What “dry sump” means in engines

A dry sump is an engine lubrication system that stores oil in a separate external tank and uses scavenge pumps to remove oil from a shallow pan, ensuring consistent oil pressure and preventing starvation during high g-forces. In contrast to a wet sump, which keeps oil in the bottom of the engine, a dry sump relocates the reservoir to improve reliability, performance, and packaging in demanding applications.

How a dry sump system works

In a dry sump setup, oil that drains into a shallow sump pan is quickly pulled away by one or more scavenge pumps. That oil—often mixed with air—is sent to a remote reservoir where it is de-aerated and stored. A separate pressure pump then feeds clean, pressurized oil back to the engine’s bearings, valvetrain, and other critical components. By rapidly evacuating oil from the crankcase, the system reduces oil windage around the rotating assembly, can maintain slight crankcase vacuum for efficiency, and delivers consistent lubrication even under sustained acceleration, cornering, braking, or steep inclines.

Key components of a dry sump

Dry sump systems include several specialized parts that work together to move, de-aerate, store, cool, and filter oil reliably under extreme conditions.

• Scavenge pumps: One or more stages that pull oil (and air) from the crankcase and timing/valve areas.
• Pressure pump: A dedicated stage that sends conditioned oil from the tank to the engine’s oil galleries.
• External oil tank: A baffled, vented reservoir designed to de-aerate oil and maintain a stable supply.
• Shallow sump pan: A low-profile pan that collects oil briefly before scavenging; minimizes windage and ground clearance issues.
• Oil cooler (common but optional): Helps control oil temperatures during sustained high load.
• Filters: Often both pressure-side and scavenge-side filtration for debris control.
• Hoses and fittings: High-quality, heat- and pressure-rated lines with secure fittings to prevent leaks.
• Pressure relief/regulation: Valves to manage system pressure and protect components.
• Breather/air-oil separator: Manages crankcase ventilation and reduces oil carryover.
• Check valves/anti-drainback devices: Prevent reverse flow when the engine is off.

Together, these components create a controlled, closed-loop oiling system that excels in environments where a traditional wet sump can struggle.

Dry sump vs. wet sump

Wet sumps store all engine oil in a deep pan beneath the crankshaft and rely on a single pump to pick up oil from that pan. Under extreme g-forces, oil can slosh away from the pickup, risking pressure drops. Dry sumps move the reservoir out of the engine, keep only a minimal amount of oil in the pan, and employ multiple pump stages, which greatly reduces aeration and starvation and allows more flexible engine placement and improved performance.

Advantages

Dry sump systems offer multiple performance and reliability benefits, particularly in motorsport and high-demand use.

• Oil pressure stability under high lateral, longitudinal, and vertical loads.
• Reduced windage losses, which can free up horsepower and improve efficiency.
• Lower engine mounting height for a lower center of gravity and improved handling.
• Greater oil capacity and better thermal management with external tanks and coolers.
• Improved de-aeration for more consistent lubrication film strength.
• Potential for controlled crankcase vacuum, reducing blow-by and oil foaming.
• Enhanced durability for endurance racing, track days, and sustained high-load operation.

These benefits make dry sumps the preferred choice when consistent lubrication and packaging flexibility are critical.

Trade-offs and drawbacks

Despite clear advantages, dry sump systems add complexity and cost compared with conventional wet sumps.

• Higher cost for pumps, tank, plumbing, and control hardware.
• Added complexity and potential points of failure or leakage in lines and fittings.
• Slight weight increase from additional components (though offset by performance gains).
• More involved maintenance and stricter service procedures.
• Longer warm-up times due to larger oil volume and external plumbing.
• Packaging space required for the external tank and cooler.

For everyday use, a well-designed wet sump is usually sufficient; dry sump systems shine when margin and performance matter most.

Where dry sumps are used

Dry sump lubrication appears wherever sustained g-forces, reliability, and packaging flexibility are essential, from professional racing to select road and aviation engines.

• Motorsport: Track and endurance cars routinely use dry sumps to prevent oil starvation.
• High-performance road cars: Examples include many Porsche 911 GT models, Chevrolet Corvette Z06/ZR1 (various generations), Mercedes-AMG GT, and supercars from Ferrari and McLaren.
• Motorcycles: Certain performance and heritage models (e.g., traditional Harley-Davidson Big Twins) employ dry sumps.
• Aviation: Numerous horizontally opposed piston aircraft engines (e.g., Lycoming and Continental) use dry sump systems for reliability and packaging.
• Off-road and marine: Applications with steep angles or sustained load benefit from reliable oil pickup.

In each case, the dry sump addresses oil control challenges that a wet sump cannot reliably manage under those operating conditions.

Maintenance and ownership notes

Because dry sump systems are more complex, following the manufacturer’s procedures is critical to reliability and longevity.

