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The oil passage hole for the crank end bearing is plugged by something. Maybe it's on purpose as it looks very smooth and uniform. But I don't see any other way that bearing could get lubrication. Fake edit: It actually looks like someone filled it with JB Weld and sanded it smooth?
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Aug 31, 2016 18:21
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 looks to me like either they put the bearing halves in on the wrong sides, so the hole in the bearing matched up with nothing and the oil port on the other case half was blocked, or maybe the bearings for that engine are only supplied with a hole and the hole just leads to nothing on the halves that don't have oil ports?
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Aug 31, 2016 18:33
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TotalLossBrain posted:The oil passage hole for the crank end bearing is plugged by something. Maybe it's on purpose as it looks very smooth and uniform. But I don't see any other way that bearing could get lubrication. It's a two stroke. The entire crankcase is an oil passage. kastein posted:An ant problem. gently caress wooden aircraft. My Lazair trailer was made of Angle iron and pieces of assorted colour aluminum flashing. The Wasps liked it so every fall was an adventure. Your friends airplane sounds like a more poisonous version of this. https://www.youtube.com/watch?v=sT7LaSbkpcg
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Aug 31, 2016 18:33
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helno posted:It's a two stroke. The entire crankcase is an oil passage] That's true for piston lubrication, but not for the crank bearings. They need oil passages to get decent lubrication internally. You can clearly see it on one side. The pin failure and heat discoloration on the rod seem to indicate the bearing failed somehow. You might find pieces of the old bearing in the dome on one side. TotalLossBrain fucked around with this message at 21:28 on Aug 31, 2016 |
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Aug 31, 2016 18:38
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Trust me this engine does not have any sort of pressurized oil system. The main bearings are ball bearings that are sealed on one side and open to the crankcase on the other. The holes you can see go into the transfer port and line up with holes on the backside of the bearing carrier so that there is a path through the bearings for fuel and oil to flow. The connecting rod ends just have slits cut in them to allow oil to get to the needles. This engine does have an oil system but it is for the reduction gear and clutch for the electric starter. It is sealed off from the crankcase. helno fucked around with this message at 19:13 on Aug 31, 2016 |
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Aug 31, 2016 19:05
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Any sort of oil you try and put in the crankcase of a two stroke is just going to get thrown up into the combustion chamber with your fuel. At most you may have a separate compartment for the water pump drive gears that takes ATF or something but the rest is lubricated by petroil.
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Aug 31, 2016 19:12
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A fair bit of oil seperates from suspension in a premix two stroke crankcase, I was surprised how there was always a teaspoon or so of oil in a 70cc piston port whenever I pulled the barrell. That was on "upright motor" traditional motorcycle style not sure about that flat twin though, no experience with oil injected motors though. It would want to be a good one before I would trust a 2 stroke & aviation, a "nip up" could be fatal.
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Aug 31, 2016 22:02
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1500quidporsche posted:Two strokes are weird, there was pretty much no warning when my kart engine let go, it maybe sounded a little different but there was next to no major power loss. They seem to be able to take a lot of abuse up to a point where they let go in a very very bad way. If you have a two stroke that suddenly runs better than ever, stop as soon as possible because it's about to explode in spectacular fashion.
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Aug 31, 2016 23:13
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iwentdoodie posted:If you have a two stroke that suddenly runs better than ever, stop as soon as possible because it's about to explode in spectacular fashion. This 100 times my 2 stroke experience is mostly tiny rc variants but drat if it isn't true. Oh wow my truck never pulls wheelies from a standstill!. Wait why is it stalling anytime I even look at the throttle. After pulling apart the motor giant hole in the top of the piston.
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Aug 31, 2016 23:18
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iwentdoodie posted:If you have a two stroke that suddenly runs better than ever, stop as soon as possible because it's about to explode in spectacular fashion. Yeah I set a halfway decent laptime, probably within a tenth of what I thought was reasonable for the conditions and it blew up four corners later. Has their ever been an explanation for why they do this? I've always heard crankcase leak but the Conrod literally exploded on mine due to fatigue so I'm not convinced. wildemere posted:It would want to be a good one before I would trust a 2 stroke & aviation, a "nip up" could be fatal. After two years of karting in a class that exclusively uses Rotax engines there's no way you'd get me up in the air with a plane that uses one. Those engines are finicky as poo poo.
