Turbocharging a CMFI engine

[Mike Pitts]

>What is  CMFI engine?

CMFI = Central Multiport Fuel Injection
One huge specialized injector feeds 6 tubes leading to poppet valves
where normal injectors would usually mount.  The injector is not like
injectors you find on regular multi-port FI vehicles.  It's quite unique.
It has a large armature that uncovers the 6 feeds when pulsed.

>I've got a BMW 535 i want to turbo and don't know how to read the fuel and
>ignition maps

Jim Conforti is the beemer expert I think.  Are you still here Jim?

>Then why not connect it to vacum and make it self regulating?

Since it's not currently vacuum controlled and is totally self-contained,
I'm
guessing I can't just plumb a line to it and have it work.  I could be wrong
though.

>I'm not really sure it is,  fuel presure varies with atmospheric anyway so
as
>long as you're above the boost by x amount you should be in the ball park.

>From what I've read, this regulator does not vary.  It attempts to keep
a constant 55 PSI.

At zero PSI, the delta will be 55 PSI.  At 10 PSI, the delta will only be
45 PSI.  I might be able to add enough pulse width to make up for it.
But I'm not sure.  The manual states that at 44 PSI, the engine becomes
undriveable.  Chip tweaks will hopefully stem that.

>Is the popet spring loaded?  can you shim the spring or replace it with a
>heavier one?

Yes, spring loaded.  I don't want to change it even if I can because
it is opened by the fuel pressure in the feed line.  Changing the spring
could adversly affect it's normal operation.  Again, I could be wrong.

>Only way I can think of is by installing a larger injector or addional
>injectors

It's not a regular injector like you see in MPFI cars though.  Maybe
I can open it up and drill the holes larger.  =8-O  But it says it's non-
serviceable.  So it's probably a sealed unit.

>Nothing wrong with that,  how about a whole new controler?

This controller also controls the transmission.  That complicates matters
somewhat.  I am trying to keep it as simple as possible (ie: no wiring,
PCM, engine, trans or intake manifold changes)  The simplest is to just
change the chip.  But I have a few concerns as stated.

-Mike
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Mike Pitts
Delray Beach, FL
mpitts at emi.net
http://www.emi.net/~mpitts/mike.htm
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