One of the most critical parts of any race car is the wiring, and it’s the reason why wiring gurus are so invaluable. Correctly wiring your race car makes any trip to the track more enjoyable, and saves you an immeasurable amount of headaches when there are issues with the car.
With any complex wiring job, there are many components that are needed, and one of the most useful is a relay. Shannon Davis of Davis Technologies, one of the smartest individuals in drag racing when it comes to electronic devices, has taken the use of a relay in the modern race car to the next level with the Relay 4, a simple, yet robust unit that will make any race car wiring project much easier.
Fundamentally, relays are a type of electronic switch that’s used to open and close circuits, either electromechanically or electronically, depending on the type of relay. A relay is able to control different types of electrical circuits by opening and closing contacts in another circuit on command.
Standard cube relays do work, but are not as reliable as the Relay 4 unit.
Different electronic devices, be it traction control devices, ignition boxes, or delay boxes, are extremely sensitive items and yield only trivial electric currents, so the relay helps those devices drive things that require more current.
Relays are in essence a bridge that covers the gap between two different electronic devices that give smaller current devices the ability to activate and run devices on a require a larger current. This allows a relay to act as either a switch that turns something on or off, or as an amplifier that turns tiny current into a larger, beastly-sized amount of current.
There are two different types of relays that you’ll see in the automotive world: the standard Bosch-style mechanical type, and the solid state relay. The mechanical relay has a pair switching contacts and an electromagnet inside the relay itself. Power needs to be shot across the coil of the electromagnet inside the relay — this causes the contacts inside to be pulled shut, thus closing the circuit and applying power to the device you want to turn on.
Using the Profiler, guys wanted to run multiple things and the Profiler didn’t have enough outputs, so we developed the Relay 4. - Shannon Davis
The solid state relay lacks the internal moving parts that the typical mechanical relay has. Inside the solid state unit is a sensor that reacts to the control signal that is applied, a solid state switching device that that moves power to the load circuit, and some type of coupling apparatus to shift the signal, and activate the switch.
The Need That Davis Technologies Addressed
Davis and his company, Davis Technologies, have changed the drag racing game with the Profiler wheel speed management device. Teams that successfully implement the Profiler into their program have seen massive performance and consistency improvements, and the Relay 4, behind the scenes, has helped make that a smooth process
“Using the Profiler, guys wanted to run multiple things and the Profiler didn’t have enough outputs, so we developed the Relay 4. Then, other racers started to use it for other things, too. The Profiler has four high amp outputs and four low amp outputs. Some of the car’s systems require more amperage than the low amp outputs can sustain on the Profiler, so that’s how the Relay 4 came about,” Davis explains.
Brad Edwards is a top level radial tire racer who found out the hard way he could use the Relay 4. “What sparked the need for me was when a five cent connector failed and burnt my motor up at Lights Out 7 in Georgia. After talking with Shannon, I saw a use for the Relay 4 in my program.
I ran the trigger wires from my Holley EFI to the Relay 4, and now the Relay 4 activates what I need it to. We wired it up and the unit worked the first time without issue and has done so ever since,” Edwards says.
Brad Edwards has been able to take advantage of the Relay 4 in his twin turbo Radial vs The World Mustang.
Another need that the Relay 4 addresses is the shortcomings of the standard mechanical relay that many racers use in their cars. “Mechanical cube relays are not that accurate or reliable since they’re mechanical and have moving parts. The Relay 4 eliminates that issue.
We discovered after testing a lot of mechanical relays that there’s a large variation between the same relays and found a high amount of variance when they’re activated. This could be an issue if you’re running your transbrake off the relay, as there will be a delay that could cost you a race,” Davis explains.
What Makes Up The Unit, And How It Works
The Relay 4 itself is a very simple device that packs loads of features into a compact package. ”What makes up the unit are four 50 amp, solid state relays that are protected with reverse voltage and transient voltage protection. The unit is un-fused, but the racer can certainly put fuses on the power feed into the relay, or on the individual power outputs, if they want.
It has quick disconnect plugs, so you can buy just the Relay 4, or the harness by itself and have a spare in your trailer in case there’s an issue. You can send the bad Relay 4 back to us for repair,” Davis says about the simple makeup of the Relay 4.
The Relay 4 is a simple device in how it functions, as Davis going on to explain: “The relays are actually 96 amp relays, but due to wire size and circuit board limitations, we rate it a 50 amps per channel. All four outputs can be triggered with a ground signal or two of them can also be triggered with a positive signal. The digital processor runs everything at a very high speed, so the relays can be pulsed, and it has a 20 megahertz switching cycle.”
How The Relay 4 Fits Into A Race Car
The Relay 4 eliminates the need for a complex wiring structure, and makes for a clean installation in any car.
With the complex nature of modern race cars, the Relay 4 fits in nicely and offers something for cars at any level. In particular, it can really simplify the entire process of wiring your vehicle. “The unit removes redundant wiring where you’re putting power and ground to every standard cube relay in a car; here, you’re just putting power and ground to one unit,” Davis says.
The Relay 4 also has a home in more complex race cars as well, Davis explains.
“It’s a nice companion to any fuel injection system or control system out there. All of those have tons of outputs, but none of the outputs have power, so you can’t run your water pump, you can’t run your fuel timers, solenoids, or parachute launchers directly — you have to run them through a cube relay. You end up running power feed, ground, trigger, and output to all of those relays. The Relay 4 eliminates all of that extra wiring for your car.”
On my car, the Relay 4 activates the spool bleed, water injection, converter bleed, and other very important systems because of how accurate and reliable it is. - Brad Edwards
Edwards backs up the idea of using the Relay 4 in a high-end race car with how he has chosen to weave it into is Mustang. “On my car, the Relay 4 activates the spool bleed, water injection, converter bleed, and other very important systems because of how accurate and reliable it is,” he says.
The Future Of The Relay 4
Davis didn’t get where he is in the racing world without being a forward-thinking type of person, and this even applies to the Relay 4. He currently has the next generation of the Relay 4 already in development.
“The new version will have four smart outputs that can be pulsed, ramped, and can monitor different things. It’s more of a programmable relay with a simple interface that can be used with a Profiler, or stand-alone that 98 percent of the racers can use. It can be a companion to the Profiler to help control multiple systems and program the accessories, sort of like an expansion box,” Davis says.Edwards sums up the true significance of the Relay 4, and demonstrates how valuable it can be, in sharing that “this unit makes wiring that much simpler, since it just has two powers, two grounds, inputs and outputs.
I was able to take almost two pounds of wiring out of the car when I installed the Relay 4. This thing is simple and robust, and it does more than you need it to do while being very easy to wire up.”
As you can see, even the simplest device can be improved and shouldn’t be overlooked in your race car (or even your high performance street car). Davis Technologies has taken the basic relay used inside a race car and found a way to weaponize it into a powerful tool that any racer can use.