Why Volkswagen Went To 5 Valve Engines

By Author: Peter Jones
Total Articles: 210
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Was Volkswagen's choice to use 5 valves inside the cylinders of their standard Volkswagen engines, instead of 3 or 4 like most other engines, just another complicated marketing device to try to grab the hearts and wallets of consumers? Or could there possibly have been more to it than their competitors would have you believe?

Valve are small devices which allow for either intake of air into or expulsion of exhaust fumes from each separate cylinder of an automobile's engine. They work by opening and closing the intake and exhaust ports in the head of a cylinder when pushed on by their attached stems. This is done by cams connected to the stems and placed on a fixed camshaft, controlled by the engine itself. Valves are usually made from high quality metal such as a steel alloy or aluminum, and sometimes hollow and crammed full of sodium to increase the transfer and transport of heat. Volkswagen engines currently use 5 valves in each cylinder.

Multi-valve engines, such as Volkswagen engines and others, are considered such when each cylinder contains ...
... more than 2 valves. This was originally invented by Peugeot in 1912 and has since become essential to modern engine design.

Placing more valves inside each cylinder increases the total space used to intake and exhaust gases to and from the engine. A greater turnover of gases improves the efficiency of combustion and increases performance and muscle, giving the car a more powerful engine and greater speed and acceleration. Increasing the number of valves is preferable to simply increasing the size of each valve because more valves sitting side by side in the cylinder gives much more overall space than 2 large valves, the sizes of which are extremely limited by the size of the cylinder itself.

After Peugeot's successful introduction of this simple geometric concept into the market, multi-valve engines quickly caught on and became standard with many large car manufacturers. In the 1960's the Honda S600 became the first consumer 4-valve vehicle, followed by many more in the 1970's including the Chevrolet Cosworth Vega, and the BMW M1. Beginning in the 1980's, both Honda and Toyota had given 4-valve engines to practically all their standard vehicle models, followed by American and European automobile manufacturers some years later.

Unlike today's Volkswagen engines, most early multi-valve engines had 3 valves. This design was cheap and easy to make, and took only one camshaft to drive both the intake and exhaust valves in each cylinder. Unfortunately, the 3-valve design proved inefficient and today most engines—with a few notable exceptions, Volkswagen engines among others—use 4 valves. The 4-valve design increases the chamber head area covered by the valves to more than 50%—a huge improvement from the original 2 valve design, which only had a 1/3 combustion chamber head area. This allows smoother breathing of the engine, and even cleaner and more efficient combustion. So why do Volkswagen engines use 5 valves?

Although the 5-valve design is usually more suited to sports cars, the makers of Volkswagen engines claim that it helps to raise the efficiency of their engines, allowing for better mileage and less wear and tear over the long term. Still, the advantage of the 5-valve design in Volkswagen engines is under fire, and many other vehicle manufacturers and their experts question these claims.

Volkswagen engines give an irregular shape to the head of their combustion chambers, allowing their 5-valve design to effectively cover more head area. This greatly enhances the high speed breathing of Volkswagen engines. A better air / fuel mixture is also theoretically possible in Volkswagen engines, due to their 5-valve design, resulting in cleaner emissions.

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