GMS OEM LT4 FUEL SYSTEM UPGRADE BUNDLE FOR 6th GEN LT1 CAMARO
MORE AIR NEEDS MORE FUEL. GIVE YOUR LT1 ROOM TO GROW.
A supercharger, camshaft, E85 can quickly change what your Camaro needs from its fuel system. Getting more air into the engine is only half the equation, you also need to deliver enough fuel at the right pressure, at the right time.
The GMS OEM LT4 Fuel System Upgrade Bundle brings together genuine GM LT4 injectors, a matching high-pressure pump, a ZL1 in-tank pump, new high-pressure hard lines, and our GMS Back Seat Fuel Pump Access Hatch in order to make this upgrade as painless as possible, while giving you 20-25% more fuel system headroom!
It is a coordinated upgrade for LT1 Camaro owners who want additional fueling headroom using factory-developed components, with the installation details and future service access considered from the start.
WHAT’S INCLUDED?
• Eight genuine GM LT4 nominal-flow direct injectors, part number 19420334, with injector seals and clips supplied in the GMS bundle.
• One genuine GM ZL1 in-tank low-side fuel pump module, part number 85170844.
• One GMS Back Seat Fuel Pump Access Hatch.
• One genuine GM LT4 high-pressure fuel pump, part number 12711668.
• One new GM LT4 high-pressure pump feed pipe, part number 12677005.
• One new GM LT4 fuel rail “S” feed pipe, part number 12677003.
WHY UPGRADE BOTH SIDES OF THE FUEL SYSTEM?
Your Camaro’s direct-injection system delivers fuel in stages. The electric pump inside the tank supplies fuel to the engine. The cam-driven high-pressure pump then raises that pressure for the direct injectors, which deliver fuel straight into the combustion chambers.
Each stage needs to keep up with the next.
• The in-tank pump must maintain adequate supply to the high-pressure pump.
• The high-pressure pump must deliver enough volume while maintaining commanded rail pressure.
• The injectors must deliver the required fuel within the available injection window.
Upgrading these components together addresses multiple potential restrictions instead of asking one larger component to compensate for the rest of the original system.
HOW MUCH MORE FUELING DO YOU GET?
The LT4 components offer measurable improvements over the standard LT1 hardware.
• Approximately 20% greater high-pressure pumping volume from the LT4 HPFP compared with the LT1 pump when operating with the same cam-lobe lift.
• Approximately 22% greater injector bench flow at the same 200-bar test pressure: roughly 22 g/s per LT4 injector versus 18 g/s per LT1 injector in published comparison data.
• A ZL1-specification in-tank pump module to support the upgraded high-pressure components.
• Higher-pressure capability associated with the LT4 system, subject to the correct calibration and supporting hardware.
These improvements work together, but their percentages do not add together. Overall capacity depends on which component reaches its operating limit first.
The practical benefit is additional fueling headroom for a properly matched performance combination—not a fixed horsepower increase from installing fuel-system parts alone.
THE LT4 HIGH-PRESSURE PUMP - MORE VOLUME WHERE IT MATTERS
The LT4 HPFP uses a larger pumping piston than the LT1 unit, increasing the amount of fuel it can displace with each pumping stroke. That additional volume helps support higher fuel demand when the engine’s airflow and power output increase.
The commonly published design-pressure references are approximately 150 bar for the LT1 system and 200 bar for the LT4 system, roughly 2,175 versus 2,900 psi. Actual commanded pressure varies with operating conditions and calibration.
Higher pressure and greater pumping volume are different improvements. Your tuner must balance pressure, available pump delivery, and injector requirements for the combination.
IMPORTANT: YOUR CAMSHAFT STILL MATTERS
Installing an LT4 pump does not change the fuel-pump lobe on your existing camshaft.
On a stock-cam SS, the new pump continues to operate from the LT1 cam’s fuel lobe. A compatible aftermarket cam with increased fuel-lobe lift can provide additional pumping displacement, but that is a separate upgrade.
This bundle does not include a camshaft, lash cap, or increased-lift fuel lobe.
If your engine already has an aftermarket cam, confirm the pump’s installed height and any cam-specific lash-cap requirements before installation.
