Injection timing

Jeffrey Engel jengel at FastLane.NET
Thu Nov 21 02:29:43 GMT 1996


Mazda Ebrahimi <kleenair at ix.netcom.com writes:

> As I understand it, it is best to inject the fuel after the intake valve 
> closes, so the fuel vaporizes on the somewhat hot cylinder head 
> surfaces.  Is this true?  Is there any advantage to injecting at other 
> times during the cycle?  If so, explain the reasoning.

Yes, please do.  Grumpy Jenkins said in his book that 85% of the fuel 
vaporization occurs in the cylinder.  'Couse he's talking race 
engines versus whatever we're running (street / HiPo / semi-race / 
whatever).  It would be nice to know what the current state-of the 
art is.

I've also heard that EFI-equipped engines are sensitive to air-speed. 
With the injectors down near the ports, I'd have thought air speed 
wouldn't be that important.

je
jengel at fastlane.net



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