No question the L8T 6.6L is a worthy successor to the L96 6.0L. It is very close in output to the Ford 7.3L and seems to deliver better fuel economy. Nonetheless for the last couple of years there has been persistent rumors that GM is considering an even larger gasoline V-8, possibly primarily for larger commercial trucks and other OEM's. For the last 6 months or so the rumors have died down a bit, but recently something showed up on GM Powertrain's website that has me wondering. What it is is a 454 cubic inch V-8 based on the LS family using the tall deck LSX high performance engine block. Now before you say that engine is old news and is just a high performance (and expensive) crate engine, the engine I am talking about is a different one. This one is a nearly completely dressed production engine that appears to use L96 intake, throttle body, and heads. In fact, the extra row of head bolts on the LSX block are visible but not used as they would be with LSX style heads. Defiantly a truck/commercial engine, and the website lists it as an 'OEM Test Unit' whatever that means. Could this be the rumored larger gasoline V-8?:
https://gmpowertrain.com/products/lsx-454-engine/