I can't help but look around at other bikes every once in a while. I'm satisfied with what i've got, but I like staying current and my brother wants a bigger bike.

He sent me a link to a 2009 yamaha vstar 1100 custom, which looks ok, i guess. But what killed it for me was that for the extra 250 or so pounds of engine and frame, and almost double the displacement of the savage, it had less torque ( i think, i don't recall that number off hand) and 62hp. 62! doesn't seem like enough on a big cruiser like that.

My two oldies ('78 XS750 and a '79 GS850) have 75hp and 80hp respectively for their 500 and 550 curb weights. I still can't imagine how an 1100 only has 62hp. seems like a waste.

Am I missing something here? is 62hp enough to make a 600lb bike spritely and accelerate faster than a school bus?

I just traded my Suzuki Burgman in for a V Star 1100. The 1100 has plenty of power to get up and go. I can keep up with everyone else off the line with it just fine. I can't do that on the Savage. I ride 2up all that time on the V Star and it handles it well, even at 70 and get on it to pass.

For comparison sake, my buddy has a VStar 650 (I forget what year now).  When he first bought it, I looked the specs up online.  I assumed being a V-twin with the same displacement as the Savage, he might have a leg up.  All said, the HP and TQ ratings were almost dead-on with the Savage 650, though his bike is heavier.  

spacepirates wrote on 07/13/12 at 11:52:52:

Not without some extra revving,...  weight makes a huge difference at launch...
That extra power helps more at highway speeds...

Horsepower is a measurement based on the work done in a unit of time, usually seconds. It has units of (force x distance)/(time). Torque is a measurement of force at one unit of distance from a central point of rotation, ie ftlbs (footpounds), or Nm (newtonmeters). Pounds and Newtons are units of force.

I believe the question is will the Savage out accelerate the 1100 vstar.
And, why does it only have 62 HP.

I have an 82 Shovelhead, FXR,,About 8 to 1 compression, listed at 55 HP, 80 cubic inch or about 1300 cc's, it will dust my Savage.
My 82 Yamaha Virago at 70 hp and 920 cc's will dust my Harley
I just sold my 748 Ducati, at 100 hp it would dust my 79 honda 750K twin cam that was modified, carbs, exhaust and cam, stock it was listed at 70 hp, the 750 K never could not outperform My Stock Virago in handling,, probably can out accelerate it.

Now the sad thing is, I sold the Ducati and bought a 1100 Honda Shadow Spirit thinking it would have a decent amount of power. Well, I  think it has about 50 HP, and not real good mileage, low 40's,,The old shovelhead out handles, accelerates more, and gets mileage in the very high 40's.  

So, where is the power in these large displacement V twin engines?
The motorcycle makers, do to the low HP figures on these current vtwins, like to quote torque numbers to hide the low HP of these engines. I can convert torque to HP if I know the rpm that this torque figure was measured at. I cannot determine the peak Horsepower from the torque value. I can get a very close estimate of the peak Horsepower from the 1/4 mile elapsed time or the 0 to 60 times, just need to know the mass of the bike and rider, frontal area, rolling resistance, air density, ,, ,,,,

As a side note,The VStar has the same motor, with newer starting system, as my old 82 model 920 Virago,,with 8 fewer HP.

The VStar, if it performs anything at all like my Virago, will out accelerate the Savage, from a stop, up a hill, at any roll on speed, down a hill, around a curve, with luggage and a passenger, compared to a stock Savage with a light weight driver, no luggage and with no passenger.

The savage has 45.5 NM (33 ftlbs), the vstar 1100 has 85 NM (63 ftlbs), of torque, well, ,, , kinda hard to use to figure acceleration.

What is force? It is a the push, measured in the above in Newtons, which I converted to pounds, and it has the dimensions of ma, or mass times acceleration. What it means is that at 1 foot away from the crankshaft of the motor, the savage will push with 33 lbs of force and the vstar will push with 63 lbs of force. I have to know the angular velocity, rpm, that this figure was taken at to use it in any calculation to determine the acceleration value of the vehicle. I don't have it so I cannot use it.
I need to convert that torque value to power, which is forcexdistance/time to calculate acceleration. Secondly, that HP number is not the peak HP number, it would be the HP value at peak torque.

