air-assisted injectors, sort of

Greg Hermann bearbvd at sni.net
Tue Sep 1 17:42:45 GMT 1998


>> Ignoring the issue of detonation, how ignitable are lean mixtures? Or
>> rather, how lean can you make the mixture and still be able to ignite
>> it? What if you allow for a seriously powerful ignition, and/or bump
>> the CR up a lot? It seems a bit weird to me that lean mixtures are
>> more prone to detonation (which indicates to me a mixture near
>> optimum, or near one of perhaps 2 optimums) and also considered to
>> be hard to ignite - or is that only at a *much* leaner A/F ratio?
>>
>I have heard reports of 26:1;  If your engine is still running above
>20:1 the extra air will prevent detonation.  The Japaneese have
>production engines, I am not sure if used yet in states.
>This is one of the reasons for the development of the wide range
>O2 sensor.
>alex


I believe the limit of flammability is at about 17 or 18:1 for gasoline in
air. Leaner than that and homogenous, it simply won't light, period. To run
any leaner average micture, one needs a stratified charge. A diesel burns
because the charge is rich enough to burn close to the droplets from the
injector. Orbital is achieving their burn with direct injection down to
80:1 AVERAGE af ratio or whatever due to stratification of the charge. With
a stratified charge, therre is no mixture to detonate in the "end" gas
(further reaches of the chamber.

Regards, Greg





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