Who needs reliability! Just fit the loudest, gnarliest engine you can cram into the engine bay of your dune buggy and point that nose towards the sky! And while I’m sure that this sort of advice will be well received by many in the Dune Buggy fraternity, it is definitely not the advice you should be paying any attention to whatsoever.
If you’re looking for a reliable engine to fit into your dune buggy you would do well not to look much further than one made by one of the major motor vehicle manufacturers such as Volkswagen, Subaru, or Ford. Their engines have been tried and tested and are far less likely to fail on the trail.
Traditionally, most engines fitted to dune buggies and beach buggies were air-cooled Volkswagen flat fours with a displacement of anywhere from 1100cc to 1600cc. Now, why would this be so? What is it about the VW flat-four that made it the first choice for many buggy enthusiasts and is this engine still the gold standard?
What is a dune buggy?
Dune Buggies, Beach Buggies, or Sand Rails are vehicles with large wheels and wide tires. They are designed for recreational use on beaches, sand dunes, sand roads, or out in the desert.
They are usually designed to be roofless with a rear-mounted engine. They can be custom-built to the owners’ specifications or they can be created by modifying an existing vehicle like the Volkswagen Beetle.
There are quite a few different types of dune buggy but we generally classify them into two basic styles. The first is also called the Beach Buggy, which are fiberglass tubs fitted to a Volkswagen Beetle chassis, these are the types of buggy that most people will associate with the dune buggy lifestyle. The Beetle chassis was originally chosen because of the rear engine layout which improves the rear wheel traction of the buggy.
And then you get the more modern iteration, the steel-framed dune buggies which are also known as Sand Rail Buggies. A Sand Rail is a lightweight vehicle that is similar in concept to a Beach Buggy but is meant to operate in open sand and desert conditions.
Sand Rails are typically manufactured by welding steel tubing together to form a light, but very strong, space frame chassis and cockpit construction.
The Volkswagen air-cooled four-cylinder engine
The VW flat-four is an air-cooled, gas-fueled, boxer engine. It has four horizontally opposed cast-iron cylinders. It has a magnesium alloy crankcase, forged steel crankshaft, and connecting rods, and cast aluminum alloy cylinder heads and pistons. It is the engine that gave the iconic Volkswagen Beetle its distinctive sound, its heart, and its soul.
The flat-four was first built in 1936 to fulfill depression-era needs for an inexpensive, low compression, reliable motor. It met this brief with no fuss whatsoever and continued in production until 2006 when the last air-cooled motor rolled off the production line. In its time it powered vehicles such as the Volkswagen Beetle and, in flat-six configuration, in the air-cooled models of the Porsche 911.
The principle of air cooling a motor vehicle engine is relatively simple. One of the main components of the air-cooled engine is its surface area and, more specifically, the strategically positioned and arranged fins on the cylinder heads which will, employing the constant flow of air over their greater surface area, keep the motor running cool by dissipating the heat generated by the pistons and the internal combustion within the cylinders, out of the back of the vehicle.
To maximize heat transfer, the larger surface area of the finned design allows for far more heat to be distributed to the surroundings. The fins negate the possibility of the heat collecting into an intense small area which would inevitably lead to overheating.
This method of open system cooling allowed for great weight savings due to the lack of any water in the system and doing away with the necessity for heat exchangers needed in a closed-loop system that a water-cooled engine must-have.
Maintenance of the cooling system was also therefore non-existent, which only enhanced the reputation of the VW flat-four and flat 6 as a reliable, bullet-proof motor. The only maintenance required was for the owner to regularly check that no damage to the fins had occurred while blasting through the desert or scrabbling up a rocky hillside.
This is a simple diagram to help explain how an air-cooled engine works:
So is a dune buggy engine reliable?
Yes, air-cooled engines have been around for decades. They have seen service with the armed forces in many countries in war zones where reliability is key. They are fitted to many different types of motor car and are still fitted to motorcycles manufactured by the likes of Honda and BMW.
However, the air-cooled dune buggy engine is reliable only if you take care of them. They are not maintenance-free and there are items to be considered at service intervals and every 2000 miles or so. If you ensure that the valves are properly adjusted, the points are clean, and your oil is changed at regular intervals then you have a motor that is going to stay the course.
Skip the task of adjusting the valves or set the engine timing wrong and you will find that your air-cooled motor will die a sudden death.
Regular maintenance by a decent mechanic will highlight potential problems such as overheating and stretching valve stems. Case bearing wear will be apparent while setting the timing and several other small issues will be avoided and ensure that your motor will keep on firing.
It is always advisable to replace any part that you suspect may be worn or, at the very least, you think may have reached its serviceable lifespan.
We have mainly discussed the venerable VW flat-four and flat-six air-cooled motors and we can thoroughly recommend them as the power plant for your dune buggy, but it would be remiss of us to not make mention of the fact that any motor, whether water-cooled or air-cooled, will, if supplied by a reputable manufacturer, be extremely reliable.
The key to reliability is maintenance and, in the rough and tumble world of dune buggies, regular maintenance is more important than in almost any other sport. If you want your engine to last. Take good care of it.