I used to think a pressure sensor driven EFI system required an air
temperature input
and a computer to work. That ruled out the pressure sensor in my feeble mind
for a
simple and cheap 555 system. I thought I needed a MAF sensor. Then I found
out that mass
air flow sensors are not linear. Then I thought well I would use a cheap
computer to
linearize the mass air flow sensor.

I have since changed my mind. All one need do to start the engine is set the
leaning
knob commensurate with the out side air temperature. Cold day set it richer.
That
simplified the system greatly and we can use an ordinary 555 system as a
manifold
pressure sensor puts out a linear signal unlike a mass air flow sensor.
TLC555 are
linear devices. PW hence fuel injected is directly proportional to sensor
voltage.  I
now agree with Tracy Crook almost.

The benefit is a much cheaper system with no need to buy a $80 or $100 mass
air flow
sensor and install it on the plenum. If it is not there it weighs nothing
and is
absolutely reliable. The other benefit is pressure sensors cost less than
$10 each so we
can use two.... one for each rotor. A little redundancy for back up use.

Since the manifold pressure is linear we don't need the super 555
microcomputer chip and
a $1 analog TCL555 will work just fine as is.

I have got to get something working soon. As I will have some engines to
test soon.


Paul Lamar



I'm sure I've missed something along the way, but is this an EFI
controller/computer you're working on?
And could you elaborate just a bit on this comment: "I
now agree with Tracy Crook almost."? I ask because at present I was planning
on using his $900+ EC3 when the time comes.

Thanks Paul.

Jay

Tracy's is not a bad system if you don't mind the price. I just think it can be done much cheaper. Also it is a bit finicky to tune. As far as I know you cannot use a laptop computer to make changes in the mixture tables. Lots of people have spent a lot of time trying to tune it. In some cases years.

Read this on the web site.
http://www.rotaryeng.net/fuel-injection.html

Paul Lamar