Re: Some details of the 2AZ-FE engine

On Jul 18, 2:16 pm, Retired VIP <jackj.extradots....@[EMAIL PROTECTED]
>
wrote:
> On Fri, 18 Jul 2008 08:36:01 -0700 (PDT), EdV <systme...@[EMAIL PROTECTED]
>
> wrote:
>
> >On Jul 18, 11:05 am, "C. E. White" <cewhi...@[EMAIL PROTECTED]
>
> >wrote:
> > There is an injector in the combustion chamber
> >> instead of in the intake tract before the intake valves. Air is
> >> admitted into the combustion chamber by the valves. Fuel is injected
> >> directly into the combustion chamber, instead of being mixed with the
> >> air in the intake tract before the intake valves.
>
> >Ahh, so the intake valves is just for the AIR and the injector for the
> >FUEL. no pre-mixing involved. The mixing occurs directly inside the
> >combustion chamber. The fuel is pressurized and not the air like in a
> >turbo setup. Thanks!
>
> Yep, you got it Edv.  But the fuel is injected into the combustion
> chamber, not the intake manifold.
>
> Of the three types of fuel injection, the direct injection has the
> capability of being the most efficient.  The air/fuel mixture can be
> precisely adjusted for each individual cylinder and for each
> individual power stroke.
>
> Throttle body injection is the least precise of the three.  It is
> basically just a computer controlled carb that uses a injection jet
> instead of a metering jet.  It's better than a carburetor but not by
> much.
>
> Multi-****t injection places one injector in the manifold runner to
> each cylinder.  This is a better scheme that allows more precision but
> it is limited on how much the mixture can be leaned out before
> pre-ignition occurs.
>
> Direct injection allows placing a rich fuel/air mixture around the
> sparkplug and a much leaner mixture in the rest of the cylinder.  By
> the time the flame front moves out to the rest of the cylinder, the
> piston has moved past top dead center and the much faster burn rate of
> a lean mixture won't hurt the engine.
>
> I hope this helps and if I've gotten anything wrong in this, I'm sure
> someone will correct me.
>
> Jack

Great! So this means its possible not to have VVTi and Direct
injection at the same time. The timing of the fuel comes from the
nozzle and not from the opening of the valves, although air enters
through the valves, its the fuel which is controlled and not the air.