September 1, 2026 Daniel Ho

How to Turbo a Lexus GS300 2JZ-GE: Fuel System, Injectors & ACIS Delete Part 1

Can you turbocharge a Lexus GS300 with the factory 2JZ-GE VVT-i engine? Absolutely. The naturally aspirated 2JZ-GE is a popular platform for turbo conversions, but building a reliable setup requires more than simply installing a turbocharger.

Welcome to Part 1 of our Lexus GS300 Turbo Build Series! After working on our Lexus IS300 3UZ swap, we're moving on to our next project: turning our Lexus GS300 into a turbocharged street and drift car.

For this build, we're using a CX Racing turbo kit, DeatschWerks 700cc fuel injectors, a 340 LPH fuel pump, a custom return-style fuel system, and a Panic Made wiring harness paired with a Link G4X ECU.

In this first episode, we're focusing on preparing the 2JZ-GE for boost. We'll upgrade the fuel pump, modify the factory fuel system, install larger injectors, prepare the OEM fuel rail, remove the factory engine wiring harness, and delete the ACIS butterfly valve.

If you're researching how to turbo a Lexus GS300 or planning your own 2JZ-GE NA-T conversion, this guide covers the modifications we're making and the parts involved.

Our Lexus GS300 Turbo Build: Parts and Setup

The 1998–2005 Lexus GS300 comes equipped with Toyota's naturally aspirated 2JZ-GE VVT-i engine. While the factory engine wasn't designed as a turbocharged application, it has become a popular starting point for enthusiasts looking to build a 2JZ NA-T setup.

Instead of swapping in a 2JZ-GTE, we're retaining our original 2JZ-GE and upgrading the supporting components to prepare it for forced induction.

Here's a breakdown of the components we're using:

Turbo Kit: CX Racing GT35 Turbo Kit
Fuel Pump: 340 LPH High-Flow Fuel Pump
Fuel Injectors: DeatschWerks 700cc Injectors
Fuel System: Custom Return-Style Conversion
Fuel Pressure Regulator: External Adjustable Regulator
Engine Harness: Panic Made 2JZ Harness
Engine Management: Link G4X Standalone ECU
Intake Modifications: ACIS Butterfly Valve Delete

One of the main components of this build is the CX Racing GT35 Turbo Kit for the 1998–2005 Lexus GS300.

This turbo kit is designed for the GS300 2JZ-GE platform and provides many of the major components needed for an NA-T conversion, including turbocharger and intercooler hardware.

We're saving the turbocharger installation for a later episode. First, we need to prepare the engine and fuel system.

Step 1: Upgrading the Lexus GS300 Fuel Pump

The first major modification in our GS300 turbo build is upgrading the factory fuel pump.

When turbocharging a naturally aspirated engine, the additional airflow requires more fuel to maintain the correct air-fuel ratio. An insufficient fuel supply under boost can lead to a lean condition and potentially severe engine damage.

For our setup, we're upgrading to a 340 LPH fuel pump to provide additional fuel delivery capacity.

How to Access the Lexus GS300 Fuel Pump

On the 1998–2005 Lexus GS300, the fuel pump assembly is located inside the fuel tank and can be accessed beneath the rear seat.

We started by disconnecting the battery, removing the rear seat cushion, and accessing the fuel pump service opening.

After disconnecting the electrical connector and fuel line, we removed the fuel pump assembly from the tank.

One thing to keep in mind is that many of these factory components are more than 20 years old. Plastic clips, seals, and connectors can become brittle over time, so take your time when removing the assembly.

Important: Before opening the fuel system, relieve residual fuel pressure using the proper factory procedure. Opening the gas cap alone does not depressurize the fuel lines. Work in a well-ventilated area away from ignition sources.

Installing the 340 LPH Fuel Pump

Once the factory fuel pump assembly was removed, we disassembled the hanger and transferred the required mounting components to our upgraded pump.

Our replacement pump used a different electrical connector, so we also needed to adapt the wiring.

When upgrading a fuel pump, it's important to verify electrical polarity, current requirements, fuel compatibility, and the condition of the original wiring.

The upgraded pump provides additional fuel flow capacity for our turbo setup, although actual fuel delivery depends on fuel pressure, voltage, and the complete fuel system.

Looking for fuel system upgrades? Explore the performance fuel system brands available at Lunatics Company.

Step 2: Converting the Lexus GS300 to a Return-Style Fuel System

With the upgraded fuel pump ready, the next step was modifying the factory fuel system to support an external adjustable fuel pressure regulator.

For our turbocharged GS300, we're converting the original fuel arrangement to a return-style setup.

Why Use a Return-Style Fuel System on a Turbo GS300?

A return-style fuel system circulates fuel from the tank to the fuel rail and sends excess fuel back to the tank through a return line.

When paired with a properly installed boost-referenced fuel pressure regulator, this arrangement can maintain the intended pressure differential across the injectors as manifold pressure changes.

