In the world of turbocharged engines and high-performance vehicles, controlling boost is crucial for optimizing power delivery and engine performance. One essential component that plays a significant role in regulating boost pressure is the wastegate. Whether you’re a seasoned enthusiast or a beginner in the automotive world, understanding the dos and don’ts of fitting external wastegates is essential. In this guide, we will explore the key aspects of external wastegates, their benefits, installation considerations, and address common questions.
- What Are External Wastegates?
- Dos for Fitting External Wastegates:
- Don’ts for Fitting External Wastegates:
- Wastegate Sizing Chart:
- Step-by-step fitting instruction for installing an external wastegate:
- Frequently Asked Questions (FAQ):
What Are External Wastegates?
External wastegates are specialized components designed to regulate and control the amount of exhaust gas that bypasses the turbine of a turbocharger, thereby regulating boost pressure. Unlike internal wastegates, which are integrated into the turbocharger housing, external wastegates are separate units that offer several advantages:
- Enhanced control: External wastegates provide precise control over boost pressure, resulting in improved power and torque delivery.
- Greater flow capacity: These wastegates can handle larger volumes of exhaust gases, making them suitable for high-performance applications.
- Flexibility: External wastegates allow for easy adjustment and fine-tuning of boost levels.
- Compatibility: They can be used with turbochargers that lack internal wastegates or have small internal wastegates prone to boost creep.
Dos for Fitting External Wastegates:
- Select the Right Size: Choose an external wastegate size that matches your engine’s power output and turbocharger specifications. Larger turbochargers may require larger wastegates to handle the increased exhaust flow.
- Proper Mounting Location: Install the external wastegate as close to the turbocharger inlet as possible. This minimizes exhaust gas turbulence and promotes better control over boost pressure.
- Plan for Heat Management: Consider the heat generated by the exhaust gases when positioning the wastegate. Ensure that it is adequately shielded or heat-wrapped to prevent heat-related issues.
- Plumbing Back the Exhaust Gas: When venting the wastegate, plumbing the exhaust gases back into the downpipe, away from sharp bends or elbows, ensures optimal flow and minimal interference with the exhaust stream.
- Use Quality Materials: Opt for high-quality stainless steel piping (such as 304 stainless) for constructing the wastegate dump tube and related components. This ensures durability and longevity in high-heat environments.
Don’ts for Fitting External Wastegates:
- Avoid Excessive Noise: While venting to atmosphere (screamer pipes) is an option, it can lead to loud exhaust noise that may not be street-legal or neighbour-friendly or be above track decibel limits. Consider the impact on your local regulations and community. Although for me personally, i like to see a cone of screaming fire out of my bonnet…
- Improper Sizing: Don’t undersize or oversize your external wastegate. An undersized wastegate may not adequately control boost, while an oversized one may result in poor turbo response.
- Neglecting Thermal Expansion: If you choose to vent the wastegate gases back into the exhaust system, ensure that you incorporate slip joints to accommodate thermal expansion and contraction.
- Incorrect Plumbing: Avoid sharp bends or angles in the wastegate dump tube, as they can disrupt exhaust flow and affect performance.
- Neglecting Tuning: Fitting an external wastegate may require adjustments to your engine management system or boost controller. Ensure that you tune your setup appropriately to achieve the desired boost levels.
Wastegate Sizing Chart:
|Turbocharger Size (Compressor Wheel Diameter)
|Recommended External Wastegate Size
|Ideal Boost Pressure Range (psi)
|40mm – 50mm
|38mm – 44mm
|5 – 20
|50mm – 60mm
|44mm – 50mm
|10 – 30
|60mm – 70mm
|50mm – 60mm
|15 – 40
|70mm – 80mm
|60mm – 66mm
|20 – 50
|80mm and above
|66mm and above
|25 – 60+
Step-by-step fitting instruction for installing an external wastegate:
- External wastegate
- Wastegate gaskets
- Bolts and nuts
- Wrenches and sockets
- Vacuum hoses (if applicable)
- Boost controller (if applicable)
- Welding equipment
Step 1: Safety Precautions Before you start, ensure that the engine is cool and that the vehicle is securely supported on jack stands or a lift. Always follow safety guidelines when working on a vehicle.
