CT5-V Blackwing Finally Gets AuxJection: What Wisher’s New Fueling Kit Means for E85 and Pulley Builds
The Cadillac CT5-V Blackwing is already one of the most capable factory LT4 cars GM has ever built, but once pulley ratio, airflow and ethanol content start climbing, the build quickly becomes a fuel-system problem as much as a boost problem. That is why Wisher Performance's new AuxJection kit for the 2022-2026 Cadillac CT5-V Blackwing is a particularly interesting release for owners who want to push the platform without turning the engine bay into a science project.
The big idea is simple: add two supplemental port-style injectors ahead of the supercharger, then control them through custom factory-ECU software rather than a separate standalone controller. Wisher says the system uses live ECU data to command supplemental fuel, while the included plumbing ties into the factory low-pressure fuel circuit without requiring the original hard lines to be modified.
Why the Blackwing needs more fuel as the combination gets serious
A smaller upper pulley spins the supercharger faster. More blower speed can move more air, and more air requires more fuel if the calibration is going to maintain the commanded mixture under load. Add a freer-flowing throttle body and intake, then switch from pump gasoline to a high-ethanol blend, and fuel demand rises again because ethanol requires greater fuel mass and volume for the same amount of energy delivered to the engine.
That is where otherwise strong LT4 combinations can run into a wall. The direct-injection high-pressure pump, DI injectors, low-side supply, commanded fuel pressure and calibration all have to work as one system. A dyno graph can look great right up until pressure starts falling or commanded versus delivered lambda begins separating at the top of a pull.
Supplemental injection is attractive because it can add fuel capacity without requiring every part of the factory direct-injection system to be replaced at once. But the key word is system. Adding injector capacity does not eliminate the need to watch low-side pressure, high-side pressure, injector behavior, ethanol content, lambda, belt drive and charge-air temperature.
What makes Wisher's AuxJection approach different
The Blackwing kit is designed around two auxiliary injectors positioned at the supercharger inlet. According to Wisher, the system is controlled by custom software using factory ECU data, so there is no separate piggyback or standalone injector controller to mount and configure.
That does not mean it is a tune-free bolt-on. Wisher requires custom ECU software for the system, and its installation information calls for a full ECU write during the initial flash. The flashing hardware itself is not included with the kit. In other words, the hardware and calibration need to be planned together from the beginning.
SMG's current Blackwing listing includes configurations for the stock LT4 supercharger and the Magnuson TVS2650. Wisher also lists broader compatibility with the Whipple 3.0 platform. Throttle-body compatibility extends from stock size through 103 mm, but combinations using a JLT 5-inch intake with a 103 mm throttle body require Wisher's low-profile coupler. The AuxJection assembly also adds roughly an inch at the supercharger inlet, so large-tube intake and relocated-idler combinations need to be checked for real-world clearance instead of assumed to fit.
Wisher's Blackwing testing is the part worth watching
Wisher has already been testing AuxJection on its own CT5-V Blackwing rather than relying only on bench assumptions. In a June 1 development report, the company documented a car equipped with AuxJection, a 2.175-inch upper pulley, NW103 throttle body, JLT 5-inch intake, the stock low-side fuel system and 76% ethanol content.
Wisher reported a 10.98-second quarter-mile at 132 mph on stock tires with that combination. The same report documented a 6.72-second 60-130 mph result after additional transmission calibration. More important from a fueling standpoint, Wisher said low-side pressure dropped to roughly 45 psi down track, while AuxJection's pressure compensation and the factory Global B wideband control kept delivered equivalence ratio in check. Those are Wisher's development results, not a guarantee of what every Blackwing will run, but the data is exactly the kind of information we want to see from a new fuel-system release.
Read Wisher Performance's CT5-V Blackwing development report.
What we would watch on the dyno
Any serious Blackwing fueling upgrade should be validated with more than peak horsepower. On a controlled pull, the useful channels include commanded and measured lambda or equivalence ratio, low-side fuel pressure, high-side direct-injection pressure, injector behavior, manifold pressure, intake-air temperature, spark activity and system voltage. If the car has a flex-fuel sensor, actual ethanol content matters too.
This is the same reason we recently covered the data channels that matter on a high-horsepower dyno pull. Peak power is the result. The logs tell you whether the system is healthy enough to repeat that result safely.
For pulley cars, the belt drive deserves the same attention. A smaller upper changes supercharger speed and belt loading, so a build that adds more air and more fuel still has to keep the blower drive stable at high rpm. Before ordering parts, confirm the entire combination: upper and lower pulley ratio, idler layout, throttle-body diameter, intake tube, fuel choice and intended power level.
Where the Magnuson 2650 fits
The new Blackwing AuxJection option is especially relevant to larger-supercharger builds. SMG carries the Magnuson TVS2650 system for the CT5-V Blackwing, and the airflow capability of a larger supercharger makes fuel planning even more important.
A 2650 does not create horsepower in isolation. It moves air more efficiently at the operating point, but the engine still needs enough fuel, octane, charge cooling and calibration to use that airflow. If low-side pressure falls away or the direct-injection system reaches its practical limit, a bigger blower simply gets you to the fuel-system limit faster. That is why the correct question is not, "How much power will this blower make?" It is, "What complete combination will support the power target repeatedly?"
Stock blower, pulley and ethanol build: a sensible order of operations
For a street-driven Blackwing staying on the factory LT4 supercharger, the cleanest path is to establish a healthy baseline first. Verify plugs, belt condition, fuel quality and current calibration. Then decide on ethanol content and pulley ratio before selecting the rest of the fuel hardware. Once AuxJection is installed, the car should be flashed with the required calibration, checked for leaks and clearance, then logged under controlled load before anyone goes looking for the hero number.
If the car is also getting a larger throttle body or intake, confirm the coupler and inlet geometry before installation day. SMG also carries the JLT Blackwing cold-air intake; availability can vary, so use the product page for current status rather than assuming a specific combination is on the shelf.
Why this release matters beyond one Cadillac
Late-model performance is increasingly about integration. SEMA's 2026 Market Report puts U.S. specialty-equipment sales at nearly $53 billion, while current PRI technical coverage continues to focus on choosing components by application instead of headline specifications. The Blackwing AuxJection release is a good example of that direction: the hardware matters, but the real value is how fueling, ECU strategy, ethanol content and airflow work together as a package.
That systems approach is also why a properly instrumented dyno session matters. At North Texas High Performance, we can install and validate late-model performance combinations on the Mainline ProHub dyno, with the ability to load the car consistently and watch the data instead of guessing from a single street pull.
SMG's Blackwing AuxJection kits are live now
The Wisher Performance AuxJection kit for the 2022-2026 Cadillac CT5-V Blackwing is live at SMG Speed Shop, with current stock-supercharger configurations plus Magnuson 2650 options listed on the product page. Finish options and flex-fuel sensor choices are available by configuration.
SMG also has a production Blackwing kit coming in for hands-on installation, testing and original shop content. That means this is not going to stay a catalog-only product for us. We want to see how it fits, how it behaves in the real world and what the data looks like on a complete Blackwing combination.
Building a pulley, ethanol or 2650 CT5-V Blackwing? Start with the fuel plan, not the final dyno number. Shop the Wisher Blackwing AuxJection kit at SMG Speed Shop, and use North Texas High Performance when you want the hardware installed and the combination verified under load.
Sources and further reading: Wisher Performance Blackwing testing; SEMA 2026 Market Report summary; PRI August 2026 industry coverage. Track and performance results cited above are Wisher Performance's reported test results. Individual results vary by vehicle, calibration, fuel, conditions and supporting modifications.