Rywire Motorsports Electronics has specialized in high performance wiring and Mil-Spec engine harnesses for the past 17 years. Over that time span, the company has supported some of the fastest cars in the world. Credited with wiring winning teams from around the world in motorsports, Rywire has had a hand in off-road trucks, land speed racing motorcycles, Formula Drift champions, Import and Domestic drag racing, pro-level circuit racing, and even SEMA show-winning builds.

Straight out of college, Ryan “Rywire” Basseri became invested in the drag racing scene. He started swapping big engines into small cars, while making wiring changes to accommodate these swaps. Basseri thrived on developing custom harnesses; he tells us this was never a challenge. As time went on, he realized there was a market for these kinds of motorsports solutions, and decided to give the industry what it wanted by opening the doors to Rywire Motorsports Electronics.

As the industry evolved, RME also made strides in building the company brand and vision; they currently offer a wide variety of custom looms for many different engines and engine management systems.

We recently spent a day at Rywire Motorsports Electronics for a behind-the-scenes look at what they do. Basseri divulged many of the tricks to building a wire harness, which parts to use, and key features to look for when purchasing a custom harness. Constructing a custom automotive wiring harness is not only a time-consuming affair, but a critical juncture in your quest to get your engine running right. Screwing up by pinning a wire wrong or improperly crimping a connector can lead to a disastrous outcome. So let’s begin!

The term “Mil-Spec wiring” is commonly thrown around in the motorsports industry, but it’s not quite accurate.

“Mil-Spec is a standard for the Military. In motorsports we use Mil-Spec as a standard for the materials used. Even though the automotive motorsport harnesses have no military approval, the M or MS part numbers reflect the Mil-Spec standard as the same materials used. Many connectors, wires, coverings, and tapes have these part number classifications,” says Basseri.

According to Basseri, “The average car guy may never need an engine or chassis loom that outperforms the factory one. He may never add a turbo, or need an ECU upgrade, but as time goes on, he might modify or swap his engine, requiring a custom harness. A motorsport-grade ECU populated by some auto parts store wire loom will never do. A client adding an ECU upgrade will benefit the most from a motorsport wire loom.”

OE manufacturers typically use the most cost-effective means possible to design and build a wiring harness. For the most part these work great, and can last a couple hundred thousand miles. But in motorsports, the racer will eventually see the failure points of these sorts of connectors. Upgrading those connectors, upgrading the wire to minimize RF noise, weight, and temperature capability, is essential to the process of harness design.

Before a custom engine harness is made, RME begins by carefully mapping out what the customer wants to implement into their engine setup. Perhaps an AEM 4-channel UEGO or E85 conversion are taken into account for the final production unit—really, whichever upgrades the customer needs.

RME maintains reams of data of specific OEM and custom engine specifications to reference when creating a harness from scratch. If the data doesn’t exist, customers can send in their original harness for RME to carefully cross reference to ensure the Mil-Spec harness will be a simple plug-and-play unit that’s quality tested pin to pin and is guaranteed to fire up your engine.

RME wire harnesses are loomed with Raychem DR-25 heat shrink covering and adhesive-lined wire junctions to keep moisture out. Each connector is crimped with pneumatic heads to ensure an OEM-level crimp every time, then tagged with a yellow identification label for easy installation. All heavy interference circuits are protected and grounded with proper wire covering.

RME was spotted mocking up a factory Nissan Skyline engine harness for a RB26DETT.

“The customer requested we implement a number of modifications going into the car including the addition of some ancillary gauges, custom electronics, and a sequential transmission. It’s become pretty typical for us to have customers asking for more than an OEM replacement harness. Over the years, we’ve gained the knowledge and resources to perform these custom setups regardless how simple or complex it might be,” says Basseri.

The newest addition to the RME lineup is the Toyota Supra 2JZ-GTE Mil-Spec harness designed specifically for the AEM Infinity engine management system. Basseri tells us that one of AEM’s top-selling Infinity systems is the one to control the 2JZ engine, reinforcing its popularity among enthusiasts.

Here’s a custom engine harness for the 1,150-horsepower supercharged ORACLE Lighting Achilles Radial Dodge Viper competing in the Formula Drift Championship series. Once the harness has been mocked up inside the engine bay, Basseri will terminate the remaining open wires to complete the project.

