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Extreme Booster Pump Review – Part Two, Test Results

In this second part of HAM’s Extreme Booster Pump Review, we look at specific results that we obtained during our testing. (For the Overview part of this review, click here).

As a reminder, the basic physics behind the Extreme Booster Pump is simple. It uses (relatively) low pressure air to inject a dose of higher pressure air into your airgun. The result is that you can fill a PCP airgun to a higher pressure than the air in your tank!

This capability is HUGELY important for big bore air rifles as they use large amounts of very high pressure air for every shot. But it can also benefit smaller-caliber airguns – particularly if they have a high maximum fill pressure – as we can see from our test results below.

For these HAM tests we used five different air rifles and two different tanks. In every case in this Extreme Booster Pump review, it worked as advertised! Each test showed an increase in pressure in the air rifle that was greater than the air pressure in the tank.

Note that there’s no “standard” pressure increase per actuation, however. This is due to the wide variety of pressures in gun and tank, together with the variety of possible tank and gun fill capacities. Here’s what we found…


Filling To 4,000 PSI With The Booster Pump.

First we filled two air rifles to 4,000 PSI using the Booster Pump. We obviously could have filled the Gauntlet 2 to its maximum of 4,500 PSI, but we wanted to see a comparison to the much smaller, 4,000 PSI max pressure tube of the American Air Arms EVOL Mini.

In each case, we filled the gun from the same large, 550 Cubic Inch capacity HPA tank.

Air RifleGun Start
Pressure
Gun End
Pressure
Increase in
Gun
Pressure
Number of
Actuations
Tank Start
Pressure
Tank End
Pressure
Gauntlet 23,200 PSI4,000 PSI+ 800 PSI43,200 PSI3,100 PSI
EVOL Mini1,500 PSI4,000 PSI+ 1,500 PSI72,700 PSI2,500 PSI

The Gauntlet 2 has a 24 Cubic Inch bottle, whereas the EVOL Mini has a much smaller capacity HPA tube of 8.3 Cubic Inches. But, we were filling the EVOL Mini from a much lower gun start pressure and a lower tank pressure.

In this Extreme Booster Pump review, the Gauntlet 2 had its pressure increased by 800 PSI with 4 actuations of the pump. So each actuation caused an increase of around 200 PSI. The tank pressure fell by 100 PSI as a result of this fill.

We increased the fill pressure of the EVOL Mini by no less than 1,500 PSI with 7 actuations of the pump. That’s about 215 PSI per actuation. In this test, the tank pressure fell by 200 PSI.


Filling to 3,600 PSI With The Booster Pump
Air RifleGun Start
Pressure
Gun End
Pressure
Increase in
Gun
Pressure
Number of
Actuations
Tank Start
Pressure
Tank End
Pressure
Impact 22,500 PSI3,600 PSI+ 800 PSI83,000 PSI2,800 PSI
Impact 13,000 PSI3,600 PSI+ 600 PSI52,800 PSI2,700 PSI

Here, we took two different FX Impact air rifles and filled them from the same large tank. Although the bottle capacities of the Impacts were the same – both at 29 Cubic Inches – the pressures in both tank and guns were different, as you can see.

In this case, each actuation produced a 100 PSI increase in the Impact 2 and 120PSI in the Impact 1. This is less than we found in the 4,000 PSI fill tests, probably due to the larger gun capacity and the lower pressure in the large HPA tank.

Extreme Booster Pump Review


Filling 3,000 PSI Marauder Rifle With The Booster Pump
Gun Start
Pressure
Gun End
Pressure
Increase in
Gun
Pressure
Number of
Actuations
Tank
Capacity
Tank Start
Pressure
Tank End
Pressure
2,600 PSI2,900 PSI+ 300 PSI2550 Cu. In.2,550 PSI2,500 PSI
2,000 PSI2,500 PSI+ 500 PSI490 Cu. In.2,000 PSI1,500 PSI
2,0003,000 PSI+ 1,000 PSI590 Cu. In.2,500 PSI1,600 PSI
2,500 PSI2,750 PSI+ 250 PSI290 Cu. In.1,500 PSI1,200 PSI
2,500 PSI3,000 PSI+ 500 PSI390 Cu. In.2,500 PSI1,600 PSI

For this test, we used the same Marauder, filling it once from the large, 550 Cubic Inc capacity tank and multiple times from a small 90 Cubic Inch tank. We also tested the Booster Pump for operation from a tank starting pressure as low as 1,500 PSI.

The Marauder has a capacity of 13 Cubic Inches.

As we can see, both size tanks worked. However, the small tank lost pressure very rapidly as it was used to fill the gun. The pressure increase in the gun varied between 125 and 200 PSI per actuation, depending on the different pressures.

Extreme Booster Pump Review


Extreme Booster Pump Test Conclusions

It works!

Typically, the air pressure in the gun increased by 100 – 200 PSI per actuation of the Booster Pump. (An actuation is pressing the green operating button once). This makes the boosting process manageable without fear of over-filling the PCP air rifle’s tank and risking potential valve lock.

A small tank can be used with the Extreme Booster Pump in an emergency situation, but really it works best with a large HPA tank.

Unless you’re connected to a shop compressor, the HPA tank provides both the low pressure air to drive the Booster Pump – in addition to the increased pressure HPA injected into the gun. That “low pressure” air requirement is relatively large compared to the capacity of the small tank, hence the large tank pressure drops we observed.

But it’s relatively small compared to the capacity of the large tank. That’s why the larger tank is a more efficient way to use the Booster Pump.

We also conducted some informal testing of the Booster Pump with a shop compressor. In this configuration, the shop compressor provides the source of low pressure air.

The result is that the HPA tank is relieved of this task and is providing only the high pressure air that enters the gun. Now there’s a MUCH lower demand for air from the tank at each actuation – a benefit that’s most apparent when using a small tank.

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Extreme Booster Pump