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RE: need help with diesel rc engine!! help asap!!
ORIGINAL: Recycled Flyer ORIGINAL: AndyW I had to do a double take when I saw how early on this thread was started. Back in the fall of 2006 I got a Norvel .15 to run on pure, B100 Biodiesel. http://www.youtube.com/watch?v=PgxIywcu7UQ There was no ether, nor kerosene, not even oil in the mix. Only 2% Amsoil Cetane Booster was added. As can be seen, the run is strong and steady. BUT, any deviation, such as throttling, would threaten the run. It would take a lot of anguished pleading to Zeus before the engine would clear its throat and continue to make the music you hear in this video. I'm convinced, as has been pointed out, that atomization of the fuel is the culprit. Neither kerosene and especially not BD, will vapourize easily. Ether is very volatile and serves that purpose well. But we want a virtual, one component fuel. One way to achieve that is to pre-heat the fuel as it enters the carburetor. Then, with the heat of the running engine, further vapourization may take place. The result of running pure, B100 to the engine, has been premature wear in the crank to case fit. MUCH compression is needed to run B100 and with the many attempts to start the engine we now have a lot of slop n the crank to case fit. We will, going forward, use a ball bearinged, Norvel .15 utilizing the more robust and bronze bushed, Enya rod. (Or more easily run the exhaust plumbing around the intake as a preheat manifold.) Cheers. But what has me visiting the idea again is the acquisition of some commercial BioDiesel and refinement of my own process. In both cases I have fuel with a much lower viscosity than I had when the video was taken. This winter will see work on a ball bearinged, Norvel .15 with a true and proper muffler that'll be bolted on. No more case distortion doing it the old way. |
RE: need help with diesel rc engine!! help asap!!
Very cool Andy. Let us know more in due course.
The "heat exchanger" concept is interesting. |
RE: need help with diesel rc engine!! help asap!!
ORIGINAL: AndyW ORIGINAL: Recycled Flyer ORIGINAL: AndyW I had to do a double take when I saw how early on this thread was started. Back in the fall of 2006 I got a Norvel .15 to run on pure, B100 Biodiesel. http://www.youtube.com/watch?v=PgxIywcu7UQ There was no ether, nor kerosene, not even oil in the mix. Only 2% Amsoil Cetane Booster was added. As can be seen, the run is strong and steady. BUT, any deviation, such as throttling, would threaten the run. It would take a lot of anguished pleading to Zeus before the engine would clear its throat and continue to make the music you hear in this video. I'm convinced, as has been pointed out, that atomization of the fuel is the culprit. Neither kerosene and especially not BD, will vapourize easily. Ether is very volatile and serves that purpose well. But we want a virtual, one component fuel. One way to achieve that is to pre-heat the fuel as it enters the carburetor. Then, with the heat of the running engine, further vapourization may take place. The result of running pure, B100 to the engine, has been premature wear in the crank to case fit. MUCH compression is needed to run B100 and with the many attempts to start the engine we now have a lot of slop n the crank to case fit. We will, going forward, use a ball bearinged, Norvel .15 utilizing the more robust and bronze bushed, Enya rod. (Or more easily run the exhaust plumbing around the intake as a preheat manifold.) Cheers. But what has me visiting the idea again is the acquisition of some commercial BioDiesel and refinement of my own process. In both cases I have fuel with a much lower viscosity than I had when the video was taken. This winter will see work on a ball bearinged, Norvel .15 with a true and proper muffler that'll be bolted on. No more case distortion doing it the old way. You seem to be only considering preheating the fuel, but what about the air going through the intake also? I know that hot air has less 'power' available for an engine but it just might help here. And if atomisation is the goal here you might consider the 'wick' systems that control line speed flyers sometimes use instead of normal spraybars. They offer the absolute best in atomisation (or so I am lead to believe) or failing that have you seen the peripheral jet system used in high performance Cox engines? Another thing to watch out for is the fuel mist coalescing upon contact with inside of the crank case and here you might want to investigate the 'paddling' effect of the conrod and crank web to stir up the mix even further. (Most engines are designed to do the exact opposite in search of speed and power.) Cheers. |
RE: need help with diesel rc engine!! help asap!!
