The Science of Oiling Systems in Performance Engines - Engine Builder Magazine (original) (raw)

Insert whatever cliché about oil and oiling systems you want. They’re cliches for a reason, and it’s true – the oiling system is arguably the most vital aspect of the engine. Oil does more than just reduce friction – it lubricates bearings, cools hot spots and cushions high-load surfaces. But under the extreme G-forces, rpm and temperatures of competition, the job gets far more complicated. Starvation, foaming, aeration, and pressure fluctuations can spell disaster if the oiling system isn’t designed with precision.

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To dig deeper into how modern oiling systems are engineered, we spoke with a few oil system and oil pump manufacturers to get their insights. They highlight both the fundamentals and the advanced strategies engine builders should consider when spec’ing a system for performance use.

Wet vs. Dry Sump: Choosing the Right System

Although dry sump systems often get the headlines in professional racing2he reality is that 98% of production-based race cars still use wet sump systems. This includes everything from SCCA and NASA track cars to grassroots circle track and drag racing. Even factory performance platforms like the Mustang, Camaro, Charger, and BMW M series rely on wet sumps.

The reason is simple – wet sumps work. It’s not always necessary to go with a dry sump system, and in many cases, the space just isn’t there under the hood. But, with a wet sump, it can be tuned. It’s a tunable part of the car, and it can be made to perform for the application.

Dry sump conversions become essential only in certain scenarios such as sustained high rpm (above 8,000), long-duration endurance racing, marine engines, and some circle track platforms where G-forces can starve a wet sump. For most builds, however, properly tuned wet sump systems are more than sufficient, and far more cost-effective.

Oil Capacity and Temperature Control

One of the first factors to evaluate is oil capacity. Stock pans on older small block Chevys and Fords typically held around 5 quarts. Popular imports like Subaru and Toyota four-cylinders hold around 5.3 quarts, while a Honda A-series pan is about 4.4 quarts. But modern performance engines have trended toward larger capacities. Chevy LS engines run 5-6 quarts, the C5 Corvette carries 6.5-7 quarts, and the Gen II Coyote requires about 8 quarts.

The more oil in the system, the more opportunity you have to scavenge and the less chance the oil runs scarce. That extra oil volume also stabilizes temperature. A larger pool absorbs heat better, spreads it out and helps preserve viscosity, which is critical for scavenging and lubrication.

Of course, simply overfilling a stock pan isn’t the answer. Excess depth can cause the crank to “swim” in oil, sapping horsepower. The solution is a smarter pan design, such as T-sump pans that increase volume without creating ground clearance issues. These designs are particularly popular in chassis cars that can’t accommodate deep pans.

Baffling, Windage and Pickups

Oil control inside the pan is just as critical as capacity. Road race and drift applications experience lateral forces in every direction, while circle track builds see constant side-loading, and drag racing is dominated by acceleration. Each discipline requires a tailored baffling system.

Baffles, trap doors and directional control panels help keep oil around the pickup. But pickup design and placement must match the pan and baffling. Pickups are meant to fit inside and position correctly into that baffling system. The goal is scavenging from the center of the baffle so the pump is constantly fed.

Most pickups use 5/8ths tubing, though some step up to 3/4” to support higher rpm and volume pumps. Tube diameter plays directly into cavitation risk. You can only pull as much as atmospheric pressure allows. If you try to bring too much volume through too small a tube, you’ll see cavitation.

Proper clearance of the pickup is also key – about 3/8ths to 1/2” between the pickup and pan floor is typical, depending on gasket stack-up.

Windage trays add another layer of control. They strip oil off the rotating crank and redirect it into the sump, reducing parasitic drag. Screen trays often show the best results on a dyno because they excel at removing oil film from the crank. However, louvered trays create a more solid barrier, making them superior in violent applications like road racing or off-road where splash back is severe. Either way, the payoff is reliability and measurable horsepower gain.

Pump Design: Flow vs. Pressure

The oil pump is the heart of the system. As such, it’s important to separate flow from pressure. The pump provides flow, while the engine’s internal clearances dictate pressure. Wide bearing clearances lower pressure, but demand more volume. Tighter clearances raise pressure and require less flow. Add in parts like piston squirters or oiling lifters and the demand goes up further.

