[Diy_efi] COP

[Adam Wade]

--- Bevan Weiss <kaizen__ at hotmail.com> wrote:

> Really want something like a 4valve per cylinder
> configuration, this allows better use of the gas
> momentum to improve volumetric efficiency at low rpm
> whilst still maintaining high rpm flow.  Have the
> valves staged, such that at low revs only one intake
> and one exhaust is open.

No reason to restrict the exhaust.  Honda has done the
staging of the intakes using hydraulic pressure from
the oil feed to determine rpm, and thus shift into
two-valve operation on the intakes.  The only drawback
I can see from an FI standpoint would be that you'd
want to set up your spray pattern to spray on BOTH
inatke valves equally...  Which would either mean two
tiny injectors per cylinder, also staged, or some fuel
sitting on a closed intake valve and wetting the
intake at low rpms, which would kill some of the
efficiency of that setup...

> Possibly have the valves as one small and one large
> (ie 4cm^2 and 16cm^2 or so) such that you could have
> different flow areas for different revs as well...
> allows for far more calculations :D

That runs you into some odd combustion chamber
geometry, though.  Not to mention how it would affect
flow in the combustion chamber with both intakes
open...  How would you determine best shape for the
intake runner?  Not that there wouldn't be questions
about that with one intake valve closed, of course,
but they would hopefully be of less concern...

> Even better would be electronically controlled
> valves, which I haven't heard anything about for a
> while.  If variable overlap and variable valve
> opening could be controlled via microcontroller that
> would be perfect...

BMW Valvetronic.  Electronically-controlled
"infinitely" variable cam timing on intake and
exhaust.  Very complex, very expensive.  :D

ObEFI:  the Valvetronic computer is based on the
MPC565 microcontroller, same one we're discussing
using for the next-gen "MegaSquirt"!  :D

=====
| 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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