|
SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> 650 single VS 650 twin.... /cgi-bin/YaBB.pl?num=1212039158 Message started by musicdorian on 05/28/08 at 22:32:37 |
|
Title: 650 single VS 650 twin.... Post by musicdorian on 05/28/08 at 22:32:37 Can anyone shed some light on what the differences (in power, torque, power to weight ratio, etc.) of a 650 thumper versus a 650 twin? I have a friend who has told me that the 650 thumper acts more like a 500 cc single than a true competitor for bikes (twins) in the the 650 cc to 750 cc range. |
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/29/08 at 01:53:03 First, there are advantages of smaller cylinders and shorter crank throws in terms of rotating mass - you can make a small light piston on a short stroke rev more easily than a big heavy piston on a long stroke. Then there's the size of the combustion chamber itself - in a big chamber, it takes longer for the wave front of combustion to spread from the spark plug and ignite the whole mixture, and the inlet charge has further to travel and more to fill, which has to take longer. Smaller chambers also have disadvantages - the ratio of volume to wall surface and inlet tract diameter is smaller, so wall friction (both in terms of piston/cylinder drag and gas drag through the ports) has a proportionately greater effect on a small cylinder than on a large one. For ultimate power, you want revs above all else so smaller is generally better. For two engines of similar capacity aiming for driveable mid-range torque at low-ish revs, the optimum is debateable but you're certainly getting into lower efficiency when the cylinder size exceeds 500cc. On performance bikes, wanting power over 10,000rpm, specific outputs seem to be highest on high-revving motors with cylinders about 150-175cc. For cars, aiming for more torque, and usable ranges up to 6000rpm, specific outputs seem to be best around 400-500cc cylinders. It's not really fair to compare the Savage’s output with other bikes of similar capacity because it was marketed for a restricted horsepower market in Europe where some categories of new/learner riders are limited to a 32hp bike, so the Savage was built down to that power. The carb, cam, exhaust, exhaust port and valves sizes are all restrictive Without those built-in restrictions, a Savage should comfortably make 45-50hp. A 650 twin in the same state of tune would make more power and not much less torque. 1973 Triumph Bonneville 650 vertical twin 49hp at 7200rpm 1975 Yamaha XS650 vertical twin 51hp at 7500rpm (37ftlb at 6000rpm) 1996 BMW F650 flat twin 50hp at 6800rpm (44ftlb at 5500rpm) 1999 Suzuki SV650 V twin 69bhp, 45ft lb And just to throw a cat among the pigeons: 1996 Suzuki Savage single 30hp at 5400rpm, (33 ftlb at 3400rpm) 1996 Virago 535 V-twin 44hp at 7500rpm (35ftlb at 6000rpm) |
|
Title: Re: 650 single VS 650 twin.... Post by Oldfeller on 05/29/08 at 03:18:37 http://www.hunt101.com/data/500/medium/Exhaust_Small_.JPG Thowing cats, huh. Amazing similarities in performance between those last two cats you tossed in. They have the same very low seat height though and weigh within 50 pounds of each other, so they both meet a crip old man's definition of "something that I can still get a leg over and light enough I can pick up if it falls over in the Hardees parking lot". One is small light quick and agile around town. The other is larger physically, can handle interstate road seams and rain grooves much better and wears a windshield. Both could get you a ticket anywhere in the USA. Sending out thoughtwaves for a new stablemate for the cats, a lightly wrecked SV650, just pondering what it would weigh if you pulled off all the torn up plastic and dull black painted just the necessary pieces of hardware. And lowered it, that seat is way too high up in the air. People would look and wonder what sort of Ducati it was, especially if somebody got them a Duc sticker and slapped it on the air cleaner. Or maybe it would be a Buell Snarl instead ..... Or an Aprilla Gnasher (bobbed and stripped wrecks can be anything you want them to be) |
|
