We prefer the term "inexpensive" over cheap," but when we're on a budget, we're just as likely to try to save a few bucks on an oil pan as the next guy. This was the case in "A Game of Rat and Mouse" (July '07), where we had to build hi-po big-block with a strict $6,500 budget. Just as most of you would do, we put as much of our money as possible into power parts, then installed a Summit Moroso oil pan kit, which includes a pan, pump, and pick-up for a paltry $200. There's nothing wrong with this setup; the parts are all of good quality and the y keep our fat-block properly lubricated. On the other hand, we couldn't help but wonder if upgrading our basic pan-or instal ling a better piece-would release a few more ponies. Question posed, we headed back to the dyno to find out.
The Enemy Below
We went for a case-study approach rather than trying to slog through theory, making changes to a proven engine combo and measuring the results. But we do want to define our goals, and Mike Johnson of JMS Racing engines puts the issue at hand succinctly: "Oil, first of all, needs to lub ricate," he tells us. "Then we'll control it for horsepower." The enemy of oil control is wind age, which is, according to Moroso's Brint McLellan, "the action of the oil getting whipped up by the crank." The term also refers to the piston-churned air in the crankcase, which does quite a bit of oil whipping itself.
The crankshaft must be properly lubricated, of course, but any oil it must carry beyond this need exacts a performance penalty, aka parasitic loss. We want every bit of horsepower available, just like you, so that's bad enough. Aeration, how ever, affects the quality of the lubrication itself. As the oil is whipped about by all that air in the crankcase, the two begin to mix; "The oil actually gets air bubbles in it," Johnson observes. "And you don't want that." Oil infused with air doesn't lubricate as well as air-free oil, and that's not a good thing for engine bearing longevity.
With either concern, the goal is the same. "The objective is to keep the oil under control by getting it down in the pan and keeping it off the rotating assembly