How does powerband work
All engines have a power band but not all engines are as noticeable to the operator as others. Four-stroke bikes have a broader range of power broader range of RPM and make it feel like the power is there for most of the gear until higher RPM where it will plateau.
Two-strokes have a shorter range of RPM for the power band. Four-strokes typically have more power on the low end, most of the mid-range and then begin falling off towards the high-end. Two-strokes make most of their power in the upper mid-range and top end.
More heavily tuned bikes have a narrower powerband and sacrafice all-round even power for a powerful powerband but little power elsewhere. Originally Posted by Beemer. Originally Posted by Ixion. To me the 'powerband' is simply the part on a dyno chart that reflects the steepest and highest part of the power curve the bell shaped part of the power curve that contains peak power.
From the engine perspective its tuned by adjustment of intake, cylinder and attenuation exhaust tuning. From the bike perspective, you factor in gear and final drive ratios.
The principle is similar for 2-smokes and 4-smokes, but the method of actually doing it is slightly different [two smokers insert complaint here]. To use an example, my old cbr ran a rev range of , rpm. It developed peak power at rpm with the slope of the bell curve starting at rpm and ending at rpm. This gave a powerband of rpm When I got it, peak torque occured at 11, rpm with the curve starting at 10,rpm and ending at 12,rpm. The term torque band is not as widely used but it should be as its just as important.
Anyhow, the two nifty has a pretty good torque band, but its in a sucky position. Primarily you can move the torque and power bands up and down the rev range by adjustment of the attenuator and megaphones changing the exahust system , you can then be more subtle by modding other bits. The gear ratios dropped of k rpm the never was precise , which meant that if I changed up gears at just past peak power, it would drop down to just on the start of the power band.
Likewise, downshifts had to be managed in a similar way. The problem with peak torque being down so low, meant that the bike was never as agressive as I wanted it to be. I'm in the process of fixing this on my with working out a new exhaust design which I think might work better. Probably to start off another argument, in really basic terms, torque is telling you how a bike will accelerate, the torque curve is telling you about the characteristics of its acceleration - but its not its actual acceleration.
The power curve is telling you how quickly the bike will be capable of acceleration how responsive it will be to throttle manipulation and is known as its driving force - its ability to drive the bike forward. The two are related to each other. A bike with high torque and now power will be sitting still, so will a bike with high power and no torque it would probably be in neutral.
In my example of the , the torque curve was flat at peak power - hence it felt sucky, but just under the power curve when peak torque occured, the bike could life the front wheel and felt like it went like the clappers.
Hence I think the bike would have been more exiting if the torque and power curve is matched. When looking at the powerband from a gearing perspective - which is important on a and cc bike.
Its important that the power band is wide enough so that the gear ratio will not cause the bike to lose its drive when a gear is changed by dropping too far below peak power out of the bell curve. Ask any rider what happens when the get the gears wrong for a corner. For small capacity 2-smokes, this is where the art of engine tuning is I think. In a 2-stroke, both the intake and exhaust ports are open at the same time. Now, enter the exhaust pipe into the picture.
It gets reflected back in two sections, a negative pressure vacuum wave and a positive pressure wave. So what does the whole picture look like together? At low RPMs, the piston is moving slower. The exhaust port isn't open yet when the negative pressure wave hits, so it's wasted. The positive pressure wave hits as the exhaust is opening, so the exhaust has to really fight to get out, further reducing power. Now when the engine hits a certain RPM range, magic happens. So if you look at the entire RPM range, at low rpms you have very little power, then when you hit a certain RPM based on the design of the pipe you get a huge power increase.
At higher RPMs, the power begins to fall off again. So you have lots of power within a certain rpm range, which is referred to as the "powerband". I think he hit it right on. Oh and for Jumbo Just to remind you incase you decide to post something again;.
I can't believe some of yall are tellin all these lies. You can only buy these powerbands at the licnesed dealers. They are made from a special rubber compound that dosen't wear under the extreme power of todays machines like the 's. The green type are for top end, and the red are for bottom.
Wilkin, you have let us down. Haaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:eek2: :eek2: :eek2: :eek2: :eek2: :eek2: :eek2: :eek2: :eek2: :eek