In 1974 both BMW and Ford had racing 6 cylinder 3.4 and 3.5 liter engines pushing 450 to 480 BHP over 8.000 PRM, running WW2 technology mechanical fuel injections, 4 valve per cyl heads, and dry sumps on iron blocks.
No need for turbos, that was rather Porsche's field who in turn was up at 700+ BHP in the late 70s 6-cylinder cars (still using that old mechanical fuel injection).
We are in 2010, with all the present days technology, I'd be surprised if Ferrari can't come up with a serious road V6 producing some notable power/torque combinations.
Let'em bring it on...
... racing, it's life. Anything that happens before or after is just waiting... (Steve McQueen / Le Mans)