Powerband?

[Quartermile]

Hi

I know what powerband is but how does it work and also what on earth is a compresion ratio as I read motorbike magazines and in the specs of bike they have the compression rato but I have no idea what it is.

[Mr. Peanut]

Definition of a powerband = the location and width of the rpms where the engine is producing peak torque values.

You are thinking of a powervalve perhaps?

http://en.wikipedia.org/wiki/2-stroke_power_valve_system

Compression ratio is a measurement of how much the gas in the combustion chamber gets squished. I.e. 5:1 would mean then gas is squished to 1/5 its original volume, 10:1 would mean it's squished to 1/10th the original volume.

Generally speaking, and with all other variables remaining constant, the higher the compression ratio, the more powerful the engine.

http://en.wikipedia.org/wiki/Compression_ratio

[onearmedbandit]

Let wikipedia (http://en.wikipedia.org/wiki/Compression_ratio) tell you.

[Smokin]

Compression ratio is a measurement of how much the gas in the combustion chamber gets squished. I.e. 5:1 would mean then gas is squished to 1/5 its original volume, 10:1 would mean it's squished to 1/10th the original volume.

Generally speaking, and with all other variables remaining constant, the higher the compression ratio, the more powerful the engine.

http://en.wikipedia.org/wiki/Compression_ratio

I has always wondered how that worked.
Cheers Mr peanut

[GR81]

Generally speaking, and with all other variables remaining constant, the higher the compression ratio, the more powerful the engine.
and often the shorter the life span lol

[Skunk]

and often the shorter the life span lol
Unless it's built to take it.

[race me!!!!]

i rebuilt my bike the other day and i had to replace my power band now it goes heeps better

[race me!!!!]

bahahahahahahahahahahahahahahahahahahaha
left handed screw driver
bucket of steam...
work as an apprentice its great!!!

[Buster]

Go to your local dealer and ask if they can have a look at your powerband. It could be faulty and might need replacing. Im saving to get a bigger powerband for my bike.

[terbang]

Hah when I was an apprentice I was sent to the parts shop for a long weight..!

[pritch]

i had to replace my power band now it goes heeps better

Are you sure that wasn't the rubber band?

[James Deuce]

I use my powerband to hold my undies up.

[McJim]

It would appear you're taking advantage of a newbie with all of these silly comments.

Your 'Powerband' is the rate of revs where your horsepower is greatest. Generally within 10% of redline. To demonstrate this find a nice quiet pice of straight road and stop (making sure there are no Police around) now put the bike in 1st and accelerate until you feel the need to change to 2nd. Now do not change gear and open the throttle fully holding it there.

You will feel steadily increasing acceleration until you get to within 10% or so of the bike's redline at which point you will feel as though someone just kicked your bike up the arse and it will shoot forward a bit. You have just found the powerband.

Compression - this is the pressure under which the bike's engine operates - older engines tend to lose compression due to wear and tear on cylinders, piston rings etc. Higher performance engines tend to have higher compression ratios. Ducati Monsters have fairly low compression ratios compared with Cagiva Raptors for example.

[James Deuce]

It would appear you're taking advantage of a newbie with all of these silly comments.



Not taking advantage. Taking the piss.

It's one of those questions that is up there with logging into CNET and asking if your PC will still work with the power turned off.


Google and Wikipedia are your friends.

[McJim]

Not taking advantage. Taking the piss.

It's one of those questions that is up there with logging into CNET and asking if your PC will still work with the power turned off.


Google and Wikipedia are your friends.

I still think your kicking some poor kid when he's down. My philosophy - if you tell someone something and they forget it they are a dumb arse - if they never knew it in the firstplace we should at least tell them so we can call them a dumb arse tomorrow....:rockon:

What the fuck is CNET? How do I get one fitted to my bike?

cheers

[bugjuice]

Head down to Colemans and have a look for these.. the improved powerband 2


<img src="http://shop.limct.com/powerband.jpg"></img>

[McJim]

Head down to Colemans and have a look for these.. the improved powerband 2


<img src="http://shop.limct.com/powerband.jpg"></img>

Cool piece of modification kit - can you fit one to a GN125 so it can out accelerate a Hayabusa?

[Mr. Peanut]

Booyah ^_^ I was right McJim :motu:

The power band of an engine refers to the range of operating speeds under which the engine is able to operate efficiently. A typical gasoline automotive engine is capable of operating at a speed of between around 750 and 6000 rpm, but the engine's power band would be more limited. The engine would typically not generate maximum torque until higher operating speeds of perhaps 2000 rpm, and torque would begin to drop off near the redline. Such an engine would be said to have a "power band" of 2000-6000 rpm.

