Injection timing

Doug Robson doug at cia.com.au
Thu Nov 21 09:51:05 GMT 1996


Jeffrey Engel wrote:
> 
> 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
Maybe it is not important as the Fuel gets squirted in\
but when i ran my 4 cvl 2litre race engine on 50mm throttle bodies the
air spedd was so low i lost 25kwatts of power compared to 45mm ones. has
to do with taper as well as venturi effect


regards\

-- 
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