to the XJR

KTM supermotos make 44bhp standard but can get about 55bhp without much trouble.

CBR600 said to be 125bhp actually made 100bhp

ducati 900ss about 75bhp

HOWEVER! As the smart people know, absolute bhp is a waste of time number anyway. On the road a wide torque spread will often give better drive than the latest peaky high HP monster and a bike with bugger all bhp but with bugger all kgs can still smoke many a big bike where we all like to ride the most: in those twisty bits

[The Stranger:Me]

I was googling around the place and found this

http://www.mcnews.com.au/Testing/Hon...no/Comparo.htm

I looked at the first chart and thought well the old GSX14 looks a bit sad at the top end.

Then I looked at the second and thought that the XJR13 has some real world roll on advantage for overtaking.

Then I looked at the 3rd and went shit look at that.

Then I looked at the last and now I'm just confused

What are you doing looking at crap bikes like that anyway, get something decent

[SPman]

my XJR1300Sp made 95 BHP in standard form but for $200 and some labour we managed to get 127bhp pretty easily.

Care to tell me how? Please.

But first, getting the front forks re-sprung.

My late lamented ZX9R, made 135.6 at its last dyno..

[idleidolidyll]

Care to tell me how? Please.

But first, getting the front forks re-sprung.

My late lamented ZX9R, made 135.6 at its last dyno..

The XJR13 is restricted by Yamaha. To make it sing you will need to toss the standard rubber manifolds and when you take them off you'll see why. They step down to reduce the inlet size and don't match the inlet size of the head.
Buy FJ1200 manifolds second hand from Aussie or Pomgolia and fit those but that isn't enough.
You've opened the lungs a bit but the airbox is also restricted. Buy the washable reusable air filter and on the opposite side of the inlet, drill another hole in the airbox that carefully fits inside the other end of the air filter. That hole should be baout half the diameter of the standard oner on the other side. Finally, fit a bellmouth into both holes and bin the awful standard air scoop, You'll also need bigger jets: I think they were 127's and you'll need to change the needle heights.
The standard muffler is Ok and fitting more open ones only gained 1 bhp. Basically by changing the inlet manifolds and opening the airbox up you are adding an extra 30%+ more flow. Torque went up from high 70's to high 80's , you'll gain around 30bhp AND it will be more economical since you'll be able to gear it up if ya want.

I can't remember where I found the info I used but I suspect it was on an aussie or brit website. You could google for it.
Dave Cole helped me do the work when he was at Haldanes, if you know Dave he might remember more of the details.

[Crasherfromwayback]

I was lucky to have worked in a bike shop with a dyno for a while and i can tell you that most manufacturers claims are bullshit.

You'd love our Dyno mate....it ain't no Dynojet jobbie!
The software alone cost more than a Dynojet Dyno. It was built for us by International Dynometers with some input from the DSIR, and it's gospel.
We take the back wheel out and drive a hydraulic pump, so it's not simply a free running spool, and obviously we get notyre slippage. If you're ever in town, call in for a demo!

[idleidolidyll]

You'd love our Dyno mate....it ain't no Dynojet jobbie!
The software alone cost more than a Dynojet Dyno. It was built for us by International Dynometers with some input from the DSIR, and it's gospel.
We take the back wheel out and drive a hydraulic pump, so it's not simply a free running spool, and obviously we get notyre slippage. If you're ever in town, call in for a demo!

you're probably right but the point was and still is that manufacturers claims are rubbish for the most part.

The most interesting bit was the comparo between different kinds of bikes.
As I mentioned, a late model R1 made 135bhp when Yamaha claimed something like 160bhp+ and in comparison an Aprilia Tuono made nearly 120.

I read somewhere else in the site a quote:
"The best modification you can make is bigger balls."

That's gospel, most people can't ride their bikes as well as the bikes can be ridden anyway

[Crasherfromwayback]

you're probably right but the point was and still is that manufacturers claims are rubbish for the most part.

The most interesting bit was the comparo between different kinds of bikes.
As I mentioned, a late model R1 made 135bhp when Yamaha claimed something like 160bhp+ and in comparison an Aprilia Tuono made nearly 120.

I read somewhere else in the site a quote:
"The best modification you can make is bigger balls."

That's gospel, most people can't ride their bikes as well as the bikes can be ridden anyway

100% correct. ALL modern sports bikes are better bikes than we are riders, it's just that only a small percentage of us can admit it. I will say though, that we came to similar HP readings with quite a few bikes. Dynojet Dyno's read low. As I mentioned, if you're ever in town come and check ours out.

[Mr. Peanut]

I bought the 14 based on the fact that it's fuel injected and has heaps more useable torque for on road situations. That and it really handles.

Low and mid range torque is awesome out of corners and it's got great pulling power. Horsepower isn't everything when you have gobs of torque on hand and as the old adage goes, there's no substitute for cubic capapacity.

Oh, normally a GSX1400 is 106bhp.

I love my 14.

And it looks f**kin staunch

[TonyB]

.... and now I'm just confused

And no bloody wonder! Jeeze talk about Too Much Info! Surely the "Torque v Road speed in one gear under top" is heavily dependant on the gearing of the bike. Doesn't this graph just say "the GSX1400 has lower gearing"??

As a general rule of thumb, in any given gear most bikes/cars will accelerate faster at peak torque than at peak power, but at any given speed they will accelerate faster at peak power than at peak torque- simply because the gear box allows you to select a lower gear and generate more torque at the wheel, the peak POWER available at the wheel is for all intents and purposes the same no matter what gear you are in.

[idleidolidyll]

You'd love our Dyno mate....it ain't no Dynojet jobbie!
The software alone cost more than a Dynojet Dyno. It was built for us by International Dynometers with some input from the DSIR, and it's gospel.
We take the back wheel out and drive a hydraulic pump, so it's not simply a free running spool, and obviously we get notyre slippage. If you're ever in town, call in for a demo!

I was thinking about your post last night and a couple of things spring to mind.
Firstly, it doesn't matter much which dyno a rdier uses to develop their bike as long as they use the same dyno after each modification. That virtually eliminates the differences between dynos and the software they run and leaves things like barometric readings for the computer to equate.
Secondly; Of course your dyno reads higher BHP numbers. Taking out the back wheel and presumably the chain reduces that 10-20kg of rotating mass to zero kg. Comparing dyno numbers between dynos is a silly pastime but comparing a dyno that is attached directly to the output shaft to a dyno that reads how much power is transmitted at the footprint of the tyre is lunacy.
IMO the really important number is the real hp delivered to the road and by decreasing the weight of that rotating mass and even fitting better tyres, more hp is delivered where it counts; on the road. That is how many manufacturers puff up their chests for bragging rights to 'most powerful' status: they don't measure the horsepower we feel when we accelerate, they only measure crank hp or output shaft hp etc. There is no uniformly used horsepower test amongst the manufacturers and comparing hp by brochure is silly.
That's why I like the rolling road tests: they deliver figures that tell the real story of horsepower delivered to the road surface and usually make a nonsense of manufacturers ratings where some remove all motor driven accessories to get the highest, but unrealistic, figures. Hell, manufacturers have even been known to remove everything but the crank and pistons and drive the motor from an outside source measuring not what the motor actually makes but what it COULD make if it didn't have to live in the real world where we need lighting, indicators, chains, tyres and wheels.
However, if a rider is only developing the motor and not the whole bike plus consistently uses the same dyno to do so, it makes little difference which kind of dyno is used.