Re: Propane EFI

["Bruce Plecan" <nacelp@bright.net>]

> Question for those familiar with the GM ECU's.   A TBI uses a constant
> frequency pulse and varies the pulse width to meter the fuel.

Only in quasi synch mode.

  A Ford IAC
> uses a constant frequency pulse and varies the pulse to meter bypass air.
> Both about the same voltage and frequency.
> Could you replace the injectors with Ford IAC's and meter the propane from
the
> vaporizer ( very low pressure gaseous flow ) and now have hacked the GM
unit
> to do propane.?   ( or low pressure CNG which someone is contemplating )

Trouble is are the Ford IAC supposed to be "vapor leak proof".  Just playing
devils advocate here, if ya already know just ignore me

> Output from the vaporizer is low pressure vapor that goes to a hose to the
> mixer.  Thimking of running the output thru a pair of IAC's to a pair of
EGR
> plates ( did I mention dual 4 barrel manifold ) under a pair of throttle
> bodies.

Oh, them ford things that go right behind the Ford Throttle Bodies?.  Sorry
ya gotta splain thing for the gm only crowd.

> Hook all the sensors up normal.  GM thinks its firing injectors - actually
> varying propane flow.  Run for a little while, hack the tables and should
be
> close.

You got alot of work to work out a pressure so that the IACs are passing a
like amount of vapor as would an injector would be.   Gees, I have trouble
following that and I wrote it..

> This way I would get EGO, spark, knock, idle air ( from GM IAC ), egr etc
> without spending a fortune.

Close enough in theory as I see it to mock something up/

> Propane carbs "love" blow thru - so by simply referencing the vaporizer, I
> could invert the rams horns and mount two small turbos and turbo it.

Ahh, Turbos....

> 8 cylinder GM TBI MAP unit should work just fine. ( Moderate cam - MAP is
> close enough without the calibration worries etc yada yada yada of a MAF
under
> boost )
> Lastly, is the GM unit hackable enough to leave the EGO on full time
 after
> warmup ) under load?   Response on a 20,000 lb vehicle is not an issue -
but
> running rich under propane is.

Hmm, this is for the ""big momma"", might just by setting TPS  PE enable to
a very high value keep C/L.  What rpm limit?
What resistance are the IACs?.
Grumpy

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