Injector Sizing: REALLY dumb question -Reply

Bruce Robertson bruce_robertson at MAIL.TAIT.CO.NZ
Thu Aug 27 22:42:11 GMT 1998


Just butting in here with my two cents worth...

I thought the whole idea of having the timing overlap was to take
advantage of the momentum of the exhaust gas passing from the
combusion chamber into the exhaust port to "scavenge" some intake
charge. The momentum of the gas is such that once the piston reaches
TDC it tries to keep going  hence creating a depression if the inlet valve
were not opening. Because the inlet valve opens the depression is
satisfied by sucking in some fresh charge. If the overlap was too large,
and the inlet opened way too soon then I suppose the exhaust gas into
the inlet would be possible - but doesn't sound too flash to me!

Bruce.




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