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Aug 31, 2016 23:26
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iwentdoodie posted:If you have a two stroke that suddenly runs better than ever, stop as soon as possible because it's about to explode in spectacular fashion. I've never experienced that in ten years of fixing, building, and destroying 2-stroke engines. If it's rich, it'll blubber. If it's lean, it'll hesitate and run very hot. If it is severely lean, or you run it WOT for long, especially at high RPM, you will probably melt a hole in the piston crown plus. If the gas has a low enough octane number, the topend will also suffer deto damage. The old adage that when it "runs better than ever, it'll blow!" is possible, but under a very narrow set of circumstances and even then I'd be suspect. Typical motor failures: 1. Run WOT, the engine all of a sudden slowly loses RPM and then seizes. Bores are ruined and so are the pistons. 2. Run WOT with high compression and lovely gas - same as 1, but with more apparent impact damage on the crown and the RPM slowdown is not as fast. Not really a concern in low compression engines. 3. Lube failure (no oil added or oil injection failed or whatever) - usually the crank will let go, spewing bearing pieces through the topend. Sometimes you get lucky on the topend damage. As for why do they blow? In my experience, those that blow suddenly out of nowhere were probably very high strung, high performance engines (obviously this doesn't apply to airplane engines and any of the yard tool engines). There is no detonation control and there is no mass air flow sensor (sleds with EFI have it, though). Any airleak will quickly lead to a lean seize or even a runaway (absent of load). Many 2-strokes won't even have a temperature gauge. If the carb was jetted rich or is not linear, then an airleak might feel like improved performance because it leans the mix. The amount of leaning out required to cause harm is big enough to cause a performance drop, though. TL, DR: High performance engine with little room for error and little to no instrumentation. RE: Rotax 2-strokes. They are certainly complicated. Many of their old PWC engines employed a rotary valve induction system which is driven off a short shaft perpendicular to and driven by the crank in a sealed, oil-filled cavity. The short shaft is made of brass. Later RFI and EFI engines used an engine-driven air compressor for induction and direct fuel injection. However, they also have traditionally been the highest horsepower engines for their size. Couple that with complexity to make all that power and Rotax engines being everywhere, and you see a lot of failures. I never liked working on them. They require lots of special tools and a fair bit more care when reassembling than Kawasakis, Yamahas, or Polaris engines. Disclaimer: my 2-stroke experience is limited to PWC, some motorcycles, and some East German cars. Perhaps someone can offer more relevant insight. TotalLossBrain fucked around with this message at 00:19 on Sep 1, 2016 |
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Aug 31, 2016 23:28
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2 stroke students should always read Gordon Jennings Bible https://www.amrca.com/tech/tuners.pdf Also Graham Bell. They are fascinating for me. Think of a highly tuned two stroke like a brass musical instrument. It has to resonate to perform. If there was ever an inexact science this is it. The research done by companies in Japan, Eastern Europe & America (mostly boat/sled motors) was intense back in the day. The development of the Mercury inline 6 & followed by the V6 & Evinrude V8's is also really interesting. The port setup on the Merc V6 was copied from an 350cc euro dirt bike. The specific output of these High Perfermance 2 cycles always made me interested in them 500cc GP bikes made over 200HP & pulled well over 200mph in the 80's, wheelies in all gears at any speed. You had to modulate the power with the rear brake... With a powerband like a light switch that hit just after 10,000RPM. The old 2l V6 Mercs on tunnel boats made over 350HP at around 9000rpm and the pushed the boat to around 140mph. Could easily beat a supercharged big-block displacement boat in circuit racing. Just amazing tech, but fragile as well. The lastest E-TEC's from BRP are also amazing, direct injection. wildemere fucked around with this message at 02:07 on Sep 1, 2016 |
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Sep 1, 2016 00:31
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My previous ultralight had a pair of Rotax 185's. Those little engines were incredibly dependable (Other than the lawn mower pull starters being ripped apart occasionally.) The R-185 is a piston ported engine so no reed valves or rotary valves to fail. It needed a little velocity stack to stop the propwash from blowing away the gas when the flow through the carb reversed every stroke. The KFM uses reed valves and has a fairly high compression ratio. It was purposely designed for aircraft use so it is tuned pretty mild compared to what you would find on a kart. Unfortunatly it is a mixed gas engine rather than having a VRO setup like more modern engines. My ultimate goal with this airframe is to run it on electric power. The two-stroke will be a stop gap so I can fly the plane as designed and get a feel for it before I replace the engine.
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Sep 1, 2016 00:33
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TotalLossBrain posted:
Mine is all bikes and quads. From DT125s and RDs to motocross bikes and Banshees. Every time I had a spectacular failure, it ran great right before. I've had minor issues crop up before that ran like poo poo, but that's normal. Even on the old slow bikes that power band is just intoxicating. Two strokes is the correct amount. Any more is a waste.
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Sep 1, 2016 01:49
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iwentdoodie posted:Two strokes is the correct amount. Any more is a waste. But enough about your Friday night.
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Sep 1, 2016 02:09
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did someone mention aircooled aircraft engines? http://bringatrailer.com/2016/08/29/13-liter-ww2-drone-engine-super-rare-franklin-0-805/
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Sep 1, 2016 03:06
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I have to imagine that by the 6th pair of cylinders you'd have to call it an air-heated engine, not air-cooled.
