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Throatwarbler posted:The way I understand it, any inline 4 stroke engine with an even number of more than 4 cylinders is perfectly balanced, because the movement of each piston is perfectly offset by another piston. You need more than 4 because of the 4 strokes of the combustion cycle each piston can only fire once every 720* of crank rotation. 4 cylinders are still somewhat imbalanced, though. At any given point, 2 cylinders have valves open, so they're balanced, but of the other two one is just starting compression and the other is firing. So there's a strong downward force, which should be balanced by compression, except the compression doesn't become noticeable until the piston's about halfway up so you still feel the shock - it's most obvious in larger motors, which is why you generally don't see 4-pots over 2.3L on a regular basis, 3L being the upper limit from what I remember. With 6 cylinders and up, there is a cylinder under compression to balance the combustion impulse in addition to the piston which is just starting its upward travel, so they balance out better. 
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Feb 9, 2013 02:20
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Fucknag posted:4 cylinders are still somewhat imbalanced They are pretty terribly unbalanced (inline), requiring a counterbalancing mechanism to make them palatable enough for normal automotive use. That's why he say an even number of MORE THAN 4 cylinders. Meaning I6 or more.
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Feb 9, 2013 02:32
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Throatwarbler posted:Who knows how fast the 177 actually is? Has it ever been tested or driven in anger by anyone? I think they could probably wring more power out of the viper engine if they wanted to, but the Viper already has bigger tires than a Veyron, on a RWD car with a conventional manual transmission I think you're hitting limits other than the engine. I think the horsepower figure on the Aston is more bragging than actually useful, it is like $2 million dollar or whatever car. Yeah it doesn't seem like a really hard-edged "racing" road car, more of a medium-sozed Grand Tourer that had the engine worked on until they could make that claim.
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Feb 9, 2013 02:36
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Here's a good article about engine balance http://www.autozine.org/technical_school/engine/smooth1.htm
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Feb 9, 2013 02:42
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Throatwarbler posted:The way I understand it, any inline 4 stroke engine with an even number of more than 4 cylinders is perfectly balanced, because the movement of each piston is perfectly offset by another piston. You need more than 4 because of the 4 strokes of the combustion cycle each piston can only fire once every 720* of crank rotation. I thought all those gigantic diesels were (are?) two-stroke, which pretty much throws 4-stroke balancing out the window.
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Feb 9, 2013 02:53
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The one I linked last page was definitely two stroke.
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Feb 9, 2013 02:57
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Fucknag posted:4 cylinders are still somewhat imbalanced, though. At any given point, 2 cylinders have valves open, so they're balanced, but of the other two one is just starting compression and the other is firing. So there's a strong downward force, which should be balanced by compression, except the compression doesn't become noticeable until the piston's about halfway up so you still feel the shock - it's most obvious in larger motors, which is why you generally don't see 4-pots over 2.3L on a regular basis, 3L being the upper limit from what I remember. With 6 cylinders and up, there is a cylinder under compression to balance the combustion impulse in addition to the piston which is just starting its upward travel, so they balance out better. Yeah, I think I was getting confused with the idea of overlapping powerstrokes, so for a 4 stroke engine you need at least  MrChips posted:I thought all those gigantic diesels were (are?) two-stroke, which pretty much throws 4-stroke balancing out the window. I guess so, the posted article says it's a 2 stroke. Throatwarbler fucked around with this message at 03:03 on Feb 9, 2013 |
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Feb 9, 2013 03:00
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Yep... definitely 2 stroke. You can see they only have one valve, which is (of course) loving massive and requires a crane to lift.
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Feb 9, 2013 03:47
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Throatwarbler posted:The way I understand it, any inline 4 stroke engine with an even number of more than 4 cylinders is perfectly balanced, because the movement of each piston is perfectly offset by another piston. You need more than 4 because of the 4 strokes of the combustion cycle each piston can only fire once every 720* of crank rotation. It's a two-stroke diesel, so that probably doesn't apply.
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Feb 9, 2013 03:49
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I5's best engine. Until you come to buy a component only sold in 4's 
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Feb 9, 2013 09:36
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Feb 9, 2013 14:08
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Cakefool posted:I5's best engine. Until you come to buy a component only sold in 4's
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Feb 9, 2013 14:16
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Fucknag posted:- it's most obvious in larger motors, which is why you generally don't see 4-pots over 2.3L on a regular basis, 3L being the upper limit from what I remember. Agreed. Some none-balance shaft big bore 4bangers that come to mind; - Nissan KA24E /KA24DE (2.4L SOHC / DOHC) - Subaru EJ25 (2.5L SOHC) (edit, it was early and I was just thinking *hurr 4cylinders*) Definitely well refined engines when vibrations and noises are considered. 