Those are good points, thanks. In fact, in my former life, running a Mine and Mill Supply Store, we sold lubrication systems for pneumatic tools and such. Typically, these would inject a special tool oil into the air lines at a measured rate. One company proved that, no matter how well atomized the input was, eventually, not far down the line, the oil would settle on to the walls of the line and make its way around the system in small droplets. One illustration of this effect is remote needle valves in some of our engines. Tweaking the main needle takes a second or so to affect the engine. That's droplets making their way to the carb.
One solution they offered was to heat the oil and that helped. But as you point out, cool air is a factor and this meant that they had to install multiple, smaller devices throughout the system. This made their product more expensive and droplets spreading throughout the system worked well enough so we didn't sell many. Never forgot that. Our engines eventually get hot, even down to the crankcase and the carb and I suppose this helps. We try our best to atomize the fuel so that it turns into a burnable, gas. That's my understanding. I tend to run my engines late into darkness with a trouble light to illuminate my surroundings. This is where, with the head off, you can see how well the bypasses do their job. With the 5 port, Norvels, (Big Migs) hand flipping, which simulates low throttle or idling, atomization is quite good. I've also seen that with a PAW .06 that was converted to glow. The AME Norvels have 3 bypass ports and they don't, at low RPM (hand flipping) don't do as good a job. But the AMEs are rigged for higher power and I assume that under full RPMs, atomization is effective enough. I suspect that this is why the Big Migs can be made to idle and transition readily while this is more difficult to achieve with the AMEs. About spray bars, I have an article somewhere that shows that a tube that sticks into the airstream is the most efficient and in fact, the way Cox does it, not so. I suppose that this is why Cox needs three holes. The simpler, Norvel 15 throttles have only a hole in the barrel to pull fuel into the engine. Installing a tube required turning in the main needle. This means that the engine was drawing the fuel into the engine more powerfully. In addition, filing a taper, (from underneath) required again, tweaking in the main needle. This in turn leaned out the idle to the point where an adjustable airbleed became effective for final tuning. This simpler throttle works as well as a two needle throttle. |
RE: need help with diesel rc engine!! help asap!!
ORIGINAL: AndyW About spray bars, I have an article somewhere that shows that a tube that sticks into the airstream is the most efficient and in fact, the way Cox does it, not so. I suppose that this is why Cox needs three holes. The simpler, Norvel 15 throttles have only a hole in the barrel to pull fuel into the engine. Installing a tube required turning in the main needle. This means that the engine was drawing the fuel into the engine more powerfully. In addition, filing a taper, (from underneath) required again, tweaking in the main needle. This in turn leaned out the idle to the point where an adjustable airbleed became effective for final tuning. This simpler throttle works as well as a two needle throttle. Please accept here that Iam no expert on these matters, I am just an avid observer. In control engines, a spray bar that ends halfway into the venturi (commonly called a spigot) has the best draw because it has the fastest airflow past it and consequently the most reliable run but due to it being centrally located has the least amount of surface area available to it in which to release the fuel into the air ( it has just one hole available to it.) Atomisation is at its worst here but being a non critical system it is very stable against load changes, G forces, throttling etc. Contrast this with a perpheral jet venturi, this has the worst possible draw as it has boundary layer friction to overcome but has the greatest amount of surface area in which to release its load. Atomisation is at its best here but it is a critical sytem and the least constant method as it varies greatly with load, G forces throttling etc. A lot of control line stunt fliers tend to like the central jet method as they prize constant runs through maneouvers above all, whereas diesel Team Racers like the peripheral jet method as they need all the speed and range they can get and to hell with the G forces! So what I am getting at here is if you have atomisation as your goal then the more jets in the greatest amount of surface area possible will benefit you and the 'tube sticking into the airstream' is the least effecient way of achieving this. I hope that this helps. |
RE: need help with diesel rc engine!! help asap!!