This is useful for turbocharged applications running aftermarket injectors and standalone engine management.

However, not every turbocharged GS300 requires a return-style conversion. The appropriate fuel system depends on your horsepower goals, fuel type, engine management, and overall configuration.

Modifying the Factory Fuel Pump Hanger

Rather than replacing the entire factory fuel pump assembly, we decided to modify the original hanger.

Our project involved adding a return connection using a bulkhead fitting and modifying the original fuel pressure regulation arrangement.

We also routed additional plumbing inside the assembly to support the new return line.

The video shows our initial fabrication process, including the use of thread sealant and epoxy. These methods should not be assumed to provide a safe or permanent fuel-system seal.

Important: Fuel tank penetrations, bulkhead fittings, seals, and hoses must be designed and rated for fuel service. Any modified assembly should be professionally inspected and tested for leaks before use.

Step 3: Installing DeatschWerks 700cc Fuel Injectors

Next, we moved to the engine bay to install our upgraded DeatschWerks 700cc fuel injectors.

The factory 2JZ-GE injectors were designed around the engine's original naturally aspirated power output. For our turbo setup, we're upgrading to larger injectors to support additional fuel delivery.

Injector sizing depends on several factors, including target horsepower, fuel pressure, fuel type, and injector duty cycle. A 700cc injector isn't automatically the correct choice for every turbocharged GS300.

Removing the Factory Intake Manifold

Accessing the 2JZ-GE fuel rail requires removing several factory intake components.

We started by removing the airbox and intake piping, followed by the throttle body and upper intake manifold sections.

There are several hidden bolts, coolant hoses, vacuum lines, and electrical connectors throughout the intake assembly.

Because we're also replacing the factory engine wiring harness, removing these components gives us better access to the wiring underneath the manifold.

Modifying the OEM 2JZ-GE Fuel Rail

Instead of purchasing an aftermarket fuel rail, we decided to modify a spare factory 2JZ-GE fuel rail.

We drilled and tapped the spare rail for a 1/8-inch NPT fitting, creating a connection for our external fuel pressure regulator.

This allows us to retain the factory-style fuel rail while adapting the system for our return-style fuel setup.

Any modified fuel rail must be thoroughly cleaned, inspected, and pressure-tested before installation. Metal debris, improperly sealed fittings, or insufficient material around a fitting can create serious fuel-system hazards.

Installing the New 700cc Injectors

With the fuel rail prepared, we installed the new injectors.

Correct injector fitment is essential. The injectors must be compatible with the fuel rail, intake manifold, electrical connectors, and ECU calibration.

Injector O-rings and seals should match the manufacturer's specifications. Old seals should not be reused unless their compatibility and condition have been verified.

Once the Link G4X ECU is installed, our tuner will configure the appropriate injector flow and characterization data.

Shop related parts: Explore our Lexus and Toyota Engine Performance Upgrades for additional components.

Step 4: Removing the Factory 2JZ-GE Wiring Harness

With the fuel injectors installed and the intake manifold partially disassembled, we moved on to removing the factory engine wiring harness.

For this build, we're using a Panic Made wiring harness paired with a Link G4X standalone ECU.

The factory harness routes throughout the engine bay and connects to the fuel injectors, ignition system, engine sensors, starter, alternator, and other components.

Some of the connectors are hidden beneath the intake manifold, making removal more difficult than expected.

We ultimately removed the lower intake manifold to gain access to the wiring underneath.

Why We're Using a Link G4X ECU

A standalone ECU gives our tuner greater control over engine operation and allows the calibration to be configured for our upgraded fuel system and turbocharger.

Depending on the setup, the Link G4X provides capabilities such as:

Custom fuel and ignition tuning
Electronic boost control
Engine data logging
Additional sensor monitoring
Programmable engine protection strategies
Support for upgraded fuel injectors

Our Panic Made setup uses a factory-style ECU enclosure and a harness configured for the GS300 application.

Although the installation is designed to simplify wiring, additional sensors and ECU configuration are still required.

We'll cover the wiring harness and ECU installation in Part 2 of the series.

Step 5: Deleting the Lexus GS300 ACIS Butterfly Valve

With the lower intake manifold removed, we decided to clean up the factory intake system by removing the ACIS components.

ACIS stands for Acoustic Control Induction System. Toyota uses this system to change intake characteristics at different engine operating conditions.

The 2JZ-GE uses a vacuum-operated butterfly valve as part of this system.

Why Delete ACIS on a Turbo 2JZ-GE?

For our specific build, we're simplifying the intake manifold and removing components that we don't plan to retain with our standalone ECU setup.

This includes the factory actuator-related components, associated vacuum plumbing, and butterfly valve.

However, deleting ACIS isn't required for every turbocharged 2JZ-GE.

The factory ACIS system can provide performance benefits under certain operating conditions, and removing it doesn't automatically increase horsepower.

Removing the ACIS Butterfly Valve

After removing the lower intake manifold, we accessed the butterfly valve assembly.

