So just how powerful is this engine? Largely generated from the
1994 Excellence article early speculation turned to myth
that the car was really producing 480 to as much as 508 HP. Speculation
was that Porsche had understated the actual figures. Porsche always
discloses its horsepower and torque figures from the engine bench.
Using this method the 'S' engine was rated at 385 HP by the factory
in its technical bulletins. Interestingly, most USA MSRP stickers
misquoted the rating at 380 HP and some of the earliest USA MSRP
stickers misquoted the rating at 355 HP (which was the HP rating
for the standard 1994 3.6 Turbo).
The following charts are non-SAE adjusted rear wheel HP dyno runs
of a stock X88 engine and an X88 engine modified with bolt on items. The stock engine (see photo of Unidentified USA Car on dyno) produced 305 HP to the
rear wheels and the modified engine produced 375 HP to the rear wheels
(a 70 HP gain). So what is the
answer? Depending on what percentage loss figure you use from crank
to wheels the stock unit most-likely produces no more than the factory
stated 385 HP at the crank.