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Let's get something out of the way, here... the title of this thread is not being facetious in the slightest: https://www.youtube.com/watch?v=42BRqshbYA0 My coworker owns a 1970 Subaru 360 Sambar. If you're not familiar with the Subaru 360, it's a Kei-class car imported to the United States by Bricklin (the same guy who brought us the Yugo!) in the late 1960's. It has a 360cc two-stroke engine producing somewhere between nothing and almost nothing for power, and even with a curb weight of 998 pounds it can barely get out of its own way. It was quite seriously marketed on the basis of it being "cheap and ugly," and being labeled as "the most unsafe car in America" probably didn't help sales too much either, so they're definitely one of the more esoteric cars to own and work on in the United States. So of course we're loving with it!  If you haven't watched the video linked at the beginning of this post, do so now and it'll give you a pretty good idea of what we're dealing with here. The plan is to take the engine and wring as much performance as feasible from it by converting to fuel injection. I have had quite a bit of experience with Megasquirt EFI and the tricks and traps of full standalone tuning with no base maps, and it was not a terribly hard sell to my coworker to push him to convert to EFI after we had to push the car into a Wendy's parking lot and let it dry out after the engine got flooded trying to start it. The primary goal is achieving improved reliability for daily drivability, but I believe that doubling the stock horsepower of the engine should be easily possible without major rework of the engine (cooling will likely be a problem, but hey, we'll cross that bridge when we come to it). The most obvious place to start with "why is this car so drat slow?" is the carb. Let's take a look at the carb!  (not visible: the drip pan intended to collect all the fuel that pours out the front of the carb in normal operation. Seriously, that's a thing on this carb)  It can't be seen from this angle, but the final diameter of the port that mates up to the intake manifold is 28mm. The engine must be gasping for breath all the way to 5500 rpm. According to some very questionable internet sources, a twin carb model resulted in 36 hp versus the 25 hp of the single-carb model. The actual intake ports on the engine side are pretty big considering the displacement. I don't think there'd be much to gain from enlarging them, at least at this point in the project. Also it'd be very easy to get debris into the engine block, and they're not the easiest thing to source at junkyards if we wrecked one due to carelessness.  To replace the carb, we sourced a Kawasaki Ninja 300R throttle body set. The 300R is fuel injected from the factory and is probably pretty similar in terms of what we can expect for airflow through the engine, so it seemed a good match to the engine. Also, it looked like the intake spacing and the spacing of the throttle bodies was about right. Sure enough:  The spacing is drat perfect. This is gonna kick rear end. Based off of some kinda sketchy gasket patterns and a whole bunch of caliper measurements, we modeled and 3D printed intake runners to mate up to the throttle bodies.  We had to take about a centimeter off the runners to avoid crowding the mouths of the throttle bodies with the engine compartment hatch, but otherwise the mockup fit went very well. We'll probably send out the drawings to be machined sometime in the next week or so. For engine management we'll be running a Microsquirt ECU in Alpha-N mode, using rpm and throttle position for controlling fueling. Between the low 6.8:1 compression ratio, the engine being a two-stroke, and the individual throttle bodies, I highly doubt that manifold pressure will tell us anything useful. We're just doing fuel for now, and we'll work on spark after we get a rough tune in place. The stock points system sucks, but it should work well enough to get things running first. I figure we'll use a coil-on-plug setup in the end, if we can fit them on the engine, otherwise we'll get a couple coils and drive each cylinder separately. O2 sensor duties go to an Innovate Motorsports LC-2. I've owned a couple of their LC-1s before, and they were reliable, well designed, and cheap. The biggest complaint I had with them was that they didn't have any way to mount to anything, so you had to zip tie it onto something. They fixed that with the latest model, and I guess they also improved response time while they were at it. Kick rear end. The coworker doesn't have any welding equipment, and I had to leave all mine with my folks back in Massachusetts, so we've gotta get an exhaust shop to weld the bung for the O2 sensor onto the exhaust, but that shouldn't be a big deal once they get past the rust on the header pipe.  An unresolved issue is how we're going to handle fuel. I suggested getting an Aeromotive 13129 FPR and then routing the return back to the drain plug on the gas tank to avoid having to cut a new return line hole and getting it welded in. The 300R uses a returnless fuel system and it seemed like too much of a hassle to work out how best to control the fuel pump without making everything too complicated. Using a fuel pressure regulator with a built-in bypass should make that decision a little easier, at least. That's all the pictures and info I have for you all so far. I think it's gonna be a pretty kickass project, and shouldn't actually end up being too terribly expensive, considering. I shall update when we get a chance to wrench on the car again, possibly next weekend?
