Dangerous injection ideas...

[Jeffrey T. Birt]

You can use the acetylene regulator with propane.  They are chemmically
compatable as far as the gases are concerned.  I would not reccomend trying
to modify such a unit and use it in an application where it could get oily
or greasy.  The regulator and oil\grease don't mix.  I work for a welding
equipment supply\service company and have heard of several horrer stories
from our apparatus repair people.

Jeff Birt

Bill the arcstarter wrote:

> OK - now I'm dangerous.
>  Just ordered a linear actuator stepper motor from C&H surplus.  Also
> got an acetylene regulator and a shaft encoder.
>
>  I'm thinking about building some sort of DIY-EFI propane system.  Am
> planning on using the linear stepper motor to replace the pressure
> adjustment of the acet. regulator to dispense propane into the test
> engine.  I think I can get away with using an acetylene regulator with
> propane.  Anyone think otherwise?  I know the pressures are similar and
> I also think that chemically they call for the same/similar type of
> hosing too.  But I may be wrong.
>
>  If I stay with propane I'll probably start out with using the riding
> lawn mower as proof of concept.  Then I'll think about converting it to
> gas (or maybe not) and putting it on in lieu of the shagged Q-jet on the
> 350.
>
>  So if Holley can build a system which computes (via lookup table) an
> injection volume as a function of engine rpm and TPS - well I bet I can
> too.
>
>  I'm thinking about using one PIC processor to manage this stepper
> motor, and another to read rpm/tps, do the table stuff and feed the
> final "fuel amt" to the 1st PIC.  A serial EEPROM device will contain
> the output mapping. You can get single eeprom parts, 8 pin ICs with up
> to 32Kbytes of memory.  Thats one heck of a lookup table.
>
>  TBD is how/if I'll arrange for the hacking/massaging of this table.
> Comments anyone?
>
>  I've seen comments about the Holley TBI heads.  You can buy this unit
> as a replacement part for about $289 or so.  There is also a similar
> unit w/o an AIV motor (air stepper).  Anyone know if I can get the
> proper wiring connectors to fit one of these TBIs?
>
>  I'm also wondering if I should go with some sort of MAP sensor instead
> of the tps, and just use tps for accel pump stuff...
>
>  Anyone have any clues as to some minimum resolution of these lookup
> tables?  I know that the GM ECUs use a megar table, something like 4x4
> or so.  Anyone also know a minimum precision of the output of this table
> - ie 8 or 16 bits?  Thanks and wish me luck!
>
> Comments invited.
> -Bill
>
>
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