Upgraded Water Pumps Cars Trucks Performance Racing OffRoad Motorhomes

Upgraded Water Pumps Cars Trucks Performance Racing OffRoad Motorhomes

Upgraded High Flow Water Pumps for Cars, Trucks; Performance, Racing, Off Road, and Motorhomes

 RACING & PERFORMANCE high-flow water pumps for racing, high performance, off-roading, Jeeps, GMs, Chevrolets, Fords, Chryslers, Pontiacs, Trucks, Towing, Motorhomes, Street Rods, 4X4s.

Edelbrock cutaway

This water pump cut-away from Edelbrock Performance shows the improved passages that allow balanced flow to both sides of the engine, the double high-grade bearings and the computer designed impeller that eliminates the dreaded cavitation syndrome.

How high can I rev my stock water pump? Will my engine run better with a high-performance water pump? Should I install a high-performance water pump on my tow vehicle, street rod, or motor home? Does Edelbrock make high flow water pumps for LS engines? Can water pumps increase the power output at the rear wheels? How much power does a water pump use? How much power can I save with a racing water pump like one from Edelbrock? What should I know about automotive water pumps?



O.E.M. parts are made for street use and not for racing or heavy-duty use;  water pumps are no exception.                                                                                                                      

The folks at Edelbrock are into their third generation of performance and racing engine manufacturing. They build their performance and racing water pumps from scratch instead of modifying OEM ones. Engineers design all the parts of their pumps from the castings to the seals to accept high temperatures, pressures, and the RPM encountered in racing and high-performance.   



Water pumps are relatively simple components but pushing them beyond their design limits can be as catastrophic to an engine as running out of oil or water. Stock water pumps do not pump enough water for racing, and they are overstressed in heavy-duty operations such as towing, off-roading, street rods, and motor homes. 

 Much like choosing any other part of a street, performance, or racing car, choosing a purpose-made water pump aims high at achieving reliability and high performance.

Stock pump
Your Grocery Getter may be happy with an auto parts store pump, but when pushed beyond its design parameters, the stock water pump is overtaxed and it fails. Image from ASC Industries.




Water pumps are composed of five essential components:

  1. The housing typically bolts to the engine block, and it houses all the pump components.
  2. The hub, mounted on the shaft, accepts a pulley and a fan.
  3. The pump shaft supports the hub. 
  4. The impeller rides at the end of the shaft.
  5. The shaft rides on roller bearings that must be perfectly aligned to avoid flexing of the shaft.
  6. Seals and gaskets retain the coolant inside the pump.



Your water pump is called upon to flow the coolant through the engine (the heat source) where it can pick up excess heat and transport it to the radiator (heat exchanger). Then, the radiator tubes and fins (the heat sinks) transfer the heat to the air. This transfer should be done as effectively as possible with low power loss and with high pressure and flow.

The flow from the water pump meets the radiator, the thermostat, or the restrictor, which pressurizes the water in the engine [in addition to the pressure created by the expansion of water] to keep the boiling point in the motor as high as possible. This pressure also pushes the coolant against the radiator tube walls to improve heat dissipation. The pressure shrinks down the steam bubbles that may be present in the casting imperfections, especially over the combustion chambers and the exhaust ports.



You see, in the heads, above the hot combustion chambers, and around the hotter yet exhaust ports, localized boiling can occur, particularly within the irregularities of the casting surfaces.  This process, known as nucleate boiling (https://www.youtube.com/watch?v=LSR-n2kDlVI) does not necessarily have an adverse effect at low engine speeds, but if left unchecked, at higher RPM, it can create some serious problems. Since air does not absorb or release heat as well as water, the air bubbles can form hot spots and detonation, and loss of power ensues. Problems start when nucleate boiling morphs into film boiling, where the bubbles converge to form a film of steam. This process, “Departure from Nucleate Boiling” (http://en.wikipedia.org/wiki/Nucleate_boiling), can be so violent that it can crack cylinder heads and blocks.