ORIGINAL: AndyW Those are good points, thanks. In fact, in my former life, running a Mine and Mill Supply Store, we sold lubrication systems for pneumatic tools and such. Typically, these would inject a special tool oil into the air lines at a measured rate. One company proved that, no matter how well atomized the input was, eventually, not far down the line, the oil would settle on to the walls of the line and make its way around the system in small droplets. One illustration of this effect is remote needle valves in some of our engines. Tweaking the main needle takes a second or so to affect the engine. That's droplets making their way to the carb. One solution they offered was to heat the oil and that helped. But as you point out, cool air is a factor and this meant that they had to install multiple, smaller devices throughout the system. This made their product more expensive and droplets spreading throughout the system worked well enough so we didn't sell many. Never forgot that. Our engines eventually get hot, even down to the crankcase and the carb and I suppose this helps. We try our best to atomize the fuel so that it turns into a burnable, gas. That's my understanding. I tend to run my engines late into darkness with a trouble light to illuminate my surroundings. This is where, with the head off, you can see how well the bypasses do their job. With the 5 port, Norvels, (Big Migs) hand flipping, which simulates low throttle or idling, atomization is quite good. I've also seen that with a PAW .06 that was converted to glow. The AME Norvels have 3 bypass ports and they don't, at low RPM (hand flipping) don't do as good a job. But the AMEs are rigged for higher power and I assume that under full RPMs, atomization is effective enough. I suspect that this is why the Big Migs can be made to idle and transition readily while this is more difficult to achieve with the AMEs. About spray bars, I have an article somewhere that shows that a tube that sticks into the airstream is the most efficient and in fact, the way Cox does it, not so. I suppose that this is why Cox needs three holes. The simpler, Norvel 15 throttles have only a hole in the barrel to pull fuel into the engine. Installing a tube required turning in the main needle. This means that the engine was drawing the fuel into the engine more powerfully. In addition, filing a taper, (from underneath) required again, tweaking in the main needle. This in turn leaned out the idle to the point where an adjustable airbleed became effective for final tuning. This simpler throttle works as well as a two needle throttle. I've often wondered about the possibility of removing the fuel/air mixing function of the venturi and putting it elsewhere. I believe that when the Fox 15BB glow was the hot c/l FAI combat motor that some of it's users found that they could inject the fuel from a bladder directly from a spraybar tapped into a single hole in the engine backplate. The fuel/air was mixed in the crankcase helped no doubt by the revolving crankweb and conrod. This would still allow the air intake to be done via a throttle, richening and leaning the fuel is another matter. Bladders don't work very well with diesel fuel, but there is a way around this. I'm wondering if a tin tank could be used pressurised by a seperate bladder containing air alone. Perhaps the system would work on suction? Numerous fuel mixing ideas have been tried over the years including a small supercharger on the intake. See below. |
RE: need help with diesel rc engine!! help asap!!
ORIGINAL: Recycled Flayer ORIGINAL: AndyW About spray bars, I have an article somewhere that shows that a tube that sticks into the airstream is the most efficient and in fact, the way Cox does it, not so. I suppose that this is why Cox needs three holes. The simpler, Norvel 15 throttles have only a hole in the barrel to pull fuel into the engine. Installing a tube required turning in the main needle. This means that the engine was drawing the fuel into the engine more powerfully. In addition, filing a taper, (from underneath) required again, tweaking in the main needle. This in turn leaned out the idle to the point where an adjustable airbleed became effective for final tuning. This simpler throttle works as well as a two needle throttle. Please accept here that I am no expert on these matters, I am just an avid observer. In control engines, a spray bar that ends halfway into the venturi (commonly called a spigot) has the best draw because it has the fastest airflow past it and consequently the most reliable run but due to it being centrally located has the least amount of surface area available to it in which to release the fuel into the air ( it has just one hole available to it.) Atomization is at its worst here but being a non critical system it is very stable against load changes, G forces, throttling etc. Contrast this with a peripheral jet venturi, this has the worst possible draw as it has boundary layer friction to overcome but has the greatest amount of surface area in which to release its load. Atomization is at its best here but it is a critical system and the least constant method as it varies greatly with load, G forces throttling etc. A lot of control line stunt fliers tend to like the central jet method as they prize constant runs through maneuvers above all, whereas diesel Team Racers like the peripheral jet method as they need all the speed and range they can get and to hell with the G forces! So what I am getting at here is if you have atomization as your goal then the more jets in the greatest amount of surface area possible will benefit you and the 'tube sticking into the airstream' is the least efficient way of achieving this. I hope that this helps. I did notice that on both the VA MK1 and MK2 engine, looking into the barrel at full bore, you could see the fuel, literally pouring out of the tip of the spigot in a smooth, narrow stream of basically, raw, liquid fuel. If any atomization was being done, it wasn't a whole lot. Atomization wouldn't produce a stream. It SHOULD be a mist. So I take your point. But the VAs run great so perhaps effective atomization leading to a gaseous fuel mix depends on other factors. One of these, I'm convinced, is how effectively the ports deliver the fuel to the combustion chamber. As five port, Big Migs work better in this regard, perhaps instead of the five port Big Mig, we work up a multi port system,,, say 12 or more. Or, instead of bypasses, how about very small spray HOLES. More complicated, unconventional systems, may work really well for their intended purpose but what I want is an RC engine running on (almost) 100% Biodiesel. An RC engine that has perfect throttling, nacherly. |
RE: need help with diesel rc engine!! help asap!!
