During the construction of a proper racing engine, attention needs to be paid to all of the small details, from ring and bearing clearances, camshaft specifications, induction system performance, and the oiling system and its capabilities.
Dailey Engineering, located in Temecula, California, specializes in the construction of custom-made roots-style dry sump oil pumps and oiling systems designed to maximize horsepower and oil control, and proprietor Bill Dailey is well-versed in the construction of such systems.
Dailey traces his roots through his father, Dr. Charles Lee Dailey, who was a pioneer in the field of space propulsion. He passed the love of all things mechanical down to Bill, who earned a degree in mechanical engineering and immediately headed into the racing industry as an engineer and designer of racing engines for Nissan’s VG-30 turbo engine. Dailey’s experience with Nissan and emerging CNC technology along with many other opportunities to consult and design racing gear for companies like Electramotive Inc. and Caldwell Development have led him to focus his energies on Dailey Engineering and his Roots-style dry sump pumps and systems.
Dry Sump Basics
There are two main types of oiling systems used today. A wet sump system has an oil pump mounted inside the oil pan and sucks oil from the pan’s sump to be distributed throughout the engine. There are advantages and drawbacks to this type of system, especially in regards to oil control, and there’s where the second design comes in.
The majority of the pump’s performance comes from the accuracy of the machining process, the tolerances, and the clearances. – Bill Dailey, Dailey Engineering
Much like a Roots-type supercharger, each section, or stage, of Dailey’s Roots-style oil pumps use a pair of meshing lobes that are designed to push fluid from one side of the pump to the other. It’s a positive-displacement design that traps the oil in the cavities surrounding the lobes, subsequently pumping it through to the outlet side of the pump.
There is typically one scavenge stage for each pair of cylinders. These suck the oil from the oil pan, and a single pressure stage works to force the oil back into the engine. Selecting the proper design depends upon the engine’s capacity and requirements; that’s where the custom designs offered by Dailey Engineering come into the picture.
In addition, dry sump oiling systems are not susceptible to oil movement issues caused by cornering or launching forces, and since they are typically mounted at the lowest point of the engine, they are gravity fed rather than requiring the pump to suck the oil upward as in a wet sump design.
The pressure pump, by virtue of its location, also performs more efficiently as it is placed lower than the oil tank and always receives positive pressure on the suction side. Dry sump oiling system designs work best in racing applications for a number of reasons. They permit the engine to be mounted lower in the chassis as there is no sump in the pan to worry about for ground clearance, along with permitting the option of moving the oil tank within the confines of the car to improve weight distribution.
The company offers two different sizes of dry sump oil pumps – fittingly named the Big Pump and Small Pump. The big pump design turns at a conventional half engine speed, which works best on an engine that can turn around 10,000 rpm. The small pump design, being of much smaller displacement, runs up to 100 percent engine speed on engines that turn 10,000 rpm. This would be comparable to a small displacement Formula 1 engine running at twice the speed of a NASCAR engine with twice the displacement. Both have similar power levels, with the exception that the smaller motor does it with a more efficient overall package.
Similarly, the small pump is approximately 65% of the girth of the big pump. The small pumps are lighter, have more flexibility for RPM range, are volumetrically and mechanically more efficient, and provide simpler packaging on the engine. As the small pump loses some of the displacement, it needs to be spun more quickly to achieve the same effect. The ultimate selection of pump style comes down to the intended use of the product, as cost, fitment, and performance all come into play during the process of system design.
Integral Pump/Pan Design
As the dry sump oil pan does not have an area for the oil to accumulate, and instead has passages machined into its base that end in outlets to the scavenge sections of the pump, pan design is inherently critical to the performance of the entire system. Each one of Dailey Engineering’s systems is custom-tailored to the particular engine platform and the required overall performance of the oiling system given the operating environment.
They offer the small and large pumps as detailed above, and for some applications, they have a unique integrated system that mounts the pump directly to the pan known as their “Signature Series”. Dailey’s unique design uses the windage energy of the crankshaft to channel the oil through one of a number of passages in the bottom of the oil pan and deliver it to the oil pump.
The pan is anywhere from 1-inch deep to 5.5-inches deep depending on the motor design, and there are no lines to contend with between the oil pump and pan. Once you bolt it on, the plumbing is done. How so? Because the pump is integral to the pan, and mounted on the side of it as an assembly, there are no individual lines to run save for those going to and from the external holding tank. This is the most unique feature of Dailey’s products – it simplifies installation and maximizes execution.
Rotational winds exist in every engine. These winds carry the oil in the crankcase, where it is scraped and delivered to the inlet slots that have been constructed into the pan’s base. The inlet slots have vacuum acting on them, as the pump is sucking on the cavity at the bottom of the pan. The inlet slots act as a vacuum cleaner to suck in the oil at high velocity, and when the oil enters the base of the pan it slows way down due to the large increase in volume known as the dead area in the pan’s base.
