[harddrivin1le]

Originally Posted by Kitdy

GM is putting back into limited production the legendary race-inspired ZL1 engine with only minor changes. Featuring an aluminum block and cylinder heads, the 427 / 7L was rated at a respectable 430 hp and 450 lb.-ft. of torque, but when Motor Trend dynoed it independently, they got 525 hp form it.

I have every vintage issue of Motor Trend and they never dynoed an original ZL1. Al they did was reiterate an unsubstantiated claim made by a GM engineer, the results of which were undoubtedly representative of what I described below.

This guy did dyno his ZL1 and it produced 375.6 peak HP in its "as installed (SAE NET) state, which is 60 HP LESS than what a brand new, base engine LS3 Corvette engine makes.

CRG Research Report - COPO 427

It finally made 523.6 peak Gross HP, but that was after the engine was stripped of all engine accessories, super-tuned and fitted with open long tube racing headers.

A second dyno test on a second ZL1 revealed virtually identical results in "Musclecar Enthusiast" magazine a few years ago.

"Muscle car legends" are rarely supported by objective facts.

Furthermore, I question your use of the term "minor changes." The only common part among the old and new engine is the block. Everything else (including heads and cam) is different.