1. Check oil level according to the specific procedure (often at operating temperature, shortly after shutdown or at idle).
2. Prime or bleed the system after oil changes or component replacement to avoid dry starts.
3. Inspect hoses, fittings, and clamps regularly for leaks, abrasion, or heat damage.
4. Service all filters (pressure and any scavenge-side screens) at recommended intervals.
5. Use the specified oil grade and quality; many dry-sump engines have strict oil requirements.
6. Monitor breather/air-oil separator function and any catch tank for excessive accumulation.
7. Verify cooler and thermostat operation (if fitted) to ensure proper oil temperature control.

Adhering to these steps helps preserve the system’s advantages while minimizing risk from the added complexity.

Terminology and common misconceptions

“Dry sump” doesn’t mean the engine’s sump is literally dry; a small amount of oil is always present in the shallow pan before scavenging removes it. Some manufacturers use “integrated dry sump” designs with multiple internal scavenge stages and a separate reservoir within or attached to the engine assembly. Also, devices like an Accusump (an auxiliary pressurized reservoir) are not the same as a true dry sump—they can help buffer pressure in a wet-sump system but do not replace the external tank and multi-stage pumps of a full dry sump.

Summary

A dry sump is a high-performance lubrication system that relocates oil storage to an external tank and uses multi-stage pumps to ensure steady oil pressure, reduce windage, and improve engine packaging. It’s common in racing, aviation, and select high-performance road and motorcycle engines. While it adds cost and complexity, a dry sump delivers superior oil control and reliability when conditions push beyond the limits of a conventional wet sump.

What is the point of a dry sump?

A dry sump does the following:

1. Keeps the engine from running dry during high-G maneuvers Opens in new tabby supplying oil from a remote reservoir, even if the sump is empty or uncovered. 
2. Lowers the vehicle’s center of gravity Opens in new tabby allowing a shallower oil pan, which enables the engine to be mounted lower. 
3. Reduces internal engine friction Opens in new tabby keeping the crankcase at a vacuum, which prevents the spinning crankshaft from churning oil into a frothy mixture. 
4. Increases oil capacity Opens in new tabto provide better cooling, lubrication, and engine longevity. 

How it works
A dry sump system uses two main pumps and an external reservoir instead of relying on a single pump and an oil pan. 

1. Scavenge pumps: remove oil from the engine’s sump and any other areas of the crankcase. 
2. A remote reservoir: (or tank) stores this scavenged oil. 
3. A pressure pump: then takes the oil from the reservoir, sends it through a filter, and forces it under pressure back into the engine to lubricate the parts. 

What’s the difference between a dry sump and a wet sump?

A wet sump system stores engine oil in an oil pan at the bottom of the engine, while a dry sump system uses an external reservoir and multiple pumps to store and circulate oil. Wet sumps are simpler and cheaper, found in most cars, but can suffer from oil starvation during aggressive driving. Dry sumps provide superior oil control, allow for a lower engine placement, and reduce crankcase windage, improving power but at the cost of increased complexity, weight, and expense.
 
Wet Sump System

• Description: The oil is stored in a large pan beneath the engine, which serves as a reservoir. 
• Operation: A single pump picks up oil from the pan and circulates it through the engine. 
• Pros: 
  • Simpler and Cheaper: Less complex and more affordable. 
  • Common: Used in the vast majority of street vehicles. 
• Cons: 
  • Oil Starvation: During hard cornering or acceleration, oil can slosh to one side of the pan, leading to temporary loss of lubrication. 
  • Higher Oil Pan: The larger oil pan restricts engine placement. 

This video explains the difference between wet sump and dry sump systems: 59sEngineering ExplainedYouTube · Jan 4, 2017
Dry Sump System

• Description: The oil is stored in a separate, external reservoir. 
• Operation: An external pump draws oil from the shallow engine sump and sends it to the reservoir. A second pump then sends pressurized oil from the reservoir to the engine’s lubrication points. 
• Pros:
  • Improved Oil Control: Prevents oil starvation by keeping the reservoir separate. 
  • Lower Engine Placement: A shallow oil pan allows the engine to sit lower in the chassis, improving the center of gravity. 
  • Increased Power: Reduces windage and improves ring seal for better performance. 
• Cons: 
  • Higher Cost & Complexity: More components and a complex system add to the cost. 
  • More Maintenance: Additional pumps and lines require more maintenance. 

Which is Right for You?

• Wet Sump: Opens in new tabIdeal for most street vehicles where budget and simplicity are primary concerns and extreme driving conditions are not common. 
• Dry Sump: Opens in new tabEssential for high-performance applications, such as racing, where maximum power, reliability, and superior oil control are critical. 

What are the disadvantages of dry sump?

Here are the main cons:

• Additional cost.
• Systems are complex.
• Added weight.
• More oil and maintenance are required.
• Drivability issues with an improper setup.
• Difficult to fit equipment into a small engine bay.
• Requires a dedicated drive belt, which can be an issue with a front-wheel drive car.

Is a dry sump system street legal?

In short, yes. Running a dry-sump system is a perfectly streetable solution, and frankly, a lot of manufacturers sell their high-performance and sports cars with dry sump systems straight from the factory.