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Two stroke engines of the future

Posted: Fri Sep 02, 2011 10:18 pm
by Suzsmokeyallan
Quite interesting,
http://www.dirt-bike-tips-and-pics.com/ ... rokes.html" onclick="window.open(this.href);return false;"

Re: Two stroke engines of the future

Posted: Sat Sep 03, 2011 2:13 am
by keithwwalker
I wonder what is holding CanAm/Bombardier/SkiDoo/Evinrude from selling a street legal two stroke? Even a dirt bike version...First one to sell a road legal version, gets my money.

I suspect that NOx emissions are still too high. US and Euro emissions laws had a movement to ban two strokes back in the 90's, as a result their NOx emissions standards are ridiculously low. Something about the hole in the ozone layer over Anarctica, which is now closed up.

If you really want to blow your mind, read up on the most awesome two stroke ever built, the Rolls Royce Crecy sleeve valve two stroke...

Re: Two stroke engines of the future

Posted: Sat Sep 03, 2011 10:24 am
by oldjapanesebikes
Suzsmokeyallan wrote:Quite interesting, http://www.dirt-bike-tips-and-pics.com/ ... rokes.html" onclick="window.open(this.href);return false;
A very good read - I admit I smiled when I read the May 23rd 2009 article, as I recall a debate on the same subject on this board :D Lots of interesting thinking on direction and possible options - it will be interesting to see how things play out longer term. 8)

Re: Two stroke engines of the future

Posted: Sat Sep 03, 2011 10:41 am
by tz375
Cresy was an interesting engine alright. supercharged rather than crankcase compression, stratified charge, direct injection and that was 1941. I knew there was a reason I liked working there. :)

OK so sleeve valves are not so good in the real world but that motor could run down to 23:1 A:F which is little short of amazing for now, let alone then.

And I love the comment from the RAE that it would have been too powerful for a Spitfire airframe and that was with the low power version. Single cylinder tests suggested a 5000 hp potential,

Re: Two stroke engines of the future

Posted: Sun Sep 04, 2011 4:42 pm
by keithwwalker
RR Heritage Society has a great book on the engine. Actually a lot of their books are great if you are that much into engineering stories...

I wonder if modern sleeve valves could work good, with modern coatings? I bet they would. I recall reading about the Crecy that it's piston sleeve sealing was so good that the oil when changed was still a golden 'colour', no staining from blowby. Not even the Merlin or Griffon could do that.

Anyway, someday someone is gonna pull one of those modern 2 strokes from Bombardier and make a killer streetbike.
tz375 wrote:Cresy was an interesting engine alright. supercharged rather than crankcase compression, stratified charge, direct injection and that was 1941. I knew there was a reason I liked working there. :)

OK so sleeve valves are not so good in the real world but that motor could run down to 23:1 A:F which is little short of amazing for now, let alone then.

And I love the comment from the RAE that it would have been too powerful for a Spitfire airframe and that was with the low power version. Single cylinder tests suggested a 5000 hp potential,