Keep in mind that putting a spraybar in the venturi reduces the area and increases air velocity. So the addition of a spraybar is changing more than one feature int he design.
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RE: need help with diesel rc engine!! help asap!!
ORIGINAL: gkamysz Keep in mind that putting a spraybar in the venturi reduces the area and increases air velocity. So the addition of a spraybar is changing more than one feature int he design. I have it from a very experienced Team Race flyer that some of the atomisation is done at the fuels entry into the engine, then is lost from the mist coalescing back onto the crankcases inner surface and then regained by the high pressure transfer system. The weak link here seems to be the cold crankcase walls so perhaps you might investigate the heating of lower crankcase by using the exhaust gases. Any heating of the intake would seem to me to be a bad idea with volatile fuels ( and just what you achieve by heating up the little amount that flows through the spraybar anyway?) but perhaps if you are using a no ether mix it just might work well enough for you. I would much rather preheat the entire fuel air mix in situ if it can be done in any meaningful way. Cheers. |
RE: need help with diesel rc engine!! help asap!!
The crankcase of the diesel is hardly cold. Much of the kerosene isn't vaporizing in the first place, and probably isn't until it's compressed in the cylinder. Being finely atomized helps vaporization at any point in it's travels through the engine. It's well known a good portion of the fuel runs along the walls of the manifolds and passages before it reaches the combustion chamber. Fuels with low vapor pressures are much more susceptible.
Perhaps Jens will post his Mills advert. |
RE: need help with diesel rc engine!! help asap!!
ORIGINAL: gkamysz The crankcase of the diesel is hardly cold. Much of the kerosene isn't vaporizing in the first place, and probably isn't until it's compressed in the cylinder. Being finely atomized helps vaporization at any point in it's travels through the engine. It's well known a good portion of the fuel runs along the walls of the manifolds and passages before it reaches the combustion chamber. Fuels with low vapor pressures are much more susceptible. Perhaps Jens will post his Mills advert. You can see why we need time to warm up the diesel engine before the last fine tuning of fuel main needle and compression screw then the engine will go in full effect. It will vary depending on weather temperature and moisture. |
RE: need help with diesel rc engine!! help asap!!
ORIGINAL: gkamysz The crankcase of the diesel is hardly cold. Much of the kerosene isn't vaporizing in the first place, and probably isn't until it's compressed in the cylinder. Being finely atomized helps vaporization at any point in it's travels through the engine. It's well known a good portion of the fuel runs along the walls of the manifolds and passages before it reaches the combustion chamber. Fuels with low vapor pressures are much more susceptible. Perhaps Jens will post his Mills advert. The lower crankcase is hardly hot either when compared to the head and my point is that if we can get all the engines surfaces that come into contact with the fuel air mix as hot as possible after the spraybar then the fuel is far more likely to evaporate into a pure gaseous state. Ihave seen diesels run better with hot cowled in lower crankcases that result in the heat soaking through the entire casting. And as to the Mills advert - do you mean the one where the head is removed from the engine and it is then spun over with the fuel air mix spraying into the air showing 'how efficient the atomisation is?' Ithink that only shows what it looks like only with the head removed and wonder exactly how it would look with the head back on! Cheers. Reference - http://modelenginenews.org/ Mills 1.3 Mk 1 "In 1944, to promote the Mk II 1.3, Mills Bros published a series of what we'd today call "Infomercials" under the title "diesel design". There were four of these as seen above. The first in the series that shows how the patented Mills transfer system provided superior atomization pegs my scept-o-meter and bends the needle. I think that with careful adjustment of the needle, any engine could be posed to show both characteristics. That's one patent I'd like to read carefully. The other pages in the series are more kosher, though rather biased to show Mills in the best light—and why not as it was their dime, so to speak." |
RE: need help with diesel rc engine!! help asap!!
Great information guys, thanks. Standard, diesel fuel contains kerosene which doesn't vapourize easily. Ether, which does. Oil, which works hard not to. Oil viscosity could be a factor I presume. So does the ratio of the components.