Haha!

[McJim]

Enjoy your gloat little person...I have seen where the power peak is in a graph of BHP versus RPM and where the Max Torque appears in a graph of Torque Versus RPM. If we superimpose one graph on top of the other we do find that there are 2 seperate peaks - they do not genarally appear in the same place. The Powerband is generally that place around the power peak which is closer to the redline than the peak in Max Torque.

Sounds as though you read an encyclopedia and didn't understand it.

Never mind - you'll get there one day.

[Mr. Peanut]

Have a look at that chart, right after the torque peak you'll notice that power begins to level off.

Remember that the power is essentially the product of the RPM and the torque. At first, decrease in torque is small and is not enough to offset the increasing RPM, so the overall product still increases. Eventually the decrease in torque becomes large enough that it outweighs the increase in RPM and we see the power start to drop. Because of this, the power peak will always be after the torque peak.

So, when you do hit your power peak, the engine is well out of its efficient operating range.

My gloat was in jest. No Hard feelings... :done:

[Mr. Peanut]

:shifty: I wonder what I've started...

[McJim]

:shifty: I wonder what I've started...

You've started nothing - I'm far too old and too experienced to hold a grudge.

I KNOW the power band is where the max power lives.
I KNOW the max torque is well before it.
My Max Torque is at 8,000 rpm
My Max Power is at 10,500 rpm
My Powerband kicks in at 9,500rpm and continues to 11,000 rpm

These are all facts I know from reading the controls in front of me.

I therefore simply disagree with your statement that the power band is the place where torque is greatest coz on my bike it's in the place where power is greatest.

Maybe your bike is different, I don't know, I suggest we open it to the more experienced bikers out there - maybe we could have a vote.

e.g. Where is your powerband?

Where the Torque is greatest.
Where the Power is greatest.

My only complaint is that I refuted your statement quietly and politely - you chose to be gregarious and mildly offensive...but then again...I've probably got a much bigger cock than you so no hard feelings eh?:rofl:

[Mr. Peanut]

So we agree to disagree? :rockon:

[McJim]

There once was a bloke called nuff - he was a fairy.


Fairy nuff:rockon:

[Mr. Peanut]

I've probably got a much bigger cock than you so no hard feelings eh?

Sorry to hear about that.

If you have a problem getting or keeping an erection, your sex life can suffer. You should know that you’re not alone. In fact, more than half of all men over 40 have difficulties getting or maintaining an erection.

You should also know there is something you can do about it. Millions of these men have already improved their sex lives with VIAGRA.

http://en.wikipedia.org/wiki/Impotence

[Lou Girardin]

Powerbands aren't what they used to be. Modern engine management has enabled designers to design engines that make good power almost from idle.
15 years ago it was unheard of to have a road engine develop 180 bhp per litre and still drive cleanly from 2000 rpm up to 13,000.
The new ZZR14 and VFR800 are good modern examples of a powerband that's engineered in. As a function of the VTec system in the Honda and, supposedly, designed into the 14 to give soft response below 5000 rpm and keep the shiny side up.
The best examples of serious steps in power are some of the old 2 strokes like RD350's and the Quacka triples. They'd hit the band and either loop or spin up the wheel in the wet.

[Mr. Peanut]

RG500... :rockon:

[Mr. Peanut]

15 years ago it was unheard of to have a road engine develop 180 bhp per litre and still drive cleanly from 2000 rpm up to 13,000.

The NSR is 15 years old, 240bhp+ per litre, does just that...ish :love:

[Lou Girardin]

The NSR is 15 years old, 240bhp+ per litre, does just that...ish :love:

It'll take WOT from 2000?

[McJim]

Sorry to hear about that.

You should also know there is something you can do about it. Millions of these men have already improved their sex lives with VIAGRA.

http://en.wikipedia.org/wiki/Impotence

Tried Viagra - air traffic control complained. Had to fit a flashing red light on the end.

[Mr. Peanut]

It'll take WOT from 2000?
I thought I stalled it on a hill once, the bloody thing tractor'd/chugged up the hill and regained its composure :shit:

Just as well I've rebuilt the engine huh?

[Coyote]

now put the bike in 1st and accelerate until you feel the need to change to 2nd. Now do not change gear and open the throttle fully holding it there.

