K-Jet /PIC Valve

[The Punisher]

James: Thanks, I'll check out that KE-Jet electronic regulator scheme. And 
the Accuracy problem of my stepper or servo system would not be a 
problem(feedback to the micro with a shaft encoder or pot). And I'm thinking 
of a valve that would require little torque(the fuel pressure would not work 
against the valve). My first thought was to just put a servo on the flapper 
valve arm but thats TOO bulky and would require a lot of power with powerful 
driver circuitry and that brings the complexity/cost back up to that of 
electronic injector driver schemes.


The only thing I wanted off the K-jet system was the injectors, lines and 
cold start injector.

I spent some time trying to draw the valve I had in mind this morning. I 
think I'll go look at some off the shelf valves before I go any further. The 
reason being the torque requirement, I can get the motors to do it, but I 
want it small,light, and inexpensive to build using mostly off the shelf,and 
common wrecking yard parts.
I DO NOT want to use the bosch fuel distributor. I wanted to use a sort of a 
spool valve but now think that a ball valve or a barrel valve would work 
fine. I'll just have to write a little more code and do more calibration 
testing to convert valve position to flow in a linear fashion. Last time I 
did this with a pic it took about 125-175Bytes of code to linearize a curve 
like a similar type curve. Also a ball or barrel valve would not require 
very much torque for a stepper or servo.
The fuel lines would all be connected to a common manifold(fuel block) sort 
of like on a race mechanical setup. This block would be fed by the 
ball/spool/barrel valve. A servo would control the the valve. A bypas 
regulator would feed the valve. The regulator would have a very simple 
restrictor valve in the return(possibly a pulsed solenoid on a pwm) but 
trimming the fuel pressure is the EASY part.

Airflow measurement will be acomplished with either map or maf. MAF seems 
MUCH simpler to program and would take up a little less code space. To get 
around the problems of restriction caused by the MAF I am thinking about 
twin medium sized units instead of one large aftermarket unit(the whole 
project is to be INEXPENSIVE) I could just add the airflow numbers together 
and get a total that way.(very little extra code needed). I have been having 
trouble finding many voltage:flow charts for common OEM MAF's(I did find 1 
chart for 2 ford MAF's)
For idle air I will probably use a gm type IAC, but does anybody know 
anything about the ford type(like on 100gazillion ford's)? I think somebody 
said they are a servo instead of a stepper.


I'm working with a 427 Big Block Chevy here so big airflow is needed! I'm 
using 4 small 1 barrel(58-60mm cant remember right now) throttlebodies off 
jap cars. These are common, compact, have a nice compact square bolt pattern 
and dont look too bad. With a custom Plenum atop a Weiand Hi-Ram I can adapt 
more or fewer throttle bodies REAL easy.(if 4x60mm is too much,3x60mm will 
be easy). I also have a 455 buick and a 400 pontiac to expirement with.

a few cold start injectors up near the throttlebodies could be pulsed if the 
injector valve proves too slow for rapid acceleration(they atomize good,even 
at low pressure) and could be used for 'cold starting'.(but cold start 
injectors are starting to get like electronic injectors and thats not the 
goal here).

Anyhow this is just an idea I came up with the other day. I AM NOT saying 
that I think this is better that a regular electronic system(but might be 
easier in a special cases). I just want to try something different.


>From: James Montebello <jamesm at lapuwali.com>

>>This is K-Jet with Lambda, and was fitted a wide variety of cars.  Later,
>KE-Jet used a better, electronically-adjustable pressure regulator to
>vary the "control pressure" for the fuel distributor.  This allows mixture
>variations with a given about of flapper movement (i.e., air mass).
>
>All of the K-Jet variants, however, still required a flapper to move
>the control plunger in the fuel distributor.  The mixture controls
>were strictly for relatively fine adjustments, as required with a
>Lambda-controlled system.
>
>The original poster wants to do away with the flapper altogether, and
>control the fuel distributor directly.  Essentially, this is a straight
>EFI problem, simply replacing injector pulse width with plunger position.
>
>A snail-profile cam and a stepper motor might do it, although I'd really
>wonder about the combination of the accuracy AND the torque requirements.
>Such steppers may exist, although I'd expect them to be expensive.
>Doctoring the plunger to operate by rotation rather than linear movement
>(as he seems to be proposing below) would also be an option, although
>you'd still have the accuracy/torque problem to wrestle with.
>
>I wish you luck...
>
>james montebello
>
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