Lexus IS300 3UZ Swap: Engine Bay Prep, ABS Delete & V8 Fitment
Swapping a Toyota 3UZ-FE V8 into a Lexus IS300 requires more than simply installing the engine. Engine mounts, exhaust and steering clearance, transmission fitment, fuel-line routing, wiring, and supporting chassis modifications all need to be addressed before the 3UZ can finally go into the car.
What started as a relatively straightforward Lexus IS300 3UZ swap has quickly turned into a complete drift car build.
With the engine already removed, we decided this was the perfect opportunity to clean up the engine bay and take care of several modifications that would become much harder once the 4.3L V8 was installed.
In this stage of the build, we're deleting the unused ABS system, preparing the car for electric power steering, repainting the engine bay, rewrapping the chassis wiring harness, modifying the exhaust for additional clearance, installing the 3UZ engine mounts, and adapting the factory IS300 fuel system.
Building an IS300 of your own? Browse our Lexus IS300 parts or check out our dedicated Lexus IS300 swap parts.
Watch the Lexus IS300 3UZ Swap Build Series
Want to see the entire swap from the beginning? Follow our Lexus IS300 3UZ-FE V8 swap build on YouTube:
Part 1: Starting the Lexus IS300 3UZ Swap
Watch Part 1 on YouTube
Part 2: Continuing the 3UZ IS300 Build
Watch Part 2 on YouTube
Part 3: Lexus IS300 3UZ Swap Progress
Watch Part 3 on YouTube
Follow along as we work toward getting the 3UZ-FE installed, running, and eventually putting this V8-swapped IS300 on track.
What Is a 3UZ Swap in a Lexus IS300?
A Lexus IS300 3UZ swap replaces the factory 2JZ-GE 3.0-liter inline-six with Toyota and Lexus's 3UZ-FE 4.3-liter V8.
The 3UZ-FE was used in several Lexus models, including the LS430, GS430 and SC430. Swapping one into an IS300 requires solutions for engine mounting, transmission fitment, wiring, exhaust routing, fuel delivery, cooling and other supporting systems.
Our IS300 is being built primarily as a drift car, so we're also using the swap as an opportunity to simplify the chassis and remove systems we no longer need.
If you're planning a similar build, Lunatics Co carries a growing selection of IS300 engine and drivetrain swap parts, including components from Xcessive Manufacturing.
Why Delete ABS on a Lexus IS300 Drift Car?
For our particular IS300 drift build, the factory ABS system was no longer being used because the car does not have its ABS sensors installed. Removing the unused ABS module also eliminates several brake lines from the engine bay and creates additional room around the 3UZ.
Once the factory engine was removed, one of the first things we noticed was how much space the ABS module and its associated hard lines occupied.
The factory ABS system has multiple brake lines running into and out of the module. With everything exposed, it essentially looks like a bundle of brake lines sitting next to where the engine needs to go.
Since the system wasn't being used on this build, we decided to remove it.
Removing the module itself is relatively straightforward. We followed the brake lines from the ABS module and disconnected the lines running toward the front and rear brakes.
The bigger project is properly replumbing the braking system afterward.
Deleting the ABS module means the brake system needs to be correctly rerouted so the brakes continue to function properly without the factory ABS unit.
It adds more work to the project, but it also gives us significantly more room around the 3UZ while creating a cleaner engine bay.
Preparing the IS300 for Electric Power Steering
Because this IS300 is being converted to electric power steering, we can remove much of the original hydraulic power steering plumbing from the engine bay.
The factory IS300 uses multiple power steering hard lines routed throughout the chassis. With the larger 3UZ going into the car, removing unused plumbing helps simplify the engine bay while creating additional room for the V8 swap.
We started by disconnecting the factory hard lines and tracing where everything went before removing them.
We're keeping some of the original components for now in case the electric power steering configuration changes later in the build.
That's something worth considering during any major engine swap.
Don't immediately throw away every factory component you remove. Until the swap is completely assembled, running and tested, you never know when you might need an original bracket, fitting, fastener or component for reference.
Cleaning the IS300 Engine Bay Before the 3UZ Swap
With the engine, ABS components and power steering lines removed, this was probably the easiest opportunity we were ever going to have to properly clean and repaint the engine bay.
We removed or moved several additional components to give ourselves better access, including portions of the chassis wiring harness, headlights and unused brackets.
The objective wasn't purely cosmetic.
Cleaning and simplifying the engine bay now should make it easier to route wiring, fuel lines and other components around the 3UZ later.
It should also make future maintenance easier without unnecessary brackets, wiring and plumbing occupying valuable space.
