[Mystic ZR-1]

Indy 1994
Roger Penske found a loop hole in the Indy rules and
with Mercedes/Illmor built a 209 cubic inch turbo OHV, 2 valve per cylinder, V8
running 1.86 bars abs of boost (that's about 12.6 pounds, not really a big number
in the serious turbo world, a pure race motor, not a stock block...)
that knocked it out of the park! Pole and race win.
Some estimates were over 1100 hp in qualifying trim!
That's about 5hp/cu in!
Rules allowed a little more boost and a few more cubes for OHV motors.
OHV/DOHC???