Re: Some details of the 2AZ-FE engine

On Jul 15, 11:57 pm, [email protected] wrote:
> Hee hee hee. 2AZFE "an advanced powerplant?" that's a good one.
> Checkout the Audi FSI 2.0T for an advanced design with a flat torque
> curve from 2000-5000 RPMs.
>
IIRC, The flat torque is because of the CVT transmission design and
not the engine. I could be wrong.
.

On Jul 16, 12:43 pm, EdV <[email protected]> wrote:
> On Jul 15, 11:57 pm, [email protected] wrote:> Hee hee hee. 2AZFE "an advanced powerplant?" that's a good one.
> > Checkout the Audi FSI 2.0T for an advanced design with a flat torque
> > curve from 2000-5000 RPMs.
>
> IIRC, The flat torque is because of the CVT transmission design and
> not the engine. I could be wrong.
> .

The old 1.8T had an essentially flat torque curve over the same rev
range and was only available with conventional transmissions. I
wasn't aware that Audi had a CVT yet, although I have missed stuff
before. I thought their new high end transmission was the dual-clutch
deal?

nate

On Wed, 16 Jul 2008 09:43:13 -0700 (PDT), EdV <[email protected]>
wrote:

>On Jul 15, 11:57 pm, [email protected] wrote:
>> Hee hee hee. 2AZFE "an advanced powerplant?" that's a good one.
>> Checkout the Audi FSI 2.0T for an advanced design with a flat torque
>> curve from 2000-5000 RPMs.
>>
>IIRC, The flat torque is because of the CVT transmission design and
>not the engine. I could be wrong.
>.

A transmission has nothing to do with torque output of an engine.
A CVT is able to keep the rpms at max torque at all times while
accelerating.

RT wrote:
> On Wed, 16 Jul 2008 09:43:13 -0700 (PDT), EdV <[email protected]>
> wrote:
>
>> On Jul 15, 11:57 pm, [email protected] wrote:
>>> Hee hee hee. 2AZFE "an advanced powerplant?" that's a good one.
>>> Checkout the Audi FSI 2.0T for an advanced design with a flat torque
>>> curve from 2000-5000 RPMs.
>>>
>> IIRC, The flat torque is because of the CVT transmission design and
>> not the engine. I could be wrong.
>> .
>
> A transmission has nothing to do with torque output of an engine.
> A CVT is able to keep the rpms at max torque at all times while
> accelerating.
Max HP speed will give best acceleration.

RT <[email protected]> wrote:
>On Wed, 16 Jul 2008 09:43:13 -0700 (PDT), EdV <[email protected]>
>wrote:
>
>>On Jul 15, 11:57 pm, [email protected] wrote:
>>> Hee hee hee. 2AZFE "an advanced powerplant?" that's a good one.
>>> Checkout the Audi FSI 2.0T for an advanced design with a flat torque
>>> curve from 2000-5000 RPMs.
>>>
>>IIRC, The flat torque is because of the CVT transmission design and
>>not the engine. I could be wrong.
>>.
>
>A transmission has nothing to do with torque output of an engine.
>A CVT is able to keep the rpms at max torque at all times while
>accelerating.

Right. Correspondingly, if you have a CVT, you can get away with an
engine that has high torque in a very narrow speed range, whereas with
a conventional transmission the engine has to be able to provide good
torque over a wider range of speeds. (ie. the torque curve has to have
a much wider peak on it).
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

This is how I understand GDI (gasoline DIRECT injection), feel free to
correct my mistake

Fuel and air mixture are injected in some kind of pressure tank where
the pressure is increased, by compressing the mixture I suppose. At
this stage the ratio of the fuel and air is adjusted for optimum burn.

This pressure tank sometimes called as a *common rail*? has a nozzle
that will release the pressurized fuel-air mixture directly into the
chamber chamber via the intake valves. This high pressure coupled with
optimum ratio allows the engine to run more fuel efficiently and, of
course, more powerful. The VVTi (toyota) will then adjust the opening
of the valves whether to inject the mixture during the intake stroke
or slightly delayed.

"EdV" <[email protected]> wrote in message
news:2e0036d7-156b-4b0e-9625-11ef7fab6a74@i36g2000prf.googlegroups.com...
> This is how I understand GDI (gasoline DIRECT injection), feel free
> to
> correct my mistake
>
> Fuel and air mixture are injected in some kind of pressure tank
> where
> the pressure is increased, by compressing the mixture I suppose. At
> this stage the ratio of the fuel and air is adjusted for optimum
> burn.
>
> This pressure tank sometimes called as a *common rail*? has a nozzle
> that will release the pressurized fuel-air mixture directly into the
> chamber chamber via the intake valves. This high pressure coupled
> with
> optimum ratio allows the engine to run more fuel efficiently and, of
> course, more powerful. The VVTi (toyota) will then adjust the
> opening
> of the valves whether to inject the mixture during the intake stroke
> or slightly delayed.

In the direct engine engines I have researched, there is no tank that
mixes the fuel and air. 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. By injecting the
fuel directly into the combustion chamber, you can create a
"stratified charge." In other words a non-uniform mixture of gasoline
vapor and air. Gasoline is very difficult to ignite if you don't have
the proper air/fuel mixture. By creating a stratified charge, you can
have a proper A/F mixture in the area of the spark plug and a lean
mixture everywhere else. The spark plug can then easily ignite the
proper mixture in the area of the spark plug and this in turn will
burn the leaner mixture elsewhere in the combustion chamber. This
allows an overall leaner mixture to be burned, resulting in higher
efficiency. Chrysler tried this years ago with carbureted engines with
limited success (tried to manipulate the mixture with combustion
chamber and intact tract shape). Honda tried something a little
different with a three valve design in the late 70's (two "regular"
valves and one smaller valve to richen the mixture near the plug).
Neither worked very well. There are a lot of great claims being made
for direct injection engines. However, the direct injected manual
transmission Mazda 5 gets worse EPA gas mileage than the regular old 4
cylinder automatic Toyota RAV4 (which is larger and heavier...).

Ed

On Jul 18, 11:05 am, "C. E. White" <[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!

On Fri, 18 Jul 2008 08:36:01 -0700 (PDT), EdV <[email protected]>
wrote:

>On Jul 18, 11:05 am, "C. E. White" <[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-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