Oil Pumps

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“With a 4-, 5- or 6-stage dry sump setup, you can also separate the top and bottom of the engine, and pull oil out of each separately. This keeps oil from running down onto the crankshaft and increasing windage and drag. It also protects the bottom end of the engine if something in the top end breaks and fails,” says Mangus.

Wade Moon of Peterson fluid Systems says many racers are using 4-, 5- or 6-stage dry sump systems today so they can pull vacuum. “People are always asking for smaller pumps and lighter pumps. So we are introducing a new RPM (Radial Ported Modular) pump design that allows pumps to be easily stacked together in a modular fashion to build as many stages as you need. Each pump has its own shaft, and the shafts are splined so they will fit together when you stack the pumps. A new port profile in the pumps also improves oil flow at all engine speeds.”

Additional components that may be used in a dry sump oil system include an external remote mounted oil filter and/or inline oil filter screens, an engine oil cooler (a must for endurance racing), a control valve for adjusting oil pressure and flow, possibly an oil pressure accumulator (which helps with engine and turbo cool down after shut down, and helps prevent dry starts), and lots of plumbing and fittings (usually -10, -12 and/or -16 hoses and fittings).

Dry sump oil systems are not cheap, and can cost from $1,800 to $2,500 or more depending on the setup used. Some high end billet pumps can cost thousands of dollars, and custom tanks can be expensive to fabricate. Dry sump oil pans and setups are available for a wide variety of engines, even four cylinders and V6s, both domestic and import.

Late model Chevy LS1 through LS7 engines come factory equipped with a dry sump system. The stock setup is certainly adequate for street applications, but for serious racing the OEM setup can benefit from an aftermarket upgrade. Gary Armstrong of Armstrong Race Engineering makes a bolt-on replacement dry sump oil pan, external tank and scavenge pump for these engines to improve lubrication.

WET SUMP VERSUS DRY SUMP
Dry sump oil systems have a number of performance advantages over traditional wet sump systems, but they are expensive and they are not allowed in some forms of racing. The external components in a dry sump system also add weight, complexity and increase the risk of oil leaks and possible loss of oil pressure if a belt or hose fails.

For those who don’t need, can’t afford or are not allowed to use a dry sump oil system, the stock wet sump oil system can be upgraded to provide the required oil volume and pressure for many racing applications. This includes replacing the stock oil pump with an aftermarket performance oil pump (standard flow or high volume), and replacing the stock oil pan with one that features a windage tray, internal baffles and a deeper and/or wider sump area to contain and control the oil.

Mike Osterhaus of Melling says his company’s product line includes stock and performance cast iron pumps, performance aluminum pumps for late model engines such as LS Chevy V8s and modular Ford V8s, and wet sump performance billet pumps for racers.

“We’re actually seeing some circle track racers switch from dry sump oil systems back to our billet wet sump oil pump. It’s a lot less expensive than a dry sump system, it’s lighter, reliable and simple to install,” said Osterhaus.

Melling has redesigned the inlet port on their cast iron Chevy small block performance oil pumps to minimize cavitation and improve flow as the speed of the pump increases. This helps prevent a drop-off in oil delivery and pressure at higher rpms when lubrication is so critical. The pumps also have a shaft that extends all the way through the gears so the gears are supported at both ends. This prevents the gears from cocking under load and dragging against the cover, which costs horsepower and increases pump wear and internal pressure losses.

Melling makes both standard volume and high volume cast iron and CNC-machined billet aluminum pumps. The high volume pumps flow about 25 percent more oil than the standard version pumps. “We also have a high volume SB Chevy pump that puts out about 10 percent more oil than stock for racers who need a little extra flow, but not as much as our high volume pump puts out.”

New this year is a standard flow version of Melling’s billet racing pump for engines that don’t really need extra oil volume. With Dart aftermarket engine blocks, for example, the engine does not require as much oil flow as a stock block. So a standard flow pump works better.

