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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> The Cafe >> Bigger bikes/engines, where does the power go? /cgi-bin/YaBB.pl?num=1342193144 Message started by spacepirates on 07/13/12 at 08:25:44 |
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Title: Bigger bikes/engines, where does the power go? Post by spacepirates on 07/13/12 at 08:25:44 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? |
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Title: Re: Bigger bikes/engines, where does the power go? Post by Cavi Mike on 07/13/12 at 08:51:41 There's something you have to remember about horsepower: Horsepower is not a measurement. Horsepower is a calculation based on RPM. On singles and v-twins that rev really low, they can't get horsepower figures like a similarly sized high-revving 4-cylinder. You know that old saying "You buy horsepower and you drive torque" Well this is why. Torque is the only figure you need to worry about and trust me, that 1100 did not have less torque than a Savage, you read something wrong. That bike will do 100mph like it's nothing. |
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Title: Re: Bigger bikes/engines, where does the power go? Post by 12Bravo on 07/13/12 at 09:22:43 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. |
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Title: Re: Bigger bikes/engines, where does the power go? Post by 360k+ on 07/13/12 at 09:26:45 Also the VStars are cruisers, not hot rods. The 1100 is rather mild compared to some sport bikes with less displacement, who can eat the VStar's lunch! Besides even the REALLY big VTwins have mild HP ratings because, by necessity, they are tuned low (their torque is pretty beefy tho). |
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Title: Re: Bigger bikes/engines, where does the power go? Post by Badass94Cad on 07/13/12 at 10:52:54 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. ;) |
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Title: Re: Bigger bikes/engines, where does the power go? Post by spacepirates on 07/13/12 at 11:52:52 I must have overlooked the torque specs. The savage has 45.5 NM, the vstar 1100 has 85 NM. The buy/ride HP/torque saying fits. Just kind of crazy to see that big of a difference. I can't help wondering how that affects riding it though. Could it still "jump" off the line like a savage? |
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Title: Re: Bigger bikes/engines, where does the power go? Post by Serowbot on 07/13/12 at 13:03:23 6467767472677E6576637264170 wrote:
Not without some extra revving,... weight makes a huge difference at launch... That extra power helps more at highway speeds... |
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Title: Re: Bigger bikes/engines, where does the power go? Post by Gyrobob on 07/13/12 at 15:36:13 Torque accelerates you to a given speed. HP determines what that speed is. A bike with huge torque at low rpm will accelerate effortlessly,.. but when the aerodynamic drag builds with the square of the speed, HP is what overcomes the drag and makes you go fast. This is why a Suzuki C90 will win a roll-on contest competing against a ZX-14, but the ZX-14 will go nearly twice as fast top-speed wise. |
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Title: Re: Bigger bikes/engines, where does the power go? Post by Johansson on 07/13/12 at 15:54:28 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. |
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Title: Re: Bigger bikes/engines, where does the power go? Post by Cavi Mike on 07/13/12 at 17:30:44 033D362B262B26440 wrote:
There are WAY more important factors involved there than HP vs. TQ and inline-4 vs. v-twin. For starters, gearing. The ZX-14 will do over 80mph in 1st gear. If the C90 was geared to make full use of its torque band instead of simply jumping to 30mph in one shot, it would NOT beat the ZX-14 out of the hole. Secondly, aerodynamics. The ZX-14 can go over 200mph because it has a very low coefficient of drag. The C90 with a ZX14 engine still isn't going anywhere. It's a brick wall. V-twins are not slow nor are they quick, it's the bike they are attached to and the gearing that puts them one way or another. Look at Aprilia and Ducati, their V-twin bikes are on par with similarly sized inline-4's. |
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Title: Re: Bigger bikes/engines, where does the power go? Post by Johansson on 07/13/12 at 17:54:38 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. |
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Title: Re: Bigger bikes/engines, where does the power go? Post by Cavi Mike on 07/13/12 at 18:17:17 In summation to that encyclopedia entry ^he^ just posted and as I said in my first reply - horsepower is not a measurement, it's a calculation. You know those huge semi's that can haul 40tons plus the weight of their own vehicle at over 80mph on the highway? Did you know they only have about 500hp? It's because they have over 1,000ft/lbs of torque, some close to 2,000. Horsepower is almost meaningless. It's a bragging right and nothing more. |
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Title: Re: Bigger bikes/engines, where does the power go? Post by rfw2003 on 07/13/12 at 18:29:47 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. |
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Title: Re: Bigger bikes/engines, where does the power go? Post by Serowbot on 07/13/12 at 18:31:47 46404B5640484916230 wrote:
A Ninja 250 has similar HP to a Savage... and it will go faster top speed... ... but the feeling of power is not there... and a Savage will launch faster... because it makes it's Hp at a lower rpm and over a wider rpm range... |
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Title: Re: Bigger bikes/engines, where does the power go? Post by justin_o_guy2 on 07/13/12 at 23:25:31 We've got some educated guys here,, I like that, |