Title: Re: 650 single VS 650 twin.... Post by PerrydaSavage on 05/29/08 at 03:41:27 Those 535 Virago's are really cool Bikes ... wish Yamahog would bring back a modern version of it (and don't say the 650 V-Star ... like the Bike, but it's too heavy)! |
|
Title: Re: 650 single VS 650 twin.... Post by Paladin. on 05/29/08 at 03:56:26 For a given displacement, the single puts out more torque than a multi. This is why the vast majority of dirt bikes are singles -- torque rules the dirt. Torque also rules when accelerating off the line. A single is quicker than an equal twin. For a given displacement, the multi can spin faster than the single, producing more power strokes per second, and thus more power. Power is what overcomes rolling and wind resistence and allow you to travel at higher speeds. A twin is faster than an equal single. OUR little single is, as others note, very mild for it's size. |
|
Title: Re: 650 single VS 650 twin.... Post by skrapiron on 05/29/08 at 05:07:15 3820263C36313A273C343B550 wrote:
For the love of god, don't let people put thoughts like that in your head. Instead of just blindly believing their clap-trap, go out and find out for your self. A quick demo ride of both bikes would definitavely answer the question, because it would be you doing the answering. If you ask here, we're likely to tell you that the Savage walks on water, gets 1,000,000 miles to the gallon, can do 1,000,000,000 miles per hour and all the talk of uncomfortable seats is hog wash. But then again, we're kind of slanted... Let me put it this way. Last weekend, I rode 700 miles over 3 days. Yes, I have better shocks on the rear and a better seat than stock, but at no time was my bike 'underpowered' or unable to keep up with traffic. Quite the opposite. Mrs. Skrapiron and I joined a 21 bike group ride from Loudonville, Ohio to Mount Vernon, Ohio, where we met my parents for dinner. We rode mid pack and never once had any trouble keeping up with the Yamaha Raider that was leading the group. That same weeked, I got nailed for 78 in a 65. The Savage can be described alot of different ways. Underpowered isn't one of them...... |
|
Title: Re: 650 single VS 650 twin.... Post by PerrydaSavage on 05/29/08 at 05:50:41 I can honestly tell you that I never, ever felt that the LS650 was underpowered ... and being that hind-sight is truely 20/20, I've come to the conclusion that it was pretty much the ideal Bike for my Riding needs ... especially now that fuel prices have gone thru the roof and I've concluded that my current VS800/S50 is waaay more Bike than I need ... once I get the rear turn signal fixed and have 'er back to show room condition, I am contemplating selling it an looking for an urban commuter ... dunno what that'll be ... could be another LS, but also wouldn't mind a Kawi 250 Ninja ... also like Honda's new CBR125RR ... maybe an EN500?? |
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/29/08 at 09:18:47 4D7C717C7974731D0 wrote:
Right, this is about every single or twin 650cc bike I can find to compare. I ddn’t include the Suzuki SV 650 because this is quite sporty and high revving and no really the same category of bike as we should compare with. But, very clearly, the average torque of the twins is higher than that of the singles. Year Make Model Layout Style Hp at rpm ftlb at rpm 1996 Suzuki Savage 650 single Cruiser 30 5400 33 3400 1999 Kawasaki KLR650 single Dirt/Trail 43 7000 35 5000 2001 Sachs Roadser 650 single Naked/retro 50 6700 41 6200 2000 Aprilia Pegaso single Dirt/Trail 50 40 650 single average 43.3hp 37.3ftlb 1973 Triumph Bonneville 650 vertical twin Classic 49 7200 1975 Yamaha XS650 vertical twin Classic 51 7500 37 6000 1996 BMW F650 flat twin Tourer 50 6800 44 5500 1989 Honda XRV650 parallel twin Dirt/Trail 57 8000 44 6000 2001 Kawasaki W650 parallel twin Retro 50 7000 42 5600 2006 Yamaha Dragstar 650 v twin Cruiser 39 6500 37 5100 650 twin average 49.3hp 40.8ftlb 1999 Suzuki SV650 v twin Sports Tourer 69 9000 45 7400 If we exclude the Savage from the single averages (after all, it is deliberately restricted), the figures for singles rise to 48hp and 39ftlb average – close to the twins, but still below on torque as well as power.. If I were to add the following bikes’ details: Year Make Model Layout Style Hp at rpm ftlb at rpm 1988 Honda XR600 single Dirt/Trail 45 6500 38 5500 