Each of the custom harnesses that RME develops uses concentric twisted wires. Concentric twist is a technique in which the wires are laid in opposing twisted directions, giving max flexibility, and minimum size to the harness bundle. A properly twisted harness can look like a garden hose, showing zero lumps or imperfect spots.

Using epoxy resin on the ends of heat-shrink tubes to secure bundled wires can be requested or omitted depending on the customer’s preference. Some clients prefer to have the ends un-sealed so service can be done more easily. Others prefer to have it as tightly glued as possible to keep the moisture out.

Ever wonder why OEM automotive manufacturers and motorsports engineers don’t solder wires or use butt connectors on their electrical harnesses? The reasons are quite compelling.

Butt connectors found at your neighborhood automotive store are not typically high-quality products. RME rarely uses them, unless it’s the only logical solution to a wiring problem. The failure modes of butt connectors are vibration fatigue and exposure to the elements.

Butt connectors create a non-flexible point on either end of the crimp. The flexing pressure reduces the cross-section which eventually causes fatigue and breaking. The same problem can also be said about a solder connection.

Deutsch Autosport ASHD, ASU, ASX, and ASDD connectors are foreign terms to many of us but did you know they are specific types and style connectors? With so many to choose from, how do you know which one is best?

“It all comes down to the type of connections or harness you want to build. The leading industry standard in circular connectors are the Deutsch AS Autosport series connectors, and similar. They come in many different pin counts, wire sizes, and density counts. They all have in common the highest of heat rating, lightest weight, connection rating, and highest quality gold tipped terminals. In the motorsport industry there is no better,” says Basseri.

We were surprised to find out that all plug-in type wire connectors have a limited lifespan. Basseri mentions that Mil-Spec or Autosport terminals are highly recommended for those repeatedly installing or removing their engines or ECU. Mil-Spec or Autosport terminals have multiple ridges built in, which allows the barrels and pins to slide into each other and connect on all sides of the pin while forming a tight fit. It’s not unusual to see a connector like this being cycled 100 to 200 times without seeing any issues.

OEM-style connectors are actually rated to a very low number of connections and disconnections, in most cases less than eight times over the life of the connector. This is not to say the connector will fail, but the plastic may weaken, and the terminal may not hold as tightly.

“The constant flexing back and forth causes the small tab on the female connector to lose its contact patch when repeatedly inserted into the male connector. The spring loading resistance gets pushed down repeatedly and will eventually fail causing a break in contact. This is known as terminal blowout. Every time the prongs are sliding into a terminal, the pins are getting increasingly flatter. It’s literally relying on a folded piece of metal inside the terminal to make contact,” says Basseri.

Deutsch plug connectors are available with either plastic or metal outer shells. The plastic connectors are popular due to their inexpensive cost in comparison to Mil-Spec type connectors. The trade-off is that Deutsch connectors still use a plastic outer shell, similar to the OEM type connectors, but the main difference is they use the same quality pins and crimp style terminals found in Mil-Spec connectors. Deutsch connectors also use a rubber seal to keep contaminants from entering inside the connectors.

Next time you’re thinking of repeatedly removing and reinstalling your factory ECU plugs as a means of anti-theft, it’s only a matter of time before those plug connectors or plastic clips will fail. You’ve been forewarned!

Quality wire versus cheap wire: Which grade should you choose?

“Experienced engine builders or wiring specialists interpret “cheap wire” differently than a DIY mechanic looking to wire up a set of headlights. There are numerous types of wire grades and types available on the market today, but we generally only use Tefzel in our large looms, and TXL for our small sub harnesses and adapters. We don’t believe anything else should be used in the automotive field,” mentions Basseri.

From top to bottom shows an automotive grade TXL wire used by most OEM manufacturers, followed by a Tefzel M22759 wire, and lastly a wire that’s RME uses that’s equivalent to a TXL grade wire.

By definition, Tefzel wires use an Ethylene Tetrafluoroethylene (ETFE) sheathing with tin-plated copper leads; these are more corrosion-resistant and allow less resistance for better continuity. Tefzel is used in aerospace and motorsports applications due to its light weight, tight-diameter tolerances, and enhanced mechanical toughness. TXL wires are constructed of thin wall Cross-linked Polyethylene (XLPE) with inner copper wire strands and are primarily used for automotive applications.