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Sep 1, 2016 03:16
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Yeah, even the IO720 in Piper Comanche 400s iirc had cooling issues on the fourth row (H-8.) I can't imagine that would cool very well without a top mounted fan and ducts like that famous... porsche? With the H12 or H16.
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Sep 1, 2016 03:23
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Sagebrush posted:I have to imagine that by the 6th pair of cylinders you'd have to call it an air-heated engine, not air-cooled. 6th pair? A mere 12 cylinders? 
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Sep 1, 2016 03:36
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That's only 4 banks, compared to 6 on the H12 he posted. And they're staggered in that pattern so that the airflow works out reasonably well even for the rearmost bank, something that the H12 loses since they are all in one plane, geometrically speaking, though I suppose they also end up in one plane vehicularly speaking as well.
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Sep 1, 2016 03:41
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Phanatic posted:6th pair? A mere 12 cylinders? I came here to post this ^^ . I've seen one disassembled in the Boeing Museum of Flight (I think - may have been that private museum in Northern Oregon instead). The size and complexity are incredible.
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Sep 1, 2016 03:44
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Isn't this is the huge multi row motor that Howard Hughes loved so much? Right into the suburbs of LA
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Sep 1, 2016 04:19
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TotalLossBrain posted:I came here to post this ^^ . I've seen one disassembled in the Boeing Museum of Flight (I think - may have been that private museum in Northern Oregon instead). The size and complexity are incredible. There's one just sitting outside at the air force museum near March AFB as well. It's so loving big.
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Sep 1, 2016 04:39
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iwentdoodie posted:If you have a two stroke that suddenly runs better than ever, stop as soon as possible because it's about to explode in spectacular fashion. Notice how all those race-winning KR-1Ss ceased to exist after about 1992?
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Sep 1, 2016 08:40
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PainterofCrap posted:did someone mention aircooled aircraft engines? Franklin has a 12 cylinder SERIES of motors. From like 350 to 500hp. https://en.wikipedia.org/wiki/Franklin_12_series Now Porsche had the 12 cylinder that powered the 917 series. With up to 1500hp...
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Sep 1, 2016 14:41
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PainterofCrap posted:did someone mention aircooled aircraft engines? Needs more Deutz love.  As big as V12
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Sep 1, 2016 14:57
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Here's the largest US radial aircraft engine ever built. Five thousand horsepower. 36 cylinders, 127 liters of displacement. https://en.wikipedia.org/wiki/Lycoming_XR-7755 Unlike typical radial aircraft engines, it was water cooled, so the cylinders were in 9 radially arranged banks of 4 cylinders each, instead of the spiral pattern usually used to get cooling air to all the cylinders. They only built two prototypes and then all their prospective customers lost interest because jet engines were taking over the market.  127 liters is just over 1.5x what my fuel tank holds. Holy gently caress. And if that's not big enough, here's the biggest the Soviets ever built. 42 cylinders. https://en.wikipedia.org/wiki/Zvezda_M503 https://www.youtube.com/watch?v=SPR8zBSNOgE From video description: quote:Motor: Zvezda M 503 A, fuel: methanol, Power: 8,000 hp Cylinders: 42 Displacement: 147.1 liters, length of ignition cable: 160 meters Number of plugs: 126, Number of valves: 168  oh yeah that thing that looks like it could swallow a basketball on the front is in fact the throttle body. And from the sound... it's turbocharged or supercharged. kastein fucked around with this message at 18:39 on Sep 1, 2016 |
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Sep 1, 2016 18:34
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kastein posted:Zvezda_M503 Holy balls. That thing moves so much air you might kickstart a weather system with it.
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Sep 1, 2016 18:43
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Ola posted:Holy balls. That thing moves so much air you might kickstart a weather system with it. You might need a weather system to start it.
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Sep 1, 2016 18:46
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kastein posted:Here's the largest US radial aircraft engine ever built. Five thousand horsepower. 36 cylinders, 127 liters of displacement. Love the announcer. MIT SCHLAGEN FLAMMEN UND BOOM
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Sep 1, 2016 20:10
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Chrysler Multibank!
