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Forum Index : Solar : Solar Steam
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi don Sounds like you have given this a lot of thought with the electronic side of the injection omly thing with that is if you inject water into the trough collector which will be in a nonsaturated state it will flash to superheated steam and cause a instentanious pessure pulse around 400 psi without a collector it will cause your govenor system to hunt or at least overpower the engine. What you need in electronic terms is a HD LC circuit to smooth out the energy pulses. On your trough collector tube I found that welding a wing on each side of the tube increased the absorbsion of energy as energy tends to reflect back off the tube Refraction I think its called, but not so much of the flatter surface, on a 1 inch tube I found that 2" X .375 " on each side was about right. Feeding imto the grid is the way to go if you dont mind being tied to the money hungry mercenaries I would have a bet each way and have a small battery bank to run the essentials in blackout conditions depending on the reliability of the grid in your location. You would need to change thw piston ring to a pressure seal ring type as ordinary rings dont do to well on steam and cut the bore out quickly due to small contact area. Also if you run much vacume it will suck oil out of the sump to some degree. Wish this thing had a spell checker! 
All the best Bob Foolin Around |
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Don B Senior Member  Joined: 27/09/2008 Location: AustraliaPosts: 190 |
Hi again Bob and others on this thread. I spent today dismantling a 3.5HP Briggs and Stratton lawnmower engine, and worked out that I can, with a little bit of work, convert it into a sort of steam engine. The main modification will be to cut and re-align the camshaft, so that I can change the inlet valve into a second exhaust valve to work alternately with the original exhaust valve on each second stroke. This means that I can use the spark plug hole exclusively for an electrically triggered injector for the inlet valve, and I will have 2 stroke steam engine, maybe. Brilliant! Then I stumble across this site http://www.greensteamengine.com/, and I realise (through my tears) that I am really just trying to reinvent a poor copy of a new type wheel. Anyhow, I will dry my eyes and probably keep plugging away just so that I can see why my idea won't work. At least it is a cheap experiment, so long as I put no value on my time. The greensteamengine site certainly answers the original thread contributor in part, at least, though it does not really deal to any extent with solar steam collectors. At least I still have some scope for some experimenting there. Regards Don B |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Don Keep on keeping on and remember the trip can be as much fun as the arrival at the destination. All the best Bob Foolin Around |
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oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
If you want to be cheeky.... I suppose you could just get rid of the lifters so the valved didn't work at all.... Then grab the angle grinder and cut a slot in the cylinder wall at about bottom dead center .... like a 2 stroke exhaust port.... Then inject with electronic timing through the spark plug. Less moving parts, and problem solved crudely but effectively. If you wanted to create a vacuume on the new "exhaust port", then fashion a suitable outlet collar to match the outlet cut..... and weld it on.... ...... must be the island air... .........oztules Village idiot...or... just another hack out of his depth |
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| Don B Senior Member Joined: 27/09/2008 Location: AustraliaPosts: 190 |
Hi Oztules Thanks for the suggestion re the exhaust, however, following the doctrine of least work (as I tend to do), the camshaft modification is easier. The B&S camshaft is cast iron, and the inlet and exhaust cams are separated by a 16mm length of cast shaft that is 13mm diameter. My junk box has yielded up some stainless tube with the same ID, which will make a nice press fitting sleeve. All that I need to do is cut the camshaft mid-way between the cams, and re-orient the second cam so that its lobe is at 180 degrees to the first (rather than the present 100 odd degrees). I will supplement the press fit of the sleeve tube with some Loctite shaft lock, plus probably some roll pins for good measure. The OD of the sleeve is less than the minor diameter of the cam lobe, so that the cam followers, which overhang the cam lobes, are still free to rotate without interference. When I was trying to get the exhaust silencer off (which I think is meant to unscrew), the outer part came off leaving me with a length of 21mm OD tube that I can attach the exhaust tubing to. Happily, what was the intake manifold, which is about 19mm OD, can be reversed to also stick out on the same side of the engine as the exhaust. All that I need is some rubber tube and a plastic tee and elbow fitting, and the exhaust is ready to go. While the exhaust valve is smaller than the inlet valve, I don't think that it will make a significant difference to the exhausting on each second revolution. To my uncalibrated eye, the inlet and exhaust lobe shape looks to be very similar, and the lift of each is the same. Murphy does not ordinarily work in my favour like this, so that I have clearly missed something. I will let