Senior Tech Team
Join Date: Sep 1998
Location: Mustang, OK USA
As stated, it is not hard to get 375hp from a 350. Chevrolet has even done it with production engines in production cars.
In 64-5, the 327 was available in a 375hp version. It was the fuel injected 327 which was available in Corvettes. Then, in 1970, the LT-1 350 in a Corvette was rated at 370hp. The 70 LT1 and Z-28 engines were EXACTLY the same engine. The LT1 in the Corvette was rated at 370hp and the Z-28 was rated at 360hp. Even though the two engines were the same, but had a 10hp difference, the reason for the difference was because the Corvette had an exhaust which had less back pressure and that was the reason for 10 more hp in the Vette. If you did absolutely nothing whatsoever but add headers to these engines and a VERY efficient 2 1/2 or 3in exhaust system, that would boost it some. These engines had solid lifter cams.
Also, BOTH the 327 (65-68) and 350 (69-70) were also available in 350 hp versions, which had hyd cams. Again, adding only headers will boost the output of these engines also.
My whole point here is that if Chevy did it with production engines (which are ALWAYS built a little on the conservative side so they will last through the warranty period----ya, right!), then it is quite easy for a home built version to top 375hp.