Choosing a spare oil pump for the engine you are manufacturing or modifying is a process to consider. Original equipment oil pumps can usually meet the needs of most inventory applications, but some pumps cannot meet the demand, especially when the engine is modified to provide more power or RPM, or to better match with heavier racing oil ( For example, 15W) compatible, if the stock bearing clearance is changed, -40 or higher) or a more dilute synthetic motor oil (eg 0W-20, 0W-40 or 5W-20).

The oil flow and pressure generated by the oil pump need to be closely matched to the application. The rule of thumb in the past is that an engine of 1000 rpm requires an oil pressure of about 10 PSI, which is still effective for many ordinary engines and many improved engines, but there are exceptions. Rotating the oil pump requires power, so the greater the flow and pressure generated by the oil pump, the greater the power drawn from the engine.

Most engines do not require much oil pressure at idle speed. In some cases, ten to fifteen PSI or less is sufficient to keep the bearings, cams, and valve mechanisms lubricated. The meter reading of 30 PSI when it is idle looks good to many people, and some people want to see higher numbers. But most engines do not need that much pressure at idle or low RPM. This wastes effort and energy.

Of course, the NASCAR engine does not need to spend much time idling, and in most cases it runs at high speeds. Therefore, the output volume and pressure of the pump can be minimized to deliver enough engine oil to keep the engine lubricated without wasting too much power to drive the pump.

In contrast, street motors idling and running at low speeds take a lot of time, so the oil pump must provide good flow and pressure at all engine speeds. On street motors, the consumption of parasitic power is no longer a problem, so this is why many street pumps are set to over-fuel the engine. Most people think it provides additional protection against oil pressure drops that could damage the engine.

1. Large capacity pump

Some people use large capacity pumps to "repair" low idle oil pressure and/or valve train noise. High-capacity pumps can of course be used for such purposes. However, if the engine idling oil pressure problem and/or the valve mechanism noise is low, there are other problems that need to be solved, such as loose or worn bearing gaps, and pressure loss inside the oil injection system itself, which may limit the oil flow of the upper valve mechanism Or the valve mechanism components are worn.

For example, on a high mileage Ford 5.4L engine, the wear of the VVT ??cam phaser can be set with the cam timing code and turned on
"Check engine lights." Replacing the crude oil pump with a large-capacity pump can maintain good oil flow to the cam phaser and eliminate coding.

On the Chevrolet LS engine with active fuel management, replacing the reserve pump with a large-capacity pump can eliminate the valve drive rattling caused by the lowered valve lifter after a cold start. GM’s solution to this problem is to redesign the lifter, but the cost of replacing the lifter may exceed $1,700-therefore, replacing the oil pump is usually a more economical solution for cold-start valve mechanisms.

Large-capacity oil pumps have higher gears, usually about 15% to 20% more oil than similar oil pumps. In some applications, high flow pumps are absolutely essential. Many of the latest models with deactivated cylinders (such as Chevy LS 5.3L and 6.0L V8 engines, and Chrysler 5.7L Hemi engines) and VVT engines require more oil flow from the lifter and cam phaser, so these parts Can work normally.

If you want to build a high-performance engine with a small clearance (for example, the 20W-50 racing oil in the main bearing and connecting rod bearing is greater than .0025?), then a large-capacity oil pump is also required. On the other hand, if you are going to build an engine with tighter main bearing and connecting rod bearing clearances, the engine will not require that much oil and the reserve pump should be able to work normally.

2. Limitations of stock pumps

One of the limitations of all oil pumps is the cavitation problem. At a certain speed, the rotation speed of the gears in the pump will be faster than the speed of oil inflow and through the pump. When this limit is reached, small bubbles or voids are formed along the rear edge of the gear, which is called cavitation. This will inflate the oil and cause the pump output to flatten or drop. For many common straight-cut double spur gear oil pumps, cavitation occurs when the engine speed exceeds 5000 RPM. For cycloidal oil pumps installed in the front or crankcase, cavitation may occur at higher speeds.

Cavitation is obviously something to be reduced or avoided because it leads to the potential risk of a drop in oil pressure and a reduction in oil flow on bearings and valve trains. Oil pump manufacturers have developed various pump designs that can reduce cavitation at higher engine speeds. One such technique is to expand the inlet of the oil pump and use a larger diameter suction pipe (for example, 3/4 inch instead of 5/8 inch). This makes it easier for oil to flow into the pump to keep up with the increase in gear speed. Another modification is that some racing pumps divide the intake air flow into two channels and distribute half on each side of the gear.

