Do more RPM's equal more HP or speed ?
 

Just wondering ...

RE: Do more RPM's equal more HP or speed ?
 

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.

RE: Do more RPM's equal more HP or speed ?
 

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

RE: Do more RPM's equal more HP or speed ?
 

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

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

RE: Do more RPM's equal more HP or speed ?
 

Yes and no

RE: Do more RPM's equal more HP or speed ?
 

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.

RE: Do more RPM's equal more HP or speed ?
 

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

RE: Do more RPM's equal more HP or speed ?
 

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.

RE: Do more RPM's equal more HP or 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.

RE: Do more RPM's equal more HP or speed ?
 

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.

RE: Do more RPM's equal more HP or speed ?
 

27 tooth pulley on a 883, 29 tooth pulley on a 1200. 883's come with a 27 because they don't have the power to pull a 29. Larger front= slower acceleration, more top end. Smaller front = quicker acceleration, less top end, all else being equal.

RE: Do more RPM's equal more HP or speed ?
 

The gearing thing (883 vs 1200; 27 vs 29 tooth) presumes you can red-line in top gear. The bike in this dyno was taken to about 6500rpm easily...with the 27 tooth sprocket that was faster than a stock 29 tooth 1200.....

http://www.head-quarters.com/html/100_x_89.html

[IMG]local://upfiles/32069/59F3B9989F284A2EB6E9928E0FFCF70A.jpg[/IMG]

RE: Do more RPM's equal more HP or speed ?
 

All things considered, the 883 gearing would be quicker off the line than a 1200 with the same mods. But in the end the 1200 with those same mods would be faster in the long run.
When you are building an engine you need to know if you are looking to be "fast" or "quick" before you even start. There's alot different approaches to each one. It all depends on how big your budget is.
In Sharley's case, he achieved both but judging by his dyno sheet, he had a sizeable budget to work with.

Edit: There is no doubt in my mind thatSharley'sbike would shock many a rider in a straight line race.

RE: Do more RPM's equal more HP or speed ?
 

Dyno's are great for producing Hp & Torque numbers but don't really factor in rider load and headwind drag when you are talking about achieving max top speed in the real world.

RE: Do more RPM's equal more HP or speed ?
 

Okay. Many good replies, lots to gleen, here is some more;

Ignition with rpm.
With the 45* V-twin engine you don't normaly see ignitinos with rpm over 7k. This is becausethe piston speed at the wall of the cylinder will be too much for any oil to keep it lubricated. The friction will kill the engine life.
Machines like the Vrod get arround this by having a much shorter stroke and larger bore. The bore keeps the HP up while the stroke drops the torque. The short stroke allows the rpm to get up to 9k+. Same with 4 cylinder jap bikes, bigger bore than stroke, higher rpm, less torque, not as quick off the line in a drag but higher top end speed.

The gearing:
The 883 & 1200 share the same primary drive & transmission. What changes is the front sprocket of the final drive. It is 27 teeth for 883 and 29 teeth for 1200. The 27 tooth is faster off the line but top end speed with a 6k rpm is only ~113 mph. The 29 tooth can get up to ~125 mph.

Cubic inches gives more power. Normaly both HP and Torque.
In order to feed bigger cubic inches you need a bigger intake, in order to get the exhaust out you need a properly designed exhaust system. In order to burn the air fuel mixture you need a good coil, wires and plug.

The attached pic compares a 26 tooth Baker front sprocket with a six speed transmission to a 27 tooth stock 883 sprocket with stock transmission, the black line to the very left is the fifth gear of a stock 1200.This is to show that with a 26 tooth front sprocket & Baker 6 speed tranny you will be able to beet a stock883 off the line and go a bit faster than a stock 1200. Stock bikes have rpm limits of between 5500 & 6000 depending on the year.

[IMG]local://upfiles/48626/C0F706397B97469494C01D0769B8AC98.jpg[/IMG]

To answer the question/subject of the post:

RPM + HP = SPEED

speed can be defined as fast off the line or top end speed depending on gearing.

RE: Do more RPM's equal more HP or speed ?
 

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