Dangerous injection ideas...

[Bill the arcstarter]

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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