1992 Yamaha XT600 single Dirt/Trail 45 6500 36 5500 And factor them up by 8.3% to equate their 600cc outputs to those at 650cc, and add them to the 650 single average, the average figures remain 48hp/39ftlb for the singles – still below the twins. Maybe I’m missing something here, but I’m not quite seeing how singles give out more torque than multis. If we look at 4 cylinder motors, Year Make Model Layout Style Hp at rpm ftlb at rpm 1981 Honda CB650 Custom 4 cylinder Custom/Cruiser 63 9000 38 800 1977 Kawasaki Z650 4 cylinder Naked/sports 64 8500 42 7000 2005 Suzuki GSF650 4 cylinder Naked/sports 78 10000 44 7800 2007 Suzuki GSX650 4 cylinder Sports 86 46 2005 Triumph Daytona 650 5 cylinder Sports 114 12500 50 11500 650 four average 81hp 44ftlb No – I still don’t see it!! |
|
Title: Re: 650 single VS 650 twin.... Post by bill67 on 05/29/08 at 10:16:39 I'll take the one with the torque at the lowest rpm. |
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/29/08 at 16:43:17 676C69693332050 wrote:
That is indeed the result of torque - but it's torque factored by gearing, and if you produce that torque at higher rpm, you can use shorter gearing to produce harder acceleration. You could have 2 engines producing exactly the same torque, but one at 3000rpm and one at 6000rpm. The one at 6000rpm could run a gear ratio twice as advantageous, and give twice the acceleration - for the same torque. That's why, contrary to common misunderstanding, it's actually power, not torque figure, which is important to racers (whether circuit or straight line). Power and torque are actually just different ways of expressing the output of an engine – power is just torque multiplied by engine speed, so the higher up the rev range you produce your torque, the more power, and the more you can gear it to get force at the wheels. It isn’t either power or torque that creates acceleration, it’s tractive force at the road/tyre interface, and that is the product of torque and gearing – and the gearing is dependent on where the engine develops its torque, ie its power. |
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/29/08 at 16:52:06 2830362C26212A372C242B450 wrote:
|
|
Title: Re: 650 single VS 650 twin.... Post by bill67 on 05/29/08 at 16:58:40 I don't like high rpm motors |
|
Title: Re: 650 single VS 650 twin.... Post by joebothehobo on 05/29/08 at 17:23:30 I agree entirely with Skrap (believe it or not). Numbers are just numbers. I currently ride a '91 GS500E, a standard/sport 500cc parallel twin with the following specs: Horsepower: 47 hp @ 9200 rpm Torque: 29.5 ft·lbf @ 7500 rpm But really, who cares? Its just a different bike. I don't feel like it makes it off the line as fast (though it definitely needs a tune up) . It starts to bog below 2k rpm. It runs 4k rpm in 4th gear at 35mph. It redlines at 11k. It handles corners flawlessly and effortlessly at any speed. It has a top speed of near 115 mph. It really doesn't like to go much slower than 15 mph. What it boils down to is that aside from a very rough guideline of "higher numbers are usually 'faster'" you really need to just get out and ride the bikes. Every bike just FEELS different, and that is ultimately whats important. Yea sure, the savage isnt a competition race bike. But most of us don't want a competition race bike either, otherwise we would have bought a CBR or a GSXR instead. Just so long as you enjoy riding it and you have enough oomph to stay safe, numbers count for very little. |
|
Title: Re: 650 single VS 650 twin.... Post by barry68v10 on 05/29/08 at 18:07:38 54687E74516A6B1F0 wrote:
That is indeed the result of torque - but it's torque factored by gearing, and if you produce that torque at higher rpm, you can use shorter gearing to produce harder acceleration. You could have 2 engines producing exactly the same torque, but one at 3000rpm and one at 6000rpm. The one at 6000rpm could run a gear ratio twice as advantageous, and give twice the acceleration - for the same torque. That's why, contrary to common misunderstanding, it's actually power, not torque figure, which is important to racers (whether circuit or straight line). Power and torque are actually just different ways of expressing the output of an engine – power is just torque multiplied by engine speed, so the higher up the rev range you produce your torque, the more power, and the more you can gear it to get force at the wheels. It isn’t either power or torque that creates acceleration, it’s tractive force at the road/tyre interface, and that is the product of torque and gearing – and the gearing is dependent on where the engine develops its torque, ie its power. [/quote] Hmmm, for a racer who isn't concerned about clutch replacement, gas mileage or drivability, I'd agree whole-heartedly, but..... Since I don't fit that category, torque at a given RPM is significant. You clutch locks up only when the engine and tranny are at the same speed, therefore...to take advantage of torque at a higher RPM you must have increased "slip" to take advantage of it either by tearing your clutch to shreds, or by use of a torque converter, since regardless of your gear ratio, the tranny is at 0 rpms and the engine is > 0 (if it's running.) Either method is INEFFICIENT and UNHEALTHY for mechanical parts. Again, no problem for racers. There's a cost to everything, multiple cylinders increases complexity, weight, and size for a given displacement. MPG will also drop. The gear ratio concept applies to racing, but not so much real life... The Savage runs 4000 rpms at 60 mph stock. What bike out there runs 16000 rpms at 60 mph in high gear?!? Whatever gearing you choose, the engine that produces torque at the lowest RPMs will take advantage of it sooner and accelerate quicker (but have a lower top speed.) |
|
Title: Re: 650 single VS 650 twin.... Post by bill67 on 05/29/08 at 18:29:33 Now that I've pasted 2nd grade am going on to 3rd. |
|
Title: Re: 650 single VS 650 twin.... Post by Paladin. on 05/29/08 at 19:31:58 291503092C1716620 wrote:
No – I still don’t see it!![/quote] That is because you are NOT looking at average torque. You are looking at the average PEAK torque. If you want average torque you need to look at the torque curve from idle up. http://www.bigcee.com/faq/KLR650_stock_dyno.jpg A stock KLR650, 33-35 ft-lbs of torque from roughly 2500 to 6000 rpm. Couldn't find any charts for a comparable twin. |
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/30/08 at 01:58:47 616271717A353B753233030 wrote:
616271717A353B753233030 wrote:
616271717A353B753233030 wrote:
However, the fact remains that cars and bikes with higher-revving motors are geared to take advantage of producing torque higher. This applies to a lot of ‘sport’ models of cars – they get a more aggressive camshaft to raise the torque curve, and get geared down to take advantage of it. It even happened in the late 60s and seventies – I seem to recall that some of the Firebird Ram Air 4 and Trans Am models with higher lift cams produced exactly the same torque peak as the standard cam, but higher up the rev range – with the result that they could run a lower differential, and that made them go quicker. In the real world. On the highway. 616271717A353B753233030 wrote:
I don’t advocate using high revving engines for bikes like the Savage – it’s fine just the way it is – but rest assured you make any vehicle quicker if you raise the torque curve and gear it to suit. |
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/30/08 at 02:10:00 31000D0005080F610 wrote:
I've worked on some motors with a guy who develops advanced nitrous systems and we always talk about 'area under the curve' rather than peak figures. I have loads of dyno charts for V8s and 4-cylinder bikes, but nothing for 650 singles and twins. Time to do some sniffing around - this is getting interesting now! |
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/30/08 at 02:41:31 This seems to be a good comparison. http://i43.photobucket.com/albums/e367/5000SE/bmw_vs_xr_dyno_5_23_03.jpg http://photos.motorcycle-usa.com/bmw_vs_xr_dyno_5_23_03.JPG http://www.biketestusa.com/Article_Page.aspx?ArticleID=71&Page=4 The two bikes produce similar ‘amounts’ of torque, in terms of spread of delivery above 25ftlb, but the BMW twin produces its slightly higher peak about 2000rpm further up the rev range than the Honda single. The article seems an impartial comparison, but this quote is relevant: “the 324-lb. XR pulls harder at lower speeds than the 412-lb. BMW. The XR's lower torque peak gives a rider immediate access to its fairly shallow well of power, but the BMW walks away from the XR during impromptu drag races, despite the Honda's better power-to-weight ratio”. |
