Slippery Situation

Racers are a picky bunch. We scrutinize parts and sweat minute details down to the thousandth of an inch. We painstakingly gap spark plugs, set valve lash, and carefully select the brand and weight of oil before pouring it into our powerplants. And why? Because oil is essential to keeping your engine alive, but did you know your oiling system might cause a loss of horsepower? Well, it's true. Like many parts on the car, the oiling system operates at a cost, and the cost is parasitic drag. Parasitic drag can be found wherever something moves or turns, and if you reduce the drag, you'll get free power. The question is how to reduce the drag in your oiling system?

For starters you must learn about oil control. Secondly, you have to identify the area(s) of increased parasitic losses within the oiling system. Thankfully, we've done the homework for you and all you have to do is read on and learn how oil control leads to increased power and extended engine life.

Your Oiling System
I'm sure that most readers know the main purpose of the oiling system. Yes, you're right, it's to lubricate the internal engine components and prevent metal-to-metal contact. Oil is also used to cool and clean certain parts of the engine. The oiling system found in most street and race engines will be a "wet-sump" system, because the oil is contained in the pan. Therefore, the pan remains wet with oil. This type of system uses an oil filter, oil pump, pump driveshaft, pump pickup, and we'll also consider the passageways in the block and heads to be part of the oiling system because they allow for oil return.

The operation is pretty basic: The pan holds the oil (usually 4-7 quarts) and the pickup (which is located about 1/4-inch from the bottom of the pan) is submerged in the oil to feed the pump. Oil is pumped through the filter and then to the crank and rod journals, then to the cam journals, up through the pushrods, and to the rockers. When oil reaches the top of the engine it drains back to the pan and continues to circulate.

Another type of oiling system is a "dry-sump" system. As the name implies, dry-sump systems feature a (mostly) dry pan, because the oil supply is contained in a remote tank. With this deal, oil is scavenged (or sucked) from the bottom of the pan by a crank-driven external pump and the oil is fed into a separate holding tank. The external pump normally has a series of stages, (usually two or three for scavenging and one to feed the engine).

Dry-sump systems have many advantages over wet-sump systems. "Because there is very little oil in the pan, the rotating assembly is not burdened with the weight of excess oil or windage," say Rob DiLella of Moroso. "And since the oil pump is mounted externally, the windage tray or screen, which serves to isolate the oil from the rotating assembly, is allowed to run the full length of the pan," he added. In addition, since there is no internal pump or pickup the pan can be flat on the bottom and this adds ground clearance. Lastly, dry-sumps are deemed safer because no oil is contained in the pan, and should you experience a major engine failure, much less oil will be scattered on the track. In contrast, with most OE-type wet-sump systems the oil pump is mounted in the crankcase and is driven internally by the camshaft, distributor or the crankshaft. It is possible to have an external pump on a wet-sump system, but we'll leave that for another day.

Reducing Drag
Let it be known that some wet-sump, high-volume pumps may sound good on paper, but may not help you win races. Often, these pumps produce upwards of 80-100 psi and, unfortunately, that's more pressure than most engines need. Excessive pressure results in increased parasitic drag because, quite simply, it takes more energy to drive the pump. In reality, it is possible to run the engine with the oil pressure lower than stock and make extra power. Many engine builders feel 25-35 psi (at idle) is sufficient.

Horsepower-robbing parasitic drag can be also found in the crankcase. In most engines, the crankshaft counterweights and connecting rod big ends are positioned halfway in the block and halfway in the oil pan where they can contact the oil. When the engine is running the rotating assembly sweeps through the oil, which results in parasitic drag and windage. (In lay terms, windage is the result of oil splashing on the crankshaft or off the pan walls.) Imagine if you tied a brick to a 6-inch piece of rope and whipped it around like a propeller. You'd be able to whip the brick pretty fast, however, if you forced the brick to pass through a bucket of oil it would encounter drag and be slowed. The oil would also splash around and that can cause aeration. The folks at Milodon agree, "At 8,000 rpm the outer part of the crank is rotating at approximately 300 mph. You know what air resistance is like sticking your hand out of a moving vehicle at 60 mph. Now factor in the extra resistance of oil and consider that the crank is rotating five times as fast." Reducing this resistance equals power and Milodon claims you can gain approximately 3 percent on a typical engine with a racing oil pan and proper oil control. That's about 9-12 horsepower on a 400-horsepower engine.

Thankfully, the aftermarket has found ways to improve performance by modifying stock systems and by creating new parts to control oil. Companies like Canton Products, Billet Fabrication, Milodon, Moroso Performance Products and Stef's Fabrication Specialties have pushed the boundaries and offer improved lubrication for your muscle Mustang or other fast Ford.