you know what it is when I have found it. Being able to use the engine's valves for the exhaust overcame a real dilemma for me, as I could not think of a way to get a large diameter solenoid valve to operate satisfactorily for this function via the spark plug hole at engine speed. I am fairly sure that a fuel injector will work via the spark plug hole as an inlet valve for a time at least till maybe rust, wear, or temperature takes its toll. I am looking at using saturated steam at about 4 to 5 bar, which means that the temperature will be somewhere around 140 to 150C, which is not too extreme. The only concern regarding how well an injector will work is the viscosity of the steam relative to the viscosity of the petrol or diesel that it was designed for, but I have yet to look into that. On the up side, the injector running on steam can stay open for almost the full stroke of the piston if necessary, rather than the quick squirt that it has to provide running on fuel. We shall see. Regards Don B |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Hi everyone; I'm back. I started this thread (and promptly forgot about it) with the intent of going from sunlight directly to electricity, but it's gotten off onto another avenue, so in that regard, I think it's time I cleared the playing field a bit: Tracking Collectors: In my experience, tracking, concentrating collectors can be very powerful, but have in inherently greater amount of danger. I've found it best to make the concentrator (parabolic dish or trough, mirror array, etc) stationary and track the sun with a flat-plate mirror (heliostat) instead of trying to move the concentrator. The reason is simple. If you move the concentrator, you move the focal point along with it and you have to somehow overcome all the problems associated with whichever "working fluid" you've decided to use and those problems can be monumental! Edit: Fiddle-faddle! I just remembered something important: I live in the USA and the sun follows a pathway approximately 38-degrees from the equator (latitude), so I track using a heliostat. This won't work if the sun's pathway in the sky is directly overhead, as would be the case for anyone living on or near the equator. So if the shoe fits . . . That is to say, if you live on the equator, all bets are off! I'll have to put on the thinking cap for y'all! Sorry about that! If you still want to make a concentrator, the easiest way is to manufacture a 90-degree cone and line the inside surface with highly reflective material. Bounce the sunlight off the fixed collector parallel to the axis created by connecting the center of the circle end of the cone and the apex. This should be a pipe run in a loop, through which you are to pass your working fluid. Depending on the size of the cone and the size of the focus's surface, you can get concentrations upward of 1,000, so be careful, this puppy can fry you nonetheless! Using Steam: The biggest problem with using steam to run an engine is lubrication. Steam is corrosive. There are two types of steam: wet and dry. Wet steam is the easiest to use, but lubrication becomes a real mess -- not unlike mixing oil with water and shaking vigorously. It's better to build the lubrication into the project using Teflon bearings or something along those lines, so you don't have to introduce liquid lube. Also liquid lubrication tends to burn and then clog as it is recirculated through the focal point. Lots of problems. Dry steam works really well -- until you run your fingers over a little leak and your fingers fall to the ground. Dry steam is usually somewhere around 2,000 psi! For all the above reasons, I use compressed "air" to run things and use solar ONLY for heating situations. I use vegetable oil as a rule, since it's cheap, clean and renewable. I've used used motor oil too, but it's really messy. If you are going to use oil as a working fluid, be sure to invert a capped pipe, which will act as an expansion relief. If you don't do this, your pressure and temperature relief valve will be going off all the time and you'll have oil in places you didn't even know you had places! Hope this helps someone out there. If anyone has a specific question, PM me and I'll answer it. If it's something that seems of interest to all, I'll copy and paste it into the body of the 4m so others can share. Cheers. Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| lwright Newbie  Joined: 14/12/2009 Location: AustraliaPosts: 8 |
Hi Don, Firstly good on you. It's interesting work. I dabbled a couple of years ago in this sort of thing but didn't have much luck. I was using a trough with Mylar film. There's a wealth of info on youtube. http://www.youtube.com/watch?v=Mlm-GVJtyio&feature=related also just search "air engine" in youtube. You might be interested in reading this paper by C.Christopher Newton. This was a beautifully built solar dish but at the end of the day he only got 1.94% efficiency! I think it's possible to do better. Maybe 5-10% http://www.redrok.com/NewtonSolarSteamManuscript.pdf I came to the conclusion that you're better off for small scale solar using an organic working fluid. The geothermal plants use Pentane. I think Freon is now banned but other refrigerants are available but maybe a bit hard to source. I actually think evacuated tubes hold more promise than dishes or troughs that need to track the sun. Here's a great little video from a New Zealand guy: http://www.youtube.com/watch?v=T3MuIcRrnRE Regards, Lee. PS What part of Australia are in you in? 
