The Nuances Of Oiling Small Block And LS Engines

While engine oil characteristics, viscosities, additives, and brand names are hotly debated in enthusiast discussions, oiling system components are discussed far less often. While every engine oil brand has its proponents and detractors — often those who cite anecdotal evidence rather than scientific findings — the discussions rarely proceed further into oil pumps, oil filters and adapters, oil pans, and other pieces that have just as much of an impact on oiling performance and engine performance and longevity. The small-block Chevrolet and LS engine platforms are likely the most widely used in the hot-rodding and performance world, and they are worthy of oiling system discussion. We thought it prudent to enlist expert Thor Schroeder of Moroso Performance Products to discuss the evolution from small-block Chevy to the LS engine and how Moroso approaches developing improvements for these platforms.

The Tradition Stands Strong

The standard small-block Chevrolet engine (1955–’96) has a block-mounted oil pump located on the rear main cap driven by a shaft from the camshaft that sucks oil from the oil pan through a short tubular pickup. Most mild performance and engines perform well with this design running 35–50 psi of oil pressure when the engine is hot. This specification depends upon the builder, the oil viscosity, and engine bearing clearances. Race engines and certainly high-rpm engines will require pressure in the neighborhood of 60–80 psi to keep engine parts lubricated effectively.

This type of pump can be effective up to 750 horsepower or more with other internal oiling system improvements in place. Since the pump is driven from the camshaft, it turns at half the engine’s speed, which means the pump speed remains at reasonable levels to provide sufficient flow without getting out of control.

The small-block Chevrolet engine uses this oil pump drive that is spun by the camshaft. While it is a proven system for street cars and milder builds, there are definitely better options for racing engines.

In factory configuration, the traditional SBC lubricates the top end of the engine first, then the camshaft, and finally the crankshaft. Some aftermarket race-oriented blocks convert the layout to prioritize the main oiling, although this is typically only necessary in the most extreme applications.

This fabricated SBC oil pan (PN 21240) fits up to 1985 blocks, including Dart and Merlin, and works well in Super Stock cars, dragsters, roadsters, and body cars. It has a double kickout design to clear large-stroke crankshafts and includes a full-length windage tray for oil control.

Schroeder has a solid list of recommendations for improving the SBC’s oiling system to enhance performance.

“Let’s start at the top of the engine and work down: Spring oilers, whether built into the valve cover or in a valve cover spacer, keep rocker assemblies lubricated and cool in continuous high-RPM applications such as circle track, road racing, and marine use. Valvetrain oil deflectors redirect oil from the pushrods to the fulcrum balls, rockers, and springs to provide maximum lubrication and cooling, while oil restrictor kits reduce oil flow to the upper assembly, leaving more oil available for the rod and main bearings. The restrictors also combat power-robbing windage by reducing the volume of oil passing by the rotating assembly on its return to the oil pan,” says Schroeder.

Spring oilers help to keep a constant flow of oil to the valve springs, keeping them cool and well-lubricated, especially in endurance and other high-stress applications. These fabricated SBC covers from Moroso have the oilers integrated into the lower rail and feature restrictor jets to control volume.

With a 41-year-long model run for the small-block Chevrolet engine in all its iterations, it’s no surprise to learn that Moroso offers 59 different oil pans for the small-block Chevrolet engine. Some of these are vehicle-specific fitments for street-strip cars. Some are for all-out racing engines with aftermarket blocks and feature many enhancements like trap doors and strategically placed kickouts to assist in oil control. Still others have been developed in response to specific class rules in different racing circles.

LS Engines Offer Improvements

Conversely, the LS uses a pump mounted to the block face driven directly by the crankshaft keyway rather than the camshaft. This arrangement is more efficient than the camshaft-drive pump used in the SBC and reduces drag on the valvetrain since it no longer has to contend with turning the oil pump. Like the small-block, the LS engine design oils the main feed gallery and lifter bores before feeding the mains. Oiling is different between the two platforms, however. The LS incorporates a long pickup tube to get into the sump and a factory-installed windage tray to reduce inefficiency.

Factory-style LS oil pumps are driven by the crankshaft and remove some of the negatives of the traditional SBC oil pump.