The early stages of a Honda S2000 engine harness that RME is building.

RME also offers a Power Distribution Module (PDM) fully populated and wired up with Mil-Spec connectors to plug into a custom RME spec harness. Using a common input bus bar, the PDM requires just one input connection to power all fuses. These units make for a really clean and compact way to allow you to wire up your existing ECU to control the fuel pump, cooling fans and any other items you may need.

Rywire GT3 Integra Type R

The Rywire JDM-spec Honda Type-R made its debut at the 2015 SEMA show. This custom-built machine displayed inside the CSF Radiator booth placed a top ten finish in the SEMA “Battle of the Builders” competition.

Resprayed in Porsche 997 GT3RS paint, the Integra has served as a rolling advertisement for RME. No expense was spared when it came time to build this vehicle.

A slew of MoTeC components including C127 digital dash with 6 I/0, LTC lambda control. The entire harness took over 400 hours of build time with an estimated 100-plus Deutsch Autosport connector terminations.

MoTeC AS terminated Pressure transducers were used for fuel pressure (2), oil pressure, MAP, exhaust backpressure (2), H₂0 pressure, front brake pressure, rear brake pressure, clutch pressure, solenoid box pressure, accumulator pressure, crank case pressure, and barometric pressure.

“When I designed the harness for this vehicle, I wanted zero plastic connectors. Every plastic connector inside the engine bay was replaced with Autosport connectors. Even with the injectors, we crimped, glued and pigtailed them to Deutsch Autosport ASX Socket Connectors. The most difficult aspect of the build was wiring it up to make it look presentable, which I think we managed to accomplish,” says Basseri. This turbocharged K24 powered Integra has also been converted to a drive-by-wire throttle system.

Inside the cabin on the passenger side floor resides the MoTeC PDM and M170 ECU.

A MoTeC 15-position CAN keypad was recessed into a custom center console.

The attention to details continued throughout the vehicle as shown with the Autosport connector also being used to power the fuel pump.

The steering wheel was modified to become the nerve center of the car. Basseri added a series of driver control buttons and rotary position switches to allow settings that can be made on the fly several times during a race.

Turning the steering wheel over reveals Shiftec paddle shifters, which trigger a Shiftec dual solenoid for air actuation control to the Quaife sequential transmission.

Basseri’s restomod Honda Civic E-AT is a true wolf in sheep’s clothing. Only when you realize how the electronics wizardry has been implemented into this old-school ride can you truly appreciate its singularity. The Civic is powered by a ’98 Integra Type-R engine with Kinsler 55mm individual throttle bodies.

Each of the throttles relying on modern drive-by-wire technology, which makes this ITB application truly unique.

“About six years ago when I was building this ’86 Civic, I decided I needed a standalone ECU so I could better control the air delivery on the ITB system. The AEM Electronics’ Infinity ECU system had H-Bridge control that I could set up for a drive-by-wire servo by motor retrofitting from an existing OEM application. We modified the motor to the ITB shaft and went testing. A lot of testing and tweaking was required as the PIDs (Proportional, Integral, and Derivative) were not set up for any exact application. We pride ourselves with our out of the box thinking. We think that maybe that first system we designed sparked the interest of some of the new designs in ITB technology out on the market. Many of the leading induction companies now offer e-throttle solutions,” says Basseri.

In 2017, Basseri returned to SEMA and the “Battle of the Builders” to showcase his newest ’01 Honda S2000 project car.

“We entered this competition to show the industry that RME is more than just building wire harnesses. We have the full capability to build custom cars, engine cooling and fuel systems and more,” he says.

Punched out to 2.5-liters, this stroked Honda F22C engine was mated to 56mm Kinsler ITBs and eight 1,000cc staged injectors. Similar to the Civic E-AT, this throttle body setup was also modified to use a DBW system.

A one-off race header, titanium exhaust, AEM Infinity ECU, fuel pumps, a RME wire loom and XRP Motorsport plumbing, along with a Nuke Performance fuel rail, regulator and filters were all custom designed for this build.

The future looks bright for Basseri and Rywire Motorsports Electronics, as the team continues to push themselves to be the industry leader in motorsports-grade wire loom solutions.