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GreenD88 Senior Member Joined: 19/05/2009 Location: United StatesPosts: 104 |
http://www.youtube.com/user/greenpowerscience?blend=1&ob=4#p /a/u/1/dI-Zl7nEzA8 Heres a guy who's running a 2 stroke on solar steam, and driving a treadmill motor. A little scary on the tubing he used but hey it worked lol, would have rather seen schedule 80 steel though. Just anyone thinking about using steam, it will eat through about anything copper, schedule 40 steel in a matter of months. Licensed Master Plumber / EPA 608 Universal License / 410a Safety Certified / Medical Gas Brazer/Installer |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
lwright Regarding the "No Petrol" You-Tube link http://www.youtube.com/watch?v=Mlm-GVJtyio&feature=related/: I find it more than curious that the single cylinder engine pictured there is running without a flywheel. Hmm . . . something inherently wrong with that picture. I've built small single-acting, single-cylinder air and steam engines for over 40 years and never once been able to make one run without a flywheel to keep it going between the bottom of the power stroke and the repeating power stroke 180 degrees out! The mass of the shaft won't carry the thing without some push for that other 180 degrees. Also, the crank and journal are counter-balanced within the thing to keep it from hopping around when it runs, so there's no potential for 'momentum' there. Maybe there's some kind of magic happening inside the thing that doesn't show. I see the spark plug is left threaded into the top of the head. Something doesn't add up here! I like to think I'm open-minded; somebody prove me wrong. Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175 |
Macgyver, Quote me if im wrong, but isnt there a flywheel on the other end of that shaft under the cowling. Fluted for creating a fan effect and forcing wind over the head and barrel. Marcus if it aint broke dont fix it!! |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
gpalterpower Yes, there is a "magneto", which is a bit larger than your fist and is segmented to draw in air for cooling. The mass of the thing is great, but it's so close to the center, it offers very little in the way of momentum. I was never able to make an engine run using just the magneto thing. All the air and steam engines I made from old lawnmower engines had to have a larger flywheel to run smoothly, though come to think of it, his little contraption did jump about a bit, so maybe that's what's going on there, I dunno. It just struck me as funny that he did a tight shot of the bare shaft spinning. Perhaps the builder of this thing modified it and that's what's happening. I can't tell by the video he posted. That guy with the big "S" on his chest is the only one I know who can see through steel; not me for sure! I'd be curious how he did the valves. The valves used as they were designed means that pressure is on top of both inlet and exhaust poppet valve forcing each against its seat. I suppose if the inlet pressure weren't too great (at least not great enough to lift the inlet valve), it could be used for air or steam, but I have my doubts (at least it never worked that way for me). To do this, the builder would have had to get into the case and completely re-work the cams. On a 4-cycle engine, the valves work every other cycle and on an air engine, the valves have to work each go-round. As I remember, there is a 2:1 gear inside the case and it also acts as an oil "slinger' to lubricate the piston, con rod, journal bearing and so on. Still, we put a couple blokes on the moon, so maybe this is all on the up-and-up, eh? Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi All I looked at a lot of these engines tied to this link but didnt see any that where performing any useful work and that seems to me to be the issue to hand to salvage some energy from the process and make some electricity from it. Most things can be forced into motion from compressed air but motion isnt useful until some power is achieved from the motion. All the best Bob Foolin Around |
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| Don B Senior Member Joined: 27/09/2008 Location: AustraliaPosts: 190 |