Sockington fucked around with this message at 14:50 on Feb 9, 2013 |
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Feb 9, 2013 14:34
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Didn't Porche put a 3.0L I4 in the 944? How did they keep that thing from shaking itself apart?
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Feb 9, 2013 14:40
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Sockington posted:Agreed. Yes, but the Subaru isn't an I-4. It's a boxer.
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Feb 9, 2013 14:47
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Edit: hahaha, it was a late night with the kids  rscott posted:Didn't Porche put a 3.0L I4 in the 944? How did they keep that thing from shaking itself apart? Balance shafts.
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Feb 9, 2013 14:48
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Sockington posted:Agreed. Flat-4s don't have the kind of vibration issues discussed above. They still have the issue of non-overlapping power strokes and have a vibration about the vertical axis due to offset connecting rods but I think the severity is much less. The old GM 2.5l Iron Duke would have been a better example. The S2000 (2l-2.2l) didn't use balance shafts, since they suck up power and add more rotating mass, and neither did the NSX V6 which was a 90* V6 engine that should have had one. It's actually more serious because the vibrations get exponentially worse as engine speed increases. The old Honda gives no fucks about your noise and vibration.  rscott posted:Didn't Porche put a 3.0L I4 in the 944? How did they keep that thing from shaking itself apart? Balance shafts. They licensed the technology from Mitsubishi who first used it on the 4G6x engines.
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Feb 9, 2013 14:50
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rscott posted:Didn't Porche put a 3.0L I4 in the 944? How did they keep that thing from shaking itself apart? Well, 944s have not exactly had the most impressive record at 24 hours of LeMons. The first one to win was piloted in part by Emanuele Pirro former Audi 24 Hours of Le Mans driver. If this onboard video of him, casually lapping Road America, periodically checking his watch isn't AI as poo poo. I don't know what is. https://www.youtube.com/watch?v=8J7LKgyFweg
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Feb 9, 2013 15:11
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I found a thing   WE BAD  I don't even    http://www.bikemenu.com/photosuniracer.html
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Feb 9, 2013 15:49
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Sockington posted:Balance shafts. Which were blatantly stolen from Mistubishi. They were even sued over it and lost. Aurune posted:Well, 944s have not exactly had the most impressive record at 24 hours of LeMons. A aging car full of expensive maintenance parts isn't reliable in a race where you have a serious budget restriction? Say it ain't so.
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Feb 9, 2013 16:41
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Throatwarbler posted:Flat-4s don't have the kind of vibration issues discussed above. They still have the issue of non-overlapping power strokes and have a vibration about the vertical axis due to offset connecting rods but I think the severity is much less. The old GM 2.5l Iron Duke would have been a better Along with the disadvantage of offset connecting rods is the larger torque variation from the different firing order. Easy to fix with a flywheel with more inertia. Also why people get rough idles when they install lightweight flywheels.
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Feb 9, 2013 17:43
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Feb 9, 2013 18:19
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The only way I will ever like a VW. 
Preoptopus fucked around with this message at 18:23 on Feb 9, 2013 |
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Feb 9, 2013 18:19
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Preoptopus posted:The only way I will ever like a VW.
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Feb 9, 2013 18:35
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Preoptopus posted:The only way I will ever like a VW. Now let's see one with the front end of a bugatti and the back end of a beetle!
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Feb 9, 2013 18:54
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jonathan posted:86 Notch You forgot the best picture 
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Feb 9, 2013 19:10
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If I owned that, I would totally replace that Tie Rod clamp with a zip tie. Just cause.
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Feb 9, 2013 19:14
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Throatwarbler posted:The S2000 (2l-2.2l) didn't use balance shafts, since they suck up power and add more rotating mass, and neither did the NSX V6 which was a 90* V6 engine that should have had one. It's actually more serious because the vibrations get exponentially worse as engine speed increases. The old Honda gives no fucks about your noise and vibration. It was only recently I learned that balance shafts on I4s turn over at twice the crank frequency. The S2000 would have a pair of shafts turning over at 18000 r/min at redline.  Another largish four pot that didn't have balance shafts (I THINK) was the Toyota TZ series found in the Toyota Previa but HAHA that van had the most convoluted accessory drive system conceivable so it's not like rotating mass was A Thing Toyota were concerned with. I don't think the RZ engines had balance shafts either but I can't be hosed to look it up.
