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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Anyone with a FSM? Conrod length? /cgi-bin/YaBB.pl?num=1451789877 Message started by Kris01 on 01/02/16 at 18:57:57 |
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Title: Anyone with a FSM? Conrod length? Post by Kris01 on 01/02/16 at 18:57:57 I'm just curious if anyone knows the connecting rod length. |
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Title: Re: Anyone with a FSM? Conrod length? Post by Dave on 01/03/16 at 16:10:29 What is a FSM? :-? |
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Title: Re: Anyone with a FSM? Conrod length? Post by verslagen1 on 01/03/16 at 16:23:56 43787562737F646279717C63100 wrote:
factory service manual |
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Title: Re: Anyone with a FSM? Conrod length? Post by Kris01 on 01/03/16 at 21:16:27 I've looked all over and can't find anything. :( |
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Title: Re: Anyone with a FSM? Conrod length? Post by cheapnewb24 on 01/03/16 at 21:37:14 Someone needs to post on a huge posterboard... [b Hmmm.... like that $20 t-shirt advertisement I'm looking at.... yeah, you know, those shirts that no one's getting anyway ;D ;D... Just take that silly thing down and replace it with something like this: [/b] "Please!, Someone!, Anyone! Tear down an LS650 engine, carefully measure the connecting rod dimensions, and post it here at their earliest convenience! The Savage community needs your measurements!" Perfect! ;D Oh! Mysterious John is going to hate me! ;D ;D ;D |
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Title: Re: Anyone with a FSM? Conrod length? Post by LANCER on 01/05/16 at 07:33:31 So are you looking for center-to-center or tip-to-tip or big end to little end or little end to big end or ... ... :D Don't ask me for actual numbers, that's just WAAAY to hard. 8-) |
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Title: Re: Anyone with a FSM? Conrod length? Post by justin_o_guy2 on 01/05/16 at 12:13:09 Im curious to know what caused the curiosity. |
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Title: Re: Anyone with a FSM? Conrod length? Post by Kris01 on 01/05/16 at 17:29:41 Center to center preferably. I recent thread got me thinking about the LS650/S40's redline RPM. I say 6500 is too high. Suzuki says differently. :D To know for sure I'll need to know the conrod length to measure piston speed accurately. |
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Title: Re: Anyone with a FSM? Conrod length? Post by cheapnewb24 on 01/05/16 at 17:47:15 The idea is that a longer rod will be easier on the engine than a short con rod as far as piston acceleration forces are concerned. We're trying to figure out how the Savage has such a red line of 6500 and a stroke of 3.7 inches. That's some tough piston forces, and this engine does 4000 rpm all day long on the highway. Compared to car engines, this is very stressful. We are trying to see how rod/stroke ratio plays into all this. |
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Title: Re: Anyone with a FSM? Conrod length? Post by cheapnewb24 on 01/05/16 at 17:59:34 6D606F6264733336010 wrote:
Length is our focus, but of course, width, weight, bearing/wrist pin size, con rod bolt size/torque, alloy composition/treatment....etc. might be helpful. Anything and everything that could possibly explain how this thing is strong enough not to spontaneously blow up would be useful. :D Lancer's got a job on his hands now. ;D Hey Lancer, don't forget to call all those retired Suzuki engineers on the phone at 12:00 in the morning to ask how they designed the Savage engine to magically not blow up. ;D After all, we know you have their number, and they love taking late night calls ;D. Don't forget to ask about which alloy they used, how it was forged, and how it was heat-treated. ;D And don't forget bearing tolerances.... Well, if Lancer isn't interested, JOG, you can do it, we all know you want to! ;D |
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Title: Re: Anyone with a FSM? Conrod length? Post by justin_o_guy2 on 01/05/16 at 18:59:39 I don't see rod length as important. Crank throw determines piston speed. A one inch rod on a crank with a 1/2 " throw is gonna have the same piston speed if you put a foot long rod on it. YOu could share the information about the rpod length affecting piston/engine . |