Hi MacGyver If you look back at my post of 5th Jan, you will see that I was intending to modify a Briggs and Stratton 3.5 HP 4 stroke lawn mower engine into a 2 stroke steam engine. I managed to cut the camshaft and re-align the inlet cam lobe so that it was 180 degrees opposite the exhaust cam. This meant that I can use both the inlet and the exhaust valves alternately as exhaust valves. So far so good. I then found a problem putting the camshaft back so that the valves lifted on the upstroke of the piston, as the camshaft lobes interferred with the crankshaft balance weights unless I set the camshaft to a position where the exhaust valves were opening way early on the downstroke. I also found that the fuel injector solenoid that I had intended to use in the spark plug hole as the inlet valve did not permit a sufficient flow rate of compressed air (at about 60 psi) to kick the piston around in any useful manner. I even found that I could improve the flow rate by carefully grinding the tip of the injector to remove the 4 metering holes and expose part of the needle valve, but this was still not enough. Initially, I just experimented by switching the injector with the existing points, but the on time was too brief and started before TDC. My next effort involved reed switches triggered by the flywheel magneto magnets, plus some electronics to give only one on and one off from the reed switches per downstroke. All that I needed now was a bigger solenoid, yet one that could handle the large number of short time pulses that would be needed to operate as an engine. Unfortunately, being stuck with early opening exhaust valves was causing major problems. I initially thought that this was the price that I needed to pay for altering the inlet cam position, till I realised that the exhaust cam, which also caused interference problems, was still in its original position on the camshaft, and must have been capable of working satisfactorily. Clearly, I had missed something, so that I need to pull the engine apart again and try to find the correct alignment for the camshaft gearing. Unfortunately, there was no alignment mark on the crankshaft of the engine that I modified (or maybe it had worn off as it is an old engine), and I was not smart enough to put one there before I dismantled it. Luckily, though, I have another identical engine in better order that I have yet to dismantle, and I can use that to check the correct camshaft gear alignment. Once I resolve the camshaft alignment problem, I think that the exhaust arrangement using both valves alternately will be very satisfactory. The main thing that I need to tackle now is to get the inlet valve solenoid arrangement working satisfactorily. My junk box has yielded up a 24V AC solenoid that may serve this purpose, though I have yet to try it. (BTW, I have found that most 24V AC solenoids work perfectly well on 12V DC). I would be very interested to hear what you were using for inlet valving in the engine conversions that you have built. I would also like to endorse Bob's remark that it is all very well to make an engine that rotates somehow, but that is not really any sort of achievement until you can get some useful (and sustained) work out of it. Regards Don B |
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| Don B Senior Member Joined: 27/09/2008 Location: AustraliaPosts: 190 |
Hi Lee Many thanks for your post, and the links (that I have yet to look at). To answer your question on location, I live just North of Brisbane. The parabolic trough in the photo looks as though it should have been able to gather some useful heat, but I would be interested to know how the sun was to be tracked with it. From my reading, it appears that a properly set out parabolic trough is like a spotlight in reverse. Unless you can somehow keep it accurately pointing directly at the sun as it moves across the sky, its energy gathering capability falls away dramatically. You almost need something like a gymbal mounting and the shadow from a set of cross hairs for this (or better yet, an automatic tracking system). It also looks as though the tube at the focus is highly polished, which is just the opposite of what you need to absorb heat. Maybe a coat of black high temperature exhaust paint would have helped (providing that you had some way of then removing the heat energy that you were collecting, like filling the tube with water). Regards Don Don B |
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| lwright Newbie Joined: 14/12/2009 Location: AustraliaPosts: 8 |
Hi Don, Tracking was achieved using a circuit that a technician friend of mine built using a couple of green LED's but just noticed you can buy one ebay for $22! http://cgi.ebay.com.au/basic-LED-Solar-Sensor-unboxed-solar- tracker-DIY_W0QQitemZ200419562043QQcmdZViewItemQQptZAU_Gadge ts?hash=item2ea9efd23b The sensor circuit controlled a windscreen wiper motor hooked to a 12v battery. A cable was wrapped around the spindle & seemed to move at the right speed. A counterweight was used on the other side. I used thin cable that would break in event of a failure (tremendous torque potential of motor) There were some reed switches at each end to stop it going too far. Seemed to track the sun pretty well. 
