One critical item that’s often overlooked in a race car project is the importance of the wiring installation and its quality. Put in simple terms, if it doesn’t look good, it probably isn’t. And even if it does look good, there are specific items that must be addressed during the installation process to ensure a quality job that won’t have you searching for issues in the pits, or worse, the staging lanes.
We caught up with the experts at Ron Francis Wiring in Chester, PA, to discuss some of the issues that novice, and even experienced installers should keep an eye out for when wiring up a new (or modifying an existing) installation.
You could tackle the task of wiring up your own hotrod using one of these nifty pre-terminated kits from Ron Francis Wiring, available for many different applications.
Ron Francis Wiring has been involved in the automotive industry for decades. The company was started by Ron Francis back in the 1970’s to address a segment of the performance aftermarket that was lacking at the time. Since then, the company has been placed in the more-than-capable hands of Scott Bowers, while Ron remains on staff to assist in research and development, along with providing email-based customer service.
Never overlook the importance of good grounds. – Scott Bowers
According to Bowers, there are ten items which can make or break your wiring installation. First and foremost is proper grounding of the harness and all related electrical items.
“The importance of grounding is often overlooked. For any individual circuit, it equals half of the circuit and can cause havoc when a ground is compromised. Make sure paint, powdercoating and rust are cleared away for any grounding location,” he explains. We’ve all seen (or been) that racer who is constantly chasing electrical issues, with individual items not turning on or off when they are expected to – many times this can be directly traced to a poor ground.”
Directly related to the grounding issues are those induced by poor battery cable connections. Bowers tells us that many installers still ground the negative battery cable to the frame of a vehicle, but there’s one problem with that. “A little known fact is that steel only equals about 20 percent of the conductivity of copper. As a result, we always recommend running the negative battery cable directly to the engine block,” says Bowers.
Hot starting problems often can be traced to poor component design. “Do you have a Chevy engine that doesn’t want to start when it’s hot? Many times it’s due to the design of the start solenoid and the available power to it. If you can jump the two large posts of the solenoid and get the engine to crank over when hot, it’s the solenoid. The solution to this problem is to get maximum power to the solenoid by shortening the length of wire from the ignition switch to the solenoid. Many times a relay to do this is the best bet,” he explains.
Many racers and enthusiasts are still in the habit of installing a fusible link, as those are what had previously been provided by the OEM’s for years. Old habits die hard in the performance industry, and fusible links are no longer an accepted way to wire a performance vehicle. “Have you ever seen one of these things light off? There’s a reason why they are not used any more. Consider a Maxi Fuse,” he says.
As seen here, a fusible link is a poor choice when wiring a vehicle. RFW’s Scott Bowers suggests Maxi fuses instead to handle larger current loads.
Maxi fuses are fast-acting, blade-style fuses that have been designed to take on larger loads than a regular ATC or ATO-style fuse, and have become the industry standard for vehicle circuit protection. Maxi fuses are commonly rated from 20 to 120 amps.
The alternator is also critical and misconceptions abound regarding the proper sizing of these units. Bowers explains, “First off, alternators only put out the amount of amperage that an electrical system needs. Bigger is, for the most part here, better. Next, as a rule of thumb, you should never constantly demand more than 80% of the alternator’s rating. So, a 100 amp alternator should never expect to deliver more than 80 amps continuously. Also consider that at idle, an alternator is only putting out a fraction of its rated capacity. Idle speed and pulley sizes do come into play here as it can affect alternator RPM at idle.”
Using the proper wire size is critical for the performance of alternators and starters. Four gauge wire is a virtual necessity for these components.
The Right Product For The Application
What about the wires themselves? According to Bowers, the type, size, and insulation style play a large part in ensuring their effectiveness. “Today’s vehicles use cross-linked wire. This wire comes in not only different gauges but different insulation thicknesses. Some of their designations are TXL, GXL and SXL. An easy way to identify this series of wire is their dull color appearance. Older automotive-grade wire is called Primary or PVC wire. The big difference here is that cross-linked wire insulation will not drip off the conductor if overheated or exposed to flame like Primary or PVC wire,” he says.
