Lee Carducci, Power-Tec Engineering
"An Insider's Look - From Birth of the LS Platform Through Tomorrow's LS Sprint Car Engine and Beyond"
One of the most fascinating talks of the conference came from Lee Carducci, a man with a background spanning everything from production and Formula 1 responsibilities at Lamborghini, to a program manager for hybrid race vehicles at Chrysler, to his role at GM Racing in the Cadillac LMP program. Having come to GM at a time when the LS was in the very early stages of Gen IV development, Carducci's presentation discussed all of the factors that go into the development of a production engine, focusing mainly on the LS7. In general, durability, reliability, NVH, and manufacturing cost all play an oft-conflicting role, as does the engine's ability to meet government regulations. As an example of the latter, Carducci explained that one of the reasons for the change to a 58X crankshaft reluctor over the old 24X was to enhance misfire detection and, hence, improve emissions performance.
For the LS7, the mandate was clear: "I don't care what it takes-you will make 500bhp, on-time, and reliable." Such was the directive of a GM executive that shall remain nameless, and the story of how the engineering team made it happen was captivating. Just a few interesting highlights: the LS7 actually started life back in 2002 with 396-inches, but it could not meet the horsepower target. In using 319 modified aluminum, though, and chilled bulkheads, the block is actually good to far more than 500 horsepower. Plus, since it's a siamesed-bore design, a whole lot of thermal design work went into the cooling system to minimize warping and distortion--Carducci cautioned that we "think about that" before changing anything cooling-wise. Also, with only 2.5 mm of aluminum between the bores, a totally different boring procedure known as "stitch boring" is used, ensuring not only roundness, but cylindricity (on the LS7, this is held to 5 microns). As a final comment, some detail was gone into on a phenomenon known as lobbing (pronounced lobe-ing)-a sinusoidal, nearly immeasurable, 1-2 micron imperfection in the bore wall that no ring set could properly conform to, and which essentially had never been discovered or explored prior to now (it likely exists in all engines to varying extents). Keeping this phenomenon to a minimum is why a deck plate is used during all machining operations to the LS7 block.
Many details were also given on LS7 cylinder head design (interesting tidbit: they are designed so that VVT and AFM can be incorporated in the future if need be!), and not only are these heads CNC-machined, they are also washed after machining with a CNC washer. After some details on a cost-effective LS sprint car engine program, Mr. Carducci ended with some tantalizing hints on what to expect in future GM pushrod V-8s: how about direct injection and independently variable intake and exhaust valve timing, even using just a single in-block cam? Bet on them, because we saw some convincing drawings. Increased fuel efficiency, reduced emissions, and even higher power levels will be possible thanks to these technologies--along with some we're sure Carducci wouldn't let out of the bag!
Will Handzel, Author
"How GM Designed and Developed the LS Platform and a Review of Current LSx Performance Trends"
The name Will Handzel should be familiar to all GMHTP readers, and he was a welcome addition to the palette of speakers at AETC. After giving props to just a few of the many at GM Powertrain who worked to make the LS engine a reality, Handzel showed a photo of a Frankenstein of an engine that the LS could have been. Known as the Venture V-8, this iron-block, aluminum-intake, Optispark-equipped horror show was fortunately deemed incapable of meeting future power, weight, NVH, and emissions requirements by GM brass. The goal was set for an engine that would instead not just be only good, but "best in class"--so began the design process on what would become the Gen III.
Handzel then went through specifics of how the LS platform was created, including how it would carry on the small-block legacy and how certain design features were decided upon. One item of interest is that the Gen III was originally designed with external oil drainbacks for the cylinder heads, a feature that would have virtually eliminated crankcase windage. Many of the challenges that engineers had to overcome were described, such as bay-to-bay breathing issues and the fact that the pushrods are not at all designed for performance, but rather for light weight (yeah, we figured that one out already!). Much of what Handzel discussed can be found in his book, "How to Build High-Performance Chevy LS1/LS6 V-8s," which is available through CarTech and recently revised and updated--be sure to pick up a copy if you haven't already.