When you’re an innovator in dry-sump oiling system technology, and developed the very first belt-driven externally-mounted dry-sump pump for American motorsports in 1961-it’s only fitting that the folks at Aviaid Competition Oil Systems have developed various bolt-on dry-sump systems for a wide range of contemporary and vintage engines.
“When you need one of these, you’ve gone well beyond the point where the stock oil system can keep up with the demands of the engine,” says John Schwarz, Aviaid’s President.
“When you think about what engine technology has done, what chassis technology has done, and what tire technology has done, we’re so far past wet sump installations that we find people driven towards us. The oil you rely on to keep the engine lubricated and alive, is the one thing in the engine that’s completely uncontrolled. With the displacement of some of these engines, the RPM the engine is driven in, let alone the external inertial forces that apply to the oil, you’re just beyond it.”
A dry-sump oiling system uses a multi-stage pump (left), with three, four, or more scavenge stages and a single pressure stage. The scavenge system pulls oil out of the shallow pan via the fitting (seen on the right), which has an entry point underneath the windage tray that can't be seen in the photo. It can also pull from a cylinder head, or turbocharger, or other part of the engine if necessary. The oil then is transferred into an external holding tank, which permits the oil to settle in the bottom through a number of baffles which help to remove the air from the oil. "When you get the oil into a vertical container, the pressure of the oil upon itself is sufficient in most instances to remove the air from the oil," says Schwarz.
When an engine is at full song-say 7,000 rpm-the perimeter of the rotating assembly is moving quickly; so quickly, says Schwarz, that it causes turmoil in the crankcase. How much turmoil? He equated it to those winds seen in a 200+mph tornado.
If you think about what you see on the television during a tornado, then imagine a drop of oil trying to fight through those types of conditions and its way from the crankshaft bearing surface into the oil pan and subsequently into the pickup.
One concern Schwarz shared with us is that people often think adding a dry-sump to their racing program is prohibitively expensive, but he explained that they can build systems-using modified stock oil pans-that run as little as $2,500 including everything but hoses, which is a drop in the bucket when you consider the cost of a complete racing engine. And he says that a simple three-stage dry-sump system is better than the absolute best wet-sump oiling system you could ever use.
“It’s insurance against that next explosion. When I’m racing, the last thing I ever want to do is worry about my oil pressure. You lose oil pressure, and it turns into a pile of slag. Extra oil’s the cheapest insurance you can have for your engine,” he says.