Evaluating the Keene Engine Driven Shop Vac





The Keene Portable Engine Driven Shop Vac is an impressive vacuum system that combines a Makita 4-cycle gas engine blower and a 5 gallon bucket fitted for two standard 2-½ inch shop vacuum hoses .  This small lightweight system carries quite a punch when it comes to vacuums and might deserve a better name like the little big guy.


Keene Portable Engine Driven Shop Vacuum System
Keene Portable Engine Driven Shop Vacuum System


Evaluating the Keene Engine Driven Shop Vac

by Titus Nelson, PE

Inventor of the Holey-Moley Digger

Testing the engine driven shop vac in the field

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 6-inch hole digger into the desert to test the vacuum unit and to see how well it powered the 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 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.

Light Weight

The light weight of the Portable Engine Driven Shop 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.

Easy Operation

The Makita 4-cycle engine 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.

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) Portable Engine Drive Shop Vacuum easily took up all the excavation material as fast as we could produce it.  For a three foot hole the Keene Engine Driven Shop 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.


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

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 setup 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

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


Test Results

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

Interesting Test Results

The Keene (HVS ) unit has two inlet ports on the 5-gallon pale 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 most noticeable aspect of this test was the sound  at the inlet to the flow section.  There was no doubt, by the sound alone, that a respectable amount of air was going through this apparatus. It was easy to hear the airflow over the sound of the Makita engine. The Makita blower, sitting on top of the pail, is rated of 365 CFM.   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.


Shop Vac Test Setup Side VIew
Shop Vac Two Hose Test Setup Side VIew



Shop Vac Test Setup End VIew
Shop Vac Two Hose Test Setup End VIew


The Gravel Pick Up Test

Can the Keene Engine Driven Shop Vac pass the gravel test?  Timing the pickup rate for 15 pounds of mixed gravel provides a good comparison test and any shop vacuum should be able to pickup up this amount of gravel in 30 to 60 seconds.

The gravel for this test is shown below.   This is a difficult test but most shop vacuums, even small ones can pass it.   The Keene Engine Driven Shop Vac was able to pick the entire 15 pounds up in 42 seconds.  This is a respectable rate beating out the 5 gallon 6 amp Dayton we also tested by 9 seconds.


15 pounds of mixed gravel used in the gravel pickup test


The Grueling 25 Pound Test

The Keene Engine Driven Shop Vac did very well for an engine driven unit on the 15 pound test but we wanted to see what it did when pushed to the limit.  A good test for this 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 and can become a catch point to slow down the sand which is very heavy and which can also impede the gravel.

In our testing of the Keene unit, we had to lift the hose a few time to help get the mixture to the canister.  Part of the problem was the canister capacity. The 25 pounds, roughly 2.5 gallons, fills the shop vac canister to the inlet ports where uptake is slowed down.

We believe the Keene unit would do an excellent job if mounted on a larger canister such as a 10 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 since, 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
Mixed Gravel, Sand, and Fine Dirt


The Comparison Numbers

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



The Keene Engine Drive Shop Vac does an impressive job when digging holes. This is the only four cycle Engine Driven Shop Vacuum we have found on the market and it compares in suction 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.  It was made for the gold prospecting industry and 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.   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.


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