Fuel injection plugs

[Howard Wilkinson]

Pat:
    It has been said that the greatest efficiency is achieved in terms
of fuel burned per hour as related to horsepower output at WOT.
Engine power output is more or less proportional to CFM airflow in a
spark ignition engine.  Thus power must be controlled by regulating
airflow as mixture is fairly critical.  Airflow may be controlled in
one of several ways.  The common way is to apply a vacuum and resist
induction....throttling..... this has the side effect of reducing
effective compression ratios at the typical 20% or so throttle at
which we cruise most cars.  Variable displacement would be another,
but so far has not been introduced.  Another is turbocharging a small
engine on the theory that it will develop greater efficiency at lower
power settings, and the boost will help it develop enough power when
needed.  This has several downsides.... Compression must be lowered,
or high octane fuel must be used or timing must be retarded, or all
three to prevent detonation... Lower compression drops efficiency when
the turbo isn't boosting... retarding the timing doesn't help output
or efficiency, and high octane fuel is expensive.  Turbocharging or
Supercharging are not the answer to our prayers unless an engine is
developed which has variable chamber size.  Even then there is the
downside that the smaller pistons and or shorter stroke will reduce
the ability to convert the cylinder pressure into torque.  We all know
Pi*Rsquared....... figure the piston surface area and multiply it by
the combustion pressure to get the push on the rod..... The longer the
stroke, the greater the leverage available to turn the push into
torque.......  I like cubes....they make power.
    The other way to reduce engine output is to load it down to an RPM
where the induction air flow is just enough to develop the power
needed to sustain the load.  The belt drive transmission you describe
is probably the simplest sytem available to do this, and in
conjunction with a stepped transmission (automatic) one should be able
to accomplish this.  In this scenerio the throttle (the one you step
on) would be directly in control of the transmission.... as you press
the throttle the transmission gears down to allow the engine to rev up
and develop power as needed.  The engine is always at full throttle
except at idle when it is throttled due to lack of any sort of load.
Such a system should work within reason....it may require conventional
throttling at very low power settings (dual mode operation).  It would
be more ideal with some sort of variable camming so that the engine
would develop efficient power throughout it's RPM range.  None of
these things is new or untried technology.  The belt drive is not a
very efficient system, but has a great virtue in simplicity.  It has
been used for many years in such diverse applications as combines,
skid steer loaders, variable speed machine drives, and
automobiles...... The Dutch built DAF used such as system.  Camming of
an engine so that it will breath well at low RPM and also at high RPM
can be handled in several ways.  The issue is overlap.  The greater
the overlap the less efficient at low RPM, but the better at high RPM.
The simplest approach is the Rhodes type lifter which contains an oil
chamber and bleed hole.... at low RPM the oil bleeds out more than at
high RPM simply as a function of time.  I have greatly changed the
running characteristics of several engines which were over cammed by
simply changing over to mechanical rather than hydraulic lifters, and
adjusting lash until I was satisfied with the result...... One such
engine has run over 50K so far with .035 lash on mechanical lifters
running on a hydraulic lifter high performance cam (FE series Ford
engine).  The other option would be a dual cam system of some sort set
up with centrifugal advance/retard.  This would allow one cam to
advance the opening times, and one to retard the closing times of two
sets of valves.  This would not be difficult to accomplish with some
engines.  Caterpillar uses such a system on injector pumps on some
engines for timing advance... it is located right on the drive gear.

                    Just some ideas.......     H.W.

-----Original Message-----
From: Pat Ford <pford at qnx.com>
To: diy_efi at efi332.eng.ohio-state.edu
<diy_efi at efi332.eng.ohio-state.edu>
Date: Friday, April 30, 1999 7:40 AM
Subject: Re: Fuel injection plugs


>Previously, you (James Ballenger) wrote:
>>
>>
>> Howard Wilkinson wrote:
>>
>> >     The most reasonable way to control engine power output is by
>> > gearing so that RPM is controlled by load.  A continuously
variable
>> > transmission system could allow an engine to operate at full
throttle
>> > all the time except at idle when it would need to be throttled.
>> > Allowing the engine to always operate at WOT would greatly
increase
>> > efficiency.           H.W.
>>
>>     Ok, I know this isnt right.  If we had continously variable
transmissions,
>> we would be running them at peak torque not at wot.  VE is greatest
at peak
>> torque, the reason we rev engines higher to acheive high horsepower
is to combat
>> inefficient gearing.  At wot, there is significantly reduced ve and
not enough
>> time to get good mixture and combustion, therefore lower torque.
The reason
>> this is an asset is because it produces more torque per unit time,
ie power.
>> With a continuously variable transmission we could run the engine
all day long
>> at peak torque and get double or triple the gas mileage, more
power, and reduced
>> wear.  Again, im just a student so tell me where i goofed but I
have discussed
>> this with others before and feel somehat confident that this is
right.
>>
>> James Ballenger
>>
>
>years ago when the Subaru Justy came out and had the ECVT ( I worked
at a subaru
>dealer at the time) the engine would if you tromped on the gas would
go up to
>the peak of the torque curve and stay there. It was amazing, the damn
things were
>only a bit slowwer then a bmw M3 ( the dealer was also bmw and saab
dealer). We
>actualy had drags with the bimmer and saabs and the 3 cyl justy was
at the top
>of the cars we sold. The fuel economy was great just the lifetime of
the tranny
>wasn't so good. The ECVT was like a snowmobile pulley system but the
belt worked
>under compression, and there was a magnetic clutch that used iron
filings to transfer
>power. The othe funny thing was reverse was just an idler after
everything else,
>the early justy would go as fast in reverse as forward.
>
>