What happens though, to the molecules of each component ? Does one bind to the other? Is this why you need ether to mix with the Castor first and then the kerosene will mix with that? In any case, with a virtual, one component fuel, we can concentrate on a mechanical means to maximize vapourization. That 1949 Mills demo is quite impressive. How do our modern, glow engines, converted to diesel compare, is the question, I guess. Can anyone post details on the innards of a Mills engine ? There are a couple of guys that do engine mods to car engines to improve power, throttling etc. etc. One of the mods is to grind slots on the outer edge of the counterbalance. And there's also some pretty weird, convoluted porting designs in some of these engines as pictured. That one is for a .30 engine. Then there's the conrod. That piece oscillates in tune with the RPM. Car engines are made to spin in the 25 to 30K range. Many have the stem of the rod shaped like a two edged sword,,, I presume to minimize drag. Our engines spin far more slowly, so drag not so important ? Then how about milling an "H" beam cross section into a rod to really stir up those droplets. |
RE: need help with diesel rc engine!! help asap!!
ORIGINAL: AndyW In any case, with a virtual, one component fuel, we can concentrate on a mechanical means to maximize vapourization. That 1949 Mills demo is quite impressive. How do our modern, glow engines, converted to diesel compare, is the question, I guess. Can anyone post details on the innards of a Mills engine ? Here are the pics.. |
RE: need help with diesel rc engine!! help asap!!
ORIGINAL: AndyW Great information guys, thanks. Standard, diesel fuel contains kerosene which doesn't vapourize easily. Ether, which does. Oil, which works hard not to. Oil viscosity could be a factor I presume. So does the ratio of the components. What happens though, to the molecules of each component ? Does one bind to the other? Is this why you need ether to mix with the Castor first and then the kerosene will mix with that? In any case, with a virtual, one component fuel, we can concentrate on a mechanical means to maximize vapourization. That 1949 Mills demo is quite impressive. How do our modern, glow engines, converted to diesel compare, is the question, I guess. Can anyone post details on the innards of a Mills engine ? There are a couple of guys that do engine mods to car engines to improve power, throttling etc. etc. One of the mods is to grind slots on the outer edge of the counterbalance. And there's also some pretty weird, convoluted porting designs in some of these engines as pictured. That one is for a .30 engine. Then there's the conrod. That piece oscillates in tune with the RPM. Car engines are made to spin in the 25 to 30K range. Many have the stem of the rod shaped like a two edged sword,,, I presume to minimize drag. Our engines spin far more slowly, so drag not so important ? Then how about milling an "H" beam cross section into a rod to really stir up those droplets. So when mixing up model diesel fuel you dissolve the ether and the castor completely then add the kero and finally the ignition improver. Secondly I am not at all impressed by the Mills advert and that is all it is. A company promoting a system that no modern engine would even look at and my scepticism is backed up by Rons Model Engineering web site.If it was scientifically proven that smashing two transfer ports fuel charges together against a piston top baffle or cutaway then why aren't we all doing it? And how easy would it be to rig a photo session like that? "Oh lets make the competitions engine flood then flick it over so that it sprays coarse droplets everywhere and make ours nice and lean and the pick the best photo out of the thirty we just shot." I have been in advertising for 35 years and I know how easy it is to make something look like it isn't. (End rant!) Car engines I know little about but I can recognise a knife edge rod when Isee one - just go talk to the go kart engine builders, this rods are deemed disposable but do indeed slice through the air rather well. The best model diesel con rods are solid and rectangular in section and need to be in order to survive the entire life of the engine. |
RE: need help with diesel rc engine!! help asap!!
