How about a 180 (30cc) glow motor?
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Tim,
Yeh, Delrin was what I was talking about. Plastic could mean anything in broad terms. Anyway, with the square drive, you would get to much movement and vibration which would flog the centre out in a very short space of time and is nowhere near accurate enough. After you press a crank together you have to balance it in a "V" block and dial gauge with a copper hammer to knock the crank into alignment. I would use a spline as an alternative to this idea but with this method of pressing cranks together it's not just the 2 cranks its the bearings in the centre of the 2 counter weights and the you also have to press the big end conrod pins with the rods on them. Your looking at 4 components to make up a 2 cylinder crankshaft without bearings. Or were you thinking of something like large bearings for the centre for support of the crank. I thought about this a while ago but found it hard to get bearings rated at that sort of speed and heat. Don't forget either that both cylinders have to be sealed individually so you don't get leakage from one bottom end to the other.
Yeh, Delrin was what I was talking about. Plastic could mean anything in broad terms. Anyway, with the square drive, you would get to much movement and vibration which would flog the centre out in a very short space of time and is nowhere near accurate enough. After you press a crank together you have to balance it in a "V" block and dial gauge with a copper hammer to knock the crank into alignment. I would use a spline as an alternative to this idea but with this method of pressing cranks together it's not just the 2 cranks its the bearings in the centre of the 2 counter weights and the you also have to press the big end conrod pins with the rods on them. Your looking at 4 components to make up a 2 cylinder crankshaft without bearings. Or were you thinking of something like large bearings for the centre for support of the crank. I thought about this a while ago but found it hard to get bearings rated at that sort of speed and heat. Don't forget either that both cylinders have to be sealed individually so you don't get leakage from one bottom end to the other.
Mark,
I have killed delrin gears with 21's. I wouldn't consider linking 2 90 sized cylinders and thier amounts of trapped compression with Delrin.
The square drive idea I had was purely for linking 2 separate conventional type crankshafts together inline. This would allow conventional bearings etc to be used as the RPM would be no higher than what they currently produce as a single cylinder engine. Think of it as 2 separate crankcases.
The sealing of the separate cases would be critical for ensuring proper tuning and performance. It also allows separate carbs per cylinder - which I understand is one of the issues with the A180V.
Wouldn't electronic fuel injection be nice
Personally I think the side by side layout is a better option than an inline twin.
Tim.
I have killed delrin gears with 21's. I wouldn't consider linking 2 90 sized cylinders and thier amounts of trapped compression with Delrin.
The square drive idea I had was purely for linking 2 separate conventional type crankshafts together inline. This would allow conventional bearings etc to be used as the RPM would be no higher than what they currently produce as a single cylinder engine. Think of it as 2 separate crankcases.
The sealing of the separate cases would be critical for ensuring proper tuning and performance. It also allows separate carbs per cylinder - which I understand is one of the issues with the A180V.
Wouldn't electronic fuel injection be nice
Personally I think the side by side layout is a better option than an inline twin.
Tim.
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The A180V used two small pins and a clamp bolt to create a centre crankshaft join. But the pins were too small and sheared. I replaced these with precision fit key-ways. Unfortunately other problems with the motor prevented me from verifying if this worked.
As mark suggests, a squre drive type connection is not good enough.
An accurate spline that is concentric and has no free play is VERY hard to make!
Plastic gears of the scale I would like to fit will not stand the duty. Besides to get them right they should be moulded plastic gears otherwise you have the same problems of generating the shape. Delrin is a trade name for acetal, which is a plastic which has similar properties to nylon, but is a bit stronger. Nothing special.
Steel gears, properly designed and made is the way to go. But these will not be easy...
My geared design is much more compact than the A180V, so has my vote!
Ian.
As mark suggests, a squre drive type connection is not good enough.
An accurate spline that is concentric and has no free play is VERY hard to make!
Plastic gears of the scale I would like to fit will not stand the duty. Besides to get them right they should be moulded plastic gears otherwise you have the same problems of generating the shape. Delrin is a trade name for acetal, which is a plastic which has similar properties to nylon, but is a bit stronger. Nothing special.
Steel gears, properly designed and made is the way to go. But these will not be easy...
My geared design is much more compact than the A180V, so has my vote!
Ian.
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Since we can add pics again, here are the simple layouts I did of the two cyl geared 180 for those who didnt seen them before.
Top view.
Ian.
View attachment 1016
Top view.
Ian.
View attachment 1016
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Top view compared to an A-90 engine to show just how compact it could be....
Ian.
View attachment 1018
Ian.
View attachment 1018
izitbrokeyet?
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now that would push a lot of fiberglass
izitbrokeyet?
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bet it consumes more fuel than a suburban....but worth it
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Kevin,
I guess it could push some big monos to quite respectable speeds! B) I would like to make one for a rigget ro take on the twin engine boats tho! B)
Nitrocrazed racing: Is two cylinders in one engine faster than two engines in one boat?
I guess it could push some big monos to quite respectable speeds! B) I would like to make one for a rigget ro take on the twin engine boats tho! B)
Nitrocrazed racing: Is two cylinders in one engine faster than two engines in one boat?
