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        riddles >> general problem-solving / chatting / whatever >> Automobile
        
(Message started by: checker on Nov 28^th, 2006, 12:50am)

Title: Automobile
Post by checker on Nov 28^th, 2006, 12:50am

This discussion invites all those interested with automobiles.
Can we increase the speed as well as the fuel effficiency of four wheeler by having optional Cylinder use via at want switch the number of cylinders.

Title: Re: Automobile
Post by SMQ on Nov 28^th, 2006, 5:38am

Probably, but with a traditional internal cumbustion engine -- gasoline or diesel -- the problem is that unless you hold either the intake or exhaust valves closed (or open) on the "unused" cylinders they will still compress air even without fuel or spark, and this useless compression wastes a lot of of the power of the engine. So much that it's actually what's used for a big-rig's "Jake Brake" engine breaking system. (That loud staccato sound you hear when a big-rig is engine-braking is the sudden release of compression from cylinders with no fuel in them.)

And while with modern electronically-controlled engines it's no problem at all to change and/or eliminate the fuel and/or spark for a cylinder, modifying the valve timing is much more complicated -- enough so that it might raise the cost of an average low-to-mid-range engine more than the fuel savings it would provide -- which is why you currently only see it on more expensive vehicles with more expensive engines.

[edit]This article (http://www.automedia.com/Variable/Displacement/dsm20050601dd/1) looks to be a reasonable introduction to the current generation of systems.[/edit]

--SMQ

Title: Re: Automobile
Post by checker on Dec 1^st, 2006, 12:17am

Thanx SMQ for providing me that link,I am exploring through the site so.....may be I get the matching details which could provide satisfaction to my idea.
Presently U r very true thanx again