I don't get that. I thought you change gear when you reach redline

[McJim]

I don't get that. I thought you change gear when you reach redline

You're absolutely correct.

[Jantar]

It would appear you're taking advantage of a newbie with all of these silly comments.

Your 'Powerband' is the rate of revs where your horsepower is greatest. Generally within 10% of redline..

Sorry, but I do believe you need to go back to some basic physics. The powerband is often a seat of the pants feeling of the point where you get maximum accelleration to the point where the accelleration dies off. However:
Power = Force x Velocity, and Force is what gives you accelleration.
Force, measured at the rear wheel is a simple function of Torque and gearing, so Force and hence accelleration wull be greatest when Torque is greatest.

The Powerband is therefore from peak Torque to Peak Power. On some bikes this is only 10% of the Rev range, on some its 50%, and on some the torque comes in so smoothly that the powert band is almost the entire rev range. My old GS1200SS is an example of peak torque at only 4000 rpm and peak power at 9500 rpm, now that is one wide power band.

[Mr. Peanut]

Here is an article which rates the NSR the best bike in the world. I hate to agree, but its pretty conclusive.

http://www.simjen.com/request.php?1

[Mr. Peanut]

Sorry, but I do believe you need to go back to some basic physics. The powerband is often a seat of the pants feeling of the point where you get maximum accelleration to the point where the accelleration dies off. However:
Power = Force x Velocity, and Force is what gives you accelleration.
Force, measured at the rear wheel is a simple function of Torque and gearing, so Force and hence accelleration wull be greatest when Torque is greatest.

The Powerband is therefore from peak Torque to Peak Power. On some bikes this is only 10% of the Rev range, on some its 50%, and on some the torque comes in so smoothly that the powert band is almost the entire rev range. My old GS1200SS is an example of peak torque at only 4000 rpm and peak power at 9500 rpm, now that is one wide power band.

Don't forget to differentiate between engine torque and wheel torque.

If wheel torque in first gear still exceeds that of second at the redline, it would be faster to shift at that point, rather than at the power peak. And so on for the remaining gears.

Not that you said anything at odds with that, I just thought was an important point.

[Edbear]

:shifty: I wonder what I've started...



LOL!!! I bet you knew exactly what you were starting...:yes:

[Jantar]

Don't forget to differentiate between engine torque and wheel torque.

Exactly. That is why I said Force, measured at the rear wheel is a simple function of Torque and gearing. It is the force that the tyre exerts on the pavement that pushes the bike forwards. That is also why manufacturers usually chose gear ratios that will allow you to change up at max power output and still stay above peak torque revs.

[Quartermile]

Hey
yea thanks that helps alot...... I guess
I can handle the insults .......I hope....
;)

[Smokin]

Hey
yea thanks that helps alot...... I guess
I can handle the insults .......I hope....
;)


You will be just fine mate.

Your skin will thicken up over time.

[jade]

2 stroke 250 powerbands are my favourite..

[Mr. Peanut]

Haha I remember that bike. Why the trip to the dark side? Should have modded the NSR :nono:

[Moxy]

I actually had a dream about about "upgrading my powerband on my bike" my "engine" was a two piece thing - a bit like a big Mr. Potato head, and inside there was a label reading "power band" with a big black rubber band wrapped around two extrusions. Once I replaced it my bike was running faster than ever.

[race me!!!!]

im quite suprised this thread has stayed on relativly on track for three pages and not hijacked!!!
fuck what are we coming to:whocares:

[Sketchy_Racer]

You're absolutely correct.


errr. No

My KR 150 has its powerband between 7-9 RPM. After you reach 9 RPM it flats off real bad. Even though it red lines a 11.

No point revving all the way to 11 when its stopped accelerating at 9 !!

[JeremyW]

If we look at it in pure physics:

Power is the rate at which your engine can convert energy. In this case from chemical potential to kinetic (and heat etc...).

Whereas torque is the twisting force your engine can produce. An hence the most efficient.

So if the powerband is defined as a point where your bike 'kicks you in the arse and wants to destroy the horizon' (in technical speak ofcourse) then you would have to say it is the point in rpm where the engine got a whole lot better at converting chemical potential to kinetic energy (assuming small changes in amount of chemical potential relative to power change) and hence your peak power.

But if the powerband is defined as the rpm range where the engine is most efficient then it will be peak torque.

I submit the powerband is the former :) From experience...

To the best of my knowledge this is right. But some people do have a habit of ripping into newbe bikers :)