In late model engines such as the Chevy LS series and Ford modular engines where the oil pump is mounted inside the front cover and is driven directly off the crankshaft, stock pumps tend to leak a lot of oil at higher rpms. “Some of these pumps look like a fire hose at 6,000 rpm,” says Osterhaus. “For these applications, we’ve redesigned the pump ports, tightened the clearances and hard anodized the housings and backing plate to improve the durability and performance of the oil pump.”

Vern Schumann of Schumann Sales & Service is introducing a new “Dual Feed” oil pump for Chevy small block circle track applications that is a “wet pump with a dry sump attitude.” The new pump has a second side inlet port that allows the pump to maintain oil flow at high rpm. The pump housing has been extended on the side to accommodate the second supply port, which provides oil at higher rpms when the gear teeth are passing by the primary supply port too quickly to fill the space between the gear teeth with oil. This can cause a drop-off in oil output and pressure at higher rpms.

“Our dyno tests have proven that this pump doesn’t suffer any loss of flow as engine speed increases, so the engine can’t outrun the pump,” says Schumann. The new Dual Feed pump will sell for around $100 (which is much less than a billet pump or a wet sump system).

Schumann’s new Dual Feed pump as well as his other pumps also use a spring-loaded steel check ball to control internal oil pressure instead of a cup valve. The check valve design won’t jam or stick like a cup valve can if the pump sucks in any debris.

The oil pumps also come with a choice of four different color coded springs so the bypass pressure can be adjusted by swapping springs. Removing a small screw allows the spring to be easily replaced. Schumann says he uses a $4000 digital spring tester to check the calibration of every bypass spring. “If the spring rate is not linear when the spring is compressed, we don’t use it. Bad springs can cause erratic oil pressure or a loss of oil pressure.”

Schumann’s oil pumps also have an external dump for the oil bypass, with a diffuser screen so the oil doesn’t splash up toward the crankshaft. The hole for the gear shaft is also beveled and has an oil supply groove and rifling inside the hole to lubricate the shaft.

Another interesting item Schumann makes are thin copper gaskets that fit between the oil pump and engine block in SB and BB Chevys. Stock pumps have no gasket here and can leak pressure and air.

Jim Bianca of Moroso says his company is introducing a new line of external dry sump oil pumps. The scavenging manifold is built right into the pump assembly, which simplifies the plumbing and installation. The pumps also have a more efficient design to pull more vacuum. “You can install this pump on the biggest drag motor and still pull 15 inches of vacuum in the crankcase.” Moroso also makes a wide variety of wet sump oil pans as well as wet sump oil pumps for small block and big block Chevys.

OTHER CONSIDERATIONS
Some racers use a vacuum pump to pull vacuum in a wet sump engine. The theory is pulling air out of the crankcase reduces windage and drag (which is one of the advantages of running a dry sump oil system). But in a wet sump engine, a certain amount of positive pressure created by blowby from the cylinders actually helps push oil toward the bottom of the oil pan and into the oil pump pickup tube.

So pulling vacuum may be counterproductive if the pump is starving for oil at high rpm. A better approach might be to use a full length solid windage tray under the crankshaft to keep the crankshaft from churning up the oil in the pan.

Another device that may be used with either a wet or dry sump oil systems is an oil pressure accumulator, such as the Accusump made by Canton Racing Products. An accumulator is essentially a self-pressurized auxiliary oil reservoir. Inside the tubular accumulator is a spring-loaded piston that traps oil pressure when the engine is running.

The compressed air behind the piston then pushes the oil back out of the accumulator to the engine if the oil supply is interrupted because the oil pump is cavitating or sucking air. The accumulator can also continue to supply oil to the bearings and/or turbo after the engine is shut off to help with cool down. It can also pressurize the oil system when the engine is cranked to prevent a dry start. Such a device can add an extra measure of insurance to any oiling system.