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Apr 3, 2015 09:00
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Cool! So am I correct in understanding that the 3D printed parts are for mockup only, and real ones will be machined once the fit has been confirmed? This thing is begging for a modern motorcycle engine swap.
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Apr 3, 2015 11:13
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I love that thing. https://www.youtube.com/watch?v=qzvmPpXTAqM
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Apr 3, 2015 12:30
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This kicks rear end! The 360 are such goofy little cars and I've always liked them. I think the vans are second in goofiness only to the trucks. Can't wait to see more.
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Apr 3, 2015 13:49
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This is going to be great. PS: we need more tiny cars in AI.
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Apr 3, 2015 14:15
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bolind posted:Cool! So am I correct in understanding that the 3D printed parts are for mockup only, and real ones will be machined once the fit has been confirmed? Correct. This is totally awesome too.
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Apr 3, 2015 14:19
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Steak Flavored Gum posted:So of course we're loving with it! Any car that makes a lotus look normal size is going to be a great car. Looking forward to this, I never thought about using megasquirt on a 2 stroke before.
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Apr 3, 2015 14:19
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I find it absolutely hilarious that the owner of the car posted about this project on the Subaru 360 Club forum and was greeted with so much haaaaate from pretty much everyone but the mod of the forum and one other guy who is doing a similar project. My favorite quote is "My 360s are not unreliable. When they have been gone through properly, they're more reliable than my '59 Thunderbird." High water mark right there! Alternatively, "I would rather trust the expertise of the original Japanese engineers than something cobbled together on my work bench at home." to which my coworker responded "And I would rather trust 45 years of automotive innovation, modern manufacturing tolerances, and an actual budget!"  W.r.t. the Lotus, I find it hilarious that here in Silicon Valley nobody seems to give a drat about it, but EVERYONE who sees the 360 comments on how awesome it is and how much they want one. I believe that after being converted to EFI, it'll be reliable and zippier enough to agree with their sentiment. 
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Apr 3, 2015 17:00
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Oh my loving god Santa did get my wish list after all. Subaru 360s and Lotuses and bike throttle bodies and Megasquirt. I live for this thread. Also the subaru makes your jack stands look huge.
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Apr 3, 2015 17:23
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So awesome! On the fueling, you could buy a cheap eBay swirl pot and cut out the bottom for the stock kawa fuel pump (most of the ones I've seen are flat mounted, with an oring gasket). Then you run a carb low psi lift pump to fill the swirl pot and the kawa pump takes care of the rest! If you can't run the Kawasaki pump, there are many of other ATVs and motorcycles with small compact in tank pump/filter/regulator combos. On the ignition system, are both cylinders in time or 180 out? I think you have to build the MS box differently if you're triggering off points, if you're buying premade, make sure to let them know.
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Apr 3, 2015 17:46
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Wait, its a two stroke?
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Apr 3, 2015 18:09
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Really cool thread, makes me really want one or really any kei car for parking in nyc.
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Apr 3, 2015 21:09
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track day bro! posted:Wait, its a two stroke? All of the 360 family are. Straight twin cylinder two stroke air cooled. I dunno when they went four stroke, was probably fairly early on. The EA engine shows up in 1966 so 1970 may be one of the last EKs sold in North America. Even the boxer design came later when they absorbed some other company, I forget the name. Edit: Wikipedia says the Sambar ended in North America after '70 (unless I read that wrong); the EK straight twin was forced to become four stroke in '76. Just for giggles it also became SOHC during its life. The fresh air vent and suicide doors are the coolest parts of the regular 360. Does the Sambar still have them? Seat Safety Switch fucked around with this message at 22:13 on Apr 3, 2015 |
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Apr 3, 2015 22:05
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Look at this little guy right heeeere. http://www.ebay.com/itm/HONDA-OEM-FUEL-PUMP-ASSEMBLY-RINCON-VT750-VT1300-16700-HN8-A62-/161464611442 This little guy, or one of its brothers, should do everything you need I would think.
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Apr 3, 2015 23:00
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Sometimes I click a thread in here and remember why AI owns
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Apr 3, 2015 23:29
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I knew this thread would be awesome just from the title, but it got even more awesome when it turned out the 360 was also a Sambar 
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Apr 3, 2015 23:41
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Seat Safety Switch posted:The fresh air vent and suicide doors are the coolest parts of the regular 360. Does the Sambar still have them? Sure does!
