[Diy_efi] EGR and Valve phasing/lift

[Alexei Pavlov]

pedward at apsoft.com wrote:
> 
> Ok, so admit I didn't know the full reasons for EGR.  The predominant reason
> I heard was the unburnt HC in the exhaust being used to supplement the fuel
> injected in the first place.  The inert gas explanation sounds like the rest
> of the picture.  Mind you my explanation came from some early 80's 5.0l
> literature (carbed), a little blurb in a repair manual I think.  In any case
> the EGR is a beneficial tool for fuel efficiency.
> 
> On variable valve lift, etc.  The problem is that valves are old and cause
> problems.  What I was thinking was making a custom head with 2 cylinders
> in the exhaust and intake tracts that rotate to allow gases through.  You
> essentially have a cylinder big enough to flow the full intake/exhaust flow
> when turned to 90 degrees, but blocks off the flow and seals the combustion
> chamber when at 0 degrees.  You could crudely control these with a camshaft
> and follower mechanism to initiate a positive locking (kinda how desmo works).
> 
> Ultimately I'd want either a stepper control or a cylinder that can be moved
> in and out ala Mikuni slide carb with solenoid control.
> 
> You could eliminate the intake tract restrictions using this type of mechanism
> and it is easily expandable to full airflow control.
> 
> I may pursue this approach for a B&S motor or some other small 4 stroke motor
> (maybe a motorcycle single).
> 
> Also, if you made the rotating cylinder large enough and located it correctly,
> you could just directly spin the cylinder with a timing chain/belt.  Since
> the camshaft moves half the speed of the crank, you could cut passages into
> the cylinder to pass/nopass gases when you wanted.  The other benefit I see
> is that the combustion chamber could be make smaller using this technology
> and you'd see a higher CR.  Perhaps it would also lend itself to lower deto
> because of smooth contours.  There are lots of ideas to be tried with this
> method of valving gases.

It seems to me that all these systems were used in the beginning of the
20th century :-) Also VW have used them on SI engines.

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