Lol, durielk, but does moving a given TRQ curve up the RPM range actually make a faster or otherwise better engine - Nope. Again, it is the shape of the TRQ curve that governs. So it should be " Broad bell shaped Torque curves RULE"!

 

I'd prefer to see a flatter torque curve....a higj torque number of course


Im calling the place today to see if i can get more info on the run

 

HotRod has a good article on torque and horsepower.

Knowing both curves gives one the ability to know how much power there is through the torque curve and how much potential for work there is through the horsepower figure, how fast it will produce the work - thus the "silly shape" of the horsepower curve. The high peak indicates how quickly the engine can produce work. The two always cross at 5250 rpm since the formula for calculating horsepower has the two equal at that rpm, if not the charts are incorrect and something is amiss. The horsepower curve will indicate the capability to continue to do work, but will start to flatten out as the torque curve drops.

Lots of complexities, but it is pretty simple to assume the engine will pull the hardest in the vicinity of the torque peak and will continue to pull hard to the horsepower peak. The torque curve also gives a good indication of how an engine will pull down low. It is pretty simple to, at a glance, see if an engine will pull strong at 3000 rpm by a visual comparison to the torque peak, maybe even take some numbers for calculation. I did that with one of my bikes and found it had torque almost 82% of the max, indicating it would pull strong. anything below 3000 was dead.



I look at the KLX stock chart and see the bike will likely pull well starting around 5000 rpm (about 80% torque max) and peak out on quickness of acceleration at around 8500 to 9000, at which point an upshift will put the bike right near the peak capability for acceleration depending on rpm drop. So I will run the 250 around 5000-6000 most of the time and when running hard will shift around 8500. Matches what the chart tells me.

 

OK, so expslains to me how honda won the motogp many years by running their engines at 18-27,000 rpm. There was no torque down low.

 

Oops.. I see i've said too much.... HORSEPOWER RULES!!!!!!!

 

I am kind of amazed at the hp of the klx350. 27 or something like that.

I went to help do a pipe dynoing on a 500cc atv with 4 different pipes. 75 freaking hp! I had to buy it. When it hits the powerband you have to be ready cause it will loop out on you. Makes you almost cry riding a stock klx trying to do a power wheelie!

 

yeah with no pumper, and no cams! Just jetted cv and a slip on

 

Well pull that 500 motor out and wedge it into your KLX frame!

 

This is what Mark is trying to explain-it is simple physics. Torque and horsepower are force and work. A simple analogy is torque accelerates you and horsepower sets max speed. Motogp engines(F1 for that matter) are perfect examples of how they make huge horsepower. Plug the 75 lb/ft of torque that they make from 1 liter of displacement at 18000 rpm and it gives you over 250hp. If that engine could only rev to 8500 rpm but still make the same 75 lb/ft of torque it would only produce 121hp.
A flat torque curve will give you a constant slope or increase in power as revs increase. That is beneficial because it doesn't produce a spike in acceleration that could overwhelm the tire. That is one of the biggest advances in bikes-having ride by wire throttle systems that can modulate power output so that it doesn't overcome available traction and launch you to the moon when the rear tire breaks loose and highsides the bike/rider.

 

looks like 500cc two stroke... not really a fair comparison ;-)