Fuel injection plugs

[James Ballenger]

Raymond C Drouillard wrote:

> Don't make the mistake of getting volumetric efficiency mixed up with
> engine efficiency.  Engine efficiency is work in / work out.  VE is air
> in / (.5 * displacement)   (for a four-cycle engine).  Torque is highest
> at the highest VE because you can get more fuel in for each revolution of
> the crank.  Power is highest at the point where you can get the most fuel
> per unit time.

At peak ve, you get the closest thing to perfect combustion.  You get a good
full charge of, hopefully, stochiomteric mix and can burn it making maximum
force and maximum fuel economy.  At max power, we are making less torque but
making it faster.  The problem here is that there are inherent combustion and
frictional ineffeciencies.  At max power (hp) we have to advance ignition and
now valve timing to try to catch up.  You get an incomplete burn of the fuel
and have a very inefficient cycle, its just that you can do this enough per
unit time to get more power.  The only reason we do this is because of
imperfect gearing.  If we have a cvt, as discussed, the point becomes moot
because we can have insanely high (numerically) gearing and torque
multiplication.  In this case we would not have a need for more power because
the transmission could be controlled as the throttle, while the engine
remains at its most efficient state.

> If you are running at the highest torque point (max VE), you have to
> throttle it down to reduce power.  This throttling, of course, reduces VE
> to the point where you get the desired power level.  Of course, this
> increases pumping losses.

There is not throttling with a cvt, the transmission is the "throttle."


> A more efficient way to reduce the power level is to reduce the engine
> speed to below max torque.  You will have about the same amount of air
> per unit time, but more air per revolution.  Actually, you will have a
> little less air per unit time because it'll be running more efficiently.
> It won't have to do as much pumping.

You won't be receiving more air, below max torque you will be getting less
air per revolution because it is not at peak ve.  At peak torque, you get
peak ve.  At peak ve, you get the fullest charge of air and fuel possible
from the engine and will be running more efficiently than at any other point
in the engines range.


> Other benefits are less wear and tear, lower windage losses in the
> crankcase, lower losses at the oil pump, etc.

If the engine is not throttled and remains where it will make peak power it
will have significantly less wear on the engine.

James Ballenger