Re: Low RPM, high torgue engine for cogeneration.
->
-> I baulk at the cogeneration bit. The interesting rig you describe is
-> liable to
-> be unprofitable to you, a good citizen helping the utility Co.
But I would also need to calculate the value of the heating fuel I
would save.  It's not just for electricity, but residence heating in
the cold season.  Not even sure I would use it outside that time of
year.  My house was built in 1750, and does not lend itself to the
mega-insulation that efficient homes have.  If I did that, it would
ruin the historic value of the place.
-> CH> The key is shaft HP.  No idea how the manufacturers rate these.
->
-> The elec output [kW] of the alternator is a good guide. Elec
-> machines can be
-> fairly precisely calculated and measured re their losses- windage, fr
-> copper loss, iron loss. Polytechnic and uni students often have to
-> do this in lab. as a curriculum requirement. I did!!
->
-> Many engine labs USE a "calibrated" generator as the method to
-> determine shaft HP. Others use a dynamometer.
Yes, but is it done at a specific, accepted temperature/humidity and
barometric pressure?  And do they have a "standard" fuel?  There are
a lot of variables besides the classic generator or dyno.  Most
high-performance shops factor all the enviromental things in for their
testing.
-> And what the efficiency is, who knows?
->
-> Well the effy is vital so you don't go broke selling your kwHr too ch
Absolutely!  That's really what this exercise is all about.  Modifying
the components to maximize the efficiency at a specific RPM and load.
-> -> CH> I have often considered using a V-8 automotive engine with
-> much -> CH> altered cam and ignition timing running at 540 RPM (PTO
-> speed) -> CH> to run a generator.  By careful selection of
-> components, it
-> -> CH> would probably be made to be quite efficient at that speed.
-> -> CH> Maybe even run it off piped-in natural gas for co-generation.
->
-> Do you think you have the necessary skill and other resources to make
-> alteration to cam [?profiles]
Cam profiles?  Yes.  I don't grind the cam myself, but I sure know of
at least a dozen very qualified shops who can handle this.  And I know
how to check the camshaft installation timing for maximum compression.
It is irrelevant if I have the knowledge/experience/equipment if I know
who to ask and what questions to put forward.  Then they make the
required piece.
-> and ig timing? Wouldn't the auto advanc
-> dodgy problem since at constant rpm the centrifugal feature would be
-> inoperable.
My intent is to use a Vertex magneto with fixed advance.
-> If you fiddle with say three different cam changes and
-> three alternative ign settings then there are 3x2 ie six set ups
-> that might be tested in order to pick an OK one. Cancel your
-> vacation away!!
With the input of the camshaft maker, I doubt I'd need to make even
one cam change.  These guys are pros.  As far as timing, what's wrong
with putting a load on the engine, and adjusting timing for maximum
RPM?  Same with fuel mixture.  Adjust for maximum RPM at a fixed load,
then either increase load or drop RPM and repeat.  If that couldn't
be dialed in within a matter of hours, I'd be *really* surprised!
Very simple process, actually...  The load becomes the dynamometer.
-> CH> not proposing that .  I was thinking about a standard
-> synchronous CH> AC generator, sized appropriately.
->
-> Hey! Is there such a thing? I fear that you will have a very limited
-> any "standard" synch generator. To any enquiry you might find just a
-> all weird!!
I'm not sure I understand your objection.  As long as the generator is
large enough so it doesn't burn out, and small enough to be realistic,
there shouldn't be a problem.  If the engine tries to run it at 59 Hz,
then it will supply no power to the grid.  As the engine tries to
increase RPM over the 60 Hz grid, it will supply power in relation
to the amount of "push" up against the 60 Hz grid.  Heck, a large
electric motor would work.
-> CH> turned.  To see if the project is practical.  So far, there has
-> been CH> some opinions offered by folks with some good experience in
-> the CH> field.  But I don't believe anyone has actually tried this.
->
-> They sure have tried it with induction generators. But you need the u
-> be agreeable because at many locations, this simple system depresses
-> supply voltage while spinning the meters backwards.
Around here I'm told they use ratcheting meters.  This separates the
power used vs. power supplied for billing purposes.  I would be very
happy to essentially break even.  Use none from the grid, and supply
none to the grid.  In essense, the power grid becomes a "flywheel"
to even things out.
-> CH> I have been working with high-performance engines for 30+ years.
-> CH> There is a tremendous body of work in improving efficiency in the
-> CH> field.
->
-> If that all means state- of- the- art then I guess you would accept t
-> to give close attention to mothering the setup. Most folk would rathe
-> basic commonplace cheap engine just run itself into oblivion then
-> replace it.
If it's built correctly, and set up as I have outlined, then maintenance
ought to be very low.
-> A fun hobby doesn't have to be cheap!    Cheers..ALEC
Nor expensive.  Interesting is a necessity, though!  
-c-
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