Heat transfer

This drawing illustrates the importance of pressure in the cooling system. Notice that boiling is not necessarily a problem. It is when the temperature reaches the nucleate point that vapor bubbles explode. Since steam does not gather heat as efficiently as water, the surfaces above the combustion chambers do not cool properly, and the engine may experience pre-ignition. The forces dissipated by the explosions can create cracks and blown head gaskets. At the same time, the ECU retards the timing, and it modifies the fuel delivery curve, reducing power and fuel efficiency.


AFCO double pass radiatorModern performance and racing radiators like the one in this picture from AFCO Racing are of the double-pass design where the water flows twice through the radiator to produce additional coolant pressure.                                                 


Stock pump

Stock water pumps are not precision pieces. The impellers are typically stamped bent-over paddles. Furthermore, auto parts pumps' bearings are inadequate for high-performance requirements. Racing/performance pumps sport O-ring seals that negate the need for sealant.



The impeller in the water pump is responsible for creating the flow; then, the radiator recreates pressure with the turbulators inside the tubes. Getting the most work from the impeller is the key to having an efficient pump and cooling system. When over-revved or when the impellers wear out a water pump cavitates.

Edelbrock impeller

Purpose made performance racing water pumps contain precision-cast powdered-metal impellers with extra-large vanes maximize the flow rate and ensure adequate pressure and volume even at lower engine speeds. This type of impeller allows running super tight clearances that improve flow and pressure. Those clearances and tolerances are closely guarded secrets. Photo courtesy Edelbrock       















PoPower is heat, and heat is power.

You may recall the V8s built in the '60s and '70s came with a power range between 185-375hp. With the availability of all the aftermarket performance components available today it has become easy to vastly improve power over the stock output. Original water pumps were not designed for this additional power and the increased demand for water flow.



pulleys 80061Racing water pumps should not be revved over 7500 RPM. Speed reduction pulleys, AFC 80061, that reduce pump speeds by 20 percent are available from APPLIEDSPEED.com. Think before installing these pulleys on a street vehicle as the pump may not flow enough coolant at lower engine speeds, and they will overheat.


 Use caution with speed reduction pulleys: Slowing the water pump speed may cause overheating when the engine runs at lower speeds on streetcars, rods, and tow vehicles. Only use these pulleys for racing.


From Smitty Smith, Edelbrock

Appliedspeed: How do Edelbrock’s water pumps help in keeping both sides of the motor at the same temperature to prevent running lean and having to run colder plugs in one of the heads?

Smith: The internal passages of all Edelbrock Water Pumps are Directional, they flow in one direction only, our design flows within 1% of each bank, and our impeller fills the entire cavity of the housing.

AppliedSpeed: What other problems can a stock water pump cause when used in racing or high-performance like towing besides overheating

Smith: Cavitation is the biggest thing that OE or stock water pumps encounter, as a simple bent over paddle-type wheels with too much area around the smaller impeller.

AppliedSpeed: How fast can our readers spin your water pumps? 

Smith: Speed, duration, and load are all factors that influence the performance of any water pump. We are comfortable to say 7,500 pump max RPM, not the engine RPM.


Cavitation is the formation of vapor cavities in a liquid – small steam bubbles that are the consequence of forces acting upon the liquid. Cavitation usually occurs when a liquid is subjected to rapid changes of pressure such as when it is pulled into a pump.That situation causes the formation of cavities where the pressure is relatively low. Later when the water meets higher pressure, the voids implode and they can generate an intense shockwave.   http://en.wikipedia.org/wiki/Cavitation. These shock waves can be intense enough to damage a water pump, crack a block or a cylinder head. To prevent the impellers from trying to pull more water than is available, performance water pump manufacturers include large pockets for the water to accumulate at the impeller entrance.

Water pump dynoEdelbrock test their racing, and performance water pumps on a water pump dyno. This tool can detect power to less than a tenth of a horsepower which    is a  feature highly desirable for racers searching for that last ounce of power and those seeking to save fuel .


