HPA 101: Which HPA Engine is Best for You

The PolarStar Jack has been gaining popularity with airsoft players that don’t want to break the bank on a higher efficiency more tunable setup. The Jack is a single solenoid drop-in unit that comes complete with a tunable FCU (Fire Control Unit) that allows for precise tuning of dwell, rate of fire, selector positions, and more!

Compatible with: V2, V3, M249, ARES EFCS / APS eSE (Amoeba), VFC 417, Ares M4, and more!

Pros: Budget friendly, easy installation, and compatible with many AEG gearboxes and maintains external gearbox functions. To add, it has a great manufacturer warranty.

Cons: Less tunability than dual solenoid systems and requires proper nozzle alignment to function correctly. Dependent on the gearbox shell being used for correct alignment. If you run into issues, professional installation may be needed.

Best for: New HPA users or those looking for a less expensive alternative. Great for those looking to maintain all aesthetics of rifle such as functional bolt catch, bolt cover, ambi-selector, and other gearbox specific external functions.

Looking for a full kit to get started? Check out our PolarStar Jack Player Kits

Similarly, the Wolverine Inferno is a basic, single-solenoid, electric-pneumatic engine that's easy to install and easy on your wallet. The simple design of this engine makes it less difficult to diagnose and fix any issues that may arise. The Inferno comes in two editions: Spartan, which has limited settings and is trigger tuned and Premium, which has a dedicated FCU (Fire Control Unit) that allows for more precise tuning of dwell, rate of fire (ROF), and burst settings.

Compatible with: V2, V3, M249 Gearboxes

Pros: Budget friendly, easy to install and to tech on. Compatible with many AEG gearboxes and maintains external gearbox functions. Great manufacturer warranty.

Cons: Less tunability than dual solenoid systems. Requires proper nozzle alignment to function correctly. Dependent on the gearbox shell being used for correct alignment. If you run into issues, professional installation may be needed.

Best for: New HPA users or those looking for a less expensive option. Great for those looking to maintain all aesthetics of rifle such as functional bolt catch, bolt cover, ambi-selector, and other gearbox specific external functions.

Looking for a full kit to get started? Check out our Wolverine Inferno V2 Player Kit (Spartan Edition) or Wolverine Inferno V2 Player Kit (Premium Edition)

The Redline N7 Electric is another entry-level, single solenoid, and easy to install HPA engine with limited tuning requirements. It gives you a more consistent velocity and accuracy when shooting because of its closed bolt design and air-balanced nozzle return and available in both V2/M4 and V3/AK versions.

Compatible with: V2 and V3 Gearboxes

Pros: Budget Friendly, Easy to install and to tech on. Compatible with many AEG gearboxes. Great manufacturer warranty. Maintains external gearbox functions.

Cons: Less tunability than dual solenoid systems and requires proper nozzle alignment to function correctly. Dependent on the gearbox shell being used for correct alignment. If you run into issues, professional installation may be needed.

Best for: New HPA users or those looking for less expensive option. Great for those looking to maintain all aesthetics of rifle such as functional bolt catch, bolt cover, ambi-selector, and other gearbox specific external functions.

Looking for a full kit to get started? Check out our Redline N7 Electric Edition V2 Player Kit or Redline N7 Electric Edition V3 Player Kit

One of the quietest engines on the market is the Wolverine Reaper. This single solenoid, closed bolt design comes in various configurations allowing you to utilize it with most airsoft guns. The Reaper airsaver feature can be tuned without the use of different nozzles or cages with a simple spring change. Known for being quiet, this engine is widely used by airsofters that want a quiet and efficient engine. The Wolverine Reaper comes in various types. The Electro Mechanic version uses a simple switch to fire, and has a very bare bones approach. The Spartan Edition uses a trigger board that is programmed by trigger pulls. The Premium Edition uses a fire control unit (FCU) that offers more tunability than the others.

Compatible with: V2 and V3 Gearboxes

Pros: Budget friendly and very efficient. Includes tunable airsaver feature and maintains gearbox external functions.

Cons: Less tunability than dual solenoid systems and also picky with nozzle alignment.

Best for: Players who want a super quiet HPA engine with high efficiency. Great for those looking to maintain all aesthetics of rifle such as functional bolt catch, bolt cover, ambi-selector, and other gearbox specific external functions.

Looking for a full kit to get started? Check out any of the following player kits we offer:

Wolverine Reaper Gen2 Player Package (Electro Mechanic Semi-ONLY)
Wolverine Reaper Gen2 Player Package (Spartan Edition)
Wolverine Reaper Gen2 Player Package (Premium Edition)

The PolarStar F1 is a different take on the traditional HPA drop-in cylinder replacement offered in the industry. The F1 utilizes a dual purpose flow control system, which regulates nozzle speed to help promote smoother chambering and better shot consistency. The PolarStar F1 is only comprised of 5 parts and has tool less disassembly. The F1 requires a slightly higher finesse during install to make sure that nozzle alignment is just right for optimal performance.

