Heritage Revamped – Baffled oil Catch Can Kit R&D, Part 1

The Corvette is essentially the definition of America’s automotive heritage. Sure, there have been some tweaks throughout the years, but for 67 years, Chevrolet has been churning out the basic formula that we Americans crave in a sports car: small block V8, power to the rear wheels, light and nimble in the corners all with an affordable price tag. For the Corvette’s 8th generation, it was more than just a tweak with the formula, but rather a reinvention. The mid-engined ‘Vette was long-awaited but has finally arrived. However, even starting from the ground up still means contending with a long-standing tradition for the internal combustion engine – blow-by.

Before we dive into the solution, let’s take a look at the problem. To start, yes, the C8’s suite of tech is quite the improvement over the outgoing C7, but there are just some aspects about an internal combustion engine that technology hasn’t solved yet, specifically blow-by. During the engine’s power stroke, even on a brand new vehicle, combustion gasses can slip past the piston rings, which add some extra pressure to the engine’s crankcase. The crankcase pressure is then recycled, and routed back through the intake system, by way of the Positive Crankcase Ventilation (PCV) or Crank Case Ventilation (CCV). Both are much more efficient and eco-friendly than just venting it out of the side of the block. The caveat, however, is that pressure is also carrying oil droplets and traces of fuel vapor that tend to stick to intake tract components, specifically the intake valves. Over time, the contaminants in the blow-by gasses will cause carbon buildup and rob your Corvette of efficiency and power.

Speaking specifically in terms of the C8’s beating heart, Chevy incorporated features on this engine that aid in the output of that 495 hp, but these features can leave this V8 susceptible to carbon buildup over time. The LT2 nestled behind the cabin is, in essence, a reconfigured LT1 suited for mid-engined applications. To optimize the LT2 for midship installation, Chevy included a full dry-sump oiling system, and of course, tuned for that extra grunt. Power improvements come by way of a combination of high compression (11.5:1) and direct injection. Both methods squeeze more power from the engine with less fuel, but there’s a catch. The high compression helps exert more downward force on the piston, thus generating more power, but that extra force means more combustion gasses will slip into the crankcase. While direct injection is a more efficient means of fueling, it eliminates the constant washing of intake valves that makes it harder for carbon to take up residence. Don’t get me wrong, these features are wondrous additions to any engine, and the C8 would be worse off without them, but there’s a trade-off.

This is the result of unprotected intake valves. Top: This is from a Volkswagen in the early days of direct injection. With no means of filtering out oil and fuel vapors, the carbon eventually built up and, in some cases, would lead to valves getting jammed. Bottom: We took a look into the head on a 2019 Hyundai Veloster Turbo with only a few thousand miles on the odometer, and you can see that there are already signs of carbon deposits on the valves. While both of these applications vary from the specific setup Chevy equipped in the C8, all three share the high compression and direct-injection combination.

Since these technologies aren’t exactly brand new, there are ways of combatting carbon buildup throughout the intake tract. Chevrolet has incorporated baffling that separates the oil from the air that’s cycled back into the intake. Still, we’ve found in the past that these systems have problems keeping up. They also drain the oil back into the pan, but since that oil also contains fuel particles, it can shorten the lifespan of the oil. With a dry-sump oil system, you don’t want to be changing your oil more often than necessary.

This is where the Mishimoto catch can comes into play. We opted for a can design that separates the contaminants from the crankcase pressure and retains them in a serviceable can. This design both protects the intake valves and maintains the oil’s service life. In the C8’s case, we’re planning a dual can set up to cover all angles of protection for the LT2. With the donor vehicle in our R&D facility, our engineering team got straight to work devising the Corvette’s catch can system. Make sure that you stay tuned for a closer look at our prototype system coming soon.

Thanks for Reading!

-Nick

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