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PolarStar F2 M4 Conversion Kit | V2 HPA Unit | HPA Drop in Kit Reviews

4.9 Rating 20 Reviews
Read Amped Airsoft Reviews


This specific F2 is designed with the M4/M16 and typical Version 2 Gearboxes in mind.    
What is F2?
F2 is essentially a Mini Fusion Engine. It offers the same adjust-ability and performance as the Fusion Engine in a cylinder sized package.
Patented Dual Solenoid Design
The dual solenoid design of the F2™ provides the same functionality as the legendary Fusion Engine™ but in a more compact, efficient and flexible design. Dual solenoids allow for the nozzle and the poppet valve to be adjusted independently of each other for unparalleled control over both the loading time and air volume used. Additionally, this makes it possible to change the firing sequence giving it the ability to operate in both true closed bolt as well as "AEG" mode.
Increased Efficiency
The F2™ incorporates a new one-piece, lightweight poppet valve design yet still operates on the same principle as the Fusion Engine™ poppet. This valve is able to operate at lower pressures and uses less air volume to function which optimizes air efficiency.
The standard F2 poppet is equivilent to the Red Low-Flow poppet of the Fusion Engine.
The robust design of the F2™ allows for an operating pressure range of 45psi to 145psi which enables it to achieve velocities from CQB to DMR while employing only one nozzle for the entire velocity adjustment range. 
Spring Loaded NozzleThe F2™ nozzle is spring biased forward which provides a consistent loading force regardless of operating pressure. It shares the same spring as the Fusion Engine™ with both light and heavy spring options available to adjust the loading force. 
Complete Tuning Control
The F2™ comes complete with a Fire Control Unit (FCU) that has an LCD display that allows you to tune your F2 to your liking! Adjust it's dwell, rate of fire, burst modes, nozzle feeding, and more!
Specifications
Velocity Range: 250fps - 500fps
Operating Presure: 45-145 PSI
Compatibility: ALL AEG
Offset and Centerline cylinders and nozzles.
Wire harnesses are available in 7.5", 13" and 18" standard lengths
Interchangeable Bushing Inserts which prevent any movement of F2 within the gearbox.
Custom nozzle lengths available.
Low velocity poppets (< 1J) available.
Light and Heavy nozzle springs available.
What is the difference between F2, F1 and JACK?
Both F1 and JACK are "open bolt" systems, meaning the nozzle is in the rearward position when the system is idle and the round is fired during the forward movement of the nozzle. F2 is a dual-solenoid system which allows for complete control over the shot cycle.
What is the warranty for F2?
F2 systems are covered by a 1 year warranty against defects in material or manufacturing.
Compatability and Nozzles
Over 20 standard F2 nozzles are available for installation into a wide range of replicas. These are numbered, rather than named, since a single nozzle is often compatible with multiple replicas. The "Original Model" listed in the table is the replica from which the nozzle measurements were taken and is for reference.
If your gun is not listed in our Compatiblity Database a recommended nozzle length may calculated by measuring your original gearbox and applying the following formula: TIP = F + B - (A/2) - .057. A more precise measurement (which accounts for the hopup and bucking in use) may be obtained by installing a nozzle into the system which is slightly too long for the replica and measuring the nozzle setback when placed into the hopup.
If you do not see a Standard Nozzle listed within +/- .010" of the calculated measurement please contact us with your gearbox measurements and we can have PolarStar cut a custom nozzle for you.
Number - Original Model
1 - M4, VFC
2 - MP5-A4 TFB, ECHO 1 (CYMA)
3 - M249, CLASSIC ARMY
4 - SR-25, G&G
5 - SR-25, A&K
6 - M240B, ECHO 1
7 - MASADA, PTS
8 - SCAR-H, VFC
9 - TAVOR COMPETITION, EF (S&T)
10 - ARX160 ELITE, EF
11 - KAC LMG, CLASSIC ARMY
12 - AK, LCT
13 - MASADA, A&K
14 - Mk43 (M60), A&K
15 - G36KV, EF (ARES)
16 - G36C, EF (S&T)
17 - AUG, CLASSIC ARMY
18 - MP5, G&G, BLOWBACK
20 - G36K, CLASSIC ARMY
O-1 - M14, G&G
O-2 - P90, CLASSIC ARMY

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Iv used many different HPA engines such as the jack, FE, wolverine inferno and reaper, and i have to say i like the F2 the best. Iv installed every single engine i listed above into my krytac m4 myself and they all fit in very snug, except for the FE which had slight alignment issues and selector plate issues. Getting back to the f2, its the most air efficient, consistent, and tunable engine iv owned. it gets about 4100 shots with a 48/3000 tank at 80 psi. it consistently hits targets at 200+ feet, and is able to shoot 290fps-580fps with a .20bb (455mm 6.03 prometheus purple, maxx hopup). Overall best HPA engine iv ever used, just make sure not to switch the poppet and nozzle solenoid wires when plugging them into the trigger board :)
Helpful Report
Posted 2 years ago
Amped shipped the engine very carefully and in a matter of days I received the item, with the included items it specified. I Installed this into my custom VFC VR-16 stinger build and its been preforming absolutely flawlessly, however I did have some issues trying to adjust the FPS as my regulator and the FCU settings were taking a while to adjust. Other than that this product is one of the best engines I have used, way better than my old F1 from polarstar!
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Posted 3 years ago
The price of admission into the hpa world can be daunting, but worth it. Installed into a krytac spr, install had its challenges, but there are plenty of videos on how to modify the shell. The F2 is awesome though.
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Posted 4 years ago
Great products I was searching online I found this website very helpful on getting me what I wanted communication with the store awesome I’ve bought several products very happy. PS 1 complaint UPS need to step up there delivery service. Recommendation give an option for delivery services DLH, fed ex. Much better delivery services.
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Posted 5 years ago
Quality + Custimer
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Posted 5 years ago
Awesome product! Dropped it in my VFC Avalon, and it shoots lasers.
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Posted 6 years ago
Thanks for a great effort to tract my items. Im now enjoying my polarstar F2. Thank u guys
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Posted 6 years ago
Good engine, required more work than expected to fit krytac m4
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Posted 6 years ago