- Junk Mechanics m4: Restore the engine, body, wheels, and missing turbocharger before serious testing.
- Engine priority: Clean damaged components and repair the engine block before changing aspiration.
- Visual setup: Use sage green paint with bronze-gold wheels for a coordinated custom build.
- Turbo upgrade: The big I6 turbo improves acceleration and top speed compared with the naturally aspirated setup.
- Testing habit: Run a baseline speed test before installing upgrades, then repeat the same route afterward.
Junk Mechanics m4 Build Overview
The Junk Mechanics m4 is best approached as a staged restoration project rather than a quick performance swap. Start by repairing the worn engine, cleaning the radiator and related parts, correcting the rusty bodywork, and replacing damaged wheels. Once the car is in dependable condition, install the large I6 turbocharger and compare its performance against the original naturally aspirated setup.
The build process combines mechanical repairs with cosmetic customization. A sage-green body and bronze-style wheels create a distinct appearance, while the turbocharger provides the main performance change. Because tuning was not available in the documented setup, the turbo should be treated as the core upgrade rather than one part of a fully optimized dyno build.
Video Highlights:
- Restores the M4 engine and replaces damaged components.
- Applies sage-green paint using the hex code
778F6D. - Fits larger tire and rim settings before repainting the wheels.
- Uses
A9947Ffor a bronze-gold wheel finish. - Tests the car before and after installing a big I6 turbocharger.
| Build Stage | Main Objective | Recommended Result |
|---|---|---|
| Inspection | Find damaged or missing parts | Identify engine, wheel, body, and turbo issues |
| Restoration | Return core components to usable condition | Clean, repaired engine assembly |
| Styling | Create a consistent visual theme | Sage-green body with bronze-style wheels |
| Upgrade | Change the car from naturally aspirated | Install the big I6 turbocharger |
| Testing | Compare performance before and after | Repeat the same top-speed route |
Restoration First
Repair the engine and clean worn parts before spending time on appearance or speed testing.
Coordinated Styling
Sage green and bronze-gold wheels give the M4 a deliberate custom identity instead of a partially restored look.
Measured Performance
Record a baseline run, install the turbo, and repeat the test so the upgrade is easier to evaluate.
Complete mechanical repairs before final styling. This reduces the chance of testing a car that still has a missing or damaged component.
Restore the Engine and Exterior
The first major phase is mechanical cleanup. Put the M4 on the lift, open the hood, and inspect the internal engine parts. The documented build required attention to the engine block, cylinders, radiator, exhaust manifold, intake, and other components. The goal is not simply to make the car look finished; each visible missing or damaged part can affect the condition display and later testing.
The radiator should receive special attention because it was visibly dirty during the build. Clean the radiator and related parts before reinstalling the engine assembly. The M4 later displayed a 92% condition rating because a turbocharger was still missing, showing why the clipboard or condition view should be checked before leaving the shop.
| Component | Action | Why It Matters |
|---|---|---|
| Engine block | Repair damaged sections | Provides a sound base for the performance setup |
| Cylinders | Restore worn parts | Supports the repaired engine assembly |
| Radiator | Clean before refitting | Removes a major visible maintenance issue |
| Intake | Clean and reinstall | Completes the intake-side engine work |
| Exhaust manifold | Clean and reinstall | Prepares the engine bay for the turbo setup |
| Turbocharger | Add after inspection | Resolves the missing upgrade component |
Move the M4 to the Lift
Drive the car to the mechanic shop and place it on the lift. Raising the car gives you access to the engine bay and makes it easier to remove the worn parts.
Remove the Damaged Engine Parts
Open the hood and take out the components that are in poor condition. Inspect the engine block, cylinders, radiator, intake, and exhaust manifold rather than replacing only the most obvious item.
Clean and Repair the Assembly
Restore the engine block and clean the radiator, intake, and exhaust manifold. Continue checking the condition view so a hidden or missing part does not remain.
Reinstall the Core Components
Put the repaired engine parts back into the M4. Confirm that the engine bay is assembled before moving to paint and wheel customization.
A repaired engine does not guarantee a finished build. If the car still shows reduced condition, inspect the clipboard for missing parts before performance testing.
Paint, Wheels, and Fitment Choices
Once the mechanical work is stable, take the M4 to the customization shop. The body begins with a rusty silver appearance, so buff the exterior until the rust-colored surface is removed. A sage-green finish uses the hex code 778F6D, which creates a muted green look that contrasts with the warmer wheel color.