The butterfly plate is secured inside the intake passage, and removing it requires care because the retaining hardware can be difficult to extract.

After removing the plate, we modified the remaining assembly and prepared the unused openings for sealing.

Any intake manifold modification should be performed with the manifold removed from the engine to prevent loose hardware or metal debris from entering the cylinders.

The completed intake assembly must be checked for proper sealing before operation.

Will an ACIS Delete Cause a Check Engine Light?

On a factory ECU-controlled vehicle, removing ACIS components can cause diagnostic trouble codes or affect engine operation.

Because we're using a Link G4X ECU, our tuner can configure the engine management system around the hardware we're retaining.

Removing emissions-related equipment may not be legal for road use. Always verify applicable requirements before making modifications.

Additional Turbo Components for the Lexus GS300

While Part 1 focuses on fuel delivery and engine preparation, the turbocharger and intercooler system are equally important parts of the overall build.

If you're planning a similar 2JZ-GE NA-T conversion, here are some additional components worth considering.

CX Racing GT35 Turbo Kit for Lexus GS300

The CX Racing GT35 Turbo Kit for the 1998–2005 Lexus GS300 is the foundation of our turbo conversion.

Designed for the 2JZ-GE VVT-i platform, the kit provides major turbocharger and charge-air system components for an NA-T build.

CX Racing Intercooler, Piping & BOV Kit

For enthusiasts who already have a turbocharger and manifold, the CX Racing Intercooler, Piping & Blow-Off Valve Kit for the Lexus GS300 is another option.

This kit provides intercooler and charge-piping components for compatible GS300 turbo applications. Always verify compatibility with your existing turbo setup.

Other Lexus GS300 Performance Upgrades

Beyond the turbo system, supporting upgrades can improve how the vehicle performs and handles additional power.

Browse our Lexus GS300 Performance Parts Collection for additional components.

What We Accomplished in Part 1

In the first episode of our Lexus GS300 turbo build, we completed much of the preparation needed before installing the turbocharger.

Removed the factory fuel pump and prepared the upgraded 340 LPH pump.
Modified the fuel pump assembly for a return-style fuel system.
Prepared the factory fuel rail for an external fuel pressure regulator.
Installed DeatschWerks 700cc fuel injectors.
Removed the factory engine wiring harness.
Disassembled the intake manifold.
Removed the ACIS butterfly valve and associated components.

Before the engine is started, the modified fuel system and intake components must be properly inspected and tested.

With the initial preparation underway, we're ready to move into the next phase of the build.

Frequently Asked Questions About Turbocharging a Lexus GS300

Can you turbo a stock Lexus GS300 2JZ-GE?

Yes. The naturally aspirated 2JZ-GE can be converted to a turbocharged NA-T configuration. Reliability depends on engine condition, boost pressure, fuel delivery, tuning, and supporting modifications.

What turbo kit are you using on the GS300?

We're using a CX Racing GT35 turbo kit designed for the Lexus GS300 2JZ-GE. You can explore the CX Racing GS300 GT35 Turbo Kit through Lunatics Company.

What size fuel injectors are you using?

We're using DeatschWerks 700cc fuel injectors. Injector sizing should be determined by your horsepower goals, fuel type, fuel pressure, and tuning requirements.

What fuel pump are you using?

We're using a 340 LPH fuel pump to support the increased fuel requirements of our turbocharged 2JZ-GE.

Do you need a return-style fuel system to turbo a GS300?

Not necessarily. A return-style system with a boost-referenced fuel pressure regulator is one option for managing fuel pressure in a turbocharged application.

Do you need to delete ACIS when turbocharging a 2JZ-GE?

No. ACIS deletion is optional and depends on the intake configuration and engine management setup. Removing it does not guarantee an increase in horsepower.

What ECU are you using for the GS300 turbo build?

We're using a Link G4X standalone ECU paired with a Panic Made wiring harness.

What's Next? Lexus GS300 Turbo Build Part 2

In Part 2 of our Lexus GS300 Turbo Build Series, we'll continue preparing the engine by installing the Panic Made wiring harness and Link G4X ECU.

We'll also work on routing the engine wiring, reassembling the intake manifold, and installing the external fuel pressure regulator.

These modifications will bring us another step closer to installing the turbocharger and getting the 2JZ-GE running under boost.

Follow along as we transform our Lexus GS300 into a turbocharged street and drift car.

Shop Lexus GS300 Turbo & Performance Parts at Lunatics Company

At Lunatics Company, we're enthusiasts helping enthusiasts build better Lexus and Toyota street, track, and drift cars.

Whether you're planning your first 2JZ-GE turbo conversion or upgrading an existing NA-T setup, we offer performance parts for your Lexus GS300 build.

Explore our selection of:

Visit LunaticsCo.com for more Lexus and Toyota performance parts, and stay tuned for Part 2 of our Lexus GS300 Turbo Build Series.

Next article Lexus IS300 3UZ Swap Part 6: Flex Fuel & First Start