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| Charlie |
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Charlie
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Joined: 27 May 2007
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 Posted: 22:41 - 07 Sep 2014  Post subject: New/old engine technology? |
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What do people make of this engine type? Will we see it on my bikes of the future?
https://www.achatespower.com/opposed-piston-engine.php
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| stevo as b4 |
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stevo as b4
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| Polarbear |
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Polarbear
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| Posted: 22:54 - 07 Sep 2014 Post subject: |
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That design was used in the marine industry many years ago by a company called Doxford. It was quite successful but overly complicated.
https://users.telenet.be/doxford-matters/figuren/Schepen/SEAHORSEgr.jpg
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Last edited by Polarbear on 22:56 - 07 Sep 2014; edited 1 time in total |
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| Fladdem |
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Fladdem
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Joined: 29 Jun 2011
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| Posted: 22:56 - 07 Sep 2014 Post subject: |
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Check out the Commer TS3, sounds mint too! 
I think it would be a bit impractical in a bike. You'd need two crankshafts at either end of the engine taking up more space on a bike, fine in a big lorry, but a bike not so good.
Why not just a DFI traditional two stroke instead? Even simpler engine design.
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| Kickstart |
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Kickstart
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Joined: 04 Feb 2002
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| Posted: 22:57 - 07 Sep 2014 Post subject: |
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Hi
Problem is bulk
Opposed piston engines have been successfully used in vehicles before (eg, Napier Deltic 2 stroke diesel). With the total piston movement twice as much for the same mean piston speed compression can be higher (although getting a high enough compression on a 2 stroke isn't really a problem, and one advantage they have is a decent combustion chamber shape). Diesels need a far higher compression which is possibly why it was used there.
Suspect with a careful choice of con rod length and the stroke for each piston then there could be a bit of an advantage by prolonging the time that the combustion has the max turning effect on one of the cranks
Possibly a bigger problem is where to put the spark plug on a petrol engine without screwing up the combustion chamber.
All the best
Keith
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| Teflon-Mike |
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Teflon-Mike
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Joined: 01 Jun 2010
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| Posted: 04:09 - 08 Sep 2014 Post subject: Re: New/old engine technology? |
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| Fladdem wrote: | Check out the Commer TS3, sounds mint too! |
https://www.oldengine.org/members/diesel/rootes-listerts3/TS34.jpg
| Fladdem wrote: |
You'd need two crankshafts at either end of the engine. |
One crank, two rockers, four con-rods.
As has been said, archictecture works OK for a Diesel; Commer motor had full spherical combustion chambers in the piston crowns, uncompromising by valves and wirhout sacrificig compression; but couldn't utilise crak-vase compression for induction, so had to be super-charged to get charge in the pot, & as a 2T relying on porting and harmonics i the exhaust, you cannot boost efficiency with a turbo,
The commer engine was about the smallest of the type to work reasonably efficiently, but was expensive to make, not wonderfully reliable and neither that powerful nor economical compared to more conventional diesel engines as they gained popularity & development.
As has been mentioned, it's nothing 'new' & It wasn't wonderful when it was. There is still scope to evolve the two-stroke; but for motorcycle applications, the advantages of 'simplicity' were pretty much mined out by the time they took on exhaust power-valves and water-cooling, and had as many moving parts as a four-stroke. Big Power they offered when reed or disc valves more than doubled trapping efficiency and gave us the Hi-Po 2T is no longer there; hasn't really since about 1984, when the much vaunted Yamaha RD350YPVS,58bhp/170Kg was rivalled by the original Kawasaki GPz600R, 75bhp/195Kg. While the inherent hindrances of total loss lubrication associated with crank-case induction; poor combustion efficiency, due to relying on porting ad harmonic resonance for cylinder scavenging, have demanded ever more elaborate solutions to make them 'emission friendly', while pegged piston rings on forced lubrication & pressed up open bearing cranks have become the weak link in reliability, where standards have moved on in 4T arena, to a degree 2T's are no where near able to rival.
And they are 'unfashionable'. There have been a lot of 'advanced' two-stroke concepts knocking about over the last 20-30 years; from simple 'semi-forced' lubrication designs through efficient stepped piston wonders, and 'multi-stroke' two strokes that only fire on a full pot 'pumped up' over op to four revolutions.Oh,upside down 2T's and four-stroke valved 2T's and many others. People keep trying, but they ever 'quite' make it, while dozens of large manufacturers put millions of man-hurs and computer modelling simulations into pushing forwards the stare of the art of a 4T engine, they are always falling further behind... in an arena most consider the future to be electric or alternative fuel, not internal combustion...
So, no, really... I don't see any revolutionary two-stroke power a production motorcycle any-time soon, if ever..... I've been waiting for one for thirty years, ent happened yet and seems less and less likely by the decade.
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Old Thread Alert!
The last post was made 11 years, 219 days ago. Instead of replying here, would creating a new thread be more useful? |
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