Just wondering ...

 

To a point RPM Were peak hp maxis out at a specific rpm same as torque peaks out at a specifc rpm. HP and torque usually peak out at slightly different rpm In big block engines on hi po cars peak torque maxis out at a slighty lower rpm lets say 4500 rpm max hp could be at 5500 rpm on the same engine To push that engine over 5500 rpm for a shift to a higher gear does not help with speed or power.

 

RPM's give you speed, but you also need more horsepower to make speed at a higher rpm. Horsepower is just a measurement based on torque. Take your max torquemultiplied bythe rpm at which you aheived it and divide by 5252 and you have your horsepower.

HP=TQxRPM
5252
Camshafts just move the torque curve which gives you more horepower at highe rpm's.
Horsepower makes you fast, Torque makes you quick. There is a difference

 

So one of thiese ignition modules that ups the available RPM does ? nothiing for me ?

Unless I ? what ... Cube inches ? More flow ? or what ?

 

Yes and no

 

For us guys that have done 883 converstions and not changed out our front final drive sprockets it does wonders. Effectively it gives us a higher top speed than a stock 1200 of the same era.

 

Being able to rev higher alone is not going to give you more speed or power. If you power band is below say 5000 rpm you will not develop more power just by winding out to 6000 rpm. You would have to modify your motor to develop power on through the higher rpm range. That would be done with cams, intake and exhaust.

Ric

 

I have to disagree as I have raced an 883-1200 converted 2004 custom with a screamin eagle ignition and it was not able to keep up with me, and you can't say it was the rider because we took off from a 40 mph speed.

 

For your bike or in general? If you have a stock internal harley, then generally raising the rev limit does not yield more hp because the hp tapers off before redline (exceptions apply). Considering gearing being the same, more rpm = higher top speed in each gear. However, in order to take advantage of that higher top speed the power needs to produce enough power. If you have a modified sportster with high performance cams, then raising the stock redline will result in more hp because the hp peak will occur after the stock redline.

If you are speaking about non-harley's, then generally motors that are able to turn higher rpms (11K or so) will produce greater hp with all other factors being equal. However, there are a lot of other factors.

 

The opposite is actually true. 1200 conversions with 883 gearing have LOWER top speed than a stock 1200. Taking into consideration just rubbermounts a 1200 with 1200 gearing will have a top speed of 125 mph. 883 gearing is only good for a top speed of 110 mph. What 883 gearing gives you is quicker acceleration.