Subject: Using 2 Megasquirts. One per rotor
From: rotaryeng
Date: 7/6/2012, 4:22 PM
To: AAAA Put this in the To box 




   This looks like a real simple way of using megasquirts on rotaries and you have
   redundancy. The engine will run on one rotor. It solves a lot of problems using just
   one Megasquirt on a rotary.

   I has the advantage of using a notebook computer with a USB connector to tune and
   save injector tables to share with other people merely by emailing them.
   Megatune is very sophisticated and easy to use tuning software that runs on a
notebook.

   IMHO this is a great idea.

   Paul Lamar

   -----------------------------------------------------------
   Using MegaSquirt ‘out of the .box’

   www.not2fast.com/megasquirt/doc/rotary_injection.doc

   MegaSquirt introduction.
   The MegaSquirt was design by Bruce Bowling and Al Grippo to be a simple and cheap
   batch fire fuel injection system. Been around for years.

   There are 2 injector driver outputs on the MegaSquirt, running off the PWM channels
   of the MCU. This allows both saturated and peak and hold injectors to be used on the
   same hardware: very clever. This allows 2 different injection events to occur in
   parallel, which suits our purposes very nicely.


   Specific needs of Rotary engines.

   The rotary engine, due to the rotor layout has a few key differences with a
   reciprocating engine. Many of these work in our favor. And remember, the otto cycle
   is the otto cycle:

   There are 2 rotors, spaced 180° apart. EFI.

   Build 2 MegaSquirts.

   Fit a pair of hall effect sensors one at 22 degrees BTDC and  one 180° later (top and
   bottom) Hook one MegaSquirt to the top sensor and one to the bottom.
   Burn in injector staging code if required.

   Ignition.
   The ignition pulse on 1 rotor corresponds to 22° BTDC on the inlet cycle of the other
   rotor, give or take the amount of advance being used. Very handy.

   Use 2 MSD capacitor discharge units per rotor. One per plug. This is what the racers
   do and is it very simple and straight forward. Each Hall Effect sensor fires two MSD
   units 22 degree BTDC.

   Injection.
   Around 220-280° is available for injection. In a reciprocating engine, you
   can ‘puddle’ fuel on the inlet port to increase the injection time. In a rotary there
   is little time for this before the next inlet cycle starts. This forces relatively
   large injectors to be used, with staged injection being a
   useful method of getting high max flow rates and a good dynamic range. For example,
   at 8000 RPM 1 revolution is 7.5ms, giving around 6ms for injection.

   In terms of injector strategies there are a couple in general use
   The best for our use here is 2 injectors in each runner.

   The code mods are very simple, if needed at all
   You get the full 6 ms for injection at high RPM
   2 MegaSquirts are needed so adding a full $100 to the costs
   Tuning will be a little more tricky as you have to set each parameter twice

   ----------------------------------------------------------------


 I had an idea of using 3 megasquirts that fed a logic box that compares the outputs
 and forwards the one that at least 2 ms boxes agree on. Not sure if it's really
 feasible since that would induce some lag in the outputs.
 Joshua

 ---------------------------------------------------------------------


 SymTech Labs' coolant temperature sensor is a standard GM CLT sensor capable of
 interfacing with all MegaSquirt ECU's. It features 3/8" NPT threads and can also be
 used as an intake air temperature sensor (IAT/MAT). Each unit is shipped with a 6"
 pigtail for easy installation.

 Intake Air Temp/Manifold Air Temp

 The big question that I have is there seems to be conflicting info. Often they talk
 about a MAP sensor but this block diagram does not show it. A Manifold Air Pressure
 sensor (MAP) can be used to control the amount of fuel injected just like an O2
 sensor. That is what Tracy does.

 Any type of feed back from an O2 sensor will not work as 100LL is death to O2 sensors.

 The MS flow chart shows a read of the MAP but the schematic shows no connection to a
 MAP sensor.

 Can anybody help me out on this? Is the sensor on the mother board? Where is it
 connected?

 BTW The megasquirt has the built in capability to send engine parameters back to the
 notebook in real time for use as an EFIS. The notebook software is already available
 to display these engine parms in real time. This is a real cheap EFIS.

 Paul Lamar


The MS3x has the map in the box. An external map can be used for
Barometric correction.

I have one. Tuning software is Tuner Studio which runs on both Windows
and Linux and megatunix which just runs in Linux.

chris smale

I have already found a way to flash a 68HC11.
http://www.orgler.it/swflash.htm
Apparently AMD makes a clone.

-------------------------------------------------------
Here is a new part directly from the maker probably more powerful than the original
MS part.

http://www.newark.com/freescale-semiconductor/mc68hc908jl8cspe/8bit-mcu-8k-flash-adc-68hc908-dip/dp/92K6991

$3.97 Three dollars and 97 cents qty one. :)

Runs MS code directly.

I have a set of MS V3 boards already that I can copy if need be.

The more I can get into this the more I like it. I am getting excited
because of the EFIS and data logging MS software is already done.

Six months ago I was thinking of writing all the software myself for a different
processor. This is a much quicker way of dong it. Just port the MS software and copy
the hardware to an aircraft specific system.

Paul Lamar

-- 
The Rotary Engine News Letter. Powered by Linux.
ACRE NL web site. http://www.rotaryeng.net
You Tube key word PaulLamar2
Copyright 1998-2012 All world wide rights reserved.