Some details of the 2AZ-FE engine
in [Toyota]
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From: EdV on 18 Jul 2008 11:36 On Jul 18, 11:05 am, "C. E. White" <cewhi...(a)removemindspring.com> 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!
From: Retired VIP on 18 Jul 2008 14:16 On Fri, 18 Jul 2008 08:36:01 -0700 (PDT), EdV <systmengr(a)hotmail.com> wrote: >On Jul 18, 11:05 am, "C. E. White" <cewhi...(a)removemindspring.com> >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-port 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
From: EdV on 21 Jul 2008 09:35 On Jul 18, 2:16 pm, Retired VIP <jackj.extradots....(a)windstream.net> wrote: > On Fri, 18 Jul 2008 08:36:01 -0700 (PDT), EdV <systme...(a)hotmail.com> > wrote: > > >On Jul 18, 11:05 am, "C. E. White" <cewhi...(a)removemindspring.com> > >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-port 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.
From: Retired VIP on 21 Jul 2008 16:54 On Mon, 21 Jul 2008 06:35:30 -0700 (PDT), EdV <systmengr(a)hotmail.com> wrote: >On Jul 18, 2:16 pm, Retired VIP <jackj.extradots....(a)windstream.net> >wrote: >> On Fri, 18 Jul 2008 08:36:01 -0700 (PDT), EdV <systme...(a)hotmail.com> >> wrote: >> >> >On Jul 18, 11:05 am, "C. E. White" <cewhi...(a)removemindspring.com> >> >wrote: >> > There is an injector in the combustion chamber >> 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. No, I think it would still be possible to use variable valve timing and direct injection at the same time. The amount of fuel is controlled by the engine computer based on info it gets from the O2 sensor, throttle position, RPM, etc. VVTi would still be a valid way to increase engine efficiency by controlling the amount of air, that's really all it controls with multi-port injection also. Jack
From: Leftie on 22 Jul 2008 00:30
Retired VIP wrote: > On Mon, 21 Jul 2008 06:35:30 -0700 (PDT), EdV <systmengr(a)hotmail.com> > wrote: > >> On Jul 18, 2:16 pm, Retired VIP <jackj.extradots....(a)windstream.net> >> wrote: >>> On Fri, 18 Jul 2008 08:36:01 -0700 (PDT), EdV <systme...(a)hotmail.com> >>> wrote: >>> >>>> On Jul 18, 11:05 am, "C. E. White" <cewhi...(a)removemindspring.com> >>>> wrote: >>>> There is an injector in the combustion chamber >>> 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. > > No, I think it would still be possible to use variable valve timing > and direct injection at the same time. The amount of fuel is > controlled by the engine computer based on info it gets from the O2 > sensor, throttle position, RPM, etc. VVTi would still be a valid way > to increase engine efficiency by controlling the amount of air, that's > really all it controls with multi-port injection also. > > Jack I think you misread the post. He was saying it's possible to not have both features, not that it's impossible to have both. |