Oil leaks inside and outside the oil pump are other issues that may damage oil flow and pressure. Worn pumps or pumps with irregular internal gaps are obviously not as efficient as new pumps with smaller gaps. The pump requires a certain internal clearance to accommodate thermal expansion, so the pump will not be constrained when it gets hot, but you don’t want the gap between the gear, housing and end plate to exceed .003 to .004?, otherwise, the internal inside the pump The pressure loss will be too great.

The tolerances of some OEM oil pumps may vary greatly. Chevrolet LS oil pumps are notorious for having large gaps, which can cause low hot idle oil pressure problems. The inventory of Chevrolet small and large gasoline pumps is even very different.

On small Chevrolet oil pumps, the acceptable tolerance is usually .003 to .005? between the teeth on the spur gear and the housing, and .003? between the gears. The end gap between the top of the gear and the cover plate (with washers) can be 0.002 to 0.0006?.

Obviously, the smaller the gap, the better the pumping efficiency. When the pump and engine oil become hot, there must be a gap to compensate for thermal expansion, but the gap should not be too large to avoid excessive leakage between the gear and the housing. Ideally, the tolerance of the new oil pump should be within the tight end of this range (0.003? between gear and housing, 0.002 to .0025? between gear and cover).

Unfortunately, some brand-new pumps are not even within the allowable tolerances, especially many low-cost and economical pumps from offshore suppliers. Regarding some of these pumps, the only thing you can say is that they are always inconsistent. One pump may be measured exactly in the middle of the tolerance, while the other will exceed specifications. Never think that a brand new pump is a compact pump that can be started and pumped effectively. Always use a feeler gauge to check the gap to ensure a good pump.

Some people will buy a small batch of new pumps, disassemble the pump and choose to install internal parts to minimize gaps. By carefully mixing and matching the gears and housing to "design" the backup oil pump, the oil flow and performance can be optimized. However, what should you do if the remaining parts are too loose to assemble the pump?

The sloppy end gap can be cleared by lowering the surface of the housing (or covering the top surface of the gear if there is insufficient clearance). However, in addition to plating or coating the inside of the pump casing, you do not need to take any other measures to tighten the gear to the casing gap.

The mold grinder can be used to carefully deburr, shape and mix the oil inlet and outlet. This can improve the flow of oil into and out of the pump. However, a better approach is to select a high-performance oil pump whose performance has been redesigned to obtain the best flow.

Compared with the crankcase oil pump, the Chevrolet LS, Ford modular engine and new Chrysler Hemi and other front-mounted oil pumps have certain advantages and disadvantages. On the bright side, they are all gear rotor pumps, and their flow characteristics are better than double straight tangential gear pumps. The front pump is also driven directly from the crankcase, which means it rotates at the engine speed, or twice the speed of the crankcase pump, which is driven by the shaft connected to the camshaft or distributor. No drive shaft will bend, twist, bend or break, and will not affect the spark timing of the engine using the distributor.

One of the disadvantages of the front-mounted oil pump is its high installation location and dryness. When the engine is turned off, the oil is often drained from the pump quickly, allowing the pump to dry for the next start. The pump also has a long suction tube that can be connected to the oil in the oil pan. Therefore, the front pump needs a longer time to self-priming and generate oil pressure after cold start, especially for oil with higher viscosity. In contrast, most pumps mounted on the crankcase are at least partially immersed in oil. This helps keep oil in the pump when the engine is off, and makes self-priming and build-up of oil pressure faster and easier when starting a cold engine. Because of these differences, front pumps usually work best when using lower viscosity motor oils, larger diameter suction pipes, and less restrictive inlet screens.

The front pump may also be difficult to align correctly. If the center of the crankshaft is not fully aligned, the pump ears will be slightly offset when the engine is started. In some cases, this may wipe the pump casing or even break its mounting bolts. When installing the pump, use a spacer to center the pump gear on the crankshaft. One suggestion is to turn the engine upside down so that it can be placed on the flywheel before installing the pump. If you don't do this, the crank will fall to the bottom of the main hole of the cylinder, making it off center. If the crank of the oil pump is then installed in this position, when the oil pressure lifts the crank from the main bearing surface, the oil pump will no longer be centered, which may damage the oil pump. If the engine is in a vehicle and cannot be fixedly installed, another suggestion is to loosely install the pump on the crankshaft, rotate the engine several times to center the pump, and then tighten its mounting bolts to secure it in place. .

