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Lexus GS300 Turbo Build Part 4: Making 370 WHP with the CXRacing GT35 Turbo Kit
September 29, 2026 Daniel Ho

Lexus GS300 Turbo Build Part 4: Making 370 WHP with the CXRacing GT35 Turbo Kit

Welcome back to Part 4 of our Lexus GS300 Turbo Build Series! After months of preparing our 2JZ-GE VVT-i engine for forced induction, we're finally taking the car to the dyno to see how much wheel horsepower our turbocharged GS300 can make.

In Part 3, we completed the installation of our CXRacing GT35 turbo kit, front mount intercooler, external wastegate, oil feed and return lines, and supporting components. We also successfully started the engine for the first time using our Link G4X standalone ECU and Panic Made engine wiring harness.

Now that the engine is running on a base map, we have a few more upgrades to complete before our dyno appointment. We're installing a Link CAN gauge, correcting our PCV system, replacing the spark plugs, improving our heat management, and making additional clearance for the intercooler piping.

By the end of this episode, our turbocharged Lexus GS300 makes 370 WHP (wheel horsepower) on the dyno!

Our Lexus GS300 Turbo Build Parts List

Here's a breakdown of the major components we're using on our 1998–2005 Lexus GS300 2JZ-GE NA-T conversion.

Step 1: Installing the Link CAN Gauge in Our Lexus GS300

Before heading to the dyno, one of our biggest priorities was installing a gauge that could display the engine data monitored by our Link G4X ECU.

We went with the Link CAN Gauge OLED 52mm because it allows us to monitor multiple engine parameters through the ECU's CAN communication system.

Panic Made also supplied us with an adapter harness, making the installation much easier.

Routing the CAN Gauge Wiring Through the Firewall

The first challenge was routing the gauge wiring from the engine bay into the interior.

Since our GS300 has already been manual swapped, we looked for an existing firewall grommet near the clutch line.

We moved several components out of the way to gain access and used a zip tie to help fish the wiring through the firewall.

After some trial and error, we successfully pulled the wiring into the cabin.

Using an existing protected wiring passage helped us keep the installation clean without creating an unnecessary opening in the firewall.

Installing the Gauge into the Factory Air Vent

Instead of mounting the gauge on the dashboard or A-pillar, we wanted a cleaner factory-style appearance.

We decided to install the gauge into the driver's side air vent using an aftermarket vent gauge pod.

We carefully removed the factory vent and lower dashboard panels to route the wiring behind the dash.

Once the vent assembly was removed, we installed the gauge pod and positioned the Link CAN gauge inside it.

The supplied mounting bracket required a small modification to fit the vent pod, so we trimmed the bracket and secured the gauge.

After reinstalling the vent assembly, the gauge looked clean and integrated nicely into the factory interior.

Monitoring AFR, Boost, Fuel Pressure and Oil Pressure

One of the biggest advantages of the Link CAN gauge is that it can display information already available to the ECU.

We configured several pages to display important engine parameters, including:

  • Air-Fuel Ratio (AFR)
  • Boost and Manifold Pressure
  • Fuel Pressure
  • Oil Pressure
  • Coolant Temperature

Our first display page shows four parameters at once. We also configured individual pages for AFR and boost pressure.

When the engine is idling, the boost display shows manifold vacuum. Under boost, the gauge can display positive manifold pressure.

For anyone running a compatible Link ECU, the Link CAN Gauge is a useful way to monitor engine data without installing multiple separate gauges.

Step 2: Cleaning Up the Intake Piping and Vacuum Connections

With the gauge installed, we moved on to correcting some of the intake plumbing.

During the previous installation, we used several rubber caps and hose clamps to close unused openings.

Although this allowed us to mock up the system, we wanted something more secure and better suited to a turbocharged application.

Under boost, poorly secured caps and fittings can become potential leak points.

Replacing Rubber Caps with Threaded Plugs

We removed the intake component and began modifying the unused ports to accept threaded fittings.

Using the appropriate drill and NPT taps for our selected fittings, we prepared the openings for threaded plugs.

