An engine-jacketing type capsule for a VW engine (VH = 0.9 to 1.31) was built and tested. The entire drive unit - consisting of the engine, clutch, transmission and output shafts -was enclosed in a relative close-fitting sheet steel capsule. The radiator, carburetor, air-filter and muffler system are outside the capsule.
A reduction in total vehicle drive-by noise of 7 dB(A) was achieved under ISO-test conditions.
The efficacy and practicability of the concept have been established. No safety or handling problems have been encounted, but service and repair are naturally somewhat hindered.
The work was sponsored by the Federal Environmental Authority of Germany.