This design of trough has a major flaw. Because the sides are enclosed, as the sun goes off axis, the light shines on the sides (caught on fire once!). What you need is open sides & the receiver needs to extend further out the sides. It's probably better to build wider rather long as I did. Here is a second prototype which was better. I'll see if I can find more pics of it. 
The receiver is actually black. It's copper pipe that I painted with flat black paint. It just looks shinny when the light is concentrated on it. Hope this helps. Lee. |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
[Quote=Don B]I would be very interested to hear what you were using for inlet valving in the engine conversions that you have built. Yup; there's an easier way. Of course, I say easer owning a lathe and I don't know if you have one or have access to one, but it's necessary. If you're going to build engines and windmills, a lathe and a mill in your shop are akin to blood in your veins; gotta have the tools! How I done it: What I did was remove the magneto and use the little tapped posts that are part of the finned head of the engine to attach my valve body. To these posts, I attached a block of aluminum (or sometimes HDBE) through which I had line-bored a cylinder to house a spool valve. Remember that these things, even though (or maybe especially though) they are small, have to run true or it won't fly. You'll need to allow enough room for the cam to wobble up and down and push a crank pin, which is attached like a lever at the cam end as well as at the spool-valve end. It will have to take up both linear as well as side-to-side motion. In a "steam" engine, there is a part called a "cross-head" and it just slides back and forth. The con rod from the piston is on one end and the crank pin is on the other. The cross-head just slides back and forth. In fact, a lawnmower engine with the valves removed and the crank case over-full of oil makes a dandy cross head. Just attach the steam engine's con rod to the top of the lawnmower engine's piston and you're off and running. The Valve: I made a brass cam and fastened it to the spindle that the magneto was hooked to. If you're lucky, you can cut off the threaded portion (some lawnmower motors) of the magneto and use it to snug up alongside the brass cam. The cam attaches to the main spindle via a set screw that YOU build. Now you see you'll need a good numbered, lettered and fractional drill bit set as well as a good set of taps and dies. Remember what I said, "Gotta have the tools!" I then cut a steel cam follower, which is part on the crank end of a connecting rod. It has two bolts (or screws) that hold the halves together in a car engine, but for my little toys, I just cut the whole thing out of steel. Steel against brass wears very nicely, but needs oiling. I used "hypoid 90", which is really grease and it stays on the exposed bearing surfaces nicely. If you're running steam, it gets hot and you'll have to figure out a way to oil it while it's in motion. A "cup" can be used, but I'm getting off subject. Whether you're running steam or air, the tolerances must be no more than a thousandth (that's .001) or things will thrash at high speed and stick at low speed. I try to shoot for a tenth (.0001). All it takes is patience and a good micrometer. See, another tool! With a "cam" you can rotate it to the exact position you want to start air or steam entering the cylinder as well as exhaust leaving (same valve). On a multi-cylinder or on a "double-acting" engine, you can mount a crescent-shaped bar to operate on the main cam and cut a slot in the bar so you can pin a lever to it and move the point at which the cam moves the bar to several degrees before or after TDC (top dead center). This will give you "forward" or 'reverse". The piston can stop on a dime and go the other direction without pause. It does it each time at the end of each stroke and really doesn't care at all. Peruse You Tube by entering "Model Steam Engines" and you'll see several examples of forward and reverse valves on the show-'n-tell stuff there. I opened up the case of the lawn mower engine and left the cams and gears inside, but removed each poppet valve, cut the stem down and replaced each in its hole. They are different shaft sizes, so be careful when you are replacing them into the engine. The new head (made of a solid piece of aluminum) and head gasket cover the valve ports and mash the old valves down against their seats so they don't leak. I also made sure there was a "breather" on the crank case, so as the guts flew around, any air displaced had a place to go. Now you know. Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Don There is a standard 3/8 solinoid valve that works OK up about 500 rpm available on ebay set it to switch on about 5 deg before TDC and switch off between 45 deg and 90 Atdc depending on load, the inertial limitations of the solinoide wiil restrict the top revs, these are available at about $24 only, or try to get a smaller one if you can 1/8 is ideal you may pick up one as a fuel controller on a dual fuel car. you will need to modify your cam so both lobes are 180 deg apart and use both ports as exhaust as the cam is Half engine speed for 4 stroke now you are using it as a two stroke cycle so unless you want to build up another lobe on each one this is easier. All the best Bob Foolin Around |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Me again Don If you plan to do some uswful work with your engine it is best to include a small inline air tool oiler in your air line as the air pressure stops the lube oil coming up around the rings as it would on a normal engine. The bore will run to dry of oil and score the alloy bore quite quickly however for a test a couple of squirts with oil can ok for a few min running. Bob Foolin Around |
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| Don B Senior Member Joined: 27/09/2008 Location: AustraliaPosts: 190 |
Hi Lee Thanks for the further comments re the tracking of your collector trough. As the width looks to be about 4 times the depth, and the collector pipe is about level with the top of the sides, I assume that it is set out as a classic top focus parabola (y = 4X sq, etc). I am intrigued at the use of the 2 LEDs as part of the tracking circuit. Were they being used as the actual photo detector devices (which I believe is possible), or were they just being used to indicate when the electric motor was running? Another question is, what did you do with the heat energy that you gathered? Hi MacGyver, Thanks for the detailed explanation on how you set up your inlet valving. Yes I do have a lathe, but I would not describe myself as a tradesman's bootlace, so that I would prefer to find all of the reasons why I can't use some sort of solenoid valve for the inlet valving till I have to finally resort to mechanical alternatives. One particular reason for looking to solenoids is that, if I can readily control the number of engine rotational degrees during which the inlet valve opens, my speed and hence power control becomes very simple. Hi Bob, I am still grappling with the XXXX Briggs and Stratton camshaft/crankshaft clearance concerns (and also a tendency for gratuitous alliteration). When set for the exhaust valve to open from 180 to 360 degrees of rotation, the exhaust camshaft lobe interferes with the con rod big end bearing. Luckily, I have on hand a blue striped butcher's apron foe occasions like this, so that tomorrow I will put it on and grind the offending corner off the cam lobe. There should still be ample meat in what is left to work satisfactorily (at least for my lifetime). I will let you know if I have any success. If I do, then I will move on to setting this up as a three cylinder engine, then maybe get more serious about a collector design. Regards Don B |
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| oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
Just a thought... if you do as Bob suggests, and build up extra lobes 180 degrees away from the current ones.... you could use the inlet valve as your inlet, and the exhaust for the exhaust, and this may give you much better air flow... rather than squeezing it in via an injector....ie each lobe is an ellipse with the cam shaft passing through the center. .........oztules Village idiot...or... just another hack out of his depth |
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