"The oiling system is a total system of parts and you have to look at each component if you want to maximize performance," says Joe Stefanacci of Stef's Fabrication Specialties. "Simply using a good pan doesn't guarantee horsepower. The key is to control the oil, so you can properly oil the engine with the minimal drag or losses.

"Production cars use (oil) for cooling and for cleaning to a degree, but that's not a consideration in racing. We want to control the gallons per minute (GPM), or in other words, how much oil goes through the engine over the course of a run. The greater the flow the more oil you have to control and the greater the potential for losses. The more flow, or GPM, the more a good pan will make a difference."

But you can't simply reduce the oil flow. You have to discuss it with your engine builder and modify the whole system. He will likely restrict some of the oil return passages to allow for quicker oil return to the sump, rather than letting it drain back through the lifter valley where it will fall on the crank and cause windage.

If you put two and two together you'll see that lowering the oil level will keep the crank from contacting the oil and that also reduces windage. This can be done by lowering the oil level, or by installing an aftermarket pan with a deep sump and/or side kickouts. Side kickouts in the pan prevent oil that is slung from the crank from bouncing off the walls and slamming back into the crank. Today, all aftermarket pan manufacturers use specially designed internal baffling to keep the oil in the sump during hard acceleration and also during deceleration.

Here at MM&FF World Headquarters we've found horsepower improvements and more reliability in almost all of our project cars by using aftermarket pans. For instance, Superfly, DOHC has a specially modified pan from Kenny Brown, and we've selected a Canton street/road race pan for the Hot Handler project that is currently underway. "The Canton 15-644 pan has a T-style sump for increased oil capacity but at the stock depth. It fits '79-up Mustangs and '80-up T-birds and is used in street and race applications. We have this pan on numerous A/Sedan, World Challenge and Grand Am Cup cars. It has a diamond-shaped road race baffle assembly with four trap door runners to direct oil to the pick up under all conditions. The kit also includes a bolt-in windage tray, oil temperature fitting, magnetic drain plug a crank scraper and a pan-mounted dip stick," says Thor Schroeder of Canton. "When you go wider you have to baffle the pan properly or the oil will be scattered at the bottom of the pan and it won't stay on the pickup," he added.

For added power, many racers install a windage tray that fits between the rotating assembly and the oil pan. Windage trays catch oil that flies off the crank and prevent it from bouncing back onto the rotating assembly. There are many designs including solid trays with louvers, mesh screen types and the Teflon(R)-coated diamond shaped one used by Stef's. "We've found our windage trays to be worth power, especially on Modular engines," says Schroeder of Canton. "The Mod engines have a deep skirt around the crank, but if you look at a stock Mod motor pan you'll notice it is very shallow. We worked with Ford on the 5.4 Cobra R and picked up about 33 horsepower. And we've seen a 17-horsepower increase on 4.6 Cobra engines," Schroeder explained.

In addition to the windage tray, most manufacturers offer crank scrapers to help control windage. A crank scraper runs the length of the pan and normally is mounted on the pan rail. The side facing the crank is contoured to follow the shape of the rotating assembly and though it does not contact the rotating assembly, it should be installed close enough to catch flying oil and reduce windage.

Yet another often overlooked area is the oil pump driveshaft. Our tip is to always install a hardened oil pump driveshaft. "Stock oil pump driveshafts tend to break when used in conjunction with high-volume pumps, heavy racing oil and at high rpm. Break a shaft and it will destroy your motor," says our source at Milodon. Perhaps that's why Milodon offers heat-treated 4130 chrome-moly shafts and they recommend paying attention to loose oil pan bolts and oil leakage, as well.

Some racers also use a vacuum pump to help evacuate air and windage from the crankcase. "Basically, the vacuum pump sucks air from the crankcase and the valve cover area. This helps to control ring flutter and helps to seal the second and top rings," says Stefanacci. "It also reduces turbulent air and oil particles in the crankcase." However, if excess vacuum is applied it can actually pull oil from the cylinder walls and the wrist pins. The specific amount of vacuum is usually dependant on the engine builder, but it's common to see about 20-23 inches of vacuum in a Pro Stock engine, about 17-19 in a Comp engine and 8-12 in stock-type engines.

It's really obvious there is an art to properly oiling your racing engine. If done right you can find a little racer's gold in the form of horsepower. And while some racers may find little to no increase, we've heard of racers picking up 20-40 horsepower.