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Title: Re: Anyone with a FSM? Conrod length? Post by cheapnewb24 on 01/05/16 at 19:18:38 Look up rod/stroke ratio. Stroke is stroke. The piston still has to travel so far during a revolution within a certain window of time. However, the rod length influences exactly how the piston accelerates and decelerates. The longer the rod, the closer the piston travel acts like scotch yoke mechanism, which produces a sine wave. The shorter the rod, the longer it stays at BDC, but around TDC, the piston is yanked harder by the rod, if that helps you to understand it. Try imagining it in your head. :) A longer rod gives smoother action, thereby reducing stress. If you don't know any of this, you might assume that the piston stays at BDC and TDC the same (like a sine wave) and that the con rod means nothing. This is simply not true. By the way, the scotch yoke mechanism was experimented with years ago, (and still is) for an alternative to the conventional crank and slider mechanism used in most engines. One benefit is that the piston stays at TDC a little longer, which may increase thermodynamic efficiency by allowing more time for the fuel to burn completely before the piston travels downward. Look up the SyTech engine and the Bourke engine. I welcome the actual engineers here to correct me if any of my points are inaccurate. ;) |
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Title: Re: Anyone with a FSM? Conrod length? Post by cheapnewb24 on 01/05/16 at 19:36:08 LOOK! LOOK! LOOK! Here it is! [smiley=vrolijk_26.gif] [smiley=2vrolijk_08.gif] http://www.motoiq.com/MagazineArticles/ID/1996/Does-Length-Matter.aspx |
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Title: Re: Anyone with a FSM? Conrod length? Post by justin_o_guy2 on 01/05/16 at 19:54:55 I read it. I looked at the graphs. Aaaand, to be honest, I don't unnerstand... |
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Title: Re: Anyone with a FSM? Conrod length? Post by cheapnewb24 on 01/05/16 at 21:11:52 Take an old junked-out briggs 5 hp flathead and spin the crank. Watch how the piston acts as it reaches TDC and BDC. I bet you might be able to watch the effect firsthand. I'm not exactly sure I've done this before with that in mind, but remembering seeing the piston move from years ago, I bet you might be able to see it. Imagine this: The crank is turning and the con rod is slanting. As it's slanting, it's yanking the piston downward faster than you would expect the crank journal alone to do. Also, when it's traveling upward, the rod snaps the piston upwards to TDC. It does this by leverage. It has to do with the angle of the con rod. If the con rod were straight all the time, only the crank journal would have an effect, but then you would have to create a slot, like a scotch yoke. But the angle of the con rod affects the leverage of the system. This leverage changes as the crank moves and the con rod angle changes. Now the angle is going to be steeper with a short con rod than with a long one. Imagine extremes here. If the con rod were ridiculously short, then it would be angled crazy steep at 90 degrees. An incredibly long one wouldn't have much angle at all. Say a 10 foot long rod with a 2 inch stroke wouldn't move all that much compared to a 2 inch rod (which might be too short to work anyway). Imagine our thumper with the piston halfway down the rod journal sideways. That con rod is going to be at an angle to reach from the wrist pin to the crank journal, now isn't it? ;) Now which is going to be angled steeper, the long or short rod? Distance traveled is the same as far as the rod journal is concerned. Now we're just talking about the distance from the wrist pin to the journal and the angle of that. Think of a circle cut into slices. If you have a big circle, the size of an arc (the outside bit of circumference) is going to be pretty big for a thin (small angle) slice. A small circle is going to need a really fat slice (wide angle). The steeper the angle, the harder the con rod yanks on the piston near TDC, making it stay near TDC for less time. The rod journal is kinda pulling things sideways, collapsing the conrod/crank journal/wrist pin complex, and yanking or snapping the piston downward. This leverage thing actually works backwards near BDC, making the piston stay close to BDC longer than otherwise. Again, if there are any mechanical engineers out there, you're welcome to help out here. I hope that helps |
