HPA Conversion Guide: Turn Your AEG into a High-Performance Airsoft Rifle

Airsoft enthusiasts are constantly seeking ways to improve the performance of their rifles. One popular modification is converting an AEG (Automatic Electric Gun) to an HPA (High-Pressure Air) system. HPA systems offer several advantages over AEGs, including:

• Consistent Performance: HPA provides a consistent gas pressure, leading to more predictable and accurate shots.
• Adjustable FPS: Easily adjust the FPS (Feet Per Second) to comply with field regulations.
• Reduced Maintenance: HPA systems generally require less maintenance than AEGs, as there are fewer moving parts.
• Quieter Operation: HPA systems can be significantly quieter than AEGs, especially when using a suppressor.
• Instant Trigger Response: HPA systems offer nearly instant trigger response, eliminating the delay found in AEGs.

This comprehensive guide will walk you through the process of converting your AEG to an HPA system. It’s important to note that HPA conversion requires some technical skill and knowledge. If you are not comfortable working on your airsoft gun, it’s best to seek assistance from a qualified technician.

Disclaimer

Modifying your airsoft gun may void the warranty. Always follow local laws and regulations regarding airsoft guns. Eye protection is mandatory when working on or using airsoft guns.

What You’ll Need

Before you begin, gather the necessary components and tools:

• HPA Engine: This is the core of the HPA system. Popular brands include PolarStar, Redline Airsoft, Wolverine Airsoft, and Mancraft. Choose an engine compatible with your gearbox type (e.g., Version 2, Version 3).
• HPA Tank: A compressed air tank to store the high-pressure air. Common sizes are 48ci and 62ci.
• HPA Regulator: A regulator to reduce the high pressure from the tank to a usable pressure for the engine.
• HPA Line (Airline): A high-pressure hose to connect the tank and regulator to the engine.
• FCU (Fire Control Unit): (For some engines) An electronic control unit to manage the engine’s functions.
• Battery: (For FCU powered engines) A small battery to power the FCU.
• Airsoft Gun with Gearbox: The AEG you want to convert.
• Tools:
  • Screwdrivers (various sizes, including Phillips and flathead)
  • Allen wrenches (various sizes)
  • Pliers
  • Needle-nose pliers
  • Wire cutters
  • Wire stripper
  • Soldering iron and solder (if needed for wiring)
  • Multimeter (optional, for testing electrical connections)
  • Gearbox disassembly tools (if you don’t have them you can use small thin screw drivers)
  • Threadlocker (e.g., Loctite)
  • Teflon tape
  • Silicone grease

Step-by-Step Conversion Guide

Follow these steps to convert your AEG to an HPA system:

1. Disassemble the AEG

Start by disassembling your AEG. This process will vary depending on the specific model, but the general steps are as follows:

1. Remove the Magazine: Ensure the magazine is removed and the gun is unloaded.
2. Remove the Battery: Disconnect and remove the battery.
3. Separate the Upper and Lower Receivers: Typically, this involves removing body pins.
4. Remove the Inner Barrel and Hop-Up Unit: Carefully remove the inner barrel and hop-up unit from the upper receiver.
5. Remove the Motor: Access the motor grip and disconnect the motor wires. Then, remove the motor.
6. Remove the Gearbox: Carefully remove the gearbox from the lower receiver. This may involve removing additional pins or screws.

2. Open the Gearbox

This is the most delicate part of the process. Work in a clean and organized area to avoid losing any small parts.

1. Secure the Gearbox: Place the gearbox on a stable surface.
2. Remove the Screws: Carefully remove the screws holding the gearbox halves together.
3. Open the Gearbox Slowly: Open the gearbox slowly and carefully, as the internal components are under spring tension. It’s best to open it with the spring facing upwards to reduce risk of parts shooting out.
4. Remove the Internal Components: Remove all the internal components, including the gears, piston, spring, spring guide, cylinder, cylinder head, and tappet plate. Keep the tappet plate, selector plate and trigger, these may be required depending on the HPA unit you choose.

3. Install the HPA Engine

Follow the manufacturer’s instructions for installing the HPA engine into the gearbox. The general steps are as follows:

1. Prepare the Gearbox Shell: Some HPA engines require modifications to the gearbox shell, such as drilling holes for the airline. Refer to the engine’s instructions for specific requirements.
2. Install the Engine: Place the HPA engine into the gearbox shell. Ensure it is properly aligned and seated.
3. Secure the Engine: Secure the engine using the provided screws or hardware. Apply a small amount of threadlocker to the screws to prevent them from loosening.
4. Install the Nozzle: Some HPA engines require the installation of a specific nozzle. Install the nozzle according to the engine’s instructions. Usually it is already pre-installed.
5. Reassemble the Gearbox: Carefully reassemble the gearbox halves, ensuring all components are properly aligned.
6. Secure the Gearbox: Secure the gearbox halves with the screws.

4. Install the FCU (If Applicable)

Some HPA engines require an FCU to control their functions. Follow these steps to install the FCU:

1. Mount the FCU: Find a suitable location to mount the FCU inside the receiver. Some FCUs can be mounted inside the stock or grip.
2. Wire the FCU: Connect the FCU to the engine and the trigger according to the manufacturer’s wiring diagram. Use wire strippers and wire cutters to ensure clean connections. Solder the connections if necessary, and use heat shrink tubing to insulate the wires.
3. Connect the Battery: Connect the battery to the FCU.

