Project Single Turbo has undergone extensive upgrades to its engine and supporting systems, most notably fuel and air delivery. To take control of these, we’ve installed a standalone ECU and upgraded the ignition system so that we’ve got consistent and reliable control of all parts of the spinning triangle combustion cycle.
With the big Turbonetics GTK turbo forcing a whole lot more air into our refreshed and fortified 13B-REW, we knew the dated OEM ignition system could not reliably provide the spark needed. To address this need, we turned to AEM and its “High Output IGBT” Smart Inductive Coils. Most engines use Capacitive Discharge Ignition (CDI) for a few reasons, including very high spark energy and the ability to run at high rpm. CDIs store their energy in a capacitor, allowing them to produce a stronger spark.
However, the caveat is the limited spark duration that can be too short and unreliable for some applications. AEM’s ignition coil has a built-in ignitor and delivers CDI-like spark, up to 103mJ of energy and up to 40kV, without the need for a CDI module. Simply put, more energy means stronger spark and more power. AEM’s coils are also capable of running higher dwell times, or the period of time that the ignition coil is turned on. We’ll revisit dwell time during our dyno portion of the build, but suffice it to say it’s a particularly important variable with rotary engines.
With our spark needs covered, next we required an ECU that’s capable of controlling these systems to produce sweet, fiery, rotary music. For this, we’ve opted to run an Adaptronic plug-and-play Select ECU designed specifically for the FD RX-7.
Although fairly new to the U.S. market, Adaptronic has been in the game since 2003, developing innovative ECU solutions for the Australian tuning market. Andy Wyatt, head Aussie of Adaptronic, states that their focus is on simplicity and reliability when developing their ECUs. According to Andy, they achieve this through their commitment to using OEM sensors and triggering systems wherever possible. However, Adaptronic ECUs have built-in parameters that can be altered if sensors are modified or changed. This allows the ECU to “grow” with modifications without the need to switch to a universal ECU that requires full rewiring of the electrical systems.
The Adaptronic Select ECU uses MAP-based VE (Volumetric Efficiency) tuning that most new ECUs are now using. What is VE tuning? Engines are simply air pumps; take away the fuel and spark and all you have is air going in and out of the motor. VE is a representation of the efficiency of the motor’s ability to move air in and out of its cylinders, or in our case, rotor housings. The higher the VE, the more fuel the ECU will add. Simply enter engine size, injector size and dead time, and MAP sensor, and the ECU does the heavy lifting, making the tuning process easier, linear, and faster. Should you have the need to switch to larger injectors, you just have to change the injector size parameter and you are good to go. No need to retune.
This ECU also has “Adaptive Behavior” and is able to self-learn under the correct conditions. When paired with a wideband, the ECU is able to Auto-Tune better than Kanye. The ECU uses closed-loop tuning with data from the wideband and is thus able to hold target AFRs rock steady as well as having real-time AFR reading during the tuning process. EGT probes can be added as inputs to provide more live data for tuning purposes. It also supports the use of E85 with a simple addition of a flex sensor.
Another advantage of the Adaptronic Select ECU is that it allows us to convert from a wasted spark to a direct fire ignition configuration, so we can use modern coils like our AEM units. In the case of rotary engines like ours, this is especially useful since the trailing plugs come in a Direct Fire configuration from the factory—but the leading plugs do not. The leading plugs fire during the exhaust phase to complete the burn for emission purposes but do not contribute to power and are therefore “wasted.” Converting to direct fire will allow the leading plugs to fire during a more useful combustion phase. Converting to direct fire also allows finer levels of ignition control, so we can maintain dwell time at higher rpm, resulting in a stronger spark due to the longer charge time.
Our Select ECU came with a host of other features you would usually find in more expensive units. The ECU has an internal 4-Bar MAP sensor and a headphone port that allows you to listen for engine knock. With an addition of a MAC solenoid, it’s also able to control boost, eliminating the need for a separate boost controller. It can be set up to control boost by gear using the OE transmission sensors, and it even features traction control through gradual torque reduction, where ignition is cut by 1 percent or more depending on which percentage you program it to reduce it by.
We’re also stoked to try the ECU’s Push to Pass feature. Similar to scramble boost, you install a switch in the cockpit that you can activate if you need more power. Once activated, it switches to a higher boost and fuel map to give you extra horsepower during straightaway duels. Just make sure you do not push it too soon, Junior.
The Adaptronic ECU shows up to the party wearing an all-black aluminum case. There are external LEDs for each ignition coil that indicate when they are firing—very useful in diagnosing ignition issues. The headphone jack, serial input, and 4-Bar MAP sensor barb also make an appearance. Again, a custom-mounting bracket was made for the ECU.
It’s also worth mentioning that Adaptronic has great customer and tech support, with an active online forum where users can post questions and get feedback on their data logs. Despite Australia being almost a day ahead of North America, assistance comes pretty quickly—you’ll notice Andy personally answering inquiries along with the rest of his team.
With our engine all but buttoned up, we are almost ready to start her up. But first we’re going to simplify wiring and then we need to fab up an exhaust system and get our wastegates plumbed in. Until then, enjoy some peace and quiet because it is about to get rotarded in here.