ORIGINAL: Recycled Flyer ORIGINAL: AndyW Great information guys, thanks. Standard, diesel fuel contains kerosene which doesn't vapourize easily. Ether, which does. Oil, which works hard not to. Oil viscosity could be a factor I presume. So does the ratio of the components. What happens though, to the molecules of each component ? Does one bind to the other? Is this why you need ether to mix with the Castor first and then the kerosene will mix with that? In any case, with a virtual, one component fuel, we can concentrate on a mechanical means to maximize vapourization. That 1949 Mills demo is quite impressive. How do our modern, glow engines, converted to diesel compare, is the question, I guess. Can anyone post details on the innards of a Mills engine ? There are a couple of guys that do engine mods to car engines to improve power, throttling etc. etc. One of the mods is to grind slots on the outer edge of the counterbalance. And there's also some pretty weird, convoluted porting designs in some of these engines as pictured. That one is for a .30 engine. Then there's the conrod. That piece oscillates in tune with the RPM. Car engines are made to spin in the 25 to 30K range. Many have the stem of the rod shaped like a two edged sword,,, I presume to minimize drag. Our engines spin far more slowly, so drag not so important ? Then how about milling an ''H'' beam cross section into a rod to really stir up those droplets. So when mixing up model diesel fuel you dissolve the ether and the castor completely then add the kero and finally the ignition improver. Secondly I am not at all impressed by the Mills advert and that is all it is. A company promoting a system that no modern engine would even look at and my scepticism is backed up by Rons Model Engineering web site. If it was scientifically proven that smashing two transfer ports fuel charges together against a piston top baffle or cutaway then why aren't we all doing it? And how easy would it be to rig a photo session like that? ''Oh lets make the competitions engine flood then flick it over so that it sprays coarse droplets everywhere and make ours nice and lean and the pick the best photo out of the thirty we just shot.'' I have been in advertising for 35 years and I know how easy it is to make something look like it isn't. (End rant!) Car engines I know little about but I can recognise a knife edge rod when I see one - just go talk to the go kart engine builders, this rods are deemed disposable but do indeed slice through the air rather well. The best model diesel con rods are solid and rectangular in section and need to be in order to survive the entire life of the engine. Rods aren't only replaced in Karts. Most model engines used in performance events will have their rods replaced as soon as the slightest wear is obvious. PAW recommends for example that the conrods in their racing engines be replaced after accumulating about two hours of high speed running. Each time my R250 has gone back to the manufacturer for a "refresh" it has come back with a new conrod as well. Sports engine conrods may very well last the lifetime of the motor, but the conrod is usually the engine part that is under the most stress and wears the quickest. A recent fashion amongst model car and buggy motor manufacturers and tuners has been the so called "Turbo" crankshaft. IIRC the shaft counterweight is sculpted asymmetrically to enhance gas flow out of the crankhole, and to promote turbulence. I'll see if I can find a picture. By the way "smashing transfer ports fuel charges together" is exactly the way that the famous "Oliver porting" works in diesels. Four peripheral ports are aligned so that the charge collides in the combustion space at the same point. Ray |
RE: need help with diesel rc engine!! help asap!!
Way back a few years ago, I started a thread about trying to eliminate the need for ether in our fuel mix. I made up a fuel that contained no ether at all, just 20% Klotz, Benol castor and 78% kerosene and 2% MEKP. I had no trouble getting the engine started by using an electric starter. The prime bottle had the usual amount of ether though.
When it was said that you can't run model, diesel engines without ether, what was really happening was that you couldn't HAND start a model, diesel engine without ether in the fuel. The engines ran just fine with no ether including a PAW and a Norvel conversion. Then it was pointed out that you can't run model, diesel engines without ether in the fuel because the castor would not mix with the kerosene without the aid of ether. Well, Klotz Benol castor oil for two strokes blended all on its own with kerosene. But only if you were above a certain temperature. That temperature was determined to be, I believe, above 60 F. So it's the much less refined castor of old that wouldn't blend with kerosene on its own. Just to set the record straight. ;) And oh boy, it looks like I'll have to get me a Mills from Ed Carlson and try and run Biodiesel in it,,, just to see. Another thing to try is to cut a step into the top of a stock, AAN, Norvel piston and regain the timing by shimming up the cylinder. It would be easy to set the engines up at night with just a starter spinning them while they pumped the fuel out. Easy too to take a video clip and get a real good look. Slow-mo and all that. Then you go and run the engines the next day. :D[8D]:D |
RE: need help with diesel rc engine!! help asap!!
Hi Ray,
Got nothing against Oliver porting but in the Mills its vastly different. The Mills piston seems to have a step machined out of it that acts as a deflector and pretty much works like running into a brick wall as far as gas flow is concerned and the term 'smashing' here is very accurate. And how much 'seperation' is achieved with both of those ports being side by side and very close together? Obviously the Oliver has no such step or deflector, nor does it need one as radial porting would prohibit this. Spiral fluting ground into the crank web and eminating from the central hole out to the periphery I have seen before - it looks very purposeful indeed! Is this pic what you mean Ray? |
RE: need help with diesel rc engine!! help asap!!
I've modified Norvel cranks, .06 and .15 that way and gained 5 to 800 RPM.