Step 2: Locate a Suitable Mounting Location Determine the optimal location to mount the external wastegate on the exhaust manifold and downpipe. Ensure that it’s easily accessible and will allow proper operation.
Step 3: Remove the Old Wastegate (if applicable) If your vehicle already has a wastegate, remove it carefully. This may involve loosening and removing bolts and disconnecting any associated vacuum lines or welding the penny valve in your stock internal wastegated turbo.
Step 4: Install the Wastegate Flange Attach the wastegate flange to the chosen mounting location on the manifold, this involves cutting the appropriate diameter hole and welding in the flange. Ensure a secure fit without any exhaust leaks. You may be better off purchasing an exhaust manifold with wastegate flange already attached for optimum flow.
Step 5: Position the Wastegate Valve Place the wastegate valve onto the wastegate flange, compressing the valve spring and tightening the V Band. Ensure to align it with the exhaust gases’ path before tightening v band..
Step 6: Secure the Wastegate Valve If provided with bolts and nuts to secure the wastegate valve to the wastegate flange. Make sure it’s firmly attached but not overtightened to allow for proper movement.
Step 7: Connect Vacuum Lines Your external wastegate will have a vacuum port, connect the appropriate vacuum hoses to the wastegate and the boost controller (if used). Secure them with clamps to prevent leaks. you should have two ports on the external wastegate, one is used if using open loop control, the both if closed loop control.
Step 8: Adjust the Spring Tension If your wastegate has an adjustable spring, set the desired boost pressure by adjusting the spring tension. Refer to the manufacturer’s instructions for the correct procedure.
Step 9: Welding (if needed) In some cases, you may need to weld the wastegate flange onto the exhaust manifold and downpipe. If welding is required, make sure it’s done by a qualified professional to prevent any damage or leaks.
Step 10: Test and Adjust Start the engine and check for any exhaust leaks around the wastegate. Adjust the wastegate settings as needed to achieve your desired boost pressure. Be cautious when making adjustments and monitor your engine’s performance.
Step 11: Final Check After making adjustments, turn off the engine and recheck for any leaks or loose connections. Ensure that everything is secure and functioning correctly.
Step 12: Reassemble Reassemble any components that were removed during the installation, such as heat shields or body panels.
Step 13: Test Drive Take your vehicle for a test drive to ensure that the external wastegate is working as intended and that you are achieving your desired boost levels.
Always refer to the specific instructions provided by the manufacturer of your external wastegate for any unique installation requirements or recommendations. If you’re not confident in your ability to install the wastegate, consider seeking assistance from a professional mechanic or tuner.
Frequently Asked Questions (FAQ):
Q1: Why would I want an external wastegate?
A1: External wastegates offer superior control over boost pressure, increased flow capacity, and flexibility for optimizing engine performance. They are especially beneficial for high-performance applications.
Q2: Is it necessary to vent the wastegate to atmosphere?
A2: While venting to atmosphere is an option, it can result in excessive noise. Plumbing the wastegate gases back into the exhaust system is a quieter alternative, provided it is done correctly.
Q3: What size external wastegate should I choose for my turbocharger?
A3: The size of the external wastegate should match your engine’s power output and turbocharger specifications. Consult with a knowledgeable tuner or reference manufacturer recommendations for guidance.
Fitting an external wastegate is a valuable upgrade for optimizing turbocharged engine performance. By adhering to the dos and don’ts outlined in this guide, you can ensure a successful installation that enhances control over boost pressure and delivers improved power and torque. Whether you’re pursuing street performance or track excellence, a properly fitted external wastegate can be a game-changer for your vehicle’s performance.
- Driftworks Forum – “Dos and Don’ts for Fitting External Wastegates”: URL: https://www.driftworks.com/forum/threads/dos-and-donts-for-fitting-external-wastegates.120897/
- Turbocharger Pros – “Guide to External Wastegate Installation”: URL: https://www.turbochargerpros.com/blog/guide-to-external-wastegate-installation
- BoostCruising – “Installing an External Wastegate: A Step-by-Step Guide”: URL: https://www.boostcruising.com/forums/index.php?showtopic=87387