The never ending search for hp
Road Master
Joined: Dec 2013
Posts: 1,238
Likes: 96
From: fort walton beach
i wouldn't have too much concern for the dyno numbers. i have seen the same bike make different numbers on the different dynos, some higher some lower. ride the bike and see if you like it. if you want more i would do a pulley swap so your not just throwing parts at your bike making minimal gains.
Grand HDF Member
Joined: Nov 2017
Posts: 4,251
Likes: 3,134
From: Texas
In general, it's not all that conducive to search for HP on a Harley; Harleys are about torque, not horsepower.
Horsepower requires revs. High-horsepower engines have very high RPM redlines. Harley's made two engines that make decent horsepower per liter (about 90-95 horsepower per liter), the Street Rod's Revolution X and the V-Rod's Revolution engine. Both have redlines around 9,000 RPM. The air-cooled Big Twin engines only rev up to 5500-6000 RPM max.
You gotta understand, horsepower is a mathematical formula defined by torque. HP = (torque X RPM) / 5252. If you don't have the RPMs, you'll never have the horsepower. Look at the Ducati Diavel's horsepower chart, it's huge, but then again so's its RPMs (it redlines at over 10,000 RPM). You'll never get "big" horsepower numbers without the revolutions. You can get tremendous torque, and that will help, and any increase in torque will result in increases in horsepower as well.
A freer-flowing exhaust can help raise torque in the high-rpm side of the chart, whereas a little backpressure can help build torque in the left side of the chart. HP requires two things: high revs, and high torque. You can't really change the revs of an existing design (although on the M8's, getting a Stage upgrade will raise the redline from 5500 to about 6200, so that helps some). But you can make more torque, and for any given rpm level, more torque = more horsepower at that rpm level.
Horsepower requires revs. High-horsepower engines have very high RPM redlines. Harley's made two engines that make decent horsepower per liter (about 90-95 horsepower per liter), the Street Rod's Revolution X and the V-Rod's Revolution engine. Both have redlines around 9,000 RPM. The air-cooled Big Twin engines only rev up to 5500-6000 RPM max.
You gotta understand, horsepower is a mathematical formula defined by torque. HP = (torque X RPM) / 5252. If you don't have the RPMs, you'll never have the horsepower. Look at the Ducati Diavel's horsepower chart, it's huge, but then again so's its RPMs (it redlines at over 10,000 RPM). You'll never get "big" horsepower numbers without the revolutions. You can get tremendous torque, and that will help, and any increase in torque will result in increases in horsepower as well.
A freer-flowing exhaust can help raise torque in the high-rpm side of the chart, whereas a little backpressure can help build torque in the left side of the chart. HP requires two things: high revs, and high torque. You can't really change the revs of an existing design (although on the M8's, getting a Stage upgrade will raise the redline from 5500 to about 6200, so that helps some). But you can make more torque, and for any given rpm level, more torque = more horsepower at that rpm level.
Last edited by FatBob2018; Feb 27, 2018 at 05:43 PM.
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6th Gear
Joined: Feb 2018
Posts: 14
Likes: 0
From: California
I'm not looking for huge numbers the bike is my daily. When I'm around. And only thing I'm going with numbers is that it seems low for what has been done. Not sure if something is being restricted or to much air flowing threw
Road Master
Joined: Dec 2013
Posts: 1,238
Likes: 96
From: fort walton beach
there are plenty of pulley combos out there, i have a 70t pulley that went on with my cams and honestly i dont know what helped more but the bike is a lot different, getting me into power quickly and staying in it during shifts on top of that 6th gear is much more usable.
Last edited by stal94gt; Feb 27, 2018 at 06:20 PM.
Road Master
Joined: Dec 2013
Posts: 1,238
Likes: 96
From: fort walton beach
Stock 133t belt. It is a tight squeeze for that belt and if you have a 132 belt it won’t fit unless you swap the front pulley. You can go to a 68t rear and use the stock belt. Next year I may swap for a 30t front but not sure if I will cause I really like the 70t still
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6th Gear
Joined: Feb 2018
Posts: 14
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From: California
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