The wheel setup needs more preparation than a simple repaint. Remove the old tires, replace the rusty wheel that cannot be repaired, and fit the new tire set. The documented build experimented with tire size 25 and a rim size of 69. These values are useful as a starting point for a similar visual setup, but fitment should still be checked from multiple angles.
| Custom Part | Build Setting | Practical Note |
|---|---|---|
| Body paint | 778F6D | Sage-green finish |
| Replacement tires | Tire size 25 | Used for the new wheel set |
| Rim fitment | Rim size 69 | Tested to reduce visible wheel gaps |
| Wheel paint | A9947F | Bronze or muted gold appearance |
| Rusty wheel | Replace, not repair | The damaged rim required a new set |
M4 Restoration Checklist:
- Buff the rusty body before applying the final paint
- Replace the wheel that cannot be repaired
- Fit the new tire set before final wheel painting
- Test rim size 69 for the desired wheel-gap profile
- Repaint the wheels with the bronze-style hex code A9947F
The body and wheel colors work because they occupy different visual temperatures: the green paint is subdued, while the bronze-style wheels add contrast. If the wheel fitment looks too large or leaves an unwanted gap, adjust the rim setting before committing to the final paint.
The tire and rim settings are customization choices, not universal performance ratings. Check the stance, wheel gap, and body clearance on your own M4 before finalizing the look.
Install the Big I6 Turbocharger
The central performance change is switching from naturally aspirated power to a big I6 turbocharger. Before the swap, the M4 felt slow and reached roughly 179–180 in the recorded top-speed test after the build’s initial run. The turbocharger added a boost gauge and produced a noticeable change in acceleration and sound during the follow-up test.
To find the correct part, use the turbo selection area and distinguish the I6 option from the V8, V6, and I4 choices. The required component for this setup is the big I6 turbo. After purchasing or selecting the part, return to the lift, open the engine bay, and install it in the turbo mounting position.
| Performance Phase | Configuration | Observed Outcome |
|---|---|---|
| Baseline | Naturally aspirated | Low power and slower launch |
| Turbo selection | Big I6 turbocharger | Correct component for the M4 setup |
| Installation | Turbo fitted in the engine bay | Boost gauge becomes available |
| Follow-up test | Turbocharged configuration | Roughly 179–180 recorded during the shown run |
| Future tuning | No tuning used in the setup | Further adjustment may require later game features |
The turbocharger is the build’s clearest performance improvement. It changes the car’s power delivery and gives the M4 a stronger reason to repeat speed tests.
Do not judge the upgrade only by the launch. A poor start can distort the result, especially if the car is not aligned or the throttle is applied inconsistently. Use the same stretch of road, begin from a similar position, and compare the highest speed reached rather than relying only on the first few seconds.
Testing Method
A controlled test makes the turbo swap easier to evaluate. First, use the naturally aspirated car as a baseline. Then install the turbocharger, confirm that the boost gauge appears, and repeat the run. Keep the route, starting point, and driving approach as consistent as possible.
| Test Factor | Baseline Run | Upgrade Run |
|---|---|---|
| Aspiration | Naturally aspirated | Big I6 turbocharger |
| Starting point | Same marked stretch | Same marked stretch |
| Launch | Controlled throttle | Controlled throttle |
| Main measure | Top speed and power feel | Top speed, boost, and power feel |
| Result use | Establish comparison | Decide whether more tuning is needed |
This method separates the turbo’s effect from cosmetic changes or random driving differences. It also gives you a repeatable routine for future upgrades if additional tuning options become available.
Use one route and one starting position for every comparison. Consistent testing is more useful than a single fast-looking run.
Best Practices and Troubleshooting
The most reliable M4 builds follow a simple priority: restore, inspect, customize, upgrade, and test. Skipping inspection can leave the car at reduced condition, while rushing into a turbo swap can make it harder to identify whether a problem comes from the engine or the new performance part.
Use the following quick-reference table when the build does not behave as expected.
| Problem | Likely Check | Recommended Response |
|---|---|---|
| Condition remains below maximum | Missing component or unfinished repair | Review the clipboard and inspect the engine bay |
| Rusty wheel remains visible | Damaged rim was retained | Replace the wheel and refit the tire |
| Wheel gap looks excessive | Rim or tire fitment needs adjustment | Test the rim setting again before repainting |
| Car still feels slow | Naturally aspirated setup or incomplete turbo installation | Confirm the big I6 turbo is installed |
| Speed results vary widely | Different launch or route | Repeat the same controlled test |
A clean build also depends on separating visual decisions from mechanical ones. The sage-green and bronze combination is a style direction, not a requirement for performance. Likewise, a larger-looking wheel setup may improve the stance without automatically improving speed.
Do not chase speed numbers while the M4 still has a damaged engine part, rusty wheel, or missing turbocharger. Fix the build state first.
Q: What is the main upgrade in the Junk Mechanics m4 build?
The main upgrade is a big I6 turbocharger installed after restoring the engine. It changes the car from naturally aspirated to turbocharged and adds a boost gauge.
Q: Which paint colors are used for this M4 setup?
The body uses hex code 778F6D for a sage-green finish. The wheels use A9947F for a bronze or muted gold appearance.
Q: Why should the engine be repaired before installing the turbo?
Repairing the engine first creates a clearer baseline and helps reveal whether reduced condition comes from damaged components or a missing turbocharger.
Q: What speed does the turbocharged M4 reach?
The documented run reaches roughly 179–180. Treat that figure as a reference from one setup and test route rather than a guaranteed universal result.