Compatible with: V2, V3, M249, ARES EFCS / APS eSE (Amoeba), VFC 417, Ares M4, and more!

Pros: Budget friendly, efficient and maintains gearbox external functions.

Cons: Less tunability vs it's dual solenoid sister, the F2. Its also picky with nozzle alignment.

Best for: Players on a budget that want higher accuracy and efficiency than a Jack, but the F2 is out of their price range.

Looking for a full kit to get started? Check out the PolarStar F1 V2 Player Kit

The PolarStar Kythera is one of the newest and more popular Mechanical Pneumatic HPA engines. It does not require an FCU or battery (which means you don't need to worry about getting caught in the rain at your 40-hour Milsim events). While the Kythera only allows semi-auto firing, its ease of use is unmatched. The Kythera contains very few parts and requires little-to-no tuning, but because of its complex design it should be installed by an airsoft technician to avoid any issues.

Compatible with: V2, V2.5 (SR-25) and V3 Gearboxes

Pros: Budget friendly, realistic trigger pull, wide velocity range, very efficient and easy to use. It does not require a battery or FCU making it weatherproof. Additionally it has a great manufacturer warranty.

Cons: Semi-locked, and less tunability. Difficult to install and my require additional gearbox modifications for fit.

Best for: Players who want the most realistic trigger feel and who want a mechanical system.

Looking for a full kit to get started? Check out our PolarStar Kythera Player Kit

Redline N7 Milsim Engine uses a Mechanical Pneumatic System and similar to the Kythera, the N7 Milsim edition does not operate using an FCU or battery making it waterproof. The Pneumatic button valve system; when fired, the trigger mechanically opens and then seals the air valve, providing excellent consistency from shot to shot. The Redline N7 Milsim Edition comes in V2/M4 and V3/AK options.

Compatible with: V2 and V3 Gearboxes

Pros: Budget friendly, consistent shooting. Does not require an FCU or battery making it weatherproof, Its the god father of mechanical systems and includes a great manufacturer warranty.

Cons: Less tuning control, and is difficult to install. Looses ambi-selector controls and is semi-locked.

Best for: Players who want a budget friendly mechanical system,. Great for airsoft DMR / sniper builds

Looking for a full kit to get started? Check out our Redline N7 Milsim Edition V2 Player Kit or Redline N7 Milsim Edition V3 Player Kit

One of the most popular HPA engines at Amped Airsoft, The PolarStar Fusion Engine may be one of the more expensive HPA engines, but it's also one of the highest-performing, most reliable, and most efficient units (once upgrades are added). This dual solenoid engine replaces your existing V2 gearbox, but should still be installed by an airsoft technician for optimal performance. Due to replacing the entire gearbox, it's tolerances offer the best performance when it comes to HPA standards.

The Fusion Engine is best suited for experienced HPA users who want to have the option to fine-tune their settings and get the most performance they can get out of an HPA system. The Fusion Engine comes with a unique nozzle system that allows you to change to a variety of different size restricted nozzles. These nozzles allow you to operate in an fps range below 300 fps all the way over 550 fps by simply swapping out your nozzle and adjusting your psi to optimal levels. Nozzle colors range in restriction levels from: Green (The most restrictive), Gold, Blue, Black, Silver, Red, and Purple (The least restrictive). Just to note, barrel lengths greatly affect your overall FPS / Joule ratings. The longer the barrel, the higher the ratings. The Shorter, the lower the ratings. Length has a drastic affect.

Preferred by Speedsofters and Milsim players alike for its sensitive trigger response and extreme air efficiency.

Compatible with: V2, M249, M240, M60 / MK43 Style Gearboxes

Pros: High performance, consistent shots, sensitive trigger response, and air efficient (once upgraded). It allows complete tuning control and 30+ RPS. This unit is built for power and reliability. Most after market upgrades are available and even gel blaster convertible. Great manufacturer warranty included.

Cons: Cost - it has a high price point. Only works with V2, M249, M240, M60 / MK43 style airsoft guns. May be difficult to tune for inexperienced users. May also loose ambi-selector and other body functions such as bolt catch and mock bolt depending on replica it's installed into.

Best for: HPA users that want the option to fine-tune settings and get the best performance. Compatible with all playstyles.