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Feb 9, 2013 19:41
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Sockington posted:Agreed. My Hino/Toyota is a 3.8L (Turbo diesel though). Lots of larger heavy duty 4 cylinders although 3000rpm is probably the upper operating speed for most of them.
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Feb 9, 2013 19:56
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I'm pretty sure the 2.3 in my ranger doesn't have balancing shafts and that's what separates it from the 2.3s in the Mazda3s
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Feb 9, 2013 20:08
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NitroSpazzz posted:You forgot the best picture Yeah I tried to post more pictures but my satellite connection from this Arctic base-camp I'm stuck at is giving me poo poo. (Not actually in the Arctic, just very remote north) More:  5.0 Aluminum DOHC Coyote motor, mounted way way back. Also notice how far forward the front wheels sit. quote:In this view you can really see just how far back the engine sits. In fact, six of the eight cylinders sit behind where the firewall originally was.  
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Feb 9, 2013 20:09
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Preoptopus posted:The only way I will ever like a VW. Functional and somehow non jarring turn signals at the top of front wheel fenders would complete this creation.
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Feb 9, 2013 20:23
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Aurune posted:Well, 944s have not exactly had the most impressive record at 24 hours of LeMons. The first one to win was piloted in part by Emanuele Pirro former Audi 24 Hours of Le Mans driver.
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Feb 9, 2013 20:37
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Previa_fun posted:It was only recently I learned that balance shafts on I4s turn over at twice the crank frequency. The S2000 would have a pair of shafts turning over at 18000 r/min at redline. The yamaha r1 has an inline 4 which has a cross-plane crank. Instead of having two pairs of pistons matching eachother, they all move seemingly at random.. It makes the power come out smoother because there isn't a momentary wait while one piston slows down and another has to speed things up again. Makes for more power and a very broad torque curve, much more l like a v4 or even a v-twin. However this completely unbalances the engine so it's the only sport bike I know of with a balance shaft. Sounds mind-boggling too but finding a video using my phone is too much effort.
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Feb 9, 2013 21:19
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https://www.youtube.com/watch?v=yg8prYId2dQ Here's a decent video of a cross-plane R1.
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Feb 9, 2013 22:02
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Cakefool posted:I5's best engine. Until you come to buy a component only sold in 4's Alright. You got me. What sort of engine non-specific part are you forced to buy in sets of 4?
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Feb 9, 2013 22:15
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tbb9 posted:I'm pretty sure the 2.3 in my ranger doesn't have balancing shafts and that's what separates it from the 2.3s in the Mazda3s The 2.3 in your Ranger is based in the 70s Pinto Lima block. They even punched that unrefined mess out to 2.5L. The 2.3 in the Mazda is a completely different motor.
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Feb 9, 2013 22:17
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Detroit Q. Spider posted:https://www.youtube.com/watch?v=yg8prYId2dQ Holy crap that sounds good. edit for worthwhile contribution:  Left 5 opens to small crest     Most from h ere: http://www.tumblr.com/tagged/reekris angryhampster fucked around with this message at 22:31 on Feb 9, 2013 |
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Feb 9, 2013 22:17
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General_Failure posted:Alright. You got me. What sort of engine non-specific part are you forced to buy in sets of 4? Sparkplugs. Whenever we did plugs on my buddy's Eurovan (2.5L I5) and Audi 5000 (2.2L I5) we would always have to hit at least two parts stores because they would stock their inventory only in multiples of four (and the multiple was almost always 1, or we just missed the 2nd-last pack of them going out the door). Once some guy for sure said he had all the plugs we needed in stock, and then when we got there argued with us that the car couldn't possibly have five cylinders and we were idiots until we got him to come outside and count the number of spark plug wires lying atop the valve cover. I would imagine you'd have the same issue with injectors assuming you could ever get enough of those magic unicorn-semen CIS-E injectors together to make a full set of four in the first place. Seat Safety Switch fucked around with this message at 23:10 on Feb 9, 2013 |
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Feb 9, 2013 23:07
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300fps Tire shake gently caress YEAH https://www.youtube.com/watch?v=mfJejgODr3E Most of these are pro-mod which is the quickest class of production car. Basically, It's a real car body with certain parts being actual factory pieces, and working doors, after this you're into funny car which is basically a short chassis flopper with a fiberglass shell.
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Feb 9, 2013 23:44
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