This particular set is for dual exhaust, thus two resistors and transistors. If
you're running a single pipe, then you can omit one of each of these
components and just wire up a single.
NOTE: This will NOT work for FI or EFI!
Parts List:
1. One Aluminum Project Enclosure measures 2-3/4 x 2-1/8 x
1-5/8 inches. You might look for a larger one as this was a bit small.
2. Two 2N3055 Power Transistors
3. Two Transistor Mounting Hardware Kits for TO-3 style case
4. Two 220-ohm 1/2-watt Resistors
5. One 30-amp Automotive style relay. You need the 5-terminal relay (see below), which
my local Radio Shack didn't have (they only had four teminal relays). If yours
doesn't carry it, check your local phone book for another electronics store or
a car stereo store.
6. One small tube of Heat Sink Compound. .
7. A few small terminal ends to fit the 6-32 mounting screws.
8. Some colored wire. I used 16 guage.
Figure out where you're going to mount everything inside the box so that
nothing clashes and you have enough room to maneuver a soldering iron.
Use an insulator from the mounting kit as a template to mark the case, then
drill the case for the transistors. The mounting kit will have two plastic
shoulder washers that go into the mounting holes from the inside. This keeps
the mounting screws from grounding to the case. Consult the back of the
mounting kit package for instructions. Use heat sink compound on both sides
of the insulator, this helps transfer heat from the transistors to the case. A
little dab'll do ya.
The transistors have two pins on the underside: One called 'base' the other,
'emitter'. The third element of the transistor is called the 'collector' and is
tied into the transistor case, hence the wires that attach to the mounting
screws. Consult the back of the package for pin configuration.
Here's the case with the transistors mounted with one screw each. I put
heat sink compound on either side of the insulators before mounting the
transistors. The pins are offset to one end and the arrow indicates the
direction of the offset. This matters only for identifying which pin is which. It
also matters which direction the resistors point. The red stripe should be
closest to the transistor, while the gold stripe is facing the relay. Solder the
'red' end of the resistor to the 'base' pin on the transistor. Solder a length of
wire (six inches long or so) to the 'emitter' pin on the transistor (green wire
in photo). These wires will run out of the box to the + side of the coils.
Mount the relay. I used 3M Weatherstrip Adhesive (black), but silicone or
epoxy would work too. Make sure you mount it in a direction that will allow
your wires to run to their proper terminals. Cut off the relay mounting tab if
needed.
The gold end of the resistors thread through the hole in terminal 86 on the
relay and attach to terminal 87a at the center of the relay. I bent a little
hook into the tip of the resistor lead and put it through the hole in terminal
87a. Solder both leads to both terminals.
Make a split-harness (orange wire in photo, again about 6 inches in length)
and mount the terminal ends. This is the power wire for the flamethrowers
and will also run outside the case to the relay up front. Make a single wire
(black in photo) with a terminal end to attach to one mounting screw, the
other end is soldered to terminal 30 on the relay. Install the mounting screws
with the orange and black wires installed. The black wire only needs to go to
one transistor.
Making a split harness: (top) strip a section of insulator and twist a second
piece of wire into it. Solder the joint and protect with heat-shrink tubing. OR
(bottom) make a simple one with 3 pieces of wire and a butt connector (you
can also twist the three together and solder them).
Here are the solder joints where the resistors attach to the relay.
Solder a piece of wire (six inches or so) to terminal 85 on the relay (yellow
wire in photo) for chassis ground.
To mount the thing in the car, you can either drill and mount the empty half
of the box, then assemble the other half onto it or get some small L brackets
from the hardware store. You should also use a grommet for the hole that
the wires pass through to prevent shorts. I also put a zip tie on the wires
inside the box to keep them from being pulled out and bending the transistor
pins to ground on the box.
Wiring for this unit and my kooky discount-table-wire colors is:
yellow: ground
orange: power from switch
green: flamethrower coil +
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To wire up the triggering relay, you'll also need a 5-terminal relay. First, disconnect the
ignition wire that goes to the engine. If you have a ballast resistor, disconnect the wire
from the input side. NOT the side that goes to the coil, the other one. If you don't have
a ballast, just disconnect from coil+.
The numbers relate to the terminal numbers on the bottom of the relay.
85 -chassis ground
86 -switch. this can be just about any kind of switch you want. I used a momentary on
pushbutton. Don't worry about size either, it only has to fire the relay and doesn't carry
heavy amperage -that's the relay's job. The other terminal on the switch itself goes to a
power source.
30 -to ignition (the key) switch. This terminal powers the relay. If you mount the relay in
the engine room, you can disconnect the coil+ wire and put it here.
87 -to the electronics. This terminal is normally off. It comes on when the relay is
triggered to fire the 'throwers.
87a -to the coil+ (or ballast resistor) on the engine. This terminal is normally on and goes
off when the relay is triggered.
Terminal 30 would normally be connected to battery, but since you want to be able to
shut off the engine at the end of the day, you use the wire from the ignition switch.
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Your local muffler shop should carry bungs to weld into the pipes to hold spark plugs. gap
em right up to .080. You can also use anti fouling tips from the auto parts store. cut off
the outside threads and enough metal to expose the plug tip. Be sure to leave enough
inside threads for the plug to screw into.
You must ground the flamethrower coil- to chassis ground! I know it doesn't make sense,
but that's how this setup works.
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To light em. drive around the 'hood to warm up the pipes. They have to be warm for it to
work. Rev it to neighborhood of 3000 (whatever you're comfortable with) hit the switch
and pump the pedal. be sure to lift your foot, then let go of the button before the engine
winds down. Works good at cruising speed too.
Also, these will increase/accelerate engine wear. You're pumping raw fuel through the
engine and it washes down the cylinder walls and contaminates your oil. Change it more
often. It'll kill a catalytic converter and doesn't work with fuel injection since the
injection shuts off when you kill the engine
Last edited by whatcanthisbe : 13th May 2008 at 10:23.
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