[Diy_efi] CX 500 EFI?

[Adam Wade]

--- "Steven P. Donegan" <donegan at donegan.org> wrote:

> Boost pressure is not directly related to engine RPM
> on a belt-driven supercharger setup. i.e. My Mustang
> can get serious boost at 700 RPM simply by hitting
> the gas :-) Similarly it can have zero boost or even
> some manifold vacuum at cruise - it's more a
> throttle position/load thing...

Does that mean the throttle plates are placed between
the atmosphere and the blower?  That would definitely
account for a lot.  And of course, it's even more
complicated with a turbo; while a given steady-state
throttle position and engine speed would produce a
particular amount of boost, that's not the case with a
turbo.  I can see where it might make best sense to
use a TPS vs. engine speed map as a "base" for timing
your Camaro, and then modify it based either on the
last x throttle position readings (looking for delta
alpha, or at least accounting for trending in the
"older" measurements), whereas I would think it would
be far easier to look at surge tank pressure vs. alpha
vs. engine speed when dealing with an exhaust-driven
turbo.  You could certainly get a LOT more complicated
with the model and measurements if you wanted to, but
I think that would be the bare minimum to properly
fuel and spark an exhaust-driven turbo on a
four-stroke ICE (or most other fossil fuel-powered
engines too).  I believe the CX500T uses a straight
"mechanical advance" (no alpha used, just engine
speed) with a retard based on surge tank pressure. 
The 650, since it integrates ignition with the rest of
the ECU, most likely uses the "bare minimum" strategy
I noted above.  It would certainly be POSSIBLE to make
a simpler system for spark timing than my "bare
minimum", but I can almost insure that the results
would be inferior when compared to the stock systems
in both bikes, thus being a big negative when
considering use as a stock replacement ECU on these
bikes in particular.

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