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Apr 4, 2015 00:13
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How does it oil itself? Has it got a separate oil pump squirting directly into the crank case independent of whatever's going on at the intake end?
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Apr 4, 2015 05:34
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I saw two of these in person (well, 360s, I don't think either was a Sambar) at the Cars & Coffee in Redmond, and man are they really, really small. I had no idea they had so little power or that they were two stroke, though that doesn't make me any less incapable of resisting their happy little faces 
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Apr 4, 2015 05:58
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Two strokes and lambda sensors don't play nicely with eachother sometimes. All that oil can foul them quickly. If it's got an oil pump feeding the bearings you are probably better off.
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Apr 4, 2015 06:06
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Slavvy posted:How does it oil itself? Has it got a separate oil pump squirting directly into the crank case independent of whatever's going on at the intake end? I'm willing to bet it has a oil tank and hose to the carb and mixes it right in the carb.
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Apr 4, 2015 07:28
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It's got a mechanical injector pump that sprays into the crankcase.
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Apr 4, 2015 08:21
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If thats a piston port then reed valves would be the best idea to getting EFI working reliably, with some other issues to overcome. Then you need expansion chambers on the exhaust Without reeds on the inlet carbs would be way easier to setup for it. Main reason is blowback, the mixture can travel through the carbs twice or more depending on RPM. With reeds blowback is eliminated. If it was mine I'd ditch the auto lube as well and go premix, get a set of 30mm flatslide mikunis, make chambers and fit reeds. Injected 2 strokes are rare, I think its only Bombardier/Rotax doing them with their E-Tech setup. Its direct injection as well. As 2 strokes are total loss lubrication the oil in the exhaust will upset the 4 cycle exhaust sensors, Also air cooled two strokes don't like running lean at all, they overheat & sieze, wrecking the barrels. I think you will kill it with EFI, sensors & computers unless you keep a very close eye on exhaust temps. Main reason is its not just air & fuel, Its oil as well and without knowing the oiling ratio how will it know how much fuel to squirt? Premix would help here. 2 strokes can be fine tuned with oil ratio. But the method tuners use is plug colour & exhaust temp. They also tune up differently depending on oil type, mineral, synth or castor. If you could get an oil tolerant sensor, ran the same oil at the same ratio and got a specific two stroke map it might work, but I would try it on something less rare than that first. Set it up using Gordon Jenning's guide, use exhaust temp & plug chops to set the mixture. Select carb sizes based on the tables in his bible. Also 2 stroke carbs are setup differently to 4 stroke carbs https://www.amrca.com/tech/tuners.pdf Many years have passed since Gordon Jennings first published this manual. ... Let's journey back to 1973 and read the book that was the two stroke bible of that ... wildemere fucked around with this message at 11:31 on Apr 4, 2015 |
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Apr 4, 2015 11:04
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wildemere posted:Injected 2 strokes are rare, I think its only Bombardier/Rotax doing them with their E-Tech setup. Its direct injection as well. https://youtu.be/QC6GHMTWJrg
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Apr 4, 2015 11:52
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BIG HORNY COW posted:Who wouldn't want a crazy powerful snowmobile engine in a tiny subaru van? That amazing compound valve in that strange black housing connecting the two cylinders! It looks to be electrically actuated variable exhaust timing. SO COOL
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Apr 5, 2015 07:23
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I know you have updates on this project. Come on man, you're letting the internet down.
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May 29, 2015 14:21
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160 hp snowmobile holy hell.
