For a stepped compression change you just add copper washers under the change over plug.If you leave the spark plug in the injector' s hole, that action does not change so much this geometry factor. If your spark plug is to be in the cast iron plug, than it receeds a bit with every washer, but i don' t think it makes much difference. A bigger difference could come from a more central position inside the combustion chamber of a DI version. This divides the flame front lenght and eliminates the "shoot" out of the prechamber. Some car manufacturers even top this by installing 2 sparkplugs opposite of each other in one cylhead. Short flame front length can give you later timing and perhaps a more homogenious "explosion" Swirl type cylheads and inlet pipes are helpful, too.
Wish you nice and interesting summer holidays! Rolf Am Freitag, 1. Juli 2011 14:19:31 schrieb Ken Boak: > Hi Rolf, > > The Listeroid at APL is a JKSon Indian copy which is an Indirect Injection > with the original Lister type pre-chamber head and a flat topped piston. > > I have not tinkered with the pre-chamber form, other than adding a > spark-plug into the cast iron plug, where the compression change-over valve > would have fitted. > > I was thinking of having some sort of arrangement like in a model > compression ignition aero-engine, where the compression ratio could be > varied with some sort of a movable "contra-piston" - but my machining > skills are not up to producing such a component. > > I hope to make significant advances with woodgas trials on my Lister this > summer. > > > > Ken > > On 1 July 2011 13:05, Rolf Uhle <[email protected]> wrote: > > Hello Ken, > > > > it all relates to many factors, piston speed, head cavern design,piston > > surface temp,timing of course,all versus flame propagation speed. > > A small "normal" 1500/1800 or even 3000/3600 engine can very well have > > slower > > piston speeds than a big oldfashioned longstroke engine. > > > > By the way, have you ever tinkered with the prechamber form in your > > Lister? > > > > Is Jim' s Listeroid DI ? Can' t ask him myself 'cause he doesn' t answer > > me any more. > > > > salut > > > > Rolf > > > > Am Freitag, 1. Juli 2011 13:29:21 schrieb Ken Boak: > > > This is an interesting discussion, which tends to make me believe that > > > > the > > > > > future of woodgas, will be ignited with the use of conventional diesel > > > engines, modified for spark ignition, rather than the initially more > > > obvious choice of a gasoline engine. > > > > > > If, as suggested that woodgas can be used without knock problems in a > > > > stock > > > > > diesel engine at a compression ratio of 17:1, then this better than > > > compensates for the loss of efficiency when used in a gasoline engine. > > > > > > As an enthusiastic user of the slow speed Lister type diesel engines, I > > > hope to be commencing some power tests on woodgas later this year. It > > > will be interesting to see how woodgas performs at the much slower > > > 600 rpm of the Lister, compared to the more normal 1500/1800rpm of a > > > direct drive diesel generator. The Lister being an old design with a > > > > relatively > > > > > long stroke of 5.5" has a mean piston speed of about 10 feet per > > > > second > > > > > - how this relates to a modern, "squarer" higher rpm engine I would > > > > need > > > > > to > > > investigate. > > > > > > > > > > > > Ken > > > > _______________________________________________ > > Gasification mailing list > > > > to Send a Message to the list, use the email address > > [email protected] > > > > to UNSUBSCRIBE or Change your List Settings use the web page > > > > http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioen > >ergylists.org > > > > for more Gasifiers, News and Information see our web site: > > http://gasifiers.bioenergylists.org/ > _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/
