IIRC, Judson used to offer a supercharger for the old 36/40hp engines. A flat four with counterbalances welded onto the stock forged crank (all stock VW cranks were forged) can really wind. Back in the day, I built a 1641cc Type III dual Weber engine that I had dynamically balanced, prior to assembly. That baby was torn down at 75k, and had no appreciable wear, whatsoever.