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May 29, 2015 15:26
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I have also been waiting for more adventure, kindled by Mad Max
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May 29, 2015 17:17
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poo poo, it's really way past time I update, isn't it? Well when we last left off, we were mocking up how we were going to put the whole thing together. Then my coworker flew to Japan for a couple weeks and I got busy at work, and not a whole lot happened. MEDIOCRE. We got some parts in:  Cheapo inline Airtex pump, not so cheapo Aeromotive fuel pressure regulator, fuel pressure gauge, a bunch of AN-06 fittings and hose. Fuel systems are important, yo.  I got voluntold to install the fuel pump. I am glad that immediately beforehand I thought to put on goggles, because in the process of doing so it seems like I got drowned in all of the gasoline that has ever been refined in the history of mankind. My coworker forgot to remove the filler cap... it was under pressure in the tank.  I suppose it also didn't help that the nipple on the fuel tank was for 5/16" hose, while we were using 3/8" fuel line like normal people. Hooray for hose clamps! Of course the entire time that I was fighting with the hose clamp trying to get it tightened down, gasoline was pouring down my arm and both of us were drat near zonked out by the fumes afterwards.  The fuel pump was in, though! It is actually mounted in a pretty good location right before the engine bay. Should be fine. Some pictures of the feed and return lines:   As part of the ongoing process of pulling lovely old parts out of the car, the leaking factory oil tank was next.  This revealed the only rust-free spot on the car:  (It leaked a lot of oil. A loooot of oil.) Eventually we realized that we really had to just go ahead and get the ITB runners machined already or else nothing would ever get done. My coworker placed the order from ProtoLabs and we had them just a few days later. Sweet! I've used their services a few times now and they're pretty excellent to deal with if you need custom parts machined quickly.   I think it came out pretty well. Conveniently, K&N had an air filter that was the right size, runner diameter, and spacing for the throttle bodies.  That logo gives something like 15 extra horsepower all by itself, right? Also pictured there is the fuel fitting we pulled off of a factory fuel line for the Ninja when we realized that it really was not going to be a good idea to just jam the fuel line on there and clamp it. The line was cheap, though... something like 12 bucks on eBay. We were really tired of working in the pitch black, so the coworker bought a new absurdly bright light fixture for the garage... Old and busted:  New hotness:  It's still too dark in there at night, but it's a huge improvement over what it was. There are some more things to update on, but this post is getting absurdly long already, so I think I'll pause for now.
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May 29, 2015 18:16
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How many amps can the charging system put out again? Those pumps can get kinda thirsty. Awesome proto part there, though. Are those SLS or something?
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May 29, 2015 21:13
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wildemere posted:
I just started reading this and so far this book is super cool.
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May 30, 2015 01:08
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Commodore_64 posted:How many amps can the charging system put out again? Those pumps can get kinda thirsty. Awesome proto part there, though. Are those SLS or something? The factory generator is about 500 W... before conversion losses. Let's just say that that is long gone. We've switched to an alternator from a John Deere tractor which more or less bolted right up. The runners are machined and bead blasted aluminum. Part of the reason for their kinda funky shape was to ensure they'd be machinable on a 3-axis CNC.
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May 30, 2015 01:23
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Steak Flavored Gum posted:The factory generator is about 500 W... before conversion losses. Let's just say that that is long gone. We've switched to an alternator from a John Deere tractor which more or less bolted right up. That's excellent. Is it a two wire alternator? I love hearing about totally unrelated parts that end up compatible. I know from experience that it's easier to just work and take pics afterwards but...could you take more pics? I love Kei trucks and had been eyeballing the regular Daihatsu Hijet imports at a shop near where I used to work. So cool.
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May 30, 2015 01:54
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It's full featured... lamp/field/sense. Because we're not using a couple of the relay slots in the fusebox we got at a junkyard, I might set the Megasquirt up to switch the alternator off while cranking. The cranking speed is much higher without that load on the engine, about 450 rpm versus 300-350 rpm with the alternator on.
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May 30, 2015 03:01
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A teaser (until I have time to finish writing things up): https://www.youtube.com/watch?v=FKtzfF1vg1U
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Jun 3, 2015 08:25
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I LOVE THESE THINGS! THEY ARE SOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO SMALL. How small? Well...   
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Jun 3, 2015 11:43
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Can you turbo this thing for double HP again?
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Jun 3, 2015 14:12
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mobby_6kl posted:Can you turbo this thing for double HP again? We'd have to make drastic modifications to the engine to keep it from blowing the intake charge right out the exhaust... the engine has no reed valves or any other form of port restriction. I think we're better off sticking to NA power with maybe some exhaust tuning cleverness. Ultimately, it's tuning the ignition timing that will make us power. Currently we're using the stock points system switching a GM HEI module to drive the coil. We'll convert to coil-near-plug once we have it generally sorted.
