EDELBROCK’S RACING & PERFORMANCE High-Flow water pumps, racing, high performance, off-roading, Jeeps, GMs, Chevrolets, Fords, Chryslers, Pontiacs, Trucks, Towing, MotorhomesPosted on
EDELBROCK’S RACING & PERFORMANCE high-flow water pumps for racing, high performance, off-roading, Jeeps, GMs, Chevrolets, Fords, Chryslers, Pontiacs, Trucks, Towing, Motor Homes, Street Rods.
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? 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?
PERFORMANCE AND RACING 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 good 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. Every part of their pumps from the castings to the seals is redesigned and improved to accept high temperatures, pressures, and the RPM encountered in racing and high-performance.
WATER PUMP BASICS
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 will not pump enough water for racing, and they can be 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.
Your Grocery Getter may be happy with an auto parts store pump, but if it is pushed beyond its design parameters the stock water pump will be overtaxed and it will fail. Image from ASC Industries.
Water pumps are composed of five basic components:
- The housing typically bolts to the engine block and it houses all the pump components.
- The hub, mounted on the shaft, will accept a pulley and a fan.
- The pump shaft supports the hub.
- The impeller rides at the end of the shaft.
- The shaft rides on roller bearings that must be perfectly aligned to avoid flexing of the shaft.
- Seals and gaskets retain the coolant inside the pump.
THE PURPOSE OF A WATER PUMP IS TWO-FOLD: Flow and Pressure
The 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.
THE MECHANICS OF COOLANT FLOW in I.C. Engines
In the heads, above the combustion chambers and around the 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, detonation, and loss of power. 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.
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 will 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 will retard the timing, and it will modify the fuel delivery reducing power and fuel efficiency.
THERMOSTATS AND RESTRICTORS
Racers often install a thermostat or a restrictor in their racing engines. In racing, this practice is no longer necessary as modern purpose-built radiators are designed to build the pressure through their tubes (turbulation) that will, in turn, create pressure in the block and heads.
Thermostats and restrictors have become moot in racing as the radiators create the pressure necessary to keep the boiling point at a maximum.
A word of caution when removing the thermostat from your cooling system; the pressure from the pump may blow off the relief valve on the radiator cap, possibly leading you to believe that the engine has overheated. If this happens, use a higher pressure cap, or one without a relief valve and install a pressure can with its own cap.
Modern 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 water pumps are not precision pieces. The impellers are typically bent-over paddles, stamped pieces. 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 restricts the flow with the turbulators inside the tubes to create pressure. Getting the most work from the impeller is the key to having an efficient pump and cooling system. When over-revved or when worn out a stock water pump will cavitate.
Edelbrock's 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.
CONSIDER THE HORSEPOWER
Power is heat and heat is power.
Most 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 greatly improve power over the stock output. Originally installed water pumps were not designed for this additional power and the increased demand for water flow.
ENGINE SPEED CONSIDERATIONS
Racing water pumps should not be revved over 7500 RPM. Speed reduction pulleys, AFC 80061, that reduce the pump speed 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 cause overheating.
|Use caution with speed reduction pulleys: Slowing the water pump speed may cause overheating when the engine is run at lower speeds like when speed reduction pulleys are installed 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, with a simple bent over paddle-type wheel with a lot of area around the smaller impeller.
AppliedSpeed: How fast can we 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 – i.e. small liquid-free zones ("bubbles" or "voids") – that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities where the pressure is relatively low. When subjected to higher pressure, the voids implode and 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.
Here is a trick for when stock water pumps are mandated by the racing rules. Reduce the clearance down to about 25-thousands of an inch at the impeller to prevent eddy flows. This little adjustment can improve coolant flow by as much as 10% while keeping the engine running cooler. A plate such as the one in this photograph will also improve flow.
Edelbrock 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; a feature highly desirable for racers searching for that last ounce of power.
With stock water pumps, cavitation can occur at increased engine speeds such as when a stock engine has been built to produce more RPM. 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 in the cooling system. https://waterpumpu.com/
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.
Computational flow dynamics and computer-aided design and machining techniques have produced remarkable results in Edelbrock’s water pumps. This graph shows 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.
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.
Cavitation is of great concern to the engineers who design water pumps as well as to those who design propellers for submarines. The steam bubbles created by the cavitation make a lot of noise when they explode, 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 distances between the impeller and body of the pump create the 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 as well as increase the temperature and the pressure of the water.
PURPOSE-BUILT HIGH PERFORMANCE and RACING WATER PUMPS
Racing water pumps such as those produced by Edelbrock put out some 30 percent more flow than stock ones. This improvement is primarily accomplished using purpose-designed and oversized cast powdered-metal impellers held at tight clearances against the pump body.
Precise machining practices are essential to maintaining the hubs and shafts perfectly perpendicular to the body to eliminate the excessive bearing load, noise and to reduce power losses and heat. Edelbrock uses high-grade bearings that are heat-treated carbon or carburized steel.
Edelbrock 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 will flow nearly fifteen percent more water over stock units. While they may look different, they will bolt right up and fit perfectly. Shown here is a Victor Series racing water pump.
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 a 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. Most manufacturers never offered a spacer and fan clutch combination. A fan spacer by itself or a fan clutch by itself is OK, but when used in conjunction the outcome can be catastrophic. When you choose a spacer be sure it is a snug fit on the shaft, and never stack spacers. Always remember that the pump was designed using a factory fan and clutch, and any variation from that will cause an additional load on the pump's bearing. The extra load can shorten the life of the pump's bearings and seals. Make sure that all components being used mate well with each other. Any misalignment or vibration in the components mounted in front of the pump will shorten the life of the pump's bearing and seal, and will in some cases cause catastrophic failure where the housing of the pump fails - causing extensive damage.
The hub height will determine the location of the pulley and the belt. When using 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.
When installing a pump, it is important to assure that all the pulleys line up. Another thing to keep in mind is the bolt circle on the hub that the pulley and fan will bolt onto. There are several different sizes, both metric and standard, and this applies to the threads as well.
Edelbrock’s Pumps Include:
- Precision-cast powdered-metal impellers with extra-large vanes to maximize the flow rate, ensuring adequate pressure and volume even at lower engine speeds.
- Extremely tight clearances between the impeller and the pump body prevent cavitation and eddy flows.
- Aggressive 3.45-inch impellers eliminate cavitation.
- Improved ports produce maximum flow, pressure, and even distribution to each side of the engine.
- Large, high-quality roller bearings on steel shafts to prevent deflection and possible contact of the impeller with the pump body
- Standard and reverse rotation pumps are available for most Chevrolets, Fords, GMs, Jeeps, Pontiacs, and Chryslers.