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RE: need help with diesel rc engine!! help asap!!
ORIGINAL: Recycled Flyer Hi Ray, Got nothing against Oliver porting but in the Mills its vastly different. The Mills piston seems to have a step machined out of it that acts as a deflector and pretty much works like running into a brick wall as far as gas flow is concerned and the term 'smashing' here is very accurate. And how much 'seperation' is achieved with both of those ports being side by side and very close together? Obviously the Oliver has no such step or deflector, nor does it need one as radial porting would prohibit this. Spiral fluting ground into the crank web and eminating from the central hole out to the periphery I have seen before - it looks very purposeful indeed! Is this pic what you mean Ray? My point about the Oliver porting was that the streams of gas collide as well. Don't laugh at Mills porting, it's still used I suspect in the modern MPjet sideport diesels. Also the Mills is an absolutely delightful sports Free Flight diesel because of it's porting. Andy, I mentioned in your previous post that you hadn't discovered anything new! An oldtimer in my club used to start his Mills .75 on a prime with an ether based brew, and while it run that out he would quickly fill the tank with a brew containing just oil and kero. It ran just the same, but then it's long been known that a mills will run on just about anything. By the way the one's that Carlson has are rather poor replica's of the Mills. The best are Doonside or Irvine which often turn up on Ebay. Pics: LHS PAW 09 TBR diesel. RHS Brodak 25 for B Class Team Race, standard and modified "Turbo" cranks Ray |
RE: need help with diesel rc engine!! help asap!!
You will be able to run a crankcase only so hot before the temperature rise in the bearing journals becomes excessive a conventional lubricants do not suffice.
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RE: need help with diesel rc engine!! help asap!!
ORIGINAL: locktite401 No I don't think so, it's far more assymmetric than that. There's a pic of my PAW 09 TBR Team Race motor below. That's the best I can find right now although I have a pic of a better example somewhere. By the way notice it's non-standard bushed rectangular section rod. It's about the fifth or sixth that motor had. My point about the Oliver porting was that the streams of gas collide as well. Don't laugh at Mills porting, it's still used I suspect in the modern MPjet sideport diesels. Also the Mills is an absolutely delightful sports Free Flight diesel because of it's porting. Andy, I mentioned in your previous post that you hadn't discovered anything new! An oldtimer in my club used to start his Mills .75 on a prime with an ether based brew, and while it run that out he would quickly fill the tank with a brew containing just oil and kero. It ran just the same, but then it's long been known that a mills will run on just about anything. By the way the one's that Carlson has are rather poor replica's of the Mills. The best are Doonside or Irvine which often turn up on Ebay. Pics: LHS PAW 09 TBR diesel. RHS Brodak 25 for B Class Team Race, standard and modified "Turbo" cranks Ray Ihave always held that the cutaway in the crank web was there to stop the conrod from eclipsing and blocking the intake journal at bottom dead centre, and since the piston speed is at its slowest at the centres the dwell time is consequently quite large. But new to me is the angling of that cutaway and the vortex it could create. Ialso note that the leading corner of the counter balance has been relieved to lessen the drag (?) And the Brodak looks like some of Lances work, no? Talk soon, Chris. |
RE: need help with diesel rc engine!! help asap!!
You would have to have a rather wild porting/timing though to have the intake open near BDC. Most engines that I have will only open the intake around 45-50° after BDC and then there is very little of the center hole that is covered. Might be other effects that give a gain?
Edit: Checked my GZ .049 and it opens around 20° after BDC, but even then it is only about half of the crank center that is obscured. |
RE: need help with diesel rc engine!! help asap!!
ORIGINAL: Mr Cox You would have to have a rather wild porting/timing though to have the intake open near BDC. Most engines that I have will only open the intake around 45-50° after BDC and then there is very little of the center hole that is covered. Might be other effects that give a gain? Edit: Checked my GZ .049 and it opens around 20° after BDC, but even then it is only about half of the crank center that is obscured. So if the rod is not fully eclipsing the intake journal then what is the cutaway in the crank web for then? Perhaps in a running engine the flow through that journal never fully stops when the port closes but simply increases to its maximum when open and slows to its minimum when closed. In other words the intake pulse never reaches zero pressure, Thoughts? |
RE: need help with diesel rc engine!! help asap!!
I seriously doubt any of this crank modding does any good at all below 20kRPM. Car engine rev upwards of 35k.
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