The engine was installed in a Timossi three-point racing hydroplane hull.[citation needed] Castoldi managed to further increase horsepower by attaching two superchargers. The result was a 502 bhp speedboat, which he used to hit a 150.19 mph top speed in October 1953 on Lake Iseo. This world speed record for an 800 kg boat still stands today.[3]
A similar hydroplane was constructed by Guido Monzino in 1954. Like Arno XI, it utilizes a Lampredi engine, in this case sourced from a wrecked Ferrari 375 MM.[4]
Today
Arno XI was later sold and raced in numerous competitions, finally retiring in 1960. It has since been restored and is expected to go for up for sale by RM Auctions for up to €1.5m.[5] In 2021 the Arno XI is for sale again at an asking price of USD$12 Million.