5. Connect the HPA System

Connect the HPA tank, regulator, and airline to the engine:

1. Attach the Regulator to the Tank: Screw the HPA regulator onto the HPA tank. Use Teflon tape on the threads to ensure a tight seal.
2. Connect the Airline to the Regulator: Connect one end of the HPA airline to the regulator.
3. Connect the Airline to the Engine: Connect the other end of the HPA airline to the engine.

6. Reassemble the Airsoft Gun

Reassemble the airsoft gun in the reverse order of disassembly:

1. Install the Gearbox: Carefully install the gearbox into the lower receiver.
2. Install the Motor: Connect the motor wires and install the motor into the motor grip.
3. Install the Inner Barrel and Hop-Up Unit: Carefully install the inner barrel and hop-up unit into the upper receiver.
4. Attach the Upper and Lower Receivers: Align the upper and lower receivers and secure them with the body pins.
5. Install the Battery: Connect and install the battery (if applicable).
6. Install the Magazine: Insert the magazine.

7. Test and Tune the HPA System

Now it’s time to test and tune your HPA system:

1. Set the Regulator Pressure: Start with a low regulator pressure setting (e.g., 60 PSI).
2. Test Fire the Gun: Test fire the gun to check the FPS. Use a chronograph to measure the FPS accurately.
3. Adjust the Regulator Pressure: Adjust the regulator pressure to achieve the desired FPS. Be careful not to exceed the field limits.
4. Fine-Tune the Settings: Some HPA engines have adjustable settings for rate of fire, burst mode, and other parameters. Fine-tune these settings to your preferences using the FCU (if applicable).
5. Check for Leaks: Check for any air leaks in the system. Use a mixture of soap and water to identify leaks. Tighten the connections or replace the Teflon tape if necessary.

Troubleshooting

If you encounter any problems during the conversion process, here are some common troubleshooting tips:

• Air Leaks: Check all connections for leaks. Use Teflon tape or replace the O-rings if necessary.
• Low FPS: Increase the regulator pressure or check for air leaks.
• Inconsistent FPS: Ensure the regulator is providing a consistent pressure. Check the engine’s settings and the condition of the nozzle.
• Engine Not Firing: Check the battery, wiring connections, and FCU settings. Refer to the engine’s manual for troubleshooting steps.

Maintenance

To keep your HPA system running smoothly, perform regular maintenance:

• Lubricate the Engine: Lubricate the engine’s moving parts with silicone grease. Refer to the engine’s manual for specific lubrication instructions.
• Inspect the Airline: Inspect the HPA airline for cracks or damage. Replace the airline if necessary.
• Check the Regulator: Check the regulator for leaks or damage. Have the regulator serviced by a qualified technician if necessary.
• Clean the Inner Barrel: Clean the inner barrel regularly to remove dirt and debris.

Choosing the Right HPA Engine

Selecting the right HPA engine is crucial for a successful conversion. Here’s a comparison of some popular HPA engine brands:

• PolarStar: Known for their reliable and versatile engines. Popular models include the Fusion Engine and F2.
• Redline Airsoft: Offers simple and efficient engines with a focus on reliability.
• Wolverine Airsoft: Provides innovative engines with advanced features, such as the Inferno and Reaper.
• Mancraft: Specializes in mechanical HPA systems that don’t require a battery.

Consider your budget, performance requirements, and technical skills when choosing an HPA engine. Read reviews and compare specifications to find the best engine for your needs.

Tips for a Successful Conversion

Here are some additional tips to ensure a successful HPA conversion:

• Read the Manual: Carefully read the manuals for the HPA engine, regulator, and FCU.
• Watch Tutorials: Watch online tutorials and videos to learn more about the conversion process.
• Take Pictures: Take pictures of each step of the disassembly process to help you remember how to reassemble the gun.
• Work in a Clean Area: Work in a clean and organized area to avoid losing any small parts.
• Be Patient: HPA conversion can be a time-consuming process. Be patient and take your time to ensure that everything is done correctly.
• Ask for Help: If you are unsure about any step of the process, don’t hesitate to ask for help from a qualified technician or experienced airsoft player.

Legal Considerations

Before converting your AEG to HPA, it’s important to consider the legal implications:

• Local Laws: Check your local laws and regulations regarding airsoft guns. Some jurisdictions have restrictions on FPS limits or the modification of airsoft guns.
• Field Regulations: Ensure that your HPA system complies with the field regulations at the airsoft fields where you play. Most fields have FPS limits and restrictions on certain types of airsoft guns.
• Insurance: Check your insurance policy to see if it covers any damages or injuries caused by your airsoft gun.

Conclusion

Converting an AEG to an HPA system can significantly improve the performance of your airsoft gun. By following the steps outlined in this guide and taking the necessary precautions, you can successfully convert your AEG to HPA and enjoy the benefits of consistent performance, adjustable FPS, and reduced maintenance. Remember to always prioritize safety and follow local laws and regulations.