In the first half of the 204s, Volkswagen engineers looked closely at the fairly limited diesel supply within the car industry. Also prompted by the first oil crisis, the development of a new generation of compact diesel power units is starting. Peugeot is already building small diesels for the 304 and XNUMX. But VW decides that the Golf concept lends itself perfectly to a much improved diesel engine. The diesel engine should not only be economical and efficient. The new diesel will also have to demonstrate performance values that correspond to engines from comparable petrol cars. The starting points form the prelude to the first VW Golf Diesel.
Volkswagen gets to work and takes the 1471 cc power source as the basis, which in the first production years – in addition to the 1.100 basic engine – also finds its way to the front of the VW Golf. Various parts are made resistant to the heavier loads that diesel technology entails.
Heavier Made PartsVolkswagen applies, among other things, reinforced valves, rods and pistons, as well as a reinforced crankshaft and a heavier cylinder head. The camshaft will be driven by a reinforced timing belt, which also operates the fuel injection pump. In addition, the battery and starter motor are equipped with a heavier weight. Furthermore, due to the higher compression ratio and higher thermal load, the combustion chambers are arranged differently.
Whirl chamber technology
In addition, the power source is equipped with swirl chamber technology. In short: thanks in part to the design of the vortex chambers, air flow losses are prevented – partly due to the resulting turbulence. It contributes to an optimal mixture between air and the diesel oil (injected at the end of the compression stroke and just before the power stroke), so that the efficiency of the combustion is higher. Volkswagen is also working on improved sound insulation with the VW Golf Diesel. A revolutionary diesel concept is born.
Golf 1.5 gasoline engine as a starting point
The basic principles for the new diesel powerplant – the transversely mounted FH petrol powerplant of the Golf 1.5 – provide scope for easily adapting the power to that of the 1.093cc petrol engine from the Golf one. Volkswagen's first diesel engine is being developed by the engineers tuned to a power of 37KW/50 HP. In combination with a compression ratio of 23,5:1, this ensures surprising performance. A top speed of 140 kilometers per hour, an acceleration from 0 to 100 km/h in 19 seconds, favorable consumption and the far-reaching degree of noiselessness make for a surprised newsreel in the seventies. Almost everything shows that in September 1976 Volkswagen is showing the world a mature variation on the diesel theme. However, the concept is not quite perfect yet.
CAV fuel pump worry baby
Volkswagen installs a pump from CAV to fuel the diesel engine. The pumps are worry children. Over time, they cause a less attractive run, leaks and smoke development. Defective pumps even cause the power source to run on crankcase vapors/oil, often causing irreparable engine damage. “Wolfsburg” also offers the option of factory-installing the much better fuel pump from Bosch. In addition, Bosch has struggled for a long time to produce the pumps at an appropriate pace. Another problem is a rapidly polluting air filter as a result of crankcase fumes. VW solves that problem by providing the air filter hose with a bypass hose, a kind of return line for the polluting vapours.
Basis for new segment
With its self-ignition power source, Volkswagen does not only show what is possible in that area. With the compact diesel, it once again unleashes a whole new segment. It takes several years (sometimes into the eighties, when the first VW diesel engine has already been enlarged and modified) before the competition tries to find an answer to this piece of diesel ingenuity.