Another problem with front pumps is oil leakage between the pump housing and its cover. Many OEM front oil pumps have fragile stamped steel covers. As the oil pressure increases at higher engine speeds, the cover will bend and bend away from the pump, causing the pump to spray oil out of the side of the housing. This causes a significant drop in oil flow and pressure. Some aftermarket oil pump suppliers use harder, more durable cast iron covers for many of these front pumps to greatly reduce or eliminate such leaks.

The pump mounted on the crankcase will also leak pressure where the pump bolts to the main cover or cylinder block. In most inventory applications, there is no gasket between the pump and the engine. If the processing degree of the processed surface is not ideal, a small gap will be left, which will leak oil and pressure. The solution is to install a thin copper or metal gasket between the pump and the engine to provide a leak-free connection.

3. New oil pump innovation

Recently, some innovations have been made in the design of oil pumps, which have solved many basic problems that plague traditional oil pumps. The dry oil pan system with external oil reservoir, vacuum pump and pressure pump are the ultimate settings for high-performance applications and racing cars. These systems eliminate most of the worries about oil shortages caused by the oil sloshing from the oil pickup in the oil pan. The dry oil sump system draws out oil and delivers it to the external oil tank, so the pump always has a stable oil supply. The dry oil pan using a series of vacuum pumps can also draw enough air from the crankcase to eliminate wind resistance, resistance and aeration of engine oil. However, dry sump systems are very expensive compared to wet sump systems and require a large number of external pipes.

One way to solve this problem is to develop a hybrid wet/dry header tank system. The system uses a scavenging pump to draw oil out of the oil pan, just like a dry oil pan system. The oil is sent to the external tank, but then it is sent back to the oil sump sump, so the front-mounted oil pump can send it to the engine. Corvette's LS7 hybrid unit can drain oil from the crankcase to reduce wind resistance and resistance, while the external oil storage tank can provide a stable oil supply for the pump. However, when turning is extremely difficult, the G-force sometimes forces the oil in the oil storage tank to flow upward and away from the pipeline connecting the oil storage tank and the oil pan, resulting in an instantaneous oil shortage. As a result, more than one Corvette racer blew the engine. The redesigned oil reservoir with improved baffle solves this particular problem.

The traditional wet bottom oil pump is also constantly developing. Oil pump suppliers have been working hard to improve their products in order to provide better performance and more reliable operation. These include design changes to reduce cavitation at higher engine speeds, as well as improvements to the oil pump's flow characteristics, pressure pulsations, and output.

4. Pump replacement and installation

When rebuilding high mileage, it is always recommended to use a new oil pump. Slotted end caps will leak internally and prevent the pump from reaching its normal flow and pressure. Re-dressing the end cap to restore the new tolerance is of course an option, but re-dressing cannot restore the wear of the housing or gear.

If high flow and/or high pressure pumps are not needed, they are not needed. If the bearing clearance of the engine is within the normal specification range and not too loose, most engines can work well with the reserve flow pump.

If the engine requires additional flow and/or pressure due to the need for an external oil cooler, a piston oiler, or a valve mechanism that requires additional fuel, it is recommended to use a large capacity oil pump. It is also recommended to use a more robust pump drive shaft because it increases the oil flow and increases the load on the pump.

If you have been worried about pump damage or reliability in the past, billet pumps are a good upgrade option. Thicker casings and stronger materials for billet pumps can usually eliminate any concerns about pump damage. Due to the larger casing and external clearance issues, some billet pumps may require a special oil pan.

Crimping straws for racing applications should be brazed to the pump casing to avoid loosening. If you have not brazed the copper tube to the pump and you do it yourself, make sure to remove the hydraulic bypass spring and valve before heating the pump casing. Another option is to switch to a bolt-on sound tube.

Finally, fill the fuel pump before ignition to prevent any unpleasant start-up accidents.

The  Oil Pumps    works by circulating oil under pressure to the engine's rotating bearings, sliding pistons and camshafts. Large-capacity fluid bearings can be used to help cool the engine. Zhejiang Yongling Hydraulic Machinery Co., Ltd. is a professional hydraulic pump manufacturer and hydraulic pump supplier in China that produces oil pumps and    Vane Pumps Cartridge Kits   . Has a provincial-level high-tech enterprise research and development center. Our products are widely used in cutting, plastics, forging, engineering, leather, pressure, metallurgy, agriculture, transportation machinery and machine tools, hydraulic stations, automatic production lines, etc. Follow us to learn about product details and technical information: https://www.china-vanepump.com/product/sqp-series-vane-pumps-with-lower-noise/sqp1-vane-oil-pump-with-lower -noise.html