The engines.

The most popular engine configuration is the Front Drive ­ direct drive engine. This is driven off the pulley end of the crankshaft. Displacements from 1600cc up to 2276cc are available. A wide variety of accessories and accessory packages are available. From single ignition ­ hand start, to dual ignition, 35 amp 3 phase alternator, accessory housing and geared starter - the choice is yours. We have direct drive engines to fit just about any engine budget.

The Flywheel Drive Engine is the least expensive engine configuration sold. An aluminum prop hub is bolted to a custom flywheel that is a little larger that a stock VW flywheel. The starter is mounted on top of the engine, laying over the engine case. It utilizes a 35 amp 3 phase alternator, mechanical fuel pump, and optional dual electronic ignition. This is also the lightest VW conversion sold with the fore mentioned options, weighing in at 146 lbs. for a 2180cc engine. This also uses a bed type engine mount. The engine that can be produced in displacements from 1600cc through 2276cc.

The Reduction Drive Engines have really opened up the range of aircraft that can use VW power. Direct drive VW's are limited to a 62" diameter prop because of tip speed. They will produce about 200 to 250 lbs. of thrust, depending upon prop manufacturer. The reduction drive engines can turn prop diameters from 72" with a 1.6:1 ratio and up to a 84" prop with a 2.0:1 ratio. Static thrust with a 72" prop is about 350 lbs. The 2:1 ratio with a 84" prop will deliver about 450 lbs. of thrust.

The re-drive engines are available in kit form. The most popular engine sizes are the 1915cc, the 2180cc and the 2276cc motors. The standard set up features starter, 35 amp 3 phase alternator, 009 type distributor, choice of drive ratio, top mounted Weber carburetor and intake manifold, accessory case and remote oil cooler. They can be fitted with either dual electronic ignition or can use one magneto and one electronic ignition system. The re-drive VW engines are used in many of the WW1 type aircraft - Kolb, several of the Cub look-alikes, Storch replicas and a few trike's (flying wings). They can deliver outstanding take off and rate of climb, when matched to the correct aircraft.

The Products.

For starters, we offer a complete range of engine kits, drives, accessories and individual parts for sport aircraft that is unmatched by any company in the U.S. or worldwide. Bearings, cams, stud kits, heads, cases, accessory case kits, cool tins, carburetors, secondary ignition systems, magnetos, plugs, wire sets, 4 different prop hub styles, instruments, piston and cylinder sets ­ you get the idea. If it's a product for VW power, we probably carry it. We also make replacement parts for some of our former competitor's engines.

So what makes our engine different?

Ok, let's examine our 2180 and 2276cc direct drive engine with dual ignition ... These are the most popular engines we sell.

The Crankshaft.

The heart of the engine is the crankshaft. It has to be able to absorb, dissipate and transmit. Our 82mm forged E4340 steel crankshaft is made specifically for aircraft use. It features a rectangle flat milled key for the prop hub. The crankshaft has a 3 degree taper on it that is mated to our Force One prop hub. The bolt that retains the hub is a fine thread bolt that is 3.5" long. The threads in the crankshaft are machined in the crankshaft about 3" down from the end. For the first 1.250" the thread is relieved so the pulling or retention loads is placed at the rear of the thread in the larger diameter of the crankshaft. This crankshaft is made specifically for the rigors of driving a propeller. It is not an "out of the box" automotive crankshaft as used by one competitor. In the 18+ years this current crankshaft design has been manufactured, it has never suffered a failure. Our E4340 crank is manufactured from a forged billet and machined in the USA. Our 1045 forged steel crankshaft is forged in Germany and machined in the USA.

The Force One Prop Hub and Main Bearing.

While not totally unique to aviation, it is in many respects when combined with our crankshaft. We recognized from early on from a number of crankshaft/prop hub failures with 82mm crankshafts and shrink fit and short tapered hubs, that perhaps it was not the best way to build stroker engines for longevity.