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Sep 1, 2016 20:16
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The Door Frame posted:I understand economic pressures, but why buy a discount utility car built to only meet import standards and nothing else? Just buy a year or two older Honda or Ford or whoever makes even uglier Subaru BRATs This is why developed car markets will never sell a super cheap bare bones car, generally (I mean unless you are mitsubishi and have literally nothing else to sell), because there's really no market for it. People who want cheap cars will just buy a used real car. They're never going to start selling new 1993 Ford Rangers again guys. It's amusing how a lot of the commentary on Chinese products seem to miss the forest for the trees. "Every piece of poo poo I ever bought that somehow was 1/10th the cost of the item that I probably should have bought has been made in China therefore everything made in China is poo poo". Why not turn it around - "Suppose there is a huge insatiable market in this place called "America" for absolutely bottom of the barrel junk that sells for a couple of bucks, and clearly there is because here we are talking about it, where would I make the products that will satisfy this market? Switzerland?". All of Apple's poo poo is made in China, and while I don't like them, they are undoubtedly well built with good workmanship. Whatever problems Apple products have originate in Cupertino, not China. You can buy a fake Apple product for 1/10th the cost too, and it too will be built in China. If you're constantly on the search for Apple products at 1/10th the cost, well I don't know what you expect.
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Sep 1, 2016 23:59
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TotalLossBrain posted:I came here to post this ^^ . I've seen one disassembled in the Boeing Museum of Flight (I think - may have been that private museum in Northern Oregon instead). The size and complexity are incredible. They also belong in the horrible mechanical failures thread. They were used to power the B-36, but were problematic in that application because they were installed as pusher props, which they weren't designed for. In a conventional tractor configuration, the cylinders are out in front of the carbs, so cold, high-altitude air passes over the cylinders, and warms up, and then gets sucked into the carb. In the pusher configuration, the carb's ingesting that cold air, the air speeds up, the pressure drops, moisture condenses out of the air and freezes, and the carbs start to ice over. So the mixture gets richer and richer until finally the exhaust has enough unburned fuel in it to burst into flame, and now you've got an engine fire. Which you don't want. Even on an airplane that has 10 engines.
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Sep 2, 2016 00:10
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Phanatic posted:They also belong in the horrible mechanical failures thread. They were used to power the B-36, but were problematic in that application because they were installed as pusher props, which they weren't designed for. In a conventional tractor configuration, the cylinders are out in front of the carbs, so cold, high-altitude air passes over the cylinders, and warms up, and then gets sucked into the carb. Four turnin' two burnin'! The B-36 is all sorts of crazy. Landing gear prototype: 
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Sep 2, 2016 00:13
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kastein posted:And if that's not big enough, here's the biggest the Soviets ever built. 42 cylinders. https://en.wikipedia.org/wiki/Zvezda_M503 I think they built that as a submarine/attack boat power plant, I think, so unlike the Lycoming there are thousands of them. Essentially the same thinking that resulted in the Deltic. The Chrysler Multibank is a wonderful bit of adaptation - it's a standard 6- cylinder motor for which all the tooling already existed with a custom oil pan that ties them together and then a bit of manifold trickery. On the flip side, while it's a novel use of existing tooling, it ws also basically horrible next to the radial engine options, and I think only the British used them in any quantity. Two turning, two burning, two smoking, two joking and two unaccounted for.
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Sep 2, 2016 00:14
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Throatwarbler posted:This is why developed car markets will never sell a super cheap bare bones car, generally (I mean unless you are mitsubishi and have literally nothing else to sell), because there's really no market for it. People who want cheap cars will just buy a used real car. They're never going to start selling new 1993 Ford Rangers again guys. Everything is made overseas (mainly China), and China has a somewhat earned reputation when it comes to product quality, due to the sheer volume of goods they produce. When something massively important like a 1.5 ton hunk of metal that will reach speeds of at least 50mph, is complete dog poo poo that literally just falls apart, it's the "Chinese quality" jokes that come up, not the questions like, "How the gently caress did this get to market? Who signed off on this import?" Because those answers are deeeepressing
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Sep 2, 2016 01:57
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kastein posted:And if that's not big enough, here's the biggest the Soviets ever built. 42 cylinders. https://en.wikipedia.org/wiki/Zvezda_M503 The best part is that with these old engines, improper starting technique could result in flooding all of the cylinders, meaning the maintenance crews would have to go in and replace all 126 fouled spark plugs. Possibly on more than one engine  I'm sure the crew chief just looooooved new pilots.
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Sep 2, 2016 02:18
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1500quidporsche posted:Two strokes are weird, there was pretty much no warning when my kart engine let go, it maybe sounded a little different but there was next to no major power loss. They seem to be able to take a lot of abuse up to a point where they let go in a very very bad way. I believe they usually run rich to cool and lube the engine. Lean them out and they will actually produce more power, for a while. So they are running really well then doom.
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Sep 2, 2016 03:12
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kastein posted:https://www.youtube.com/watch?v=SPR8zBSNOgE That load he's pulling at 2:00 is 23 tons of iron. Also, lmao at these German 'country' events. TotalLossBrain fucked around with this message at 04:07 on Sep 2, 2016 |
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Sep 2, 2016 04:05
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Friends supercharged R32 time attack car had a failure last weekend, initial tear down showed this...
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