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Title: Re: Anyone with a FSM? Conrod length? Post by LANCER on 01/06/16 at 05:42:44 Everything affects everything else. When you change one aspect it dictates changes elsewhere, whether crank throw or rod length. I don't remember what the maximum piston speed that is traditionally acceptable, my mind has lost it. But there is a limit, and everything has to be constructed around that. The newer materials may have extended it slightly, but if so I doubt it would be by much. I just found this; hope it is helpful. According to this guy the material science is critical in keeping a piston together as the forces increase. There are some interesting numbers here. ************* 2RobHughes (Automotive)23 Mar 04 22:17 I work for a company that races and sells high performance motorcycle engine parts...here's a post I put up on one of the enthusiast boards when people started talking about wanting to raise the redline of their bikes from 5K to 6K or more. FYI the bike is Yamaha's Warrior an air cooled V-twin that displaces 102ci stock and the connecting rods are scary long and skinny...lol From the postings: At 5000 rpm your piston goes from a complete stop to 66mph in 2 1/4 inches in just .003 seconds. Interesting Warrior Engine facts/figures: Engine RPM/ Piston Velocity mph/ G's exerted on rotating mass. 1000 / 13.25 / 40.49 2000 / 26.50 / 161.98 3000 / 39.76 / 364.47 4000 / 53.01 / 647.95 5000 / 66.26 / 1012.43 6000 / 79.52 / 1457.90 7000 / 92.77 / 1984.36 For Comparison at "redline": Chevy 350 Engine RPM/ Piston Velocity mph / G's exerted on rotating mass. 6000/ 62.20/ 1140.15 Formula 1 engine Engine RPM/ Piston Velocity mph/ G's exerted on rotating mass. 17,000/ 83.56/ 361.27 2004 R1 Engine Engine RPM/ Piston Velocity mph/ G's exerted on rotating mass. 12,500/ 78.58/ 250.12 2004 R6 Engine RPM/ Piston Velocity mph/ G's exerted on rotating mass. 15,500/ 79.98/ 315.69 2004 V-Rod Engine RPM/ Piston Velocity mph/ G's exerted on rotating mass. 9000/ 76.14/ 174.50 OK guys for those who are not bored by this...here's the math. I did my math in feet, just to keep from having to change the numbers up at the end, but trust me it's the same. Warrior Stroke=113mm or .370735 feet. Distance traveled by crank per revolution 1.16632 feet (remember that the circumfrence is "pie"* diameter) Revolutions per minute=5000. Distance crank travels per minute=5831.608202 feet Distance crank travels per hour=349896.4921 feet or 66.2682 miles per hour. So if the crank shaft is traveling at this rate the pistons reach this max velocity twice per revolution at 9 o'clock and 3 o'clock since they are traveling at the exact speed that the crankshaft is, remember at 12 and 6 o'clock the pistons are "stopped". To calculate the G-Force you have to take your revolutions per second (rps) which is 83.3333 (at 5K)and figure how long it takes for one revolution or .0120 seconds (1/83.3333). The piston goes from a dead stop at 12 o'clock to full speed (or 97.1934 ft/second) in 1/4 a revolution or in .0030 seconds. So the average acceleration in a second needs to be calculated or how many times per second does this event occur 1/.0030 = 333.333 times per second, now multiply this by the speed at full acceleration (97.1934*333.333) gives the figure of 32397.82 ft/second/second as the average acceleration. G-Force is 32ft/second/second. Divide 32397.82 by 32 to get the average G's exerted on the parts...or 1012.432 G's. Whew....if you hung with my math you deserve a gold star...lol A piston weighs in at around 400grams, so at full G's right when it is stopping it "weighs" an astonishing 892.79 lbs!!! The g's are exponentially related to the RPM and crankshaft length relationship. The Warrior crankshaft goes from 33mph at 2500rpms with 253G's to 66mph at 5000rpms and 1012G's. At 10,000 it would be 132mph with 4050G's. The F1 crankshafts are, I forget exactly, but like 1.65 inches. Do the math Gotta, no scare tactics here, pure physics. I was just joking about the connecting rods, but it is something to think about when you start wanting to get a few more revs out of your bike. This calculation has nothing to do with bore or weights in the calculations demonstrated. Rob Hughes Orient Express Powersports |
