Lube System

With the LT1's torque in LS7 territory, and with new demands placed on the lube system by active fuel management and variable valve control, it was deemed that the LT1 needed a higher-volume, higher-pressure oiling system with a greater dynamic range. GM Powertrain went through dozens of iterations on the lube system before arriving at a variable-displacement, duel-pressure pump. This crank-driven pump is partially controlled by the engine management system; a sensor reading pressure off the second main journal was deemed the end point of the lube circuit where pressure is typically at its lowest. The engine management reads pressure from the second main bearing and controls a solenoid that varies or dithers the pump's pressure valve orifice between its two extremes. This maintains an ideal lube circuit that has the advantage of low parasitic loss under low load, and a robust protective capacity during severe use.

For those Corvette customers wanting to autocross, drag race, or road race their cars-and here we're talking about way more than what's typical-Chevy will be offering the LT1 with an optional dry-sump lube system. This raises oil capacity from 6.5 quarts to 10.2 quarts, and ups the ante with an air/oil separator, external sump tank, and a two-stage scavenger-style oil pump. It's worth noting here that even without the dry-sump's oil/air separator, the LT1 features new oil/air separator schemes in the valve covers and the LOMA-and that's on top of improved bay-to-bay venting in the block's design and a seriously effective windage tray/crank scraper mounted to the cross-bolted nodular iron main caps.

Before we know it, we’ll be plucking these jewels from junkyards and seeing them shipped to our door in crates.

Like the wet sump system, the dry-sump's pump will have variable-displacement, dual-pressure control, but it adds a gerotor-style scavenge pump stage that is better suited to capturing oil that's heavily foamed or entrained with gas bubbles. We'll also note that this will be the first time in over 20 years that Chevy has not recommended a pure synthetic for the Corvette (typically Mobil 1). The LT1 oil spec is the Dexos spec-a semi-synthetic 5W30.

Airflow

At a glance, the LT1's cylinder heads and intake don't look all that different from the LS3, but looks are deceiving. The Gen V architecture is all new from the block up, and significant changes were driven by the combustion system. The LT1's cylinder heads are the product of 75 design iterations that aimed at maximizing combustion efficiency. Engineers analyzed mixture motion and pressure dynamics in an effort to convert the least amount of fuel into the greatest amount of energy, and by the time of the design cutoff, the powertrain team had settled on a satisfying array of improvements.

Given the efficiency of direct injection, it's not surprising that engineers settled on large 2.13-inch hollow intake and 1.59-inch hollow sodium-filled exhaust valves. Air is admitted into the chambers at a very shallow 12.5-degree angle versus the LS3's 15 degrees. (The exhaust also gets help at 12 degrees versus the LS3's 15.) Intake ports are rectangular like the LS3, but the location of intake and exhaust valves has been reversed from the Gen IV, providing a slight bump in efficiency and better packaging.

It is perhaps the combustion chamber and piston face that contribute the most to the high-efficiency DI equation, with their shapes being the culmination of all that computational fluid dynamics. Each combustion event is a well-choreographed dance of high-swirl mixture motion, with atomized fuel entering at the ideal time to cool the chamber. Then on cue, a centrally located plug lights a precisely shaped fuel slug at just the right moment when it produces the greatest force gradient on the sculpted piston top.

All this permits a much higher static compression ratio, which in turn supports a very delayed intake valve closing (remember, fuel isn't coming through the intake valve anymore so there's mostly upside to a late intake closing). All this is great for building torque, lowering emissions, and extending the upper end of the powerband.

The Future ...

The LT1 is just the first salvo in the Gen V engine family. If the past is any indication, Chevy and GM with filter variants of the Gen V into trucks and other cars in the coming years. The next-gen technologies employed in the LT1 will also find themselves in other engine families present and future. Who knows, maybe we'll even see them with other technologies like turbocharging, independent variable valve control, and regenerative braking. All we know is the clock is ticking on tighter fuel efficiency standards, and at the rate of technological improvement that the LT1 has shown us, the future certainly looks bright.

It won't take long for the LT1 and its variants to populate the new vehicle fleet in the coming years. Before we know it, we'll be plucking these jewels from junkyards and seeing them shipped to our door in crates. It might seem scary dealing with direct injection at the moment, but it really poses no more of a problem than fuel injection or computer control did back in their early days. We can be forgiven for entertaining the idea that our hot rodding world might come to an end with tighter CAFE regs, but thankfully the true hot rodders at GM Powertrain dug their heels in and came up with a winner. And for that, we can give each other a high five.