- Mechanical HPA conversion for AEGs
- Easy installation - Everything included
- For Version 2 (M4 / AR-15 / AR-9) gearbox
If you're a realism enjoyer becoming HPA-curious, this will convert you! The Kythera SA Mechanical HPA Engine Conversion Kit from PolarStar Airsoft is a mechanical HPA conversion kit for M4/AR-15 and AR-9 AEGs, designed as a drop-in replacement for the cylinder group of the version 2 gearbox.
Being a mechanical system means you don't need a battery, don't need to avoid rain and get to enjoy the feel of a trigger system designed to simulate real steel single-stage triggers, complete with an authentic, tactile break and reset. This variant of the Kythera is locked to semi-automatic fire only, making it ideal for those who prefer a precise double-tap to a burst.
While you don't get the programmable trigger and electronic tuning options of the JACK™ or F2™ engines, the Kythera SA is ideal for milsim skirmishers looking for a leap in performance, DMR builders seeking the easy route to a reliable high FPS build or CQB specialists seeking a realistic yet incredibly snappy trigger. If you seek next-level performance and realism in equal measure, the PolarStar Kythera SA belongs in your build!
Fast Delivery
Delivery & Postage
Here at Patrol Base, we send all our packages from our Warehouse based in the UK with the exception of European Warehouse Items. All of our parcels are sent with specially picked couriers to ensure your parcels get to you on time and in one piece.
For more information please check out our Delivery Information Page.
Estimates
Below are some rough postage prices for orders. Please note these are subject to change and are only a rough guide. For a more accurate postage estimate please use the Postage Calculator at the basket.
UK 3-5 day Standard
£6.95
From
Dispatched with 24hr UK mainland
£8.95
From
Highlands / Islands
£24.99*
From
* Please note that Scottish Highlands, and Islands postage prices can vary wildly. Please refer to the Postage Calculator at the basket for the lowest possible price.
Returns
We want you to be absolutely happy with our products and services, so we provide the simple Patrol Base guarantee: if on receiving your item you are unhappy with your item for any reason then simply send it back to us. We will replace or refund the item.
You can return any item for any reason whatsoever, even if you have just changed your mind, within 14 days of receipt of the order. This is in addition to your rights under the Consumer Protection (Distance Selling) Regulations 2000.
For more information on returning products, and how to do it please visit our Returns Policy Page.
Description
If you're a realism-focused player looking for the next step in performance, the PolarStar Airsoft Kythera SA Mechanical HPA Engine Conversion Kit should raise an eyebrow! This semi-auto locked mechanical HPA engine is designed as a drop-in cylinder group replacement for M4/AR-15 and AR-9 version 2 gearboxes, offering the performance perks of HPA with a realistic trigger and no need for a battery.
The trigger of the Kythera is one of its highlight features; a fully adjustable trigger designed to simulate real firearm triggers, offering a tactile break and reset for unparalleled authenticity. The internal firing valve is also balanced, keeping this realistic trigger feel consistent, regardless of input PSI or velocity.
Designed to complete a full shot cycle as soon as the trigger is pulled, the Kythera provides the proven closed-bolt performance of the Fusion™ and F2™ engines in a full mechanical system with a realistic trigger feel other HPA engines simply can't provide. This also means you don't need to release the trigger to chamber the next BB and recharge firing air, resulting in a faster trigger response and less chance of double-feeding with strong magazine feed springs.
The mechanical valve system of the Kythera results in incredible consistency, providing the same amount of pressure on the valve at the exact same time over the firing cycle, regardless of trigger input. This is what makes this a great engine for DMR builds: speedy trigger response, superb consistency, minimal firing noise, and the ability to be adjusted to up to 500 FPS on 0.20g BBs!
Running from the back of the engine, we have what is known as the "universal charging cord", a robust steel cord designed to cock the spool valve if pressure drops below the operating range of the system. While the Kythera cocks the spool valve automatically when pressurised, the use of a balanced valve means the valve can stall and require manual cocking, usually when air runs out completely. The charging cord is designed to be routed through the pistol grip, but could also be attached to the charging handle through improvisation, if you're the techy type!
If you prefer well-placed shots over hosing the enemy team down with full auto, the Kythera SA is the HPA engine for you. Packing all of the HPA performance perks into a mechanical engine with no battery or wiring, and a super-realistic adjustable trigger, the Kythera SA HPA Engine from PolarStar Airsoft is the perfect middle ground between a realistic GBBR and an "easy mode" AEG build!
Features
- Mechanical HPA kit for AEGs - For Version 2 gearbox (M4/AR-15 & AR-9)
- Semi-auto only - Ideal for DMR or CQB builds
- Easy installation - Includes everything needed to install
- Replaces the cylinder group - Drop-in installation
- Waterproof - No need to stop shooting when the heavens open!
- No battery required - All you need to shoot is air
- Universal charging cord - Can be used to reset the valve when air is low
- Realistic trigger - Provides authentic break and reset, adjustable via set screws
- Operating range: 60-180 PSI
- Adjustable velocity - Adjust FPS by altering input PSI on your regulator, range: 270-500 FPS on 0.20g BBs
- For Version 2 gearbox (M4/AR-15 & AR-9 AEGs)
- HPA Bottle, airline & regulator required
Package Includes
- PolarStar Airsoft Kythera SA Mechanical HPA Engine Conversion Kit
- Filter fitting
Specification
General
Parts & Accessories Type | Electric Internal Parts |
|---|---|
Internal Part Type | Complete HPA Engine Conversion |
 | Custom Parts |
Construction
 | Black, Bronze, |
|---|---|
 | Aluminium, brass & steel |
Internal Part Construction | Steel, Aluminium, |
Part Specific
Part for Power Source Type | Electric |
|---|---|
Package Includes | Complete HPA Engine Conversion for V2 Gearbox |
Electric Part Specific
 | V2 Gearbox |
|---|---|
Gearbox Version Compatibility Variant | Version 2 |
Size guide
Parts Fitting
Upgrades and Downgrades should only be undertaken by experienced players, or Airsoft Technicians. Please note, changing any internal parts of a weapon voids its warranty unless done in-house by our staff.
Please ensure that when fitting parts the part purchased is the correct part, as once a part has been fitted we cannot accept return.
We do know that players love to tinker, so we're here to give you help should you require it, and if needed you can get in touch with our workshop for more help!
Unique Parts
Please note that some parts may be unique to a specific brand of weapon. For example: Parts for an ASG M4A1 may not fit an ICS M4A1.
Parts from the same brand typically have a high chance of fitting, though be warned, some replicas use unique parts, so please ensure the part will fit before you attempt to fit it.
If you require help with fitting any parts feel free to get in touch with us via our Contact Us Page.
For more information with fitting parts, or should you require help, feel free to get in touch with our Workshop Department via our Contact Us Page.
Terms and Conditions relating to parts fitting can be read on our Terms and Conditions Page.