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evilrider said:

Not sure what they are for the 1250 big bore kit, but the stock xb12 engine is supposed to be ~103 hpand ~84 ft-lbs at the crank. Redline is 6,500 rpm's. The stock warrior engine redlines at 5,000 rpm's with ~80 hp and ~100 ft-lbs at the wheel.

If you want to compare the big bore kits, I imagine the 1250 kit is something around 95-100 ft-lbs, while the warrior 110" kit is more like 130 ft-lbs.

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skybejef said:

+1

You are riding this bikein the real world, on the street, with stoplights, and not at Bonneville on the salt flats.Just get the most torque that you can and don't worry about horsepower. The Warrior engine isn't a high rpm engine so unless you boost it, you aren't going to get Superbike type HP numbers from it. People obsess over HP, buttorqueis what you feel when you crack the throttles open and the bike lunges forward.

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You can get real close if not at 1HP per CU but you have to go with at least a compression ratio of 10.25:1 and aftermarket cams, and full system pipe. Best news is the engine is soooooo simple to work on you can do ityourself fi you have some tools and a manual.

Torque may be king but I have never had my Warrior 60' times beat my Busa 60' times at the drag strip and my Warrior had 117 ft-lbs of fun torque where the Busa was just under 96 ft-lbs.

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Locate and compare the Buell piston data to this and you'll see changing the jug diameter versus stroke gives you HP one way, TQ the other.

This is all Warrior data at different cubes:

About Increasing Cubic Inches: (97mm= ~3-13/16"+)(113mm= ~4-7/16"+) Long Stoke = Torque

97 mm bore 113mm stroke = 1670cc = 102ci (stock is 8.36:1 compression)(87 octane fuel)

100mm bore 113mm stroke = 1775cc = 108ci (typically 10.5:1 compression)(91 octane fuel)

101mm bore 113mm stroke = 1802cc = 110ci (typically 10.5:1 compression)(91 octane fuel)

106mm bore 113mm stroke = 2000cc = 122ci (typically 10.5:1 compression)(91 octane fuel)

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Pretty freakin' awesome little Datsun.Rif said:Here's a little lesson on torque.

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A lot of folks say torque is all that matters and that HP is some mathematical equation that doesn’t mean much. The truth is, HP tells you a lot more than torque. That’s why HP is the most popular measurement when used with engines.

How can this be so? Torque at the crank of an engine is not what we ride on, whether in a car or on a bike. The power is transferred through a set of transmission gears. That’s what makes knowing HP so important.

Since engines produce power curves that have varying shapes it is difficult to explain using different bikes paired up against each other. Therefore in my representation we will use two engines, each making identical torque, 100 ft. lbs. Both engines will make the same torque from idle to redline. One will be a V-twin that revs to 5000 rpm, the other an in-line four revving to 10000 rpm. The 5000 rpm motor will make a max of 95.2 hp. The 10000 rpm motor will make a max of 190.4 hp.

Both bikes (using torque x rpm / 5252) make the same torque and hp from idle to 5000 rpm (one continues to rev to 10,000). If both machines used the same crank to clutch (say 2:1) reduction we would see a 100% increase in torque entering the trany. Also the rpm of the trany input shaft would be cut in half. So now we see a torque of 200 ft. lb. for each bike with a max input shaft rpm of 2500 for the V-twin and 5000 for the four. If first gear has identical reduction in each bike as well (let’s say another 2:1) the output shaft rpm would be cut in half and the torque doubled again. Now you have an output of 400 ft.-lbs with 1250 rpm for the twin and 2500 for the in-line four. Let’s double the gear reduction at the rear wheel another 2:1 for both bikes. You now have rear wheel torque of 800 ft-lb. for each bike and a max rpm of 625 for the twin and 1250 for the in-line four. Assuming a 2 ft. tire diameter tire each bike will turn 8.92 mph per 1000 rpm of engine speed.