|
Title: Re: 650 single VS 650 twin.... Post by klx650sm2002 on 05/30/08 at 04:18:30 These two power curves are both dynojetted, KLX valves are 37/32, Savage's are 33/28 and as std. I think KLX has a little more cam, I think Lancer can give you high forties out of a Savage though. http://i119.photobucket.com/albums/o147/klx650sm2002/horsepower3.jpg As the comparison above shows more valve area and more revs gives more power this is where a multi scores over a single. Clive W :) |
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/30/08 at 09:15:29 06373A37323F38560 wrote:
Can't argue with that, and I've ridden a KLR650 so I can confirm the torque is great for lifting the front wheel. But, as you'll see below, the spread of torque you get from the single is just lower down the rev range than from twins and fours - they have significantly wider spreads of more torque, they just start higher. The only real advantage of the thumper is that the torque is very low and allows you to pootle round town in high gear without changing down (which is great in itself and makes them fun to chug round on) - but it certainly isn't going to make a single out-torque or out-accelerate a twin or multi. http://i43.photobucket.com/albums/e367/5000SE/600ccsportbiketorque.jpg |
|
Title: Re: 650 single VS 650 twin.... Post by furious70 on 05/30/08 at 09:36:27 Quote:
AMEN! Quote:
Double AMEN! Americans like 'the feel' of low rpm torque, and trade it for high performance all the time. Who doesn't like the feel, I have a diesel truck and love it to death, for its purpose. The savage may as well be a diesel, it's tuned to have grunt off the line, feel 'bigger' than it is, and then fall flat on its face like a diesel would. Suits the bike for sure, but the engine itself is not in any way designed for high performance (whether you can get more than factory hp out of it or not). Aside from an engine sounding buzzy to some, a high rpm motor (esp. with modern variable valve timing) and the correct gears and tranny (6spd please) make for a _very_ satisfying experience. You don't even need to always gear up to make it faster. There used to be a great article using LS1 cars as an example, equal cars cept one's tq curve was essentially 1000rpm higher than the other. That extra 1000rpm spent in each gear more than made up for the early onset of tq of the stock motor. At the bottom of each gear the stock car was stronger, but the modded car spent longer in each gear, taking advantage of the torque multiplication longer, and therefore easily beat the stock car to the end. In real world driving, you may find a gear change would be more satisfying around town, but it wasn't needed to be faster. |
|
Title: Re: 650 single VS 650 twin.... Post by verslagen1 on 05/30/08 at 10:14:16 477B6D674279780C0 wrote:
Technically I disagree with you. Power is not a function of rpm's and torque, otherwise HP and torque curves would be a function of each other and there would be no need to map each curve. Power is the ability to move X pounds a distance in an amount of time. Torque is the ability to twist a shaft. And traction is the ability to transmit power to the road. And stating that traction equates acceleration assumes power to be greater than traction. Acceleration equates to the lesser of the 2. ie. spinning wheels at start, yet slow times at the trap. |
|
Title: Re: 650 single VS 650 twin.... Post by Robertomoe on 05/30/08 at 11:34:00 Horsepower is actually calculated using torque and RPM's (Torque x Engine speed) / 5,252 = Horsepower Here's a weird, confusing chart that looks like its made for lawnmowers http://www.elec-toolbox.com/Formulas/Motor/hpconv.gif |
|
Title: Re: 650 single VS 650 twin.... Post by verslagen1 on 05/30/08 at 11:45:35 Hmmm, 1000 HP lawnmower.... you related to Tim Allen? |
|
Title: Re: 650 single VS 650 twin.... Post by furious70 on 05/30/08 at 11:46:05 Quote:
For most bikes the latter 1/2 of this is true, the Savage, the Rebel, and some others, it's not. Quote:
TQ at a higher rpm will make more horsepower, it's a mathematcal fact. Quote:
|
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/30/08 at 12:48:52 687B6C6D727F797B702F1E0 wrote:
You only need to have a read out of the torque curve for an engine, and you can plot power, or vice versa – you’re quite right that you actually don’t need to map each curve, when you’ve seen enough dyno printouts you can see both in your head with just one on the sheet! Torque is indeed ‘twist’ on a shaft, force times distance hence lbs ft. Power is a bit more of a leap of faith because it’s harder to visualise, but in automotive terms: Power = tractive force x velocity (That’s why you need 8 times the power to go twice as fast against wind resistance – power is tractive force times speed, and wind resistance (the tractive force required) is proportional to the square of speed, so power required is cube of speed increase – a 100hp car which can hit 100mph would need 800hp to hit 200mph). Power is also voltage times current, and energy is the integral of power just to complicate matters! I wrote an Excel spreadsheet a few years ago into which you can enter your power (or torque) curve, gearing details and vehicle weight, and it will work out your tractive force at the wheels and give you 0-60 and quarter times – it is very accurate too against real world tests and manufacturer’s figures. I’ll dig it out and post a link to it on here somehow (it’s quite a big file, something like 300 lines of iterative calculation for each point on the curves). I don’t see how there’s an assumption that power is greater than traction – though it often is. Tractive force transmitted through the wheels is limited by available traction (as you state), but that tractive force is measured in pounds of thrust, or Newtons, and it is that which decides your acceleration back to one of our old high school formulae: F=ma force = mass x acceleration. |
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/30/08 at 12:51:51 687B7C67617B7D393E0E0 wrote:
|
|
Title: Re: 650 single VS 650 twin.... Post by furious70 on 05/30/08 at 13:00:49 Quote:
Very interested in playing around with this! Quote:
The point I was trying to make was that you measure tq and you calculate horsepower. The reverse is not true. So while you can manipulate the formula to solve for TQ if you know HP and rpm, it's a moot point because you had to know the tq value to get HP in the first place. That manipulation of the formula is only useful for determining what tq an engine would need to produce at a given rpm for a theorical HP goal in mind or something. |
|
Title: Re: 650 single VS 650 twin.... Post by skrapiron on 05/30/08 at 13:05:42 This is entertaining.... Numbers flying everywhere! My head hurts trying to process all the info..... All I know is my Savage can comfortably cruise all day long at interstate speeds, delivers close to 60mpg AND can carry 2 adult riders (comfortably what a suprise that was) for a 40 minute ride down the highway during a group ride. It does everything the other bikes do. The difference is, mine is paid for......Thats all that matters to me! |
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/30/08 at 13:12:16 5C4F4853554F490D0A3A0 wrote:
|
|
Title: Re: 650 single VS 650 twin.... Post by furious70 on 05/30/08 at 13:19:46 sorry for the fuzzy language in my first post. I do prefer to be precise about this stuff, as fuzzy language allows concepts to go on misunderstood, and that doesn't help anybody. Sorry if we hijacked a bit, but this technical conversation is key to understanding why a Savage might feel powerful to some of you yet anyone with a Ninja 250 would blow your sidecovers off. And more power to you if you can 2 up and be comfortable. I can't ride my wife's bike for 20min without being ready to get off it, because of the ergonomics and the engine. |
|
Title: Re: 650 single VS 650 twin.... Post by KwakNut on 05/30/08 at 13:23:37 4251564D4B51571314240 wrote:
|
|
Title: Re: 650 single VS 650 twin.... Post by rigidchop on 05/30/08 at 20:30:37 i think i'll just ride mine, and leave the techy arguing to all of you. |
|
SuzukiSavage.com » Powered by YaBB 2.2! YaBB © 2000-2007. All Rights Reserved. |