Hoverhawk Corporation

We ship WORLD-WIDE, easy-to-assemble Propulsion kits in easy-to-ship component packages and bolt-on belt reduction air drive units. We continue to expand our line of products to serve our customers' needs.

Belt Reduction Drive for Subaru EA81 Engines for Airboats, Hovercraft & Aircraft

Subaru ea81 engine belt reduction drive unit for airboats,hovercraft,
aircraft. Subaru EA81 PSRU

This aircraft-grade PSRU bolts to the flywheel end of your EA81 engine. Your flywheel must be minimumly machined to accept the provided "driving" lower pulley. Provision is provided for installing your own bolt-on, off-the-shelf electric starter. The reduction ratio is 2.2857 to 1. The propeller mounting flange provides the SAE-1 bolt pattern. Cost is $2,990 USD, plus shipping. Shipping weight is 25 pounds/11 Kg. A properly prepared, normally aspirated Subaru EA81 engine may produce up to 100 HP at 5400 engine RPM. We will offer pre-machined flywheels and electric starters for this PSRU off-the shelf, as an option, or you may provide your own. We will provide instructions for your flywheel modification. Pay by bank wire transfer or use www.TransferWise.com world-wide.  Request a quote by email: hoverhawkcorp (at) gmail.com .

We also offer the complete engine with belt drive ready to operate, for pusher or tractor, for airboats, hovercraft or aircraft use. CALL OR EMAIL US FOR OUR CURRENT PRICE !

EA81 Subaru Engine with Belt Drive Unit

Subaru EA81 Engine complete with our belt drive ready to use


Belt Reduction Drive for Air Cooled Industrial Engines!

Our rugged belt reduction drive unit is designed for industrial engines, including the popular Predator, Honda, Kohler and Briggs/Vanguard and similar single or twin cylinder Chinese-made clone engines. These engines are commonly used on hovercraft, small airboats and industrial ventilation systems. This drive comes ready to install on your engine. Developed specifically for the harsh marine environment. It is designed for engines up to 40 horsepower which turn up to 4000 RPM maximum, and is constructed primarily of aluminum and stainless steel for durability in a wet environment. The V-belt is quiet and efficient. The muffler and exhaust system on some engines may have to be re-located or modified to provide clearance for the reduction drive to mount. Specify the reduction ratio when ordering. 

A reduction drive unit allows use of a larger diameter propeller, turning more slowly, for more propeller efficiency (more thrust per HP) and quieter operation.  Our reduction drives come with Rotax 75mm bolt circle pattern with a standard 1 inch centering pilot, face plate and 5/16 inch propeller mounting bolts.  Choose the particular Reduction Drive that meets or exceeds your engine's maximum horsepower output. We will help you match a propeller to your particular reduction drive choice.

Number of  Drive Belts

Ratios Available

*Price USD

Maximum HP Supported

Mounting Plate Style

3 Belts (Predator 22 hp)




Short plate

3 Belts




Long Plate

3 Belts




Long Plate

4 Belts




Long Plate

4 Belts




Long Plate

4 Belts




Long Plate

4 Belts




Long Plate

4 Belts-All stainless steel & aluminum construction



18 to 40

Long Plate

NOTE:  Stock HF Predator engines may use either the short or long (universal) backing plate. Honda, B & S, Chinese clones and HP modified Predator engines must use the Unversal plate. Kohler engines use the long plate with the Kohler mounting bolt pattern. All reduction drives include a belt tensioner. All drives are rated up to 4,000 engine RPM. Allow a  week to 10 days to ship when ordered.   *Plus shipping cost.

Email us with any questions:  hoverhawkcorp(at)gmail.com

BeltDriveVbelt1LS.jpg (15982 bytes)

Belt Drive components included

BeltDriveVbelt2LS.jpg (23077 bytes)

Belt Drive Mounted on a HF Predator 22 HP Engine
(Prop extension not shown)

Email Us: hoverhawkcorp(at)gmail.com

Our Reduction Drive works VERY well with Ultra-Props too !
Belt Reduction Drive Installation Torque Specifications:

(4) 3/8 inch Backing Plate Mounting SS bolts-15 ft.lbs. or 180 in. lbs.
(6) 5/16 inch Propeller Mounting SS bolts--11 ft.lbs or 132 in. lbs.

