Thanks!!

[robert joseph dingli]

Mike et al.

> 	Now, you mentioned that sequential fuel injection is pointless at high
> power ranges, but I still have trouble with the idea of dumpin' fuel into a
> cylinder when the intake valve is closed.  Yeah I know turbulence should
> keep the fuel suspended and that this happening 50 times a second at 6000
> RPM's but....

Many OEM efi system deliberately fire the injectors while the inlet valves
are closed.  This ensures that the back pressure on the injectors is even
and thus all the cylinders get similar fuel rates.  A side benefit of this
scheme is that a full sequential system is not required as it doesn't matter
when the fuel is injected at low duty cycles as long as it's when the valve
is closed.  A banked (eg. 2 banks of three injectors for a 6 cyl) system
suffices.

On the other hand, I've come across a few research reports which detail the
fractional improvements in efficiency, response and power output possible
when the end of injection timing is optimised for sequential systems.  The
main benefits appear to be in ultra lean burn high turbulence systems at 
light loads.

There is also the issue of pressure fluctuations in the fuel rail.  Sequential
firing lessens the pressure drop resulting from injector opening as the events
are spread out evenly.  It also allows pressure oscillation feedback
measurements for individual cylinders which can be used to detect faulty 
injectors and to estimate individual injector fuel flow characterisitics.
The overall injector noise can also be less.

Ultimately sequential injection is my final aim, but for now, my two bank
plus proportional auxilary staged injection system will suffice.

Robert
-- 
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             Robert Dingli           r.dingli at ee.mu.oz.au

Power and Control Systems                 Thermodynamics Research Lab
Electrical Engineering                    Mechanical Engineering
   (+613) 344 7966                           (+613) 344 6728
  University of Melbourne, Parkville, 3052, Victoria, AUSTRALIA
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