Looking for a full kit to get started? Check out our PolarStar Fusion Engine V2 Player Kit or PolarStar Fusion Engine M249 Player Kit

Recommended efficiency upgrades:

1x Amped Airsoft Custom Fusion Engine Plus Nozzle

1x Amped Airsoft Custom Low Flow Pre-Shimmed Poppet (Purple)

1x Lightning Banjo by S2 Airsoft Designs

2x PolarStar Light Poppet Spring 

The PolarStar F2 was the winner of the “Best HPA Engine” in the 9th Airsoft Players Choice Awards... with good reason. The F2 is the only existing cylinder-style engine with two solenoids. PolarStar compares the F2 to a more compact and budget-friendly Fusion Engine—and its PSI output range makes this engine compatible with most airsoft guns and works for both CQB and outdoor playstyles.

PolarStar also provides an F2 option for offset nozzles.

Compatible with: V2, V3, M249, ARES EFCS / APS eSE (Amoeba), VFC 417, Ares M4, and more!

Pros: Easy installation, compatibility, and complete tuning control. Sensitive trigger response and it a highly efficient unit out of box with further efficiency upgrades available. Maintains gearbox external funtions.Great manufacturer warranty included.

Cons: Cost - has a high price point. May be difficult to tune for inexperienced users.

Best for: Players who want the best performance that fits into any gun and compatible with all play styles. Great for those looking to maintain all aesthetics of rifle such as functional bolt catch, bolt cover, ambi-selector, and other gearbox specific external functions.

Looking for a full kit to get started? Check out our PolarStar F2 Player Kits
Looking for the Offset Nozzles? Check out our Offset Nozzle F2 Units

Recommended efficiency upgrades:

1x PolarStar Light Poppet Spring

1x PolarStar Gold Low Flow Poppet for F2

The Wolverine Hydra is similar to the Inferno but with an offset nozzle. This unit is another high-performance, reliable HPA engine from Wolverine! Similar to the Wolverine Inferno, but with an offset nozzle so you can finally HPA that SVD or P90.

Compatible with: Ares Tavor, G&G M14, G&G F2000, TM P90, PDR, Real Sword SVD, Thompson, TM M14, Type 97

Pros: Budget friendly and easy to maintain. Great manufacturer warranty included.

Cons: Less tunability than dual solenoid systems. Slightly more involved installation due to additional fitment of trigger board / universal wiring kit

Best for: Players who have an airsoft gun that uses an offset nozzle such as a p90, SVD, etc.

The Wolverine BOLT is an HPA conversion kit for players that want to HPA their Bolt Action airsoft sniper rifles. The Wolverine Bolt provides impressive consistency and quiet shooting, while saving up to 50% of your air per shot using Wolverine's Airsaver technology. This electro pneumatic conversion kit does not require an FCU, and only requires a small battery. however, Wolverine also offers the BOLT M version, which is fully mechanical and does not require either. Both versions offer a smooth, spring free action that make it easy to stealthily keep sights on target, improving speed and accuracy of follow-up shots!

Compatible with: JG Bar10, Amoeba Striker, Silverback SRS, Tokyo Marui VSR-10, and more

Pros: Stealthy and quiet, while being highly efficient. Easy to install and available in multiple versions.

Cons: May not be available for your specific rifle. May require special fitment

Best for: Players who want to HPA their airsoft sniper and who want a wider FPS / Joule range

Although these are not HPA engines, we feel they are worth mentioning. In order to HPA your GBB (gas blowback) airsoft guns, you can tap your mags or run an adapter.

Previously Tapping a magazine required you to drill a hole into an existing GBB magazine, rethread the hole, and install an HPA tap. However, we make it easy by offering premade HPA valves that screw into existing GBB pistol magazines.

Our hpa valve tap allows you to connect your air tank and regulator to your magazine using a one of our Amped Lines. This is by far the least expensive route, as long as you are using one of our pre-existing valves and the threading matches. Popular valve tap brands are for WE / KJW, KWA, JAG Scatter Gun, and Tokyo Marui (TM). We offer a wide variety of taps from our own brand, TAPP Airsoft, and CQB Russian Taps.

Simply pick up a matching tap, unscrew your existing valve and add the new one. Then your magazine is able to accept your choice of line and regulator setup.

Each of these HPA engines has something special to offer and choosing one depends on your airsoft needs and your budget.

The choice of which HPA engine is best for you depends on your preferences, playstyle, budget and compatibility. If you're new to airsoft or HPA, stick with a unit that's easier to use, budget friendly, or does not require additional tuning.

There are many more different HPA engines on the market today. Each one of them has its benefits and drawbacks. It is important to understand which HPA engine will work best for your needs.

Shop our entire collection of HPA Engines and accessories here and feel free to reach out to us if you have further questions