[Diy_efi] CX 500 EFI?

[Steven P. Donegan]

'real' superchargers - ie Roots style ones are used in throttle, blower,
intake engine sequence. Paxton/Vortech/etc and many if not all
turbocharger setups are normally blow-through - ie supercharger,
throttle, intake sequence. There are weird exceptions :-) In some
systems, typically airplanes, turbochargers are not necessarily there
for boost - but for turbo-normalized purposes - ie maintain 1 bar from
sealevel to whatever the operating ceiling is...

On Wed, 2007-01-10 at 18:48 -0800, Adam Wade wrote:
> --- "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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> 
> 
>  
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