Supercharged, unreliable, unsuccessful sadly.

Other early very high power engines:

http://en.wikipedia.org/wiki/Novi_engine - 1941 450bhp to 1966 840bhp, equally unsuccessful

http://en.wikipedia.org/wiki/Mercedes-Benz_W125 - 1937 600bhp, championship winner

Well, controlling 16 sparkplugs with a mechanical distributor at that rpm was always going to lead to timing issues. That much power from such a little engine, when it did work, is amazing to me.