After tapping the ports, we thoroughly cleaned the component to remove metal shavings and debris before reinstallation.

The result was a cleaner intake assembly with fewer temporary hose clamps and rubber caps.

These changes helped us improve the appearance of the engine bay while addressing potential pressure leaks.

For related components and upgrades, browse our Lexus and Toyota Engine Accessories Collection.

Step 3: Correcting the 2JZ-GE PCV System for Turbocharging

Another important issue we discovered involved the factory PCV system.

Thanks to feedback from Known Worldwide, we realized that our original crankcase ventilation arrangement needed additional attention before operating the engine under boost.

The factory 2JZ-GE PCV system was designed around the naturally aspirated engine's operating conditions.

When converting the engine to forced induction, the crankcase ventilation system must be configured so that boost pressure cannot pressurize the crankcase through an inappropriate connection.

Removing and Modifying the Valve Cover

To correct our setup, we removed the intake components and valve cover to access the factory PCV connection.

We decided to modify the valve cover opening to accept a threaded fitting connected to our catch can system.

For our installation, we used a 1/2-inch NPT-to-hose-barb fitting.

We carefully tapped the opening and used grease to help capture metal shavings during the process.

Afterward, we cleaned the component and installed the fitting with appropriate thread sealant.

We then reinstalled the valve cover and prepared to reroute the catch can hoses.

Important Note: The modification shown in our video is specific to our engine and catch can arrangement. Proper crankcase ventilation requires more than installing a larger fitting. Check-valve placement, ventilation capacity, crankcase pressure, and emissions requirements must all be considered.

Planning a Future Catch Can Upgrade

Our current catch can is a temporary solution for this stage of the project.

We already know that we want to upgrade to a larger and cleaner system in the future.

For now, our priority was correcting the plumbing before the dyno session and verifying that the crankcase ventilation system was suitable for the planned testing.

If you're researching similar upgrades, explore our Engine Accessories and Supporting Upgrades.

Step 4: Installing NGK V-Power Spark Plugs on the Turbo 2JZ-GE

While we had the intake components removed, we decided it was a good opportunity to replace the spark plugs.

We hadn't replaced the plugs earlier in the build, and we wanted to install a fresh set before our dyno appointment.

For this setup, we selected NGK V-Power spark plugs, part number 4644.

Setting the Spark Plug Gap to 0.030 Inch

Before installing the new spark plugs, we checked their electrode gaps.

For our current setup, we targeted approximately 0.030 inch, or thirty-thousandths of an inch.

Some of the plugs measured closer to 0.035 inch out of the box, so we carefully adjusted the gaps before installation.

We used a spark plug gap tool to check the clearance and make small adjustments.

Spark Plug Tip: The correct spark plug type, heat range, and gap depend on the engine, ignition system, boost pressure, and tune. Our 0.030-inch setting reflects what we used for this build, not a universal recommendation for every turbocharged 2JZ-GE.

Removing the Old Spark Plugs

We removed the existing spark plugs using a magnetic spark plug socket.

The old plugs showed visible wear, reinforcing our decision to replace them before tuning.

We then installed the new NGK plugs and reassembled the intake components.

Step 5: Adding Turbo Heat Protection

With the intake and spark plugs finished, we moved on to additional heat management.

Our CXRacing GT35 Turbo Kit places the turbocharger and exhaust components inside an already crowded engine bay.

During Part 3, we wrapped the downpipe and added heat protection to nearby components.

For Part 4, we also worked on installing a turbo heat shield.

The shield required some adjustment to fit around the turbocharger properly.

Heat management is especially important when the engine bay contains aftermarket wiring, hoses, intercooler piping, and other supporting components.

Proper thermal protection can help reduce heat exposure, but it should always be combined with adequate clearance and secure component mounting.

Step 6: Installing the Additional Pressure Sensor

Next, we installed a digital pressure sensor supplied by Panic Made.

We originally considered installing the sensor at a different engine location, but decided to use an existing accessible port instead.

