[Diy_efi] EGR and Valve phasing/lift

[Perry Harrington]

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.

If you still don't picture it, just think of a ball petcock used for water
shutoffs.

--Perry

-- 
Perry Harrington			Data Acquisition & Instrumentation, Inc	
perry at dainst dot com					 http://www.dainst.com/

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin

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