AuxJection FAQ
Stock LT4 Supercharger | LT1/LT4 Whipple 2.9L/3.0L Fitment
Please review fitment before ordering. AuxJection compatibility depends on supercharger setup, throttle body, intake tube, and belt drive configuration.
- Stock LT4 Kits are only compatible with stock LT4 supercharger platforms and LT1/LT4 Whipple 2.9L/3.0L applications
- 2015-2019 Corvette Z06
- 2016-2024 Camaro ZL1
- 2016-2024 Cadillac CTS-V
- Compatible with stock throttle body up to 103mm bore
- Adds approximately 1 inch to the supercharger snout
- Depending on your intake, minor tube or coupler modifications may be required
- This product does not fit Camaro ZL1 with a standard Roto-Fab intake
- Roto-Fab Big Gulp and JLT large tube intakes are compatible with minor modifications; fitment of other large tube intakes is not guaranteed
- May have belt-to-throttle body clearance issues with aftermarket idler relocation brackets; fitment is only guaranteed with the stock belt drive setup
- DO NOT use with VP Import, Q16, or other MTBE oxygenated fuels
Magnuson 2650 Supercharger Fitment
Please review fitment before ordering. AuxJection compatibility depends on supercharger setup, throttle body, intake tube, and belt drive configuration.
- Magnuson 2650 Kits are only compatible with supported LT1/LT4 Magnuson 2650 applications
- 2015-2019 Corvette Z06 and Stingray
- 2016-2024 Camaro SS and ZL1
- 2016-2024 Cadillac CTS-V
- Compatible with stock throttle body up to 103mm bore
- Adds approximately 1 inch to the supercharger snout
- Depending on your intake, minor tube or coupler modifications may be required
- This product does not fit Camaro SS or ZL1 with a standard Roto-Fab intake
- Roto-Fab Big Gulp and JLT large tube intakes are compatible with minor modifications; fitment of other large tube intakes is not guaranteed
- May have belt-to-throttle body clearance issues with aftermarket idler relocation brackets; fitment is only guaranteed with the stock belt drive setup
- DO NOT use with VP Import, Q16, or other MTBE oxygenated fuels
Whipple 3.0 Supercharger Fitment
Please review fitment before ordering. AuxJection compatibility depends on supercharger setup, throttle body, intake tube, and belt drive configuration.
- Whipple 3.0 Truck/SUV Kits are only compatible with Whipple 3.0 for 2019+ trucks and 2021+ SUVs with a 5.3L or 6.2L engine
- Requires a stock 6.2L throttle body at minimum
- Aftermarket 103mm throttle bodies are also compatible
- The stock 5.3L throttle body is NOT compatible with the AuxJection assembly
- Adds approximately 1 inch behind the throttle body
- The supplied Whipple intake tube has been verified to fit with the additional AuxJection thickness; fitment of other aftermarket intake systems is not guaranteed
- DO NOT use with VP Import, Q16, or other MTBE oxygenated fuels
Cadillac CT5-V Blackwing Fitment
Please review fitment before ordering. AuxJection compatibility depends on supercharger setup, throttle body, intake tube, and belt drive configuration.
- Cadillac CT5-V Blackwing Kits are only compatible with the stock LT4 supercharger platform, Whipple 3.0 supercharger, and Magnuson 2650.
- 2022-2026 Cadillac CT5-V Blackwing
- Compatible with stock throttle body up to 103mm bore
- Adds approximately 1 inch to the supercharger snout
- Depending on your intake, minor tube or coupler modifications may be required
- Stock Throttle body and Intake fit without modification
- JLT 5 inch Large Tube Intake combined with 103mm throttle body is compatible with the addition of our 5 inch to 103mm throttle body coupler; fitment of other large tube intakes is not guaranteed
- May have belt-to-throttle body clearance issues with aftermarket idler relocation brackets; fitment is only guaranteed with the stock belt drive setup and TooHighPSI Slayer
- DO NOT use with VP Import, Q16, or other MTBE oxygenated fuels
AuxJection Basics
What is AuxJection?
AuxJection is an auxiliary fuel system for LT-based platforms designed to work with the factory ECU strategy. It adds supplemental fuel when the direct injection system reaches its limit, without relying on a standalone controller or traditional port injection setup.
How does AuxJection work?
AuxJection does not spray all the time. It delivers a calculated fuel pulse only when the direct injection system can no longer meet fuel demand on its own. In other words, it supplements the factory DI system when airflow and fuel demand move beyond what DI can support by itself.
Will AuxJection make the vehicle run rich all the time?
No. AuxJection is designed to add fuel only when needed. It is not constantly dumping fuel into the intake regardless of load.
Will AuxJection still behave like stock?
Yes. The goal of AuxJection is to integrate with the factory ECU strategy as if it were a factory option. The system is only used when needed and should require very little maintenance outside of normal vehicle maintenance.
Fueling and Power Support
Why use AuxJection instead of larger direct injectors?
Larger aftermarket direct injectors for LT platforms can get expensive quickly and still come with tradeoffs. In many cases, an aftermarket high-pressure fuel pump is also needed along with the larger direct injectors. AuxJection provides supplemental fueling while keeping the factory ECU in control.