An engine with wider bearing clearances or additional oiling features will require a higher volume pump. Too much pump, however, raises pressures unnecessarily and creates more heat. Too little pump results in low pressure and loss of hydrodynamic lubrication.

The type of power adder also influences pump choice. Naturally aspirated engines can run tighter clearances, but boosted or nitrous-fed combinations see higher cylinder pressures and often require looser bearing clearances. The added oil film acts as a cushion under shock loading, which in turn requires more flow from the pump.

Advances in Pump Technology

In recent years, oil pump technology has advanced significantly. Melling’s helical asymmetrical gears improve efficiency and reduce noise, while billet aluminum housings save weight and incorporate integral pickups. Aluminum housings are hard-coat anodized for surface hardness and wear resistance. Cast housings are also treated with protective coatings to minimize wear during dry starts.

At Schumann’s Sales & Service, where wet sump oil pumps have dry sump attitudes, they’ve been focused on forged and billet aluminum housings, as well as gear rotor GPB (gear pressure balance) technology, GPM flow and improving gear-to-gear pumps with a paddle wheel gear.

The paddle wheel gear incorporates cup cavities in the idler gear that shoot oil at high velocity to the outlet of the pump. The cups move oil about two to three times faster in feet per second at the same gear rpm. You’re using less horsepower to move the oil, and the pump’s output can better keep up with engine rpm.

These various options, innovations and improvements in pump technology still rely on the customer’s budget, the engine and oiling system packaging and how extreme the engine’s duty cycle will be.

Crankcase Windage and Aeration

Perhaps the most dangerous enemies of an oiling system are windage and aeration. An oil pump cannot pump air, after all. Windage keeps oil suspended around the crank instead of letting it drain back to the pan. Aerated oil might reach the sump, but once full of bubbles, the pump can’t build stable pressure.

The result is oil starvation, pressure fluctuation, and in worst cases, catastrophic bearing failure. Preventing aeration comes back to the fundamentals – proper baffling, pan capacity, windage control, and matching the pump and pickup to the application.

Oil System Accessories: Cooling and Accumulators

Beyond pumps and pans, accessories can significantly improve system performance. Oil coolers and heat exchangers keep viscosity in check, reducing breakdown at high temperatures. At Canton Racing Products, they’ve been touting the Accusump oil accumulator.

The Accusump is like an insurance policy. It stores additional oil under pressure and discharges it the instant the engine sees a pressure drop. That surge of oil can prevent the wear and hot spots caused by even a momentary loss of flow. Available in different sizes, the Accusump uses a piston design with oil on one side and compressed air on the other, ready to deliver oil when the system demands it.

Application-Specific Tuning

Every racing discipline places unique demands on the oiling system. Like many other areas of the engine, the oiling system can be “tuned” to fit a specific application.

Drag racers often prefer lower-volume pumps paired with lighter viscosity oil to free up horsepower, since runs are short and cooling demands are limited. Circle track and endurance builds on the other hand, need higher-volume pumps and larger-capacity pans to maintain stable pressure and temperature over long duty cycles. Marine applications similarly require robust flow for extended high-rpm use.

The lesson is that the oiling system can be thought of as a fixed orifice. Builders must match the pump to the engine’s actual demand, not just install the biggest pump they can find.

The most common oiling failures in high-horsepower builds include starvation from poor pan design, cavitation in pickups, aeration from inadequate windage control, and mismatched pump volume. Overlooked factors often include the total oil demand of the engine once bearing clearances, squirters and accessories are considered.

Too much pump can be just as problematic as too little – creating excessive pressure, added heat and wasted energy. The sweet spot is a system that consistently maintains safe minimum pressure without consuming unnecessary horsepower.

Conclusion

The oiling system is not just a pan, or a pump, or a tray – it’s a holistic design that must be tailored to the engine and its intended application. Whether the build is a grassroots bracket racer with a wet sump, a road race car with a baffled T-sump, or a high-rpm endurance machine that justifies a dry sump, the principles remain the same: maintain pressure, control windage, manage temperature, and match flow to demand.

If you can address oil volume, baffling, windage, your pump and pickup selection, plus accessories like coolers and accumulators, you’ll have a system that prevents low oil pressure situations and frees up horsepower.

For engine builders, it’s a reminder that oiling systems deserve the same engineering attention as any other part of the build – because it’s the one system every other component depends on. EB