However, the crank-driven pump design of the LS has positives and negatives. Since the pump turns at the same speed as the crankshaft, the oil can see cavitation when RPM rises to race-type levels. Oil control has always been an issue for the LS engine; the factory even cast windows into the block to help the oil pass around the bottom end quicker, but that has the unwanted effect of creating windage once the engine gets away from factory operating parameters. And if there’s one thing you don’t want in your engine oil, it’s air — because air doesn’t lubricate nearly as well as oil. Moroso offers 51 different pan designs for the LS platform to provide the end-user with the perfect design for the intended engine usage scenario.

The Moroso 22943 windage tray fits 15 different Moroso rear sump LS oil pans and works with ARP main cap studs. It captures the oil thrown by the rotating assembly and helps it drain into the sump.

Optimize The System To Provide Big Benefits

Whether you have a traditional small-block or an LS-based engine, classic oiling system tricks apply. Schroeder says that crankshaft scrapers, whether mounted in the oil pan or between the pan and block, do an excellent job of controlling windage by removing excess oil from the crankshaft. Similarly, a windage tray will capture the oil thrown from the rotating assembly and allow it to drain into the sump without splashing back on the crankshaft. This strategy improves horsepower and lowers oil temperatures.

Moroso recommends that its crankshaft scrapers be trimmed to within .045-inch of the crankshaft counterweights and connecting rods to get the best results. It will help to peel oil from the rapidly-rotating assembly and get it into the oil pan.

“We also recommend oil pans with a deeper sump to contain the oil down farther away from the rotating assembly. Trap door baffles in the sump keep the oil contained around the oil pump pickup during hard acceleration, deceleration, side-to-side movements like in road racing and drifting, or to the left side of the sump like in circle track racing. Lastly, oil pump pickups can be specifically designed to improve performance by how they are shaped to ingest oil from a certain oil pan area,” says Schroeder.

The baffle in the pickup of this pan is designed for a road racing application. There are trap doors on all sides of the baffle to trap the oil inside the baffle and ensure the engine has a constant oil supply.

These seemingly small changes to the oiling system can pay big dividends for engine performance. Several are more effective in all-out racing engines, but low-cost, high-reward crankshaft scrapers, windage trays, and trap-door baffles will benefit any engine.

Engine bearing clearances will be different depending upon the intended usage of the engine. Since we have previously covered the topic in great detail in this article, we won’t rehash it here.

Introducing The Dry Sump (Sorta)

GM engineers used a different plan in LS7, LS9, and Corvette Grand Sport engines to combat the aeration challenge. These use the same crankshaft-driven oil pump style as all other LS engines, but a hybrid external dry-sump configuration with a windage tray mounted under the crankshaft. In these engines, the pan catches the oil before it is scavenged into the external storage tank. Air is separated from the oil as it passes through the tank’s internal-baffle system; the gasses are passed back into the combustion chamber through the PCV system. Finally, the oil is directed through the filter, the external cooler, and back into the block. In this configuration, the pump contains two rotor sets — one rotor for the scavenge (suction) side and one (pressure) to supply clean oil back into the engine.

The external oil tank layout on these engines allowed GM engineers to remove the air from the engine oil while retaining the same basic configuration for the oiling pump and system.

“For 2021, Moroso has introduced four LS-specific external, dry-sump oil pumps. Each of these pumps mounts in the factory A/C bracket holes on the right side of the engine block and a front motor plate.  The external oil pumps we offer are a single and a two-stage, while the dry-sump pumps are a three- or four-stage design,” said Schroeder.

Dry sump oiling systems rely on an external pump (left) and a shallow pan (middle) whose only job is to catch the oil before it is scavenged out by the pump and delivered to an external oil tank (right) for de-aeration and return to the engine.

In Conclusion

It is important to remember that the oiling system’s performance is directly dependent upon the components used in a build and for the builder to determine the best course of action in that respect. High volume pumps can be a wise investment, but if the engine is on the mild side, it may be overkill and starve the bottom end of needed oil. It is critical to understand the planned usage for the engine and select parts according to that usage. Moroso’s technical staff can assist you with selecting the products that will prime your engine for success — whether you’re rolling old-school or new-school.

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About the author

Jason Reiss

Jason draws on over 15 years of experience in the automotive publishing industry, and collaborates with many of the industry's movers and shakers to create compelling technical articles and high-quality race coverage.
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