If they both weigh the same and they both have the same aero dynamics the higher revving motorcycle will win the drag race. Why? Both bikes are putting the same torque to the rear wheel, right? BUT, the lower revving motor has to shift at exactly ½ the rpm of the 10,000 rpm motor. (Around 44 mph) Guess what? Second gear results in a torque reduction due to taller gearing. The end result is that the 5000 rpm bike lowers its torque to the rear wheel by same % as the gear increase and ends up delivering less torque while the 10000 rpm engine continues to accelerate at the same 1st gear rate. Before the end of second gear, the race is over for the 5000 rpm bike.

What if we give the V-twin 5000 rpm bike the ability to pull to 89 mph before shifting into second gear? Well, it would have to start with gearing 100% taller at some point in the drive line. If the gearing from output shaft to the rear wheel was 1:1 instead of two to one, the bike could pull to 89 mph just like the inline four. Unfortunately, that means that in first gear the torque to the rear wheel is only 400 ft-lbs. That’s a huge disadvantage for the twin. Even if the 5000 rpm motor were hot rodded into making 150 ft-lbs. of torque at the crank, it would only be making 600 ft.-lbs. at the tire.

Of course we could run the bike with the old gearing scenario, but it would still need to shift to second gear at 44 mph. The torque advantage to the rear wheel at launch would be given up as soon as the bike shifted to second gear.

This may be tough to envision, but it’s not unrealistic. Consider that a bike like a 2008 Hayabusa weighs 610 lbs. with a half tank of fuel and produces only about 105 ft.-lb. of torque. It doesn’t out class a Warrior in the torque dept. by any means, but it can reach a speed of 113 mph in just the EIGHTH mile. A warrior works hard to reach 110 in the quarter. Twice that distance. The ‘08 Busa will hit 142 in the quarter with a sally like me on board.

What about business and engineering? If you offer me a situation where I need at least 225 ft.-lb of torque to turn a shaft at a say 1000 rpm and you present me with the option of two motors, I would pick the higher hp motor (assuming budgetary and space constraints are met).

Why? I know I’ll have enough torque no matter what (This is assuming all other things remain equal). Let’s use in our example one motor making 50 hp and the other making 40. If they make the same power at the same rpm (let’s say 5000) the 50 horse motor is producing 52.52 ft.-lbs. of torque, while the 40 hp motor is making 42 ft-lb. Adding a gear box to reduce the rpm to reach the 1000 rpm target, the 50 horse motor is delivering 260 ft.-lbs., while the 40 horse unit is delivering 210 ft.-lbs.

Of course you could show a motor that makes 40 ft.-lbs. at 5000 rpm and a motor that makes only 2 at 10000 and show me how the higher torque motor can “win a drag race”, but what you’ve just shown me is a 5000 rpm motor with 38 hp and a 10000 rpm motor with 3.8 hp. Guess which one I would have picked shown HP only?

The point here is that there is much more to understand than just torque numbers alone. Once you know the hp you begin to understand the relationship of torque and rpm. I know that a 100 hp motor will make more power than the 50 hp motor. If those values appear at the same rpm, then the torque is identical to hp number. If I need to make that power at a certain rpm then one already knows the higher horse motor can deliver more torque (again all things being equal) at any target rpm. You can try doing the math by making the lower hp number motor turn slower to deliver more torque, but it will always require a gear change great enough to reach it’s target rpm that the delivered torque will be lower than the higher hp motor.

When many more variables are involved, one needs much more info to determine what engine or electric motor design is best for a given situation, but the same rules apply.

The beauty of a high torque V-Twin is that in most riding situations one can run the engine at lower rpm and still be in the fat part of the torque curve, owing mostly to the long stroke and subsequently smaller diameter ports that reach a high velocity at lower rpm. The resultant higher cylinder filling capability (usually) at that part of the rpm range yields a very flexible engine through the rpm range in which many V-Twins operate.

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aznwrr said:Mr Shelby "HP sell cars, TQ wins races!"

Boost it and it solves all your problems.

I'll have to agree with that. A friend of mine had a Toyota Supra. That was a 3.0 liter engine. It was making 750 rwhp and 700 rwtq with about 42 psi of boost out of a single turbo. That thing was a rocket ship.

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and here I always thought it was traction that won races

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Arkansas Warrior said:

Or to put it another way-- Horsepower determines how hard you hit the wall; Torque determines how far you take the wall with you.

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