What kind of power can AuxJection support?
Power support depends on the full combination, especially the low side, high side, camshaft fuel lobe, and ethanol content. We have made over 850 whp on a stock LT4 high side, stock cam, full E85, and a low side maintaining 70+ psi. We have also made over 950 whp on full E85 with an aftermarket camshaft and +30% fuel lobe.
Can AuxJection support full E85 on a stock LT4?
Yes, depending on the rest of the setup. Low-side pressure may drop slightly at higher RPM, but AuxJection factors low-side pressure into the injector flow calculation to account for that.
What does the rest of the fuel system need to look like to take AuxJection to its max potential?
For maximum potential, an aftermarket camshaft with at least a +30% fuel lobe is recommended so the direct injection system can operate at its highest potential first. A strong auxiliary low-side fuel system that can maintain 70+ psi is also preferred. We have had great results with DSX auxiliary pump systems, including the DSX dual-bucketed pump for Camaro applications.
Fitment and Applications
What applications are currently supported?
The current focus is factory LT4-based supercharged applications.
Does AuxJection work with stock throttle body and 103mm throttle body setups?
Yes. The current LT4 AuxJection kit fits both stock and 103mm throttle body setups. The flange inside diameter is 103mm.
Does AuxJection work with Whipple setups?
Yes. The current LT4 AuxJection kit supports Whipple 2.9L and Whipple 3.0L supercharger LT1/LT4 setups.
Does AuxJection work with Magnuson setups?
Yes. AuxJection is available for Magnuson 2650/2650R LT1 and LT4 applications, including Camaro, Corvette, CTS-V, and CT5-V Blackwing platforms.
Does AuxJection work with ProCharger, turbo, or centrifugal setups?
Not currently. We do not recommend AuxJection for ProCharger, turbo, or centrifugal applications until more testing is complete. These setups require a different configuration and are not currently a released fitment. We need proper engine dyno data and validation for that configuration before offering a kit.
Does AuxJection work with LT1 applications?
LT1 applications are currently supported only when using a stock LT4 supercharger, Whipple 2.9L / 3.0L, or Magnuson 2650 supercharger setup.
Does AuxJection work on Global B applications?
Yes, Truck/SUV Whipple 3.0 and CT5-V Blackwing applications.
Escalade-V and Corvette C8 support coming soon.
Does AuxJection work with the 2014-2018 Trucks and SUV's?
We do not have anything planned as of right now. It's a possibility for a future kit, but nothing is confirmed yet.
Flex Fuel & Kit Setup
I already have a flex-fuel sensor. Can I reuse it?
You can reuse your existing flex fuel sensor, but the AuxJection harness and fuel lines are designed to be installed a specific way. Existing flex fuel kit hardware and wiring may need to be removed and replaced with AuxJection components according to the installation instructions.
How many injectors does AuxJection use?
The AuxJection plate uses two FID 2200cc injectors.
Does AuxJection use a standalone controller?
No, AuxJection is driven directly from your stock ECU.
Can AuxJection be removed/reverted?
Yes. AuxJection is designed to be a straightforward supplemental fueling solution and can be easily removed.
Testing and Results
Has cylinder-to-cylinder distribution been tested?
Yes. We conducted engine dyno testing with AuxJection and reviewed cylinder-to-cylinder fueling distribution during testing. Results are published in our tech blog.
Does AuxJection make more horsepower?
AuxJection is primarily designed to add fuel capacity, not act as a power adder by itself. That said, some combinations may pick up power from the cooling benefit of ethanol being introduced into the supercharger.
Will AuxJection help with intake air temperatures?
Yes. We have consistently seen significant charge temperature drops when AuxJection is actively spraying ethanol into the supercharger.
Will AuxJection damage the blower or rotor coating?
Based on our early testing, AuxJection has not shown visible signs of rotor coating wear. Since the system is designed to be an alternative to traditional methanol injection, it does not affect the rotor coating any worse than a properly set up methanol system. We currently have test vehicles with over 11,000 miles using the kit.
Tune File & First Flash
When should I send my tune file?
Do not send your tune file immediately after ordering. Each AuxJection kit includes an instruction card with your Kit ID number. Once you receive your AuxJection kit, use your VIN and Kit ID Number from that card to email your tune file for modification.
Where do I send my tune file?
Email your current tune file to: AuxJection@wisherperformance.com
Please DO NOT send it to the sales email.
What should the email subject line be?
Use your VIN number and Kit ID number in the subject line.
Example:
1G1Y82D47L5000324_#010126_01
Including both the VIN and Kit ID helps avoid delays.
What file types are accepted?
Accepted tune file formats are:
.HPT or .BIN
How long does the tune file process take?
Most modified tune files are returned within 1-3 business days after the tune file is received.
Do I need to “Write Entire” on the first flash?
Yes. Once your modified file is received, the first flash MUST be done using “Write Entire.”
AuxJection will not function at all unless you do this step.
Is the tune file and first flash process the same for Global B platforms?
The tune file submission is the same, but the first-flash process is different for the Global B platforms. Follow the Global B installation instructions carefully and complete the required first-flash steps exactly as outlined.