The gauge (or thickness) of wire to use for power cabling depends specifically on how much electrical current the component to be powered will consume under operating (and overload) conditions. Wiring sizes measure from smallest to largest on a numerical scale, with zero for the largest size of wire and larger numbers as the wire size decreases.
This diagram illustrates proper vehicle grounding – both to the engine block, and also directly back to the battery, as your vehicle’s steel frame has only 20% of the conductivity as copper wire does.
Typically an automotive application will have at most 00-gauge wire at the battery connections, starters and batteries using 4 or 6-gauge wire, and smaller electrical components like fuel pumps and fans using 12 to 16-gauge wire. 16-gauge wire is often used in headlight and taillight applications. Proper wire sizing needs to be selected based upon the amp draw of the component. When in doubt, go one gauge bigger and you should be in good shape.
A proper fan relay kit like this one will turn the fan on and off at pre-determined values and will offer you a measure of protection when using an electric cooling fan. High-draw components like fans and fuel pumps should always be run through a relay.
Back To The Ground
Revisiting the alternator and ground issue, Bowers says, “Many do not realize that the alternator depends on a good ground to complete a circuit path as well. Powdercoating and/or painting will compromise the grounds and will cause charging problems for sure. We’ve even heard of some alternator manufacturers shipping alternators with ground wires.”
Carrying the current load through a switch is also a no-no, according to Bowers. “Be sure to use relays on heavy amperage items like electric fans and fuel pumps. Putting a heavy load through switches not designed for it can greatly reduce their life and leave you down and out between rounds. Plus, when these items are not running on a relay, they may end up generating enough power to keep the engine running after shut down, making you scratch your head.”
Be sure to use relays on heavy amperage items like electric fans and fuel pumps. Putting a heavy load through switches not designed for it can greatly reduce their life and leave you down and out between rounds. – Scott Bowers
On the subject of electrical relays, you can’t necessarily assume a relay is good if you can hear it click during operation. If you suspect there is an issue, the test process is simple. You need an ohmmeter to check and see which pins are connected to each other. You should typically find an ohm value of 50 to 120 ohms between two of the pins – this is the control circuit. The remaining two pins should read either OL (infinite) if it’s a normally open relay, or 0 ohms (continuity) if it’s a normally closed relay.
If the coil (two connected pins) show a value of less than 50 ohms, it could not be operating properly and replacement is suggested. If none of the pins show a coil value, and all show OL or 0 ohms, it should also be replaced.
Sending Unit Values
One item we’ve encountered before on our own projects is that of improper sending unit values – it was a pain in the butt to diagnose, yet there’s a simple solution. Bowers explains, “If you use aftermarket gauges (or non-original gauges to the vehicle), make sure the gauge(s) use the same value sending units as what’s installed in the engine/vehicle. The user might deem the wiring as the culprit, but many times the reason is new sending units were not used. If the gauge manufacturer has provided new sending units, use them, unless you can determine their operating range is equal to the one you are using.”
Having the proper tools is critical to achieving your goal – which is all of the components working properly, all of the time. Buy a good set of crimpers and wire strippers, use soldering techniques whenever possible, and avoid wire taps at all costs!
Sending Units or Sensors?
This last one may be common sense, but if there’s anything we’ve realized in years of working with automobiles, it’s that common sense often flies out the window when you get wrapped up in trying to diagnose an issue with wiring. “Many enthusiasts confuse gauge sending units and fuel injection sensors. They are different and their values are different. Make sure to use sending units for gauges, and sensors for fuel injection,” he says.
While we certainly haven’t covered every wiring issue you may encounter during your build, we hope we’ve addressed some of the major items to get you off on the right foot. Scott Bowers and the team at Ron Francis Wiring have been instrumental in helping us understand some of the pitfalls that enthusiasts may run into, and have given us a solid leg up on any potential issues we may face in the future. There’s something to be said for experience, and this group of craftsmen and women have it in spades. Check out the shop tour!