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Title: Re: Anyone with a FSM? Conrod length? Post by verslagen1 on 01/06/16 at 07:42:39 At 6500 rpm our piston goes from a complete stop to 71.56 mph in 3.7 inches in just .0023 seconds. Engine RPM/ Piston Velocity mph/ G's exerted on rotating mass. 1000 / 11.01 / 34.7 2000 / 22.02 / 138.9 3000 / 33.03 / 312.5 4000 / 44.04 / 555.6 5000 / 55.05 / 1250 6000 / 66.06 / 1467 Stroke=94 mm or .3084 feet. Distance traveled by crank per revolution .968864 feet Revolutions per minute=6500. Distance crank travels per minute=6297.6 feet Distance crank travels per hour=377,856.9 feet or 71.56 miles per hour. |
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Title: Re: Anyone with a FSM? Conrod length? Post by Kris01 on 01/06/16 at 18:06:58 One more thing to consider is ring flutter. With 0.0463"-0.0469" (per Suzuki) rings, 6900 is about the max RPM before the rings start deforming. I can bore you with the math if you like. I still don't believe with a 94 mm stroke that 6500 RPMs is safe. But I have no math to back that up. The con rod is probably close to 6.5". |
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Title: Re: Anyone with a FSM? Conrod length? Post by Dave on 01/07/16 at 02:55:21 I was able to do a measurement of a crank that I have....and it is somewhere around 165mm (6.4961"). |
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Title: Re: Anyone with a FSM? Conrod length? Post by norm92de on 01/07/16 at 07:37:24 Didn't Cycle or Cycle World publish piston speed with their road test figures? I seem to remember a piston speed of 2500 or 2550 being quoted as the max for reliability. I used to operate Pratt and Whitney R2800 engines with a 5.75" bore and a stroke of 6" The max RPM was 2700. We always observed a manifold pressure of at least the RPM selected because of piston ring flutter which could cause top ring land failure. Not a good thing!!! Our piston speed was 4200'/ min at max RPM. Sorry for straying off subject a little. |
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Title: Re: Anyone with a FSM? Conrod length? Post by Kris01 on 01/07/16 at 18:05:53 2700 rpm with a 6" stroke and you were seeing 4200 ft/min? I'm calculating 540 ft/min average. 2 * stroke * rpm/60 2 * 6 * 2700/60 = 540 ft/min |
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Title: Re: Anyone with a FSM? Conrod length? Post by Art Webb on 01/08/16 at 07:34:39 566F746E2D2C1D0 wrote:
This is where Art's eyes glaze over and he just nods and goes 'uh huh' ;D |
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Title: Re: Anyone with a FSM? Conrod length? Post by verslagen1 on 01/08/16 at 07:59:12 0D342F357677460 wrote:
Of course I'm guessin' what '/60' is for. |
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Title: Re: Anyone with a FSM? Conrod length? Post by Dave on 01/08/16 at 09:01:23 003922387B7A4B0 wrote:
The 4,200 ft.min is the distance the crank pin travels.....so I guess that is also the speed of the piston when the crank pin is 90 degrees to the piston travel. The distance the crank pin travels in one rotation would be Pi x D, which is 3.14 x 6 inches.....18.8496 inches....or 1.5708 feet. If the rotation is 2,700 rpm...then 2,700 x 1.5708 feet is 4,241 feet/min. It appears that what Kris01 was calculating was the average piston speed per second.....and not the maximum speed. The total distance that the piston travels in one minute (6" up and 6" down = 12" total) times 2,700 rpm = 32,400 inches...divided by 60 is 540 inches per second average.......or 2,700 feet/minute average. |
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Title: Re: Anyone with a FSM? Conrod length? Post by norm92de on 01/08/16 at 11:11:36 I always thought that my R2800 pistons were travelling at more than 6MPH? ;D My calculation is of course "quick and dirty" since it doesn't take into consideration the con-rod length/angularity part of the equation. Getting back to my question does anybody remember the motorcycle magazines posting max piston speeds regarding longevity? On my savage I rarely go over 5500 RPM. The 94MM stroke gets the piston and its acceleration up there. |
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Title: Re: Anyone with a FSM? Conrod length? Post by Kris01 on 01/08/16 at 17:45:37 7D6E686B797E7E1C0 wrote:
After the last few posts you're not the only one! ;D Thanks for the correction guys. It's good to have someone double check your math at times. ;) |
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