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Title: Re: Bigger bikes/engines, where does the power go? Post by Johansson on 07/14/12 at 05:12:34 When I was a kid there was a motorcycle shop quite aways from me. My friends and I would go there occasionally to look at the bikes. This was the early 70's. One bike always stood out, one that I always liked the most. It was a 500cc single cyclinder cruiser. I don't remember if it was a yamaha or a suzuki. The dealer sold both brands. I always wanted one. 40 years later I bought a single cylinder 650 Savage, because I liked it. It does not run currently, stripped threads in the head that need repair. I bought the bike because I like it. Does it go fast? No. Does it accelerate fast? NO. Does it stop fast? No. Comfortable? No. All these negatives and the bike still appeals to me. The bike does'nt fit me, my friends say I look funny on it, even laugh a little, at me. I still drive it, like it and enjoy it. My Nephew has a Ninja 250r that I have not gotten a chance to drive. It has 26.4 hp at the rear wheel at 11,000 rpm. 15.58 sec at 81.98 mph in the quarter mile. maximum torque is 13.6 ftlbs at 9750 rpm. The Savage has 30 hp, or 31 hp at 5400 rpm. I don't know if that is measured at the rear wheel. So it should have more acceleration with the same mass as the Ninja. It would certainly have more torque, it runs with half the rpm. The Savage engine is 2.6 times larger that the Ninja's engine. Will the Savage out perform the Ninja? I doubt it, maybe the first few feet. It is not designed to launch, the riding position is not so good on the Savage. Aerodynamics are horrible on a cruiser. The Ninja designers have implemented some aerodynamic improvements on the Ninja. Better aerodynamics means that it takes less power to drive at all speeds except stopped. The Ninja probably presents a smaller frontal area, further decreasing the hp requirements. Horsepower is meaningless? It is not a measurement? It certainly is a calculation, and we certainly do measure it. We measure the force, the distance, and the time and that gives us power. Torque is also not meaningless. We measure it, calculate its value and use it to determine the required strength of the crankshaft, more torque, larger crankshaft, and then we recalculate the torque at each stage of the drive system to properly size the components of the entire drive assembly. Torque values are not used to calculate acceleration. Tractors have massive rear wheel torque numbers. That does not equate to acceleration. They have large torque numbers at the crankshaft. If I am going to the dragstrip I am not going to use a supercharged tractor motor and win any races. Funny cars have large torque, power, and rpm values. They spin that motor as fast as they can. The volume of the cylinders are maximized. Camshafts are designed to optimize the intake of energy at the highest rpm's possible. To further increase the energy intake of the engine they pressurize the the fuel air mixture to push even more energy into each cylinder every cycle.. and then use the higest compression that is possible. Say a little prayer before they launch I imagine. Can the performance of the Savage be increased? Yes. Not the best platform, but yea. Of all street bikes that I have driven, the Savage has the poorest overall performance. If you are looking for perfomance, you purchased the wrong bike. You buy a Savage because you like it. |
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Title: Re: Bigger bikes/engines, where does the power go? Post by WD on 07/14/12 at 05:58:45 I've owned 2 Kawasaki Vulcan 800s. The first was an 800A, the 21" front wheel model. The second was a Classic, the 16" front wheel model. Identical engines, transmissions, final gearing from the factory. Speedometers topped out at 120 mph... Classic could not break 80mph, 800A twisted the gauge apart once, twisted the hub drive unit apart once. Setting aside the better looks, better handling and better ergonomics of the A model... the A was the better bike. Why? Lighter and more aerodynamic. The Classic put more energy out the tailpipe trying to push a cinder block through the air. Need another example? I have a 2.3l 5 speed Ranger, had a 2.3l 5spd Fox-body Mustang. Car was faster and more fuel efficient. Same engine, trans, gearing... All aerodynamics and weight. Almost bought a 650 V-star until I looked closer at it. Was never a fan of the old 535/700 Viragoes, no way I was paying that kind of money for a tart in a prom gown... When the fancy wrappings come off, you end up with the same thing. |
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Title: Re: Bigger bikes/engines, where does the power go? Post by Charon on 07/14/12 at 10:46:16 The 250 Ninja and the S40 are an interesting comparison - and I happen to have both. Both have about the same horsepower, around 25 or so. Their weights are similar, about 395 for the S40 and about 350 for the Ninja. The S40, according to published reports, is faster 0-60 mph. But the Ninja has a higher top end, usually reported at 95-100 mph against the S40 in the 85 mph range. As a rough rule, naturally aspirated engines will produce about one ft-lb of torque for each cubic inch of displacement. The Ninja displaces 15 inches, and produces around 13 ft-lbs. The S40 displaces 40 inches and produces around 30 to 35 ft-lbs, so both are in the range where they would be expected to be. At highway speed (say 60 mph) the Ninja turns about 7500 rpm; the S40 about 4000. The difference in torque is compensated for by the difference in gearing, so the torque at the rear wheel (and thus the ground thrust) is about equal. As it happens, the fuel consumption in mpg is similar, implying production of about equal power. In actual riding, there are lots of differences aside from the riding position and suspension. From a stop the S40 has to be treated gingerly on gravel roads lest it spin the wheel. In town the Ninja can take right-angle street turns in high gear, while the S40 lurches unless downshifted to perhaps third. Once at highway speed the Ninja's acceleration feels considerably more effortless than the S40, in any appropriate gear. Those are my observations, based on my experience with my own bikes. Your experiences may differ. |
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