Sami et all,
What an engine it was, yes 1.5 litre, because the Formula regulations in the early 50's were 1.5 litre supercharged or 4.5 litre normally aspirated.
49.5 bore with 47.8 stroke ( 93 cc /cylinder!! ) official claimed output 600 BHP @ 12,000 RPM.
The RR superchargers contribution to boost is clearly seen in the following 280 bhp@8000 RPM, 350bhp@9000RPM, 430 BHP@10,000 RPM and nearly 500 BHP at 11000 RPM
Boost pressure at the highest was 72 PSI
Not being satisfied with this they ended building an H 16 after this one!!!