so here is where i get confused. on buells website it rates the xb9 at 92hp and the xb12 at 103hp. yet after reading the asb exhaust shootout, they dynoed the xb9 an 79rwhp and the xb12 at 101rwhp. why is the 9 so much less than buells number when the 12 is only 2hp less than buells number.
hp numbers
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upthemaiden
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did they do the same exact mods to the 2 bikes? Maybe the 12 got some special treatment and it's putting out more power, and they just stuck the exhaust on a stock xb9 so it's not getting much?
Dyno numbers are always way different than what you get from the manufacturer, but I see what you're talking about with the discrepancy between the two bikes.
They should stop with all the torque/hp numbers, and just get straight to telling you what it takes to make the bike wheelie. It'll be much easier for people to judge what they want. "well this bike needs to you stand up and bounce it in 2nd, but this one will lift the front wheel with a smooth roll on of the throttle in second", I mean that just makes more sense to me.
Dyno numbers are always way different than what you get from the manufacturer, but I see what you're talking about with the discrepancy between the two bikes.
They should stop with all the torque/hp numbers, and just get straight to telling you what it takes to make the bike wheelie. It'll be much easier for people to judge what they want. "well this bike needs to you stand up and bounce it in 2nd, but this one will lift the front wheel with a smooth roll on of the throttle in second", I mean that just makes more sense to me.
Midnight82
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Agreed, in the real world, guys don't spend their weekends on Dynos, they spend it raping the turns.
BuddhaBuell
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thats a beautiful quote Midnight [up]
GW 04 XB12R
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i would take the dyno numbers over Buell's. I would venture to say they pumped up the 9's numbers to make it sell better. Doing the math (though I know it WON'T be exact) the XB12 puts out 103/12= 8.58hp per 100cc using Buell's numbers. The XB9 puts out 92/10= 9.2hp per 100cc. Should it really have that much higher power/displacement ratio?
From the dyno, the XB12 is 101/12= 8.42hp per 100cc, and the XB9 is 79/10= 7.9hp per 100 cc. Seems more reasonable, though still not 100% accurate.
I believe ASB's dyno runs over Buell's claims.
From the dyno, the XB12 is 101/12= 8.42hp per 100cc, and the XB9 is 79/10= 7.9hp per 100 cc. Seems more reasonable, though still not 100% accurate.
I believe ASB's dyno runs over Buell's claims.
Well, Buell is claiming flywheel power
Also, you're looking at it all wrong: the 9 is more effecient at its peak horsepower engine speed (7500rpms) than the 12 is at it's peak horsepower engine speed (6800rpms)
Both motors have a flat and long torque curve, and since HP is just torque*rpm/5252, the higher the rpms you go, the better your hp will be (unless your torque curve falls off)
If you ran the 12 out to 7500rpms, it would make a theoretical 9.9hp/100cc, almost the same as the 9
Also, you're looking at it all wrong: the 9 is more effecient at its peak horsepower engine speed (7500rpms) than the 12 is at it's peak horsepower engine speed (6800rpms)
Both motors have a flat and long torque curve, and since HP is just torque*rpm/5252, the higher the rpms you go, the better your hp will be (unless your torque curve falls off)
If you ran the 12 out to 7500rpms, it would make a theoretical 9.9hp/100cc, almost the same as the 9
they used an 05 XB9 and an 04 XB12
when the engines were updated (2008 for the 9)decent gains were seen in the xb9 but not as much in the 12.
I am willing to bet that the late 9 may truly have 92 at the crank but in the uk they are rated at 84 and that may be more accurate.
the 9 and 12 are also listed as only being 5lbs different in weight, that cant be right either.
when the engines were updated (2008 for the 9)decent gains were seen in the xb9 but not as much in the 12.
I am willing to bet that the late 9 may truly have 92 at the crank but in the uk they are rated at 84 and that may be more accurate.
the 9 and 12 are also listed as only being 5lbs different in weight, that cant be right either.
airbrushgary
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There usually is a 7%-9% decrease in HP at the back tire compared to at the crank.
but why the difference of 2 HP with the XB12, and 13 with the 9? seems a bit off of those percentages.
9% loss of 92HP would only be a little over 8HP
9% loss of 103HP is about 9.3 HP, these numbers do not reflect an accurate difference between the two measurments.
The reason there is a difference between the flywheel and rear wheel is because of drivetrain loss. The 9 and 12 have the exact same wheel weight and gearing, but different primary drive gears. Because of the shorter gearing, the 9's drivetrain has more resistance at higher rpms (which is where is makes up the power difference on the 12)
I would be interested to so a stock 12 with a 9 primary gear on the dyno.
I would be interested to so a stock 12 with a 9 primary gear on the dyno.
