Fuel injection plugs

Pat Ford pford at qnx.com
Fri Apr 30 18:34:29 GMT 1999


Previously, you (Howard Wilkinson) wrote:
> 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.  

I'm with you up to here. why a stepped automatic? the justy used a clutch,
an electronically controlled set of pulleys and the reverse idler, and dif.

there was no other transmissions. the tach when you jumped on the fun pedal
went to around 3500 rpm ( it was around 10 yrs ago, I don't remember the 
exact #) and then the pulleys did all the work. when you eased up on the 
pedal the ratios changed gradualy from torque peak down to whatever was 
needed to keep the engine load signal ( I believe it was duty cycle from 
the injector) in a given range. It worked, and felt like driving a diesel  

>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

I should have mentioned the economy mode but as I said that was a while 
ago 8-)

> 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,

I knew some combines had then ( I worked on 2 or 3 over the years)

> skid steer loaders,

aren't bobcats hydrostatic

> 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

that must make a racket, but sounds fun

> 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.

honda vtech does this doesn't it??

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

cool one thing I really like about this group is all the different ideas 
that come up

> 
> -----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.


--
Pat Ford                           email: pford at qnx.com
QNX Software Systems, Ltd.           WWW: http://www.qnx.com
(613) 591-0931      (voice)         mail: 175 Terrence Matthews          
(613) 591-3579      (fax)                 Kanata, Ontario, Canada K2M 1W8




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