EIGHT LT4 INJECTORS - MORE DELIVERY WITHIN THE AVAILABLE WINDOW
Direct injectors have a limited amount of time to deliver fuel during each engine cycle. As RPM and fuel demand increase, that available window becomes increasingly important.
The LT4 injectors provide more flow than the LT1 injectors at the same test pressure, helping deliver the required fuel with less injection time under comparable conditions. This bundle supplies eight matching nominal-flow GM LT4 injectors, rather than mixing LT1 and LT4 injectors or combining different flow classes.
• Genuine GM injector assemblies, part number 19420334.
• Nominal-flow LT4 specification.
• Approximately 22% more flow than LT1 injectors at 200-bar bench-test pressure.
• Injector seals and clips included in this GMS bundle.
• Correct injector characterization and fuel-system calibration required.
ZL1 IN-TANK PUMP - SUPPORT THE HIGH SIDE
A larger high-pressure pump still needs a dependable supply of fuel. The included GM ZL1 low-side pump module upgrades the in-tank portion of the package to complement the LT4 high-pressure components. Available delivery depends on operating pressure, voltage, fuel temperature, and the vehicle’s tank and transfer-plumbing configuration. Raising the requested pressure alone does not guarantee more usable flow.
Before installation, verify the SS tank configuration and any required ZL1-style jet-pump or internal transfer-line components. Those additional conversion components are not listed as included in this bundle.
THE GMS ACCESS HATCH - PLAN FOR THE NEXT UPGRADE, TOO
Fuel-system work should not become a major teardown every time you need to inspect, service, or upgrade the in-tank pump. Our GMS Back Seat Fuel Pump Access Hatch provides access to the pump area from inside the vehicle once properly installed.
That means the value extends beyond the initial installation. Whether you are checking a connection, servicing the pump, or planning the next stage of your build, convenient access makes future work easier, and will save you hours during installation.
• Access beneath the rear seat.
• Useful for future pump inspection, service, and upgrades.
• Purpose-built GMS solution for the application.
NEW HARD LINES INCLUDED - FINISH THE JOB PROPERLY
The bundle includes both specified LT4 high-pressure hard lines, part numbers 12677005 and 12677003. These one-time-use lines are included so the conversion can be assembled with new components rather than relying on previously tightened high-pressure sealing connections.
Confirm the fuel-rail connection design before ordering, particularly on vehicles with replacement engines, changed rails, or later-design fuel-system components.
WHO IS THIS BUNDLE FOR?
• Modified LT1 builds approaching the capacity of the original fueling components.
• Owners planning a heads-and-cam combination with increased fuel demand.
• Customers who prefer genuine GM fueling hardware.
• DIY owners who value improved access for future in-tank pump service.
WHAT ABOUT HORSEPOWER AND ETHANOL?
Fuel-system parts support horsepower; they do not create it by themselves. There is no single horsepower ceiling that applies to every combination. Fuel type, cam-lobe lift, RPM, boost, commanded lambda, rail pressure, and available injection time all influence the final result.
Ethanol blends require more fuel delivery for comparable airflow and lambda, so a combination that has adequate capacity on gasoline may run out of fueling headroom on a higher ethanol blend. This bundle does not include a flex-fuel sensor or flex-fuel calibration. Discuss your intended fuel and power goal with GMS and your tuner before selecting the package.
WHY BUY THE GMS BUNDLE?
The value is in upgrading the fuel path as a coordinated package, and including the parts that make the installation and future service more practical.
FITMENT & INSTALLATION NOTES
• Intended for compatible Gen 6 Camaro SS LT1 applications; confirm year, body style, injector bore size, tank configuration, and fuel-rail connections before ordering.
• This injector selection is for the compatible 7.5-mm configuration. Vehicles with different injector bores require a different selection.
• ECU recalibration is required for the LT4 injectors and high-pressure pump conversion.
• Review fuel-pump-control calibration and low-side supply requirements with your tuner.
• Additional tank-transfer components, installation consumables, or vehicle-specific parts may be required.
• Verify low-side supply, commanded versus actual rail pressure, lambda, and injection timing under load before increasing power.
• Installation and tuning are not included.