The wiring connector was already nearby, which made the installation much easier.

We removed the existing fitting, installed the new sensor, and connected it to the engine wiring harness.

This allowed us to continue preparing the ECU's sensor monitoring configuration before the dyno.

We're using the Panic Made Engine Wiring and Link G4X ECU Setup, which has helped simplify the wiring portion of this build.

Step 7: Modifying the Front Bumper for Intercooler Clearance

One of the final challenges before dyno day involved the front bumper and intercooler piping.

During the initial turbo kit installation, we discovered that the intercooler piping needed more clearance than we originally expected.

We also ran into interference with the factory windshield washer fluid reservoir.

Removing the Washer Fluid Reservoir

To make additional room for the piping, we removed the washer fluid reservoir.

This helped create the space needed to position the intercooler piping, although it also meant we would need to address the washer system later.

Trimming the Front Bumper and Fog Light Housing

We also needed to trim portions of the front bumper and fog light housing to clear the intercooler piping.

The required trimming was more extensive than we initially anticipated.

We carefully removed material from the interfering areas and repeatedly checked the bumper fitment.

Eventually, we were able to get the bumper installed with the charge piping in place.

Some areas were still extremely tight, so we planned to revisit the final fitment after the dyno session.

For anyone installing a similar kit, be prepared to check bumper clearance carefully. Our experience with the CXRacing GS300 GT35 Turbo and Intercooler Kit shows that additional trimming and adjustments may be necessary depending on the vehicle and installation.

Step 8: Preparing the Link G4X ECU for Dyno Tuning

With the major mechanical work finished, it was finally time to prepare the car for its dyno appointment.

Our Lexus GS300 was running on a base map, but it wasn't fully tuned yet.

We worked with Panic Made to improve the initial ECU configuration and get the engine running well enough for the next stage of the project.

The support from Panic Made made a huge difference, especially because wiring and standalone engine management were some of the most intimidating parts of the build when we started.

Our setup uses a Link G4X ECU with a custom Panic Made Full Engine Wiring Harness.

The ECU allows our tuner to configure fuel delivery, ignition timing, sensor inputs, boost control, and engine protection strategies.

For the trip to the dyno, we planned to keep boost control conservative until the tuner could verify the engine's behavior.

Important: A base map is not a substitute for a completed tune. A modified vehicle should only be operated after its mechanical condition, fueling, ignition, and safety systems have been verified by qualified professionals.

Step 9: Dyno Tuning Our CXRacing GT35 Lexus GS300

After working late into the night and finishing the remaining preparation early the next morning, we finally made it to our dyno appointment at Super Fast.

This was the moment we'd been waiting for throughout the entire turbo build.

Our Lexus GS300 started life with a naturally aspirated 2JZ-GE VVT-i engine. After upgrading the fuel system, installing the turbocharger hardware, and converting to standalone engine management, we were finally ready to see the results.

Checking the Base Map Before the Dyno Pulls

Before making full dyno pulls, the tuner worked on the ECU calibration and checked the engine's operation.

The goal was to get the engine running smoothly and make the necessary adjustments before testing its power output.

Our Link G4X ECU provides the tuning flexibility needed for our turbocharged setup, while the Link CAN Lambda Wideband System provides air-fuel ratio information used for monitoring and tuning.

Final Dyno Results: 370 WHP

After completing our dyno tuning session at Super Fast, our turbocharged Lexus GS300 produced approximately 370 WHP (wheel horsepower)!

We saw a final result around 369–370 WHP and decided to call it an even 370 WHP.

With our CXRacing GT35 Turbo Kit, Link G4X standalone ECU, Panic Made wiring harness, and upgraded fuel system, we were able to make 370 horsepower measured at the wheels from our 2JZ-GE VVT-i engine.

This is a huge milestone for our Lexus GS300 NA-T build, especially considering that we started with a naturally aspirated 2JZ-GE engine.

Final Dyno Result: 370 WHP

The dyno session gave us our first completed power result, but there's still more testing and refinement ahead as we continue working on the car.

