This is the second Tracy computer that I have wired.
I am now in charge of 3 of them. There is more to
this than just a schematic.

I decided to do a little preliminary planing to avoid
the rats nest result :) Hopefully this will
make it easier for other people to do it.

I also re-drew Tracy EC2 schematic to make it more clear.
The PCM module has a male 15 pin D sub min connector
so I will order a female 15 pin break out board from Winford
Engineering. http://www.winfordeng.com/products/brk37.php
tomorrow. I did not draw or wire in the coil and injector disable
switches as I don't need them for the test stand.

Tracy recommends soldering  to mating D sub min connectors but
unless you are a young, skilled electronics technician with good
eyesight that will be problematic. Therefor and hence the break
out boards.

Basically there are three wiring bundles or cables.

Cable 1 Injectors. 4 wires.

Cable 2 Coils.  4 wires

Cable 3 A user interface panel called the PCM with 11 wires.

Everything but the injectors are low current
five volt circuits so very small wire can be used.

One of the little tricks I discovered is buy old cheap parallel
printer cables. They have 18 wires in them, all of a different
color, shielded with a ground wire in a sturdy vinyl jacket.
They come up to 12 foot lengths. Cut off the connectors and
throw them away.

Ideal for the cable from the PCM to the EC2.

The wires from the EC2 to the coils are low curent
as well but there are only 4 so any old RS232 cable
can b used. These cables are obsolete for PC's so they should be
pretty cheap. The advantages of having the cable in a nice heavy
protective vinyl jacket are not all obvious. Finding unique colors
is less of a problem as each cable will have a limited number of wires.

The injectors are another matter as high currents are switched
by power transistors in the EC2. Tracy recommends 20 gage as
I recall so you will have to make up a cable with 4 color coded
20 gage wires in it. There is a product called Flex Guard Convoluted
tubing. That will take the place of the vinyl jacket and serve as well.
That can be bought from DigiKey or Fry's.

The key to this plan is all coils and all injector need
what Tracy calls switched 12 volts. All that means is you
cannot just connect the injectors and the coils to the battery.
It must be switched off when the master switch goes off.
The reason this is so is these device are also connected to
transistors in  the computer that might leak current and
run down the battery. Therefor we need a fairly heavy wire
from the master switch to the top of the engine going
to a 12 Volt bus bar to supply both injectors and coils.

I found a boat bus bar that looks like it will work
great. Lots of boat stuff is higher quality than automotive
stuff.

If that is made available on the top of the engine it would be
convenient to the coils and the injectors. Of course
engine ground will be there as well for the coils.

Hopefully I can make a large improvement in the neatness of
the ACRE test stand wiring. Also with the help of the break out
boards one should be able to wire this up in an hour.
Hopefully this is going to save you a lot more time
that that.

Wiring errors and failures are a major cause of
alternate so-called "engine" failures.

Stay tuned when I get this thread done with input from
the electronic techs on here and the test stand engine
running I will post it to the web site for future builders
using Tracy's computer.


Paul Lamar

Check out this YouTube comparison of the LS1 & LS2 "Yukon" coils.
http://video.google.com/videoplay?docid=-6218245369765754251#

Mark

Remember the V8 engine fires every other rev while
the RX8 coils fire every rev. Not only that the RX8
coil need to fire at 9000 RPM while the V8 6500 RPM.

a 5 millisecond dwell is marginal for a rotary
at 7500 RPM.

My hopes are on the second gen RX8 coils.

Paul Lamar

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

I am rapidly discovering these older RX8 coils are very
sensitive to exact routing of the trigger, ground and power
supply wires. I think a large capacitor would help on
top of the engine from the switched 12 Volt supply to
engine ground. The trigger wire from the EC2 to the
RX8 coil must be well shielded. 2 ms was inadequate
for a stable trigger so I upped it to 3 ms.
The failure mode seems to be double or triple
trigger. That drastically increases the dwell time
over heating the coil.

Now it could be the spark is out in the open and that
could be part or all of the problem. With the spark
inside the combustion chamber it could be a whole new
ball game. I won't know until I get this system
running. Early Morse code radio transmitters were
merely spark gaps. dot dot dit dit.

If you crash in the wilderness take one
of these coils and make a spark transmitter with
a long wire antenna. It will go out over a wide range
of frequencies.

I also don't know what Tracy is using for
a dwell time. I did see 20 ms at cranking speed.
If that is the same dwell at 7500 RPM that would
be a disaster of the highest order for any coil.

Tracy, what is the dwell at 7500 RPM???

At 7500 ms we have only 8 ms to work with.
In other words that spark plug must fire
every 8 ms. That is not a lot of safety margin.

Since just about everybody agrees the GM coils
require 5 ms so I don't think they are a good
idea regardless of the generation. LS1, LS2 etc..

In the Chev V8 at 6500 RPM the GM coils are only
required to fire every 18 ms. In other words
every other rev.

I do hope the 2nd gen RX8 coils are going to work
better and I am supposed to get a set today.

I am also going to get Jeff to make up a heat
sink to mount the RX8 coils. It will require
a clamping bar so the connector end can be in
good contact with the heat sink. You will be able
to buy it directly from Jeff.

Here is a good extrusion to start with.
Should be 8 inches long with the coils
mounted cross wise on 2 inch centers.

Send your coils to Jeff and he can take
a clean up cut on the bottom to make
close contact with the heat sink.
Use heat sink grease to mount the coils.

Paul Lamar

As far as soldering the sub d connectors for the EM2/3 and EC2, I'd
recommend using machined pins and crimping them with the specialized
crimper made for the task. Your results will be uniform, more foolproof,
and you won't get solder wicking up the wires and creating a potential
stress point. Also required is an SAT-004 four point crimper. You will
get absolutely consistent results using machined pins and the proper
crimper.

go here  http://www.steinair.com/connectors.htm

This is just an example, if there are less expensive suppliers, then
please someone post them.

I'd also recommend a pin removal tool in case of a pin being installed
in the wrong hole.

Brian Trubee