Evaluating the Keene Gas Powered Wet Dry Vac

The Keene Gas Powered Wet Dry Vac is an impressive gas powered Shop Vacuum that combines a Makita 4-cycle gas engine blower and a 5 gallon bucket fitted for two standard 2-½ inch shop vacuum hose adapter/deflectors .  Because of compact engineering, this small lightweight 5 gallon bucket vacuum system carries quite a punch when it comes to vacuums.  As a result, a name like the little big guy might be more fitting.

The following analysis is the result of field testing and testing with instruments and comparison testing with other shop vac systems.

Field testing the Keene Gas Powered Wet Dry Vac.

One way to test a piece of equipment is in the field.  We took the Keene Portable Engine Driven Shop Vac unit along with a Holey-Moley Post Hole Digger into the desert to test the vacuum unit and to see how well it powered the Post Hole Digger. The digger requires a good healthy air flow rate in the 150 to 200 CFM range so this was going to be a good test for the gasoline engine driven vacuum.  The ground we were digging in was hard packed red clay, so we were going to give the digger a good field trial too.

  • This Gas Powered Wet Dry Vac is light weight.

The light weight of the Gas Powered Vac was the first thing we noticed.  Fully loaded with hoses, gas and oil the system came in at under 25 pounds.   It was easy to carry the Keene unit with one hand and a 6-foot Holey-Moley Digger over the shoulder with the other hand.  We made the ¼ mile walk to our test hole location without breaking a sweat.

  • The Gas Powered Wet Dry Shop Vac system is easy to operate.

The Makita 4-cycle gas powered wet dry vac started right up on the first pull of the starter cord. The four cycle Makita engine doesn’t require a mixture of gas and oil making it very convenient.  We noticed that engine was a lot quitter than the old two cycle engines.  We hooked up the vacuum hose and could feel a good suction on vacuum end.   The hose hooked right up to the digger and we started digging a hole.   This was actually pretty amazing to be able to take such light weight equipment into the field and dig a precision hole as soon as we arrived on location. The unit operated just like a gas powered shop vac.  In addition, because the unit is gas powered, there is no worry about water getting into the fan, so the unit works well around water.

  • When it comes to fuel economy the Keene Gas Powered Wet Dry Vac rates high.

This  Gas Powered Vac runs for hours on a tank of regular gasoline and using less gas contributes to the light weight.   When carrying a gas operate engine vacuum, the last thing you want to be carrying is a lot of gas. As a result this vacuum will run all day on a gallon of gas.

  • The Keene Engine Driven Shop Vac digs a great hole.

We were able to dig a 6-inch diameter hole 12-inches deep in just a few minutes through some pretty hard ground.   The Holey-Moley Digger was perfect for the job and the Keene (HVS) Gas Powered Shop Vac easily took up all the excavation material as fast as we could produce it.  For a three foot hole the Keene Gas Powered Wet Dry Vac would require dumping at least twice.


Holey-Moley Digger Hole
6-inch hole dug with the Holey-Moley Digger in Red Hard Pan Clay using the Keene HVS.


  • The easy on/off Gamma Lid makes dumping the bucket easy.

This Gas Powered Wet Dry Vacuum has the Makita 4 cycle engine mounted on a modified Gamma Lid that only requires a few rotations to take it off the bucket. Therefore this bucket is easy to dump when it is full. The Gamma Lid has an O-Ring seal that ensures a solid vacuum.

  • One drawback when using the Keene gas powered shop vac is dust.

The Keene unit does not have a filter on the engine fan inlet inside the bucket.  The allows for fine dust particles to escape the system and at times can create quite a cloud of dust.   It would be nice to have a filter option for this system.

Finger guard allows dust to go through the unit.

Testing the Gas Powered Shop Vacuum

After digging the hole in the desert, it was time to go back to the shop and test the Gas Powered Shop Vacuum for flow and gravel pick up rates.

  • The Flow Test Setup

The following photo shows the flow test setup using 7-feet of 2-½ inch hose and a transition laminar flow section consisting of 2-feet of 3 inch pipe and 2-feet of 4 inch pipe.  Our flow meter was set up on the entrance to the pipe.

 Shop Vac flow testing
Flow Test Station – 2-feet of 3″ pipe and 2-feet of 4″ pipe with Flow meter at the inlet.


  • Smart phone flow meter

To test the Gas Powered Shop Vacuum air flow rate we used the ABM-100 Smartphone Anemometer to measure the flow rate.  This is a fantastic little device that provides exceptionally accurate results.  It is highly recommended that a flow section be used to provide smooth laminar flow for best results.

ABM-100 Smartphone Anemometer
ABM-100 Smartphone Anemometer


Looking over the Test Results.

  • Air Flow Rate

Running at full speed the Keene (HVS) Portable Engine Driven Shop Vac pulled in an impressive 180 CFM.  This rates right up there with high end Rigid and Shop-Vac vacuums. These systems pull around 180 to 200 CFM.  Check out our article on testing the Rigid WD19560.

  • Interesting Test Results

The Keene Gas Powered Shop Vacuum unit has two inlet ports on the 5-gallon bucket so we decided to try them out in a parallel setup shown below with two 3-foot sections of 2-½ inch hose connected directly to the flow section.   The results were unexpected as we were able to pull an impressive 300 CFM.

The result and most noticeable aspect of this test was the sound  at the inlet to the flow section.  No doubt, by the sound alone, a respectable amount of air was going through this apparatus. Because of the volume flow, It was easy to hear the airflow over the sound of the Makita engine. The Makita blower, sitting on top of the 5 gallon bucket, pulls 365 CFM without a hose.   This unit may have some interesting possibilities for improving the suction side of the assembly with a larger suction hose.  However, this may be at the expense of reducing the gravel pickup rate so careful evaluation would need to be done.