Compact, Efficient, Reduction Drive/Propeller Air Drive Combinations For Airboats and Hovercraft
1) You supply 22 HP Harbor Freight Predator Engine-4,000 Max. RPM (cost under $600)
Add our bolt-on 1.68 to 1 belt drive--$799
Add our 42 inch 3-blade T5 fan with adjustable pitch--$329
90+ pounds thrust typical at full throttle.
2) You supply 22 HP Harbor Freight Predator Engine-4,000 Max. RPM (cost under $600)
Add our bolt-on 1.68 to 1 belt drive--$799
Add our 36 inch 3-blade T5 Fan with adjustable pitch--$329
82+ pounds thrust typical at full throttle.
3) You supply 13 HP Harbor Freight Predator Engine-3600 Max. RPM (cost under $400)
Add our bolt-on 1.68 to 1 belt drive--$799
Add our 31 inch 3-blade T4 Fan with adjustable pitch--$239
55+ pounds thrust typical at full throttle.

An engine tachometer is essential to set your blade pitch to its optimum. Disable the engine governor, then set/adjust the prop/fan blade pitch angle of attack to act as the engine governor, to limit full throttle maximum engine RPM to, or just below, engine RPM redline.

Belt Reduction Drives for industrial air-cooled engines and Subaru EA81 Engines Bolt-on belt reduction air drives for Airboats Hovercraft and Aircraft Briggs Predator Kohler Subaru EA81 Engines belt reduction drive for sale on sale air cooled inductrial engines Subaru EA81 engines hovercraft aircraft hovercraft kits ultra props ultraprop hovercraft thrust air drive airboats hovercraft supplies airboat supplies propulsion thrust propellers ducted fan ducted propeller Bolly propeller

Revmaster aircrsft engine VW based engine

Revmaster R-2300 VW-Based 85 HP Aircraft Engine--PRICING Completely assembled and test run before shipping…$9,400.00 USD., plus shipping cost.  Includes E4340 forged four main bearing, aviation crankshaft, starter, alternator system, dual CDI ignition, oil cooler, oil filter, large capacity oil pump, intake manifold, RevFlow carburetor with mixture control, SAE1 Propeller bolt pattern, 85 HP at 3200 rpm continuous, 170 pounds dry.   OPTIONAL ACCESSORIES ARE AVAILABLE such as Exhaust system, engine mount, engine mount hardware, prop crush plate and alternate air source/ram air filter assembly.  This engine is not limited to only wood propellers !  Revmaster has been in business continually since 1959 !  Sensenich wood and carbon adjustable propellers are available for this engine, Call 1-251-609-0969

Revnaster Thrust Bearing and flange  setup

The Revmaster propeller flange and their unique thrust bearing setup shown above. No "shrink-fit" prop flange to break your crankshaft or to come loose causing your propeller to depart from your aircraft  Since the thrust load is absorbed by the thrust bearing on the propeller shaft next to the propeller, the crankshaft journals are not being pulled or pushed, or otherwise stressed, by the hundreds of pounds of thrust produced by the propeller. Other VW-based engine conversions use the main bearing on the flywheel end of the engine as their "thrust bearing",  on the opposite end where the propeller is mounted !!




Contact Telephone Numbers:

1-251-609-0969 in United States
+1-251-609-0969 outside United States

Email:  hoverhawkcorp (at) gmail.com






Prices, specifications, and availability are subject to change without notice. Products and materials advertised on this website are sold with the understanding that the buyer assumes all risks and hazards involved in their use or application. Buyer/User acknowledges assumption of all risks, hazards and further indemnifies seller by purchasing and/or using or reselling the products advertised and sold on this website. No express or implied warranties asserted nor fitness of merchantability claimed by Seller.

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