Is the claimed 405hp from GM's all-aluminum LS6 for Real?
By David Vizard
On paper at least, GM's crate motor program appears to offer engines that deliver excellent results in terms of bang for the buck. But the speed equipment business in general seems to thrive on optimism. Nowhere is this more evident than when it comes to making power claims. Although one would expect a big, reputable corporation like GM to be honest it would not go amiss to have such independently verified.
What started as a passing interest was the introduction of GM's latest crate offering--the Z06 Corvette version of the LS6 (GM part # 12578104), ended up as a major test project. Here was a lightweight, sophisticated, all-aluminum engine which, in smog legal form, has a claimed output of 405 SAE hp. It pulls from dead smooth idle to the redline at 6600 and delivers great mileage to boot. A little research revealed that, in the form shown in our heading shot, a copy of this engine can be had for a street price of some $7,300 (Scoggin-Dickey Parts Center). Try building a comparable 23-degree small block Chevy for anything less than about $12,000.
If this Z06 crate motor makes the claimed power then it's certainly a good buy, but as hot rodders other considerations also influence our purchases. To appreciate this we need to consider what drove the original small-block Chevy to such popularity. In a word--it was 'potential'. As it came from the factory it was good but there was a lot left in it and that was what made it so attractive to hot rodders. This leads us to ask if GM has done all the hot rod work for us on this Z06 engine. Is it essentially 'topped out' or is it such a good design that in spite of producing big numbers in stock form there is much more to be had? The intent here is to find out just what this engine can deliver in both stock form and modified.
For a dyno that has LS6 engines run on it almost daily the services of More Performance in Charlotte, North Carolina were called upon.
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