Product Description
Serious L5P fueling for serious power. The S&S Diesel L5P-CP3-12 Conversion Kit replaces the factory HP4 with a battle-tested CP3 using a 12mm pump for high output in competition applications. Designed specifically for the 2017–2023 GM Duramax 6.6L L5P, this kit delivers stable, efficient fuel at elevated RPM and load.
Fitment
- 2017, 2018, 2019, 2020, 2021, 2022, 2023 Chevy/GMC Duramax 6.6L L5P
- Competition use only. Tuning is required for CP3 conversion on L5P platforms.
Why Upgrade to a CP3 on L5P?
- Proven CP3 architecture with strong high-RPM efficiency and durability.
- 12mm pump supports aggressive injector and turbo setups in racing environments.
- Stable delivery and improved longevity vs. HP4 when properly supported and tuned.
What’s Included
- 12mm CP3 pump (L5P-configured)
- High-pressure hard lines to factory rails
- Feed and return fittings/lines as required for the conversion
- Electrical provisions/harness items as required for CP3 retrofit
- Mounting hardware and installation components specific to L5P
Recommended Supporting Parts
- Aftermarket low-pressure lift pump (15–20 PSI) – CP3-compatible supply is required.
- L5P performance injectors matched to your power goal.
- Custom L5P tuning calibrated for CP3 conversion and target power.
- Fuel filter upgrades & contamination-prevention components for system protection.
Helpful Notes
- This is a competition-use-only kit. It is not emissions compliant for on-road use.
- Do not feed a CP3 with factory L5P in-tank pump pressures intended for HP4 systems; use a CP3-compatible lift pump and consult your tuner.
- Professional installation and calibration strongly recommended.
Yes. Unlike some LML CP3 conversions, the L5P platform requires ECU tuning to operate a CP3. Plan tuning as part of your install.
Is this kit emissions legal for street use?
No. This is clearly labeled competition use only and is intended for off-road/racing applications.
What lift pump pressure should I run?
Target approximately 15–20 PSI to the CP3 and avoid factory HP4-level supply pressures. Use a CP3-compatible lift pump and verify with your tuner.
What power level is a 12mm CP3 suited for?
General guidance places a 12mm CP3 in the ~up to ~1000 RWHP range when paired with proper injectors, air system, and tuning. Actual results vary by combo.
Does the kit include every nut and bolt?
The kit includes the L5P-specific pump, lines, fittings, and conversion hardware required for the CP3 swap. You’ll still need a CP3-compatible lift pump and calibration.