Gas Powered Wet Dry Shop Vac Two Hose Test Setup Side VIew



The Portable Engine Driven Shop Vac Two Hose Test Setup End VIew


The Gravel Pick Up Tests

Sucking up gravel is difficult for shop vacuums. Therefore, the perfect test is to time the pickup rate for 15 pounds of gravel.  As a result, this provides a good comparison test.  Therefore,  any shop vacuum should be able to pickup up this amount of gravel in 30 to 60 seconds.

  • 15 Pounds in 42 seconds is an impressive gravel pick up rate.

The gravel for this test is shown below.   This is a difficult test, however most shop vacuums, even small ones can pass it.   For the Keene Gas Powered Wet Dry Shop Vac to pull the entire 15 pounds up in 42 seconds is impressive.  As a result this rate beat the 5 gallon 6 amp Dayton, also under test, by 9 seconds.


15 pounds of mixed gravel used in the gravel pickup test of the gas powered wet dry vac


  • The Grueling 25 Pound Test

The Keene Engine Driven Shop Vac did very well for an engine driven vac.  The 15 pound test was pushing this vacuum to the limit.  A harder test for this unit is the pickup rate test using 25 pounds of mixed gravel, sand, and fine dirt.  This is difficult because the mixture is much denser and the fine dirt will fill the grooves in the hose.   This can become a catch point slowing down the sand which is very heavy and which can also impede the gravel.

As a result of our testing of the Keene unit, we found that lifting the vacuum hose a few times was a help in getting the mixture to the canister.  Therefore, the problem then showed itself to be the bucket capacity. Of the 25 pounds of gravel, roughly 2.5 gallons, fills the shop vac canister to the inlet ports where uptake slows down.

We believe the Keene unit would do an excellent job if mounted on a larger canister such as a 7 gallon bucket.   However, one has to be careful with accumulating too much weight to lift.   Since 25 pounds is a comfortable weight to lift in a bucket, there doesn’t seem to be any reason to go to the larger size unless digging holes.  A 6-inch diameter hole will produces about 2 gallons per foot of depth.   A three foot post hole would produce roughly 6 gallons so a larger canister might make sense, but a double fill on the Keene unit is easy to handle and the Keene unit easily handles all the sand and gravel that a hole digger can produce.


Mixed Gravel, Sand, and Fine Dirt


  • The Comparison Numbers

Gravel Pickup Rate 5 Shop Vac Comparison
Gravel Pickup Rate 5 Shop Vac Comparison


The Vacuum Test

We were able to obtain a vacuum test gauge and measured the vacuum of this unit.   The Keene gas powered shop vac pulls 14″ of H20.   Where this may seem low for a vacuum, when moving dirt, it is the volumetric flow that counts so the 180 CFM flow rate more than makes up for the low suction vacuum


The Keene Gas Powered Wet Dry Vac does an impressive job when digging holes. This is the only 5 Gallon Bucket four cycle Makita Gas Powered Wet Dry Vac available on the market.  Furthermore, it compares in flow rate to top end contractor and commercial grade 12 amp home units.  The light weight of the unit makes it an easy choice to take into the field.  In addition, it meets requirements for the gold prospecting industry.  As well it does a great job of handling gravel.

The unit has some limitations such as capacity, however when full, the bucket, without engine, weighs in at 25 pounds which is more than enough to be carrying in a bucket. The bucket and handle are perfect for that wight of material.  The Makita engine is a fine engine that is easy to fill with gas and oil and it runs all day on a tank of gas.   In addition, the engine starts right up on the first pull of the starter cord just like you would expect from a quality engine.   We give his unit a top rating for an engine driven shop vacuum and it will give you good dependable service in the field.

Can it be improved?

Based on our evaluation of the Keene Gas Powered Shop Vac, we were able to improve it.

  • The Makita Engine

As a result of this testing, Cat 6 Tools, now has a new product using the same reliable Makita Engine.  This Makita Gasoline Powered Filter Bucket provides some unique advantages.

  • Increased Capacity – 6 gallons

Using a heavy wall 7 gallon plastic bucket with a tangential inlet on the side raised to the top 1/4 of the bucket, the capacity is increased to 6 gallons, which is 300% over the Keene unit.


7 Gallon Gas Powered Wet Dry Vac with 4-cycle Makita engine
  • Increased flow rate

By adding a tangential side inlet to the bucket, the flow rate of the system was improved to 230 CFM which is an increase of 50 CFM over the Keene unit.  When moving gravel and dirt, volumetric airflow is key and we were able to achieve this with the highly efficient tangential inlet.  In addition, we added a low loss vacuum hose that has prevents accumulation of sediment in the hose grooves.   This also added to the improved operation of the system.

Makita 4 cycle engine powered vacuum, vacuum filter bucket 7 gal. Uses Ridgid Vac filters.
  • Increased Suction

The tangential inlet allows for more efficient airflow  and we were able to increase the vacuum suction to nearly 15 inches of water.  This is a small amount however, it was improved.

  • We added a filter for dusty conditions

The most unique improvement on this new vacuum bucket is the addition of a filter.  As a result, the filter holder uses any of 5 Ridgid filters available at Home Depot.  Therefore in really dusty environments a HEPA filter is available.  In addition, just a sponge filter is available for water conditions.   Or the unit can be configured with only the filter guard and run without a filter.  This provides a full range of filtration unlike any other gas powered wet dry vacuum on the market.

Tangential Gas Powered Vacuum 7 gal Filter Bucket Lid


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