GMS OEM LT4 FUEL SYSTEM UPGRADE BUNDLE FOR 6th GEN LT1 CAMARO
MORE AIR NEEDS MORE FUEL. GIVE YOUR LT1 ROOM TO GROW.
A supercharger, camshaft, E85 can quickly change what your Camaro needs from its fuel system. Getting more air into the engine is only half the equation, you also need to deliver enough fuel at the right pressure, at the right time.
The GMS OEM LT4 Fuel System Upgrade Bundle brings together genuine GM LT4 injectors, a matching high-pressure pump, a ZL1 in-tank pump, new high-pressure hard lines, and our GMS Back Seat Fuel Pump Access Hatch in order to make this upgrade as painless as possible, while giving you 20-25% more fuel system headroom!
It is a coordinated upgrade for LT1 Camaro owners who want additional fueling headroom using factory-developed components, with the installation details and future service access considered from the start.
WHAT’S INCLUDED?
• Eight genuine GM LT4 nominal-flow direct injectors, part number 19420334, with injector seals and clips supplied in the GMS bundle.
• One genuine GM ZL1 in-tank low-side fuel pump module, part number 85170844.
• One GMS Back Seat Fuel Pump Access Hatch.
• One genuine GM LT4 high-pressure fuel pump, part number 12711668.
• One new GM LT4 high-pressure pump feed pipe, part number 12677005.
• One new GM LT4 fuel rail “S” feed pipe, part number 12677003.
WHY UPGRADE BOTH SIDES OF THE FUEL SYSTEM?
Your Camaro’s direct-injection system delivers fuel in stages. The electric pump inside the tank supplies fuel to the engine. The cam-driven high-pressure pump then raises that pressure for the direct injectors, which deliver fuel straight into the combustion chambers.
Each stage needs to keep up with the next.
• The in-tank pump must maintain adequate supply to the high-pressure pump.
• The high-pressure pump must deliver enough volume while maintaining commanded rail pressure.
• The injectors must deliver the required fuel within the available injection window.
Upgrading these components together addresses multiple potential restrictions instead of asking one larger component to compensate for the rest of the original system.
HOW MUCH MORE FUELING DO YOU GET?
The LT4 components offer measurable improvements over the standard LT1 hardware.
• Approximately 20% greater high-pressure pumping volume from the LT4 HPFP compared with the LT1 pump when operating with the same cam-lobe lift.
• Approximately 22% greater injector bench flow at the same 200-bar test pressure: roughly 22 g/s per LT4 injector versus 18 g/s per LT1 injector in published comparison data.
• A ZL1-specification in-tank pump module to support the upgraded high-pressure components.
• Higher-pressure capability associated with the LT4 system, subject to the correct calibration and supporting hardware.
These improvements work together, but their percentages do not add together. Overall capacity depends on which component reaches its operating limit first.
The practical benefit is additional fueling headroom for a properly matched performance combination—not a fixed horsepower increase from installing fuel-system parts alone.
THE LT4 HIGH-PRESSURE PUMP - MORE VOLUME WHERE IT MATTERS
The LT4 HPFP uses a larger pumping piston than the LT1 unit, increasing the amount of fuel it can displace with each pumping stroke. That additional volume helps support higher fuel demand when the engine’s airflow and power output increase.
The commonly published design-pressure references are approximately 150 bar for the LT1 system and 200 bar for the LT4 system, roughly 2,175 versus 2,900 psi. Actual commanded pressure varies with operating conditions and calibration.
Higher pressure and greater pumping volume are different improvements. Your tuner must balance pressure, available pump delivery, and injector requirements for the combination.
IMPORTANT: YOUR CAMSHAFT STILL MATTERS
Installing an LT4 pump does not change the fuel-pump lobe on your existing camshaft.
On a stock-cam SS, the new pump continues to operate from the LT1 cam’s fuel lobe. A compatible aftermarket cam with increased fuel-lobe lift can provide additional pumping displacement, but that is a separate upgrade.
This bundle does not include a camshaft, lash cap, or increased-lift fuel lobe.
If your engine already has an aftermarket cam, confirm the pump’s installed height and any cam-specific lash-cap requirements before installation.
