Without a quality supply of oil, an engine won’t stay alive for long, especially in demanding racing applications where loads and forces greatly exceed those of a typical passenger car engine. Over the years there have been many inventions designed to improve engine oiling in those situations. One of the most prominent inventions is the dry sump oiling system, produced by many different manufacturers for a wide range of engine platforms and racing styles.
Armstong Race Engineering, Inc. is one of those manufacturers; company proprietor and inventor Gary Armstrong is one of those folks who provides an education in every conversation – he holds five US patents on dry sumps and air/oil separation devices. He says dry sump oiling systems are very efficient, however, as a function of their operation there are large amounts of air introduced into the oiling system that must be dealt with. Armstrong has developed a unique product to supplement those dry sump oiling systems called the Spintric. It’s a passive air/oil separator on the next level, and in fact, Armstrong claims it’s a patented item you can’t get anywhere else.
Improving upon traditional dry sump oiling is not an easy task, but Armstrong has the experience and know-how to do so. In fact, he builds testing rigs to prove out his ideas, and is unwilling to release his inventions to the public before he’s sure that they will perform as advertised. The man simply eats, breathes, and sleeps fluid dynamics. Read on to learn more about the Spintric, how it works, and what it can do when plumbed into a dry sump oiling system – without requiring any external power source.
The Basics Of Lubrication
Regardless of the dry sump, there is inherently air included, and any way of getting rid of it is a good thing, – Gary Armstrong, ARE
A wet sump design gets its name from the submerged oil pump and pickup that traditionally resides inside the engine’s oil pan; sucking oil through the pickup, the pump is typically driven in some fashion by the camshaft or crankshaft and provides oil to the engine’s circuits through a variety of passages. These work sufficiently in many applications, but as the demands on the oiling system go up, the performance of a wet sump design falls off.
“The challenges in designing and building racing cars and particularly racing engines is one of the greatest and most challenging sciences,” says Armstrong.
“Couple that with the extreme G forces developed in today’s race cars, and dry sump system design and function becomes one of the most important aspects of the racing engine’s longevity. Also, the nature of constantly going faster creates new demands all the time. Sometimes solving one problem creates another.”
One of those problems – fitting dry sump oiling systems with multiple stages to handle the engine’s oiling requirements – forces the pump to move massive quantities of oil through the system, and also introduces massive quantities of air into the equation in the process.
Pulling the large amount of oil through the system has many benefits, especially in the realm of reducing crankcase pressure; the air has to go somewhere, and in most cases that’s back to the oil tank to be processed out of the vent.
In 1983, Armstrong patented a design to help process the air/oil mixture using a centrifuge within the pump, between the scavenge sections, but he knew he could go one step farther and remove the separator from between the pump sections–that’s where the Spintric enters the equation.
How The Spintric Assists In Solving The Problem
The Spintric gets plumbed into the oiling system after the scavenge sections and before the tank to provide a solution to the oil aeration problem.
The oil/air column already exhibits the inertia needed as it follows the Spintric’s internal trajectories and makes its way back to the oil tank; the Spintric takes advantage of this force by routing the mixture through a set of specially-designed channels inside the unit. This allows the air to separate from the heavier oil, and the air subsequently exits the Spintric through a set of specially-designed orifices inside the unit’s core.
From there, the air is routed to the very top of the oil tank and vented to the atmosphere, while the oil is returned to the the tank with measurably less air contained within the mixture.
Armstrong cautions, “The separation is not 100%, nor is it with any air/oil separator, but through more than a year in development, the internal design is very efficient, normally separating anywhere from 30 to 70 percent of the air from the oil line. I think we all agree that any amount of air removed is a good thing.”
Consider that any racing engine relying on a dry sump oiling system only has one pressure stage, but two, three, or potentially even four scavenge stages, and it’s clear that there’s a massive amount of air induced into the system during operation.
The Spintric in Operation
Cooling The Oil
In a typical dry sump oiling system that does not use a Spintric, cooling the oil can sometimes be a major concern, especially in an air-cooled application with a radiator-style cooler. The hot air inside the oil column does not cool nearly as fast as the oil does, and this can result in inefficiencies within the system.
The addition of the Spintric has the added benefit of providing cooler and more consistent oil temperatures thanks to the denser concentration of oil and lighter concentration of air in this type of system. The cooler can transmit the heat to the surrounding air more consistently and efficiently.
“Especially in multi-stage pumps, overcoming all that air creates a depression in the crankcase, and can result in advantages in itself,” he says.
“The fact remains that it all travels back to the tank through the scavenge return line. Regardless of the dry sump, there is inherently air included, and any way of getting rid of it is a good thing.”
By splicing into the scavenge return on its way back to the tank, the Spintric is placed squarely where it’s needed most.
“The important thing to point out is that the Spintric does not rely on gravity, as a vent can and the dry sump tank itself does,” says Armstrong.
“Once the air is freed from the oil inside the Spintric, it cannot go back – it is as reliable as centrifugal force itself. I actually like to call it ‘centripetal force’ as the air is going to center. Nevertheless, the physics involved work extremely well.”
- A – Dry Sump Pump scavenge outlet – Return to Tank – Applies to All Pumps
- B – Inlet to Spintric – Keep Line size the same (A) through (G)
- C – Outlet from Spintric – (De-aerated oil back to tank)
- D – Install Oil Cooler Here (Optional)
- E – Oil Inlet to Tank – Same as before, from Pump (A)
- F – Air Relief from Spintric to Tank Top
- G – Air Relief recommended
The operation of the Spintric is similar to the amusement park ride called the Gravitron; as the ride spins faster, the rider gets stuck to the wall of the ride. The rider is the oil, and the air is in the center, separated from one another by the force of the spinning ride. The Spintric works along these basic principles. The faster the heavy oil moves, the harder it’s flung into the passages of the unit, while the air is separated and pushed out the center.
In an effort to tailor the design of the Spintric to a number of different engine designs, the company now offers three different sized units to more closely match the dry sump pump’s dimensions.
Each of the Spintric designs has been developed and engineered to help provide optimum deaeration of the oil in the respective application.
A -12AN air relief deflector fitting is recommended for the top of the oil tank, regardless of Spintric design. This fitting helps to “clean up” the air returning into the top of the oil tank and out to the vent can.
As an interesting aside, the company is also selling Spintrics to industries Armstrong never expected. A major jet engine manufacturer has ordered a number of units to help with misting in their engines; he’s supplied a number of them to power plants that are using them in turbine-driven power-producing applications.
Through an ingenious application of physics, the Spintric uses the energy created by the moving oil to do the work of removing the air from the processed oil in a dry sump oiling system, without adding a single moving part – all it takes is a few new fittings and some time to plumb it in. Development of problem-solving products like this is the stuff that keeps Gary Armstrong up at night, and keeps race engines all over the world working more efficiently.