SKU: 45111087037

Fusion Engine™ Drop-In Kit V2 Gen 3 M4/M16

Sale price$314.95 Regular price$349.95
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Description

Fusion Engine™ Drop-In Kit V2 Gen 3 M4/M16The Original HPA Rebel The Fusion Engine was released in 2011 and was the first new HPA system to hit the airsoft market in over two decades. This is the system that started the HPA revolution and has set the benchmark to which all other systems are measured. Although many have followed it, the Fusion Engine is considered by most to be the best. This system won "Best HPA Engine" the very first year Popular Airsoft added the HPA class to their Players'

 The Original HPA Rebel

The Fusion Engine™ was released in 2011 and was the first new HPA system to hit the airsoft market in over two decades. This is the system that started the HPA revolution and has set the benchmark to which all other systems are measured. Although many have followed it, the Fusion Engine™ is considered by most to be the best. This system won "Best HPA Engine" the very first year Popular Airsoft added the HPA class to their Players' Choice Awards.


This is a complete drop-in system which replaces the entire AEG gearbox with a full CNC machined lightweight aluminum chassis. It is the most adjustable system we produce with the widest range of adjustment in both velocity and rate of fire. Being a dual solenoid, closed bolt system so you are able to adjust the poppet valve (firing air) and nozzle (feeding) independently for full control over both the loading time and air volume used. PolarStar Filter Fitting included.


Being a true closed bolt system it is easier to achieve a high level of accuracy since it is not as critical of the hop-up configuration as an open bolt system. Additionally, it does have the best feeling trigger since the trigger micro-switch is custom fit to the frame so the trigger has a distinct break, hard stop and short reset.



 

Gel Ball Compatible 

Fusion Engine HPA conversion kits can also be configured for use in gel ball systems.

Please contact us for information on ordering Fusion Engine  systems for gel ball use.

 

 

 

 

Velocity: 550fps w/ .20g @ 120psi.
Like other HPA systems, the velocity of the Fusion Engine™ can be fine tuned by adjusting the input pressure. However, there are also 6 nozzles available each with a different level of restriction which allows you to shift the velocity adjustment range up or down in large increments. This allows the Fusion Engine™ to have the widest velocity adjustment range of any of our systems.
ROF: 30rps+
The maximum cyclic rate of the Fusion Engine™ is affected by several factors such as the operating pressure as well as the quality of the magazine and BB's used. However, 30 rounds per second is achievable in most standard configurations.
Air Efficiency: 400+ shots from 13/3000 @ 1.5J  w/ .28g
This system was primarily designed to deliver maximum power so air efficiency was not a critical part of its development. However, thanks to the modular design of its poppet valve, the system can be fine tuned using more restrictive valve stems and shims which allows air efficiency to more than double when operating at traditional field velocities.
(Test Configuration: Black Poppet / Blue Nozzle / 6.05x375mm Barrel)
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 45111087037

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4.1 ★★★★★
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Giovanna Surace
Belleville, US
★★★★★ 5
Perfect for College Students!
Color: Grey
I first bought this chair back in August of 2023. I used it nearly everyday for several hours. The chair just broke recently- the metal frame bent on the bottom of the chair (probably due to long term sitting and leaning to one side). This a great chair for college students looking for a more affordable but comfortable chair. The wheels move nice and smooth, the arm rests move up and down, and the back mesh of the chair is supportive, comfortable and breathable. To me, the seat of the chair is slightly bigger than a normal desk chair. It reclined decently far back and had a wide range of height adjustments. I just reordered this chair because I love it so much! I recommend this for anyone looking for a affordable, but comfortable desk chair!
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Reviewed in the United States on January 6, 2026
M
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me
Louisville, US
★★★★★ 5
as great as any 400 $ chair for so much less
Color: Black
This chair is wonderful. Easy to assemble, great home office size, not to overwhelming, very soft seating , great back support, adjustable in height and back. This chair meets all the expectation of a great chair.
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Reviewed in the United States on May 19, 2026
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Verified Purchase
Amazon Customer
Draper, US
★★★★★ 5
This is the chair! Stop looking! You found it!
Color: Grey
Seriously, it's just a great chair. It's comfy, it works, it's well made and it's a fantastic price. I picked this up after trying a "criss cross" style chair that simply was NOT working for everyday, all day home office work. This chair is great and I love that the arms can go up, which turns it into a great art chair as well! The back support is solid, although it's not cushioned at all so you may find putting a little lumbar pillow will help (it hasn't bothered me but over time the elasticity of the mesh has worn a bit) It was very easy to put together and I've been using it everyday, for 8-10 hours a day for several months now. For price you can't beat it. It's also wide enough of a seat I can sit cross crossed.
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Reviewed in the United States on June 26, 2025
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Valerie Gaston
Grantham, US
★★★★★ 3
Cheap and pretty comfortable, but poor adjustment functions.
Color: Black
Chair is pretty comfortable, wheels are solid and it holds height well. Biggest issue is the lean lock, even when engaged the chair does not hold an upright position, so if you're like me and prefer sitting relatively straight, this chair does not offer much support when doing so. Not bad for the price, but I would generally look elsewhere unless you don't care much for adjustment.
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Reviewed in the United States on February 11, 2026
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Malckiah
Bozeman, US
★★★★★ 4
Pretty nice. Good price for a good quality chair.
Color: Black
Nice overall. Decent back support, but not really much going on there. Very sturdy chair and is comfortable. The adjustments are just enough to make it good. I would buy it again. rolls great. Easy to put together. perfect adjustable height. It works for my son who is around 5', my wife who is 5' 3 and also me and I am 5' 10.
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Reviewed in the United States on July 22, 2025

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