The Force One Prop Hub rides in a bearing that the case is machined out for. The Force One Bearing is pressure lubricated, utilizes 2 seals, one for dust and one for oil. The total bearing area is 4 to 5 times what a standard VW #4 bearing's surface area is. But the important point is the hub is supported in the bearing instead of being attached forward of the bearing, as is the case when using a shrink fit or standard tapered prop hub. As the fit between the hub and the crank is on a 3 degree taper, it can be removed repeatedly without wearing out either tapered surface. With shrink fit hub, the .002" interference fit will eventually erode with multiple removals.

With our Force One Hub, we can still use the brass distributor drive gear to drive a secondary or primary ignition system. Another competitors crankshaft does not have the brass gear on the crankshaft and cannot use a primary or secondary ignition in the distributor hole.

2180 and 2276cc Camshafts

Our camshaft, while based on a popular design for automotive use, is custom ground to our specifications for aircraft use. It is designed to provide maximum horsepower and torque in the 3000 to 3400 rpm band. We keep the duration low and add enough lift to pack the cylinder as full as possible. This cam lets the engine idle without lopping and offers quick acceleration without stumbling. Other manufacturers use standard off the shelf automotive camshafts. All our 2180cc and 2276cc kits come with new lifters that feature a .024" oil feed hole drilled in the center to provide positive oil lubrication to the lifter/cam lobe face. These kits also feature 5/16" steel pushrods (no aluminum here for higher lift cams) and new rockerarm assemblies.

Most of the other hard components will be standard from whom ever you purchase your engine or kit from. The case, forged billet pistons and cast steel cylinders, oil pumps, cylinder heads, gasket sets and the like, all come from a small source of manufacturers and will be pretty common to all conversions.


This is another area where we are very different from some of our competitors. Starting with the accessory case, we supply a fully "closed" accessory case. This simply means the flywheel is enclosed in the case. One competitors X case features an open rotating flywheel. With our accessory case the starter position can be ordered in the 12:00, 6:00 or 9:00 position.

We have a standard 35 amp 3 phase alternator that is mounted inside the accessory case. One of our competitors has only a 20 amp single phase alternator for standard equipment.

Almost 30 years ago GPASC started using the geared starter which you now see as standard on most VW sport aircraft conversion. This lightweight 8.5 lbs. starter has an internal start solenoid, eliminating the need for an external one.

Our flywheel is unique to the industry. We are the only company we know of that builds and uses a light weight 100% steel flywheel, weighing in at only 5.5 lbs. Other companies use a combination of aluminum and steel to keep the weight down. We can boast that the steel flywheels have never had a failure. Aluminum and aluminum/steel ones can't say that.

Ignition Systems.

Primary Ignition. Yes, we still use what some competitors describe as old and antique - a magneto. But there is a good practical reason that is lost on some. The Slick 4316 and 4220 magnetos, do not need a power source, do not have external rotating magnets, is easy to hook up, and most important, you can start the engine by hand if the battery fails. With one competitor's ignition system, if the battery is dead or the starter is broke you won't go anywhere until you replace one or both. Their engine has to rotate 200+ rpm to start the engine. No starter, no battery - no starting.

Secondary Ignition. We offer a wide variety of secondary ignition systems that will fit just about any application. Our standard low height secondary ignition system (only 1.310" tall) fits in the standard VW distributor hole. This ignition system is the "standard" secondary on most of our engines. This system must be in the off position when starting.

009 Distributor - The 009 distributor can be used as a primary or secondary ignition system. When the cap is replaced with our 90 degree distributor cap it makes a lower height/attractive installation. The 009 can be upgraded to electronic ignition if needed.

Oil Pump Secondary Ignition ­ This ignition system replaces the oil pump cover plate. The bottom driven gear of the pump is modified and a shaft engages the gear. This system uses the same components as our low height system.

The low height secondary and oil pump secondary ignition systems feature dual redundant coil packs and can fire spark plug gaps up to .042" if required.

In Review:

Take a look at our web site. You will quickly see that we offer the widest range of products for VW sport aircraft engine conversions - period! We can help you to custom tailor your engine to the airframe, the aircraft will meet or in many cases exceed the performance specifications listed by the manufacturer. If the builder prefers, they can also order from us just the parts they desire to build the "prefect" engine.

Great Plains Aviation Supply LLC
Orders and Information: 402-493-6507