Painting the Engine Bay Graphite Gray Pearl
We decided to keep the Lexus engine bay close to its original Graphite Gray Pearl instead of introducing another bright color.
The exterior of the IS300 is already yellow, while the engine has blue and gold accents. There is already plenty happening visually with this car.
Rather than making the engine bay another focal point, we wanted a cleaner and more neutral background that would allow the 3UZ itself to stand out.
After cleaning and scrubbing the engine bay, we masked the areas we didn't want painted and prepared the shock towers, radiator support and surrounding sheet metal.
The Graphite Gray Pearl was refreshed and finished with clear coat.
Once sunlight hit the finished paint, the pearl became much more noticeable. It's still subtle, but the engine bay now looks significantly cleaner and more finished.
Rewrapping the Lexus IS300 Wiring Harness
The chassis harness had previously been opened for wiring repairs and modifications, so we decided to rewrap the visible portions using automotive harness tape.
With freshly painted sheet metal, leaving an old and partially opened harness in the engine bay didn't make much sense.
The old loom was carefully opened using a razor blade.
This part requires patience. A razor can easily damage the insulation around the wiring underneath the loom, potentially creating electrical problems that are difficult to diagnose later.
Once the old material was removed, we cleaned the harness and started applying fresh harness tape.
Some factory-wrapped sections were still in good condition. Instead of completely stripping those areas, we wrapped over them where necessary to create a more consistent appearance and provide additional structure.
The end result looks considerably cleaner and much closer to a professionally assembled automotive harness.
Does a 3UZ-FE Fit in a Lexus IS300?
Yes, a 3UZ-FE can fit in a Lexus IS300, but the swap requires the correct mounting solution and careful attention to engine position, exhaust clearance, steering clearance and transmission fitment.
This is where the build started moving away from cosmetic improvements and back toward actually fitting the V8.
One of our biggest concerns was exhaust clearance.
The existing exhaust flange occupied more space than we wanted around the steering and transmission area, so we cut the flange from the exhaust with plans to replace the connection with a more compact V-band setup.
We had also previously removed the factory exhaust manifold heat shields because they interfered with clearance.
While the manifolds were accessible, we cleaned them and applied VHT FlameProof coating.
It's not a replacement for professional ceramic coating, but it cleans up the appearance while providing a high-temperature coating.
Finding Every Millimeter of 3UZ Exhaust Clearance
The 3UZ fitment is tight enough in certain areas that even the profile of a bolt head can matter.
We found one bolt positioned extremely close to the exhaust.
Instead of leaving the larger bolt head in place, we replaced it with a lower-profile button-head bolt.
The replacement sits considerably flatter while still providing enough engagement to secure the component.
It sounds like a minor modification, but engine swaps often come down to finding a few additional millimeters of clearance.
Exhaust position, steering clearance, engine position and transmission placement all interact with one another.
Installing Xcessive 1UZ/3UZ Engine Mount Brackets
One of the most important parts of putting a 3UZ into an IS300 is properly positioning the engine in the chassis.
For this build, we're using components from Xcessive Manufacturing.
Lunatics Co carries the Xcessive Manufacturing 1UZ/3UZ Engine Mount Brackets for the 2001–2005 Lexus IS300.
These brackets are specifically designed for Toyota UZ-series V8 swaps into the IS300 and support both the 1UZ-FE and 3UZ-FE.
Engine position affects almost every other part of the swap, including:
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Exhaust clearance
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Steering clearance
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Transmission placement
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Shifter position
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Driveshaft alignment
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Drivetrain angles
That's why getting the engine mounting solution right is such an important step in a 3UZ IS300 swap.
Lunatics Co also carries Xcessive Manufacturing 1UZ IS300 urethane engine mounts for compatible UZ swap configurations.
For more swap-specific components, browse the complete Lexus IS300 swap parts collection.
Adapting the Lexus IS300 Fuel System for the 3UZ
The factory IS300 chassis fuel line also needs to connect to the 3UZ fuel rail.
On the chassis side, we installed an adapter that converts the factory fuel-line connection into a barb-style fitting.
That provides a connection point for the hose that will eventually run from the chassis fuel line to the engine.
The engine side required additional modification.
The existing fuel rail connection used a fitting that needed to be carefully removed before we could adapt the line.
We protected the engine and open fuel-system components before carefully cutting relief slots into the fitting.
Extra caution is necessary when performing any fuel-system modification.
Residual fuel can create a serious fire hazard around sparks or other ignition sources, and open fuel-system components need to be protected from metal shavings and other debris.
After making the relief cuts, we were able to peel the old fitting away and expose the connection underneath.
That gives us what we need to continue routing fuel from the IS300 chassis to the 3UZ.