With stock water pumps, cavitation can occur at increased engine speeds. There, the impeller tries to grab more water than the volume of water that arrived in the pump inlet pocket. Cavitation is the formation of vapor (steam) bubbles in the cooling system. These bubbles form when the coolant temperature reaches the boiling point determined by the pressure that is present at the tip of the impeller blades. https://waterpumpu.com/

cracked hub

Higher engine speeds, long fan spacers, and torsional vibrations induced by the belt and a fan can damage stock water pumps. In this image, the crack started adjacent to the rib support. A well-designed water pump has an ample number of ribs that are radiused to spread the load over a larger surface.

graph pressure flow


Computational flow dynamics and computer-aided design and machining techniques have produced remarkable results in Edelbrock’s water pumps. This graph shows the Edelbrock flow rate and a pressure increase from 23 PSI and flow of 57 gallons per minute with the stock GM LS1water pump to 33 PSI and 68 GPM for the Edelbrock 8896.




pressure vs flow

All aftermarket performance water pumps are not created equal. This graph shows the difference in flow and pressure from an overseas pump and an Edelbrock one. Edelbrock’s years of research and development in arenas like NASCAR, SCCA, NHRA, and Off-Road Racing have created unsurpassed efficiency and reliability in water pumps. Edelbrock water pump flow rate 


Bubble trail
Cavitation is of great concern to the engineers who design water pumps as well as to those who design propellers for submarines. When the steam bubbles explode they make a lot of noise, and they can tip off an antagonist of the sub’s proximity. In a water pump, the cavitation can cause damage to the pump and the engine as well as increasing the temperature and a loss of pressure in the coolant. What is more, creating the bubbles requires energy robbed from the power produced by the engine that propels the prop or pump.



Excessive clearance between the impeller and body of the pump creates eddy flows. The distance can be from poor quality control on the part of the manufacturer or corrosion that has diminished the length of the impeller paddle. There, the water becomes pressurized, and as it attempts to escape between the blades and the pump body, it creates “eddy flows.” This phenomenon imparts axial vibrations that can damage the seals and the bearings. 



By using purpose-designed, and oversized cast, powdered metal impellers of tight clearances help companies like Edelbrock accomplish water pumps that flow some 30 percent more than stock ones.

Precise machining practices are essential to maintaining the hubs and shafts perfectly perpendicular to the body to eliminate excessive bearing loads, noise, and to reduce power losses and heat. Edelbrock uses high-grade bearings that are heat-treated carbon or carburized steel.

pump racing

Performance racing water pumps do not need to run over 7500 RPM. To reduce the speed of water pumps, speed reduction pulleys are available from APPLIEDSPEED.com. When properly installed, the water pumps flow seventeen percent more water over stock units. While they may look different, they bolt right up and fit perfectly. Shown here is an Edelbrock Victor Series racing water pump.


Gilmer belt

When tested, Edelbrock water pumps showed a temperature drop of a minimum of 17 degrees over the stock units or otherwise performance pumps and a reduction of 10 percent in parasitic drag. This image shows the beefy and well-radiused support ribs at the snout to accept high RPM and possible increased loads from additional belts or wide Gilmer belt like are used in racing.




Some Advice from ASC Industries and Water Pump University

Fans, Clutches, and Spacers 
The goal of any retrofit is to get the fan spaced into the shroud for max cooling, but be careful how you get there. When you choose a spacer, be sure it is a snug fit on the shaft and never stack spacers. Always remember that most pumps were designed using a factory fan and clutch, and any variation from that can cause an additional load on the pump's bearing.

Hub Height

 Hub height

The hub height determines the location of the pulley and the belt and if you use a Gilmer belt arrangement plan to run the belt near the center of the pulley. Image courtesy of ASC Industries. Measure the hub height from the base of the gasket surface to the top of the hub, where the pulley will bolt-on.



The Best Performance Racing Water Pumps Include:

  1. Precision-cast powdered-metal impellers with extra-large vanes to maximize the flow rate, ensuring adequate pressure and volume even at lower engine speeds.
  2. Extremely tight clearances between the impeller and the pump body to prevent cavitation and eddy flows.
  3. Aggressive 3.45-inch impellers eliminate cavitation.
  4. Improved ports produce maximum flow, pressure, and even distribution to each side of the engine.
  5. Large, high-quality roller bearings on steel shafts to prevent deflection and possible contact of the impeller with the pump body, and Ford long and short.
  6. APPLIEDSPEED.com makes water pumps available with standard and reverse rotation for most Chevrolets, Fords, GMs, Jeeps, Pontiacs, and Chryslers.









Share this post...

Previous post Next post


Leave a comment