EIGHT LT4 INJECTORS - MORE DELIVERY WITHIN THE AVAILABLE WINDOW
Direct injectors have a limited amount of time to deliver fuel during each engine cycle. As RPM and fuel demand increase, that available window becomes increasingly important.
The LT4 injectors provide more flow than the LT1 injectors at the same test pressure, helping deliver the required fuel with less injection time under comparable conditions. This bundle supplies eight matching nominal-flow GM LT4 injectors, rather than mixing LT1 and LT4 injectors or combining different flow classes.
• Genuine GM injector assemblies, part number 19420334.
• Nominal-flow LT4 specification.
• Approximately 22% more flow than LT1 injectors at 200-bar bench-test pressure.
• Injector seals and clips included in this GMS bundle.
• Correct injector characterization and fuel-system calibration required.
ZL1 IN-TANK PUMP - SUPPORT THE HIGH SIDE
A larger high-pressure pump still needs a dependable supply of fuel. The included GM ZL1 low-side pump module upgrades the in-tank portion of the package to complement the LT4 high-pressure components. Available delivery depends on operating pressure, voltage, fuel temperature, and the vehicle’s tank and transfer-plumbing configuration. Raising the requested pressure alone does not guarantee more usable flow.
Before installation, verify the SS tank configuration and any required ZL1-style jet-pump or internal transfer-line components. Those additional conversion components are not listed as included in this bundle.
THE GMS ACCESS HATCH - PLAN FOR THE NEXT UPGRADE, TOO
Fuel-system work should not become a major teardown every time you need to inspect, service, or upgrade the in-tank pump. Our GMS Back Seat Fuel Pump Access Hatch provides access to the pump area from inside the vehicle once properly installed.
That means the value extends beyond the initial installation. Whether you are checking a connection, servicing the pump, or planning the next stage of your build, convenient access makes future work easier, and will save you hours during installation.
• Access beneath the rear seat.
• Useful for future pump inspection, service, and upgrades.
• Purpose-built GMS solution for the application.
NEW HARD LINES INCLUDED - FINISH THE JOB PROPERLY
The bundle includes both specified LT4 high-pressure hard lines, part numbers 12677005 and 12677003. These one-time-use lines are included so the conversion can be assembled with new components rather than relying on previously tightened high-pressure sealing connections.
Confirm the fuel-rail connection design before ordering, particularly on vehicles with replacement engines, changed rails, or later-design fuel-system components.
WHO IS THIS BUNDLE FOR?
• Modified LT1 builds approaching the capacity of the original fueling components.
• Owners planning a heads-and-cam combination with increased fuel demand.
• Customers who prefer genuine GM fueling hardware.
• DIY owners who value improved access for future in-tank pump service.
WHAT ABOUT HORSEPOWER AND ETHANOL?
Fuel-system parts support horsepower; they do not create it by themselves. There is no single horsepower ceiling that applies to every combination. Fuel type, cam-lobe lift, RPM, boost, commanded lambda, rail pressure, and available injection time all influence the final result.
Ethanol blends require more fuel delivery for comparable airflow and lambda, so a combination that has adequate capacity on gasoline may run out of fueling headroom on a higher ethanol blend. This bundle does not include a flex-fuel sensor or flex-fuel calibration. Discuss your intended fuel and power goal with GMS and your tuner before selecting the package.
WHY BUY THE GMS BUNDLE?
The value is in upgrading the fuel path as a coordinated package, and including the parts that make the installation and future service more practical.
FITMENT & INSTALLATION NOTES
• Intended for compatible Gen 6 Camaro SS LT1 applications; confirm year, body style, injector bore size, tank configuration, and fuel-rail connections before ordering.
• This injector selection is for the compatible 7.5-mm configuration. Vehicles with different injector bores require a different selection.
• ECU recalibration is required for the LT4 injectors and high-pressure pump conversion.
• Review fuel-pump-control calibration and low-side supply requirements with your tuner.
• Additional tank-transfer components, installation consumables, or vehicle-specific parts may be required.
• Verify low-side supply, commanded versus actual rail pressure, lambda, and injection timing under load before increasing power.
• Installation and tuning are not included.
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