Power
This is how it is calculated, classical physics,
Take a load of bricks and put them into a box. Put the box on a surface. Hook a scale to the box, and pull. The scale will read a number, like say 35 lbs. It takes 35 lbs of force to pull this box. The box may have 500 lbs of bricks in it, doesn't matter, the pulling force is 35 lbs.
I pull the box 100 feet. Forcexdistance or energy, is 35lbs x 100ft is 3500 ftlbs of energy. This energy could be measure in calories, Calories, Kcalories, Joules, WattHours, British Thermal Units,, but I like working with ftlbs

I pulled this box 100 feet in 35 seconds,

The power is 3500/35, or 100ftlbs/sec.
1 HP is equal to 550 ftlbs/sec
100/550 is equal to .18 hp,,

I pull this box 100 feet in .35 seconds
3500/.35 is equal to 10,000 ftlbs/second
10,000/550 is equal to 18 hp.

746watts is equal to 1 hp, We used 13,428 watts, POWER, to move this box 100 feet. About the power used by 223 60 watt light bulbs.

How much energy did we use to move this box? Say we used a 100 percent efficient electric motor.

In the first example, and in the second example, the energy used is the same, we just spread it out more , used more time, in the first example.
13,428 watts x .35 seconds/3600 seconds x 1 hour is equal to 1.3 watthours.
Electricity is billed in KilowattHours.
1.3 watthours/1000 Kilowatthours = .0013 KilowattHours,,14 cents a killowattHour

It cost me .0013 x14 cents = .02 pennies to move this box.

This is what power is. The amount of energy in a given amount of time.

Thermodynamics,
Power in an engine,
Volume, The size of the cylinders is the volume.
The cylinders suck in gas and air, a volume of energy,.

Energy/time is power

The time is the time that it takes for that cylinder to rotate twice, the cylinder charges every other cycle.
If the engine doubles in speed, The angular time halves
Example
The original speed is 900 rpm, or 15 cycles a second.
Lets just say our engine sucks in 1000 units of energy every other cycle. Our energy intake would be averaged at 500 units every cycle, at 15 cycles a second,,or 15 x500 units/1 second or the power would be
7500 units of power.

Double the speed of the motor, 1800 rpm. 30 cycles a second
30 cycles a second x 500units of energy/cycle/1 second,,
Now we are generating 15,000 units of power.

If you are still following me, a single cylinder cannot, generally speaking, spin as fast as a twin cylinder engine of the same volumetric size. a four cylinder engine can spin faster than a twin engine of the same volumetric size.

THE FASTER YOU CAN SPIN THE MOTOR, THE MORE ENERGY THE MOTOR WILL USE FOR A GIVEN AMOUNT OF TIME.

Compression ratio, the higher the compression ratio, more  of the hydrocarbons are transformed into compounds that release more heat, more energy can be extracted from each volume of fuel charge. Gasoline does not like high compression, it needs to be refined more, increasing its cost, so, it is not generally more efficient on a dollar basis, or cost per mile.

It is more efficient, on our available fuels, to use a large, high volumetric motor, spinning slowly, to generate the power needed. The problem is that the engine cost more, is heavy, and won't fit under the hood, aerodynamics,, tires etc. A slow spinning engine needs a larger flywheel, which affects acceleration, I could just go on and on and on

Back to Torque. Compare 2 motors, one is 250 cc that spins at 5000 rpm
The second is 500 cc that spins at 2500 rpm.
Both motors make 25 HP
The 500 cc motor in this case makes twice the torque as the 250cc motor.
Both will accelerate the same vehicle at exactly the same rate.

I was a Major in Physics, I am trying to simplyfy some rather complex problems of thermodynamics.

Torque means absolutely nothing to me. I do not shop torque. I want to know how much energy I use in a given amount of time and that is HorsePower.

If I had a calculator here, Or, if any one wants to know the acceleration rate of the Savage vs the VStar, I'll get my calculator and calculate it for you.

Actually most big rigs are avg around 430hp stock and 1050 ft/lbs to 1150 ft/lbs of torque depending on the size of the engine.  They can easily be turned up with just a programmer though to 500hp and 1350 ft/lbs or higher depending on the engine as well and what turbo was outfitted on it stock. Most of them that you see around the 2000 ft/lbs torque mark have lots of mods or were the older mechanical diesels or some of the Cats.

R.F.

We've got some educated guys here,, I like that,