What We Accomplished in Lexus GS300 Turbo Build Part 4

  • Installed the Link CAN Gauge OLED 52mm.
  • Routed CAN wiring through the firewall.
  • Installed the gauge in a factory-style dashboard vent pod.
  • Configured displays for AFR, boost, oil pressure, fuel pressure, and coolant temperature.
  • Replaced temporary intake caps with threaded fittings.
  • Modified the valve cover connection for our catch can plumbing.
  • Installed NGK V-Power 4644 spark plugs.
  • Set the spark plug gap to approximately 0.030 inch.
  • Added a turbo heat shield.
  • Installed an additional digital pressure sensor.
  • Removed the washer fluid reservoir for piping clearance.
  • Trimmed the bumper and fog light housing to clear the intercooler piping.
  • Prepared the Link G4X ECU for dyno tuning.
  • Completed our dyno session at Super Fast.
  • Achieved approximately 370 WHP with our turbocharged 2JZ-GE.

Frequently Asked Questions About Our Lexus GS300 Turbo Build

How much horsepower did your turbo Lexus GS300 make?

Our Lexus GS300 made approximately 370 WHP (wheel horsepower) during the dyno session featured in Part 4. This is horsepower measured at the wheels, not estimated crank horsepower.

What turbo kit did you install on the GS300?

We installed the CXRacing GT35 Turbo & Front Mount Intercooler Kit for the 1998–2005 Lexus GS300 2JZ-GE VVT-i.

What ECU are you using for the 2JZ-GE turbo conversion?

We're using a Link G4X standalone ECU paired with a Panic Made Full Engine Wiring Harness.

What gauge did you install in the GS300?

We installed a Link CAN Gauge OLED 52mm into a driver's side dashboard vent pod. It displays multiple engine parameters communicated by the ECU.

What spark plugs are you running in your turbo 2JZ-GE?

We installed NGK V-Power spark plugs, part number 4644, and set the gap to approximately 0.030 inch for our current setup.

Why did you modify the PCV system?

We needed to correct the crankcase ventilation plumbing for our turbocharged engine. Our goal was to avoid an unsuitable pressure path into the crankcase and improve the connections to our catch can system.

Did the CXRacing turbo kit require bumper modifications?

On our Lexus GS300, we needed to trim parts of the front bumper and fog light housing for intercooler piping clearance. We also removed the washer fluid reservoir during the installation.

Can you drive a turbocharged Lexus GS300 on a base map?

A base map is only an initial calibration and does not establish that a vehicle is safe to drive. Fueling, ignition timing, engine protection settings, mechanical condition, and operating limits must be verified before operation.

What's next after making 370 WHP?

Our next step is to continue testing the car, evaluate how it drives, and address any remaining issues. We also need to replace the worn front tires before further road testing.

What's Next? Lexus GS300 Turbo Build Part 5

Now that our Lexus GS300 has completed its first dyno session and produced approximately 370 WHP, it's time to see how the car performs outside the dyno shop.

In the next episode, we'll be testing the car, evaluating the driving experience, and continuing to work through any remaining issues with the build.

We also have more improvements planned, including cleaning up the engine bay, refining the catch can system, and addressing the remaining intercooler piping clearance.

Stay tuned for Part 5 of our Lexus GS300 Turbo Build Series!

Shop Lexus GS300 Turbo Parts at Lunatics Company

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

If you're planning your own 2JZ-GE NA-T conversion, explore these products and collections:

Engine Management Partner: Visit Panic Made for compatible engine wiring and Link ECU packages. You can also find the Link CAN Gauge and Link CAN Lambda through Panic Made.

Visit LunaticsCo.com for Lexus and Toyota performance parts, build guides, and more automotive content.

Important: Turbocharger and emissions-related modifications may be restricted to off-road or competition use. Follow applicable regulations. Engine management, fuel systems, crankcase ventilation, and turbocharger installations should be inspected and verified before operation.

Next article Lexus GS300 Turbo Build Part 3 | CXRacing GT35 Install and First Start