For builds requiring additional fuel-system upgrades, Lunatics Co also carries the Xcessive Manufacturing IS300 Fuel Pump Mod, which is designed to provide full battery voltage to higher-output fuel pumps.
What Parts Do You Need for a Lexus IS300 3UZ Swap?
A Lexus IS300 3UZ swap can require engine mount brackets, engine mounts, transmission mounting components, a swap-specific driveshaft, fuel-system components, wiring solutions, exhaust fabrication and supporting chassis modifications.
The exact combination depends on the transmission, engine position and other components being used.
Some useful places to start include:
Rather than trying to install everything at once, we're addressing each system individually as the build progresses.
Do You Need a Custom Driveshaft for an IS300 Engine Swap?
Depending on the engine and transmission combination, an IS300 swap may require a different driveshaft configuration.
Lunatics Co carries the Xcessive Manufacturing Swap Driveshaft / Driveline for the 2001–2005 Lexus IS300.
These drivelines are built specifically around engine and transmission swap applications, with configurations based on transmission choice, engine placement and differential location.
If you're running custom mounts, a different differential or a nonstandard engine position, driveshaft measurements and compatibility should be confirmed before ordering.
Why We're Building a 3UZ IS300 Drift Car
The 3UZ-FE offers a completely different approach to building an IS300 drift car compared with keeping the factory 2JZ-GE or building a turbocharged JZ setup.
For this project, the goal is to build the IS300 around the naturally aspirated V8 while simplifying the chassis and creating a clean, functional engine bay.
The swap still requires plenty of fabrication and problem solving.
Exhaust clearance can be extremely tight. Engine positioning matters. The fuel and wiring systems need to be adapted. The transmission and drivetrain need to work with an engine the chassis was never originally designed to use.
That's exactly why we're documenting the entire process.
Instead of only showing the finished car, we want to show the smaller problems and solutions that actually go into building a 3UZ-swapped Lexus IS300.
Lexus IS300 3UZ Swap FAQ
Can you put a 3UZ in a Lexus IS300?
Yes. A Toyota/Lexus 3UZ-FE V8 can be swapped into a 2001–2005 Lexus IS300. The swap requires the appropriate engine mounting solution along with consideration for exhaust, steering, transmission, wiring and fuel-system fitment.
What engine comes in a Lexus IS300 from the factory?
The first-generation U.S.-market Lexus IS300 came equipped with the 3.0-liter 2JZ-GE inline-six. Our build replaces the factory inline-six with the 4.3-liter 3UZ-FE V8.
What motor mounts do you need for a 3UZ IS300 swap?
Our build uses Xcessive Manufacturing components. The Xcessive 1UZ/3UZ Engine Mount Brackets are specifically designed to position Toyota UZ-series V8 engines in the 2001–2005 Lexus IS300 chassis.
Does a 3UZ fit in the IS300 engine bay?
Yes, but clearance can become tight around the exhaust, steering and transmission. Engine positioning and the components used for the swap significantly affect fitment.
Do you need a custom driveshaft for a 3UZ IS300?
The required driveshaft depends on the transmission, engine position and differential configuration. Lunatics Co offers Xcessive Manufacturing IS300 swap drivelines built around multiple swap configurations.
Where can I buy Lexus IS300 swap parts?
Lunatics Co carries a dedicated Lexus IS300 Swap Parts collection with engine, transmission and drivetrain components for modified IS300 builds.
What's Next for Our 3UZ IS300?
What was supposed to be a simple engine swap has turned into a complete engine bay overhaul.
So far, we've tackled:
- ABS removal and brake-system preparation
- Factory power steering line removal
- Electric power steering preparation
- Engine bay cleaning
- Graphite Gray Pearl engine bay paint
- Chassis harness rewrapping
- Exhaust manifold cleanup and coating
- Exhaust clearance modifications
- Lower-profile hardware for additional clearance
- 3UZ engine mount installation
- Fuel-line conversion
Most of these jobs add time to the project, but they're considerably easier to complete while the drivetrain is still outside the car.
Our goal isn't simply to put a 3UZ into an IS300. We're building a clean and functional 3UZ-powered Lexus IS300 drift car while documenting the problems, modifications and solutions required to make the combination work.
The next major milestone is attaching the 3UZ to the transmission and continuing the drivetrain installation.
Follow the complete build on YouTube:
Watch Part 1 of the Lexus IS300 3UZ Swap
Watch Part 2 of the Lexus IS300 3UZ Swap
Watch Part 3 of the Lexus IS300 3UZ Swap
Building your own IS300? Shop Lexus IS300 swap parts, browse our complete Lexus IS300 parts catalog, or explore Xcessive Manufacturing parts at Lunatics Co.