I know this thread is snaking around. Just letting Scott know, that while Zenoah has a 4 port, MHZ has developed a 6 portCylinder for their 22.5 cc ...This hi-tech cylinder type is used in Formula 1 racing engines....
sorry for the delayed response making this thread a bit disjointed
View attachment 1029
sorry for the delayed response making this thread a bit disjointed
View attachment 1029
DaveMarles
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CMB did make some .90 prototype 5 port liners. I test ran them for a couple of years and did a lot of various test modifications on them ( changing roof angles, entry angles, bypasss ports etc) but the 3 port engine performance was just as good and so CMB dropped the idea of going over to 5 port.EatMyShortsRacing said:
Dave
EatMyShortsRacing
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Ian I am starting to believe you have far too much time on your hands!!!
Dave I saw some of the 'interesting' stuff that came out of CMB years ago when they were trying to figure out how to make the old Valvola 21 go so I can imagine that would have happened for other engines also. My question is how quantifiable was your testing and how was the rest of the engine (read crankcase) configured to test these porting theories?
Without a good Dyno it can be hard to compare engines and also what may work well in submerged drive applications may not be as great in surface drive and even between surface drive monos and hydros. Surface drive is a whole new ball game for manufacturers that started in submerged drive. I was there years ago when CMB engines first came to Australia and was amongst the first to run them in hydros here. CMB were great for submerged drive but it took a lot to get them to be a good hydro engine. I am learning this over again with the A engines.
I am also a firm believer that one of the dramas in multiport engines is getting the right pressure in each port to get the fuel to do what you want it to do. For instance if the port area in the liner is the same for 4 transfer ports ( example being a 5 port engine) but the case limits the flow more in one pair of ports than the other you may have a problem in the case, not the porting. Yes the permutations and combinations increase exponentially with the number of ports in the engine so this argument could go on forever.....
Dont get me wrong, I am not trying to discredit your views or findings Just I see this as an extremely complex issue and without Ferrari funding the R&D we have to do the best we can with limited resources. I just believe that a proper multiport engine should outperform those with 3 or 4 ports.
EMS Racing Only Users Lose Drugs
Dave I saw some of the 'interesting' stuff that came out of CMB years ago when they were trying to figure out how to make the old Valvola 21 go so I can imagine that would have happened for other engines also. My question is how quantifiable was your testing and how was the rest of the engine (read crankcase) configured to test these porting theories?
Without a good Dyno it can be hard to compare engines and also what may work well in submerged drive applications may not be as great in surface drive and even between surface drive monos and hydros. Surface drive is a whole new ball game for manufacturers that started in submerged drive. I was there years ago when CMB engines first came to Australia and was amongst the first to run them in hydros here. CMB were great for submerged drive but it took a lot to get them to be a good hydro engine. I am learning this over again with the A engines.
I am also a firm believer that one of the dramas in multiport engines is getting the right pressure in each port to get the fuel to do what you want it to do. For instance if the port area in the liner is the same for 4 transfer ports ( example being a 5 port engine) but the case limits the flow more in one pair of ports than the other you may have a problem in the case, not the porting. Yes the permutations and combinations increase exponentially with the number of ports in the engine so this argument could go on forever.....
Dont get me wrong, I am not trying to discredit your views or findings
Just I see this as an extremely complex issue and without Ferrari funding the R&D we have to do the best we can with limited resources. I just believe that a proper multiport engine should outperform those with 3 or 4 ports.EMS Racing Only Users Lose Drugs
EatMyShortsRacing
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Oh and Ian, I studied your drawings in detail and you didnt leave enough space between the liners for high flow transfer ports in the case.
EMS Racing Stirred, not shaken
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Turbosun,
Nice looking cylinder, tell us more! Is it steel or chrome plated aluminium? If plated, does the chroming stay on okay with a ring running past the port edges?
Ian.
Nice looking cylinder, tell us more! Is it steel or chrome plated aluminium? If plated, does the chroming stay on okay with a ring running past the port edges?
Ian.
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Craig,
I have a bit more time at the moment now that I am not building other peoples engines and my own engines and boats for the nats! Now I just have to do engines and boats for the NAMBA and IMPBA nats.....
I also left enough room in that drawing for transfer ports as wide as currently used in the A90's. If you want bigger ports than the cylinder spacing would need to be increased, but that isnt really a problem! B)
Personally I am not convinced about the multi-port engines. Seems these are going to have more port walls and edges for the same total port area, thus are going to have higher flow losses. Your little MAC 21 screamer is a 3 port wonder!
Probably the multi-port liners are going to have better control in the way in whihc they control and direct flow in filling the cylinder, but to actually make this a benefit would require a LOT of testing I think!
Nitrocrazed racing: Not enough distractions....
I have a bit more time at the moment now that I am not building other peoples engines and my own engines and boats for the nats!
Now I just have to do engines and boats for the NAMBA and IMPBA nats.....I also left enough room in that drawing for transfer ports as wide as currently used in the A90's. If you want bigger ports than the cylinder spacing would need to be increased, but that isnt really a problem! B)
Personally I am not convinced about the multi-port engines. Seems these are going to have more port walls and edges for the same total port area, thus are going to have higher flow losses. Your little MAC 21 screamer is a 3 port wonder!
Probably the multi-port liners are going to have better control in the way in whihc they control and direct flow in filling the cylinder, but to actually make this a benefit would require a LOT of testing I think!
Nitrocrazed racing: Not enough distractions....
G
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chrome plated aluminum. special alloy. no ring problems reported from the field...
Mike Bontoft
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I just received the update to the NAMBA rule book and the under engine classification it now says X class has a limit of 22.009cc or 1.34cu in. I am currently working on a big glow engine and have invested quite alot of time in it. Was this voted in and did I miss something :angry: :angry: :angry: :angry:
Mike
Forwarding to Al Hobbs
Mike
Forwarding to Al Hobbs
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