The “Signature Series” integral pan/pump design is used to control oiling in the LS engine with great success and is one of the company’s most popular, with 12 different designs. Variations have been successful in the Daytona Prototype series, the ADAC series in Europe, the New Zealand Supertoures, the NASCAR LS spec engine, the deserts of Baja or countless record runs in drag racing. However, the LS engine is known for several oiling system issues including very high windage due to the deep-skirt Y-block casting, where the crankshaft is whipping around at high speed while it sits in the oil bath in the oil pan’s sump.
To try and combat these issues, GM moved to a dry sump design for production engines like the LS7, LS9, and C6 Grand Sport Corvette, where there is an internal oil pump but external oil tank to remove the oil bath from the equation. All of these systems suffer from an inherent design flaw using a gerotor style oil pump running at crank speeds. Stop sign to stop sign high performance is much different than sustained high RPM race track situations. Race engines especially can see large gains from installing a system like Dailey’s integral design for ultimate race-proven oil control.
“Through the channels to the pump, we slow the velocity down with line sizes equivalent to a -16 which creates less pressure drop. We route the oil between the pan and pump approximately six inches to eighteen inches of internal cavity that is large cross-sectionally,” says Dailey.
The pans are crafted from 6061-T6 billet aircraft aluminum, is O-ring sealed in each area where oil could escape, and includes protective screens glued into each section to prevent any potential debris from entering the pump system.
Importance Of Machining Tolerance
As all of Dailey’s parts are CNC machined from billet aluminum, he feels that much of the success of the product is due to the stringent tolerances built into their design.
“The majority of the pump’s performance comes from the accuracy of the machining process, the tolerances, and the clearances. The more accurately you can make the parts, the tighter you can make the clearances. It doesn’t matter how accurate the part is, if it’s true position is off and running out of round, that’s an inaccurate part. So it’s a combination of the accuracy of the profile as it’s manufactured in true position,” he explains.
For example, if the hole where the rotors slips over the shaft isn’t machined concentrically to the rotors, the rotors won’t process the oil properly. If the shaft is machined perfectly, the rest of the pump’s design can follow that lead and be machined more precisely.
Much like the tolerance between engine bearings and oil clearances determine oil pressure, the pump and its internal parts clearances determine the performance of the given components.
A loose and sloppy fit of these components equals a poorly-designed product, according to Dailey. It assists in assembly when there is more clearance, but it results in an inefficient pump in the process.
“If we were to take 100 of our oil pumps and take them all apart, mix up the parts, and put them all back together, every one would perform as every other one did before we took them apart. We don’t blueprint them because we don’t have to, they’re ‘given good’. You have to do that in the design process and the manufacturing process which makes the assembly process that much easier. That’s what we strive for – the quality of making the product. We call it smart manufacturing. We tool up properly up front so we can make parts good and fast, but very, very accurate,” says Dailey.
The company currently has over 1000 unique configurations of their oiling system products in use today, with inlet and outlet size, pump capacity, number of stages, and overall performance all variables that are controlled according to the particular application in practice.
The Pump Dyno
One way the company assures the end user that the system will work as intended is through the use of their pump dyno, which performs a number of functions that permit Dailey to evaluate a particular system’s operating tendencies. The dyno measures oil flow quantity at the intended pressure to check the pump’s operation. In addition, it uses an air blowby meter to simulate blowby along with an air separator to demonstrate how well the system is cleaning up the air/oil mixture generated by the engine’s windage, and how the overall oiling system design performs in use.
“An engine is a huge air pump that generates a lot of airflow; pistons generate blowby, you have to be able to do something with it, and that’s what we try to simulate with the pump dyno,” says Dailey.
The company uses the dyno to assist in the development of products like oil pressure regulators, to determine the pressure curves of a particular system, and to evaluate system operation. They can also test scavenge efficiency on the rotors by testing different clearances, oil viscosity changes, and those individual items on overall system operation.
“What I’ve learned is that I can give the same setup to ten different engine builders, and it will behave differently on every engine because each builder does things uniquely different. It’s not one-size-fits-all, but the goal is to give the customer the pieces they need as we consult on their individual projects. Each customer has a different level of expertise, and we try to keep them on the right path for their project.”
An engine is an assortment of multiple parts designed to perform specific tasks individually. The oiling system is one of the most important component packages, yet often one of the most overlooked in the quest for ultimate performance, especially at the upper echelons of competition.
With proper planning during the development process to select each of the engine’s pieces, achieving the desired performance objectives becomes an elementary task. Oiling system component selection can make or break the project from the outset, and companies like Dailey Engineering can assist in the proper procedure.