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Jun 3, 2015 21:30
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I'm a bit of an old school two stroke user, I made a bit of an effort post here earlier. I'm glad you got it running on EFI. But I'm still worried about that little vintage two stroke running modern four stroke induction. Without reed valves, fueling and oiling will be a big issue. I see it has crankcase oil injection (controlled by a cable from the gas pedal) as standard and that was designed for 16-20 or so HP on a piston port motor. If you are hoping to increase the output then better lubrication will be critical. I would either delete the Subarumatic oiling system completely and go 30:1 premix on synth or 25:1 on castor. Or overhaul it completely paying special attention to the little end/cylinder bore crankcase bypass and supplement with at 10:1 or so in the gas tank. Make sure the oil pump is still operational from the gas pedal. A long run downhill with the throttle shut can kill an air cooled two stoke. I'd hate to see that little guy lean out and sieze. Locking up the wheels at highway speed... Ask any two stroke guy how he knows... With oil use fully synthetic Silkolene or Motul bike oil, or even better, castor oil for that sweet smell. (only two stroke guys know this) Actually running castor can give as much as 10% more power under high load conditions and its varnish combustion byproduct is also a lubricant. This also gives a few seconds of control under the previously mentioned full throttle seizures, Mineral oil is instant death, Synth less so, Castor is a 3 or 4 second rundown. The downside is ring sticking and more frequent rebuilds. I do it for the aroma and the safety. Read that Gordon Jennings book, its right in this era. Raise the exhaust ports and keep an eye on exhaust temps. Smooth out the transfers as well. Get a pyro kit like the Kart guys use, go for 1100 degrees Celsius about one inch from the head. These old two strokes are more like musical instruments than any other motors, they run on special resonance and tuning like artists and are as temperamental as such. But when performing well they are the dirty, screaming, smelly works of art I admire... The two stroke 500cc bikes from the eighties & early ninties pulled well over 200mph on carbies... around 180+hp Mercury 2 liter V6 outboards made over 300+ hp. on carbs, with methanol though.  This stock oiling setup would not do much more than 30hp tops, when adjusted correctly... Especially when your running lean. Or if that crankcase to top end lube passage is slightly blocked. Both the fuel & oil systems were gravity fed and the oil pump is attached to the throttle somehow. I'm not trying to rain on your parade just prevent a possible failure. The oil system is always total loss with two strokes and usually the failure mode when you get it wrong. Most power with old style two strokes comes from fuel type, expansion chamber design, exhaust port heights compression ratio, squish band setup. Then its the art of tuning... Ignition timing is fairly static until you get above 5 or 6 thousand revs. Then read the book. Its the opposite of four strokes... Then came variable height exhaust ports & digital ignitions... Hence the crazy power from 500cc GP bikes & Motocross bikes from that era. Still used carbies then as well. In my opinion a pair of 30mm flat slide carbs & 30:1 synthetic premix & a good two-stroke tuner would make more power than any "adapted from 4 stroke tech EFI setup" on that old piston port motor. Two strokes have a "big gulp" in-out type of induction without reed valves. Its very different from the constant vacuum of your average four stroke. wildemere fucked around with this message at 06:55 on Jun 4, 2015 |
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Jun 4, 2015 03:18
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Thankfully the oil pump's dynamic range is actually pretty limited. It's about three times as much oil per rev at full throttle as it is with the throttle fully closed, but it's still a fair whack. We will definitely take into consideration doing some premixing anyway, as I too have raised an eyebrow at the oiling system and its potential adequacy for full power runs. I will continue to disagree with your statement about carbs though, as I see no physical reasoning why a carbureted setup should be better suited to run a two-stroke motor than a properly tuned EFI system. Yeah, pressure pulses from the engine will oscillate in the carbs and add extra fuel, sure. Those pressure pulses won't magically behave differently with EFI, though, and they can be accounted for in determining the fueling table for the engine. The actual physical intake path is essentially identical to the carbureted setup, the exhaust path is exactly identical, and the dynamics of the engine should be largely unchanged. I'm not sure what you mean by "four-stroke induction" either, as the injectors are timed to fire at approximately the same time the carb would be feeding fuel into the intake charge. That too can be adjusted. I'm aware of the differences in ignition timing between two- and four-stroke applications, and spent the weekend reading about them. For now we are running off of the factory points system as a timing source for the ignition module, but we will switch to full spark control later on when we've got things settled as far as oiling goes and have a base tune. The factory distributor is an extremely basic design and I'm not sure it starts to retard after torque peak like it should on a two-stroke. From talking to a couple other folks who have converted their 360s to EFI, it appears that it has a nominal cranking advance of 6 degrees BTDC, ramps up to about 30 degrees BTDC at 3k rpm, and then flatlines around there. This is most definitely more advance than we want at higher rpm and load, and cutting that back might help free up some torque up at 5k+. The factory redline is only 6k rpm so... a lot of this is future work after we take care of prepping the engine for more. Thankfully there's a dyno shop not too far away in San Jose where we'll probably bring the car to tune things up when we're ready for that.
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Jun 4, 2015 07:37
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