[Diy_efi] timeframe to get equal fuel distribution

[Adam Wade]

--- gngrbrd_man <keith.wilson at telus.net> wrote:

> I think what may be being missed here is that the
> fuel injector can be placed in the cylinder wall,
> below the ring level during compression/
> ignition/early burn, so that it is only exposed to
> the cylinder pressure when the piston is far enough
> down that the exhaust port is uncovered,

Your compression ring would last about five minutes
running back and forth over the tip of a fuel
injector.  The injector probably wouldn't look much
better.

Injecting into the cylinder port would probably be a
much better answer, and accomplish the same ends.

> Come to think of it, this just made me think of a
> rotary.  It may be possible to do direct injection
> into the moving 'chamber' in such a way that
> the trailing seal moves past the injector just
> before the leading seal passes the plug,
> giving "direct injection" into the compressing
> gases, long after the exhaust port is closed, but
> not into the combustion chamber.

The problem there being you'd need fairly high
injection pressure and there's almost no space between
the rotor and the trochoid, so all the fuel would
wet-spray right onto the trochoid.  That might work
okay in a hot engine, although I'm not sure you'd get
a very homogeneous mixture that way.

> Viola, no fuel blowthrough, even with long port
> overlap, but less complexity than true DGI. ;)

That's pretty much the way I think all the GDI systems
work in full torque-demand mode, with a full
homogeneous mixture and the ability to begin injection
after the exhaust valve has closed (using a
four-stroke as the example here), and thereby there
being no raw fuel blown out the exhaust (an increasing
concern with misfire being so damaging to catalysts
these days).

I doubt you would get most of the touted benefits of
GDI by operating only in that mode, but then again, I
doubt you could get them anyway with a rotary.  ;)

=====
| Adam Wade                       1990 Kwak Zephyr 550 (Daphne) |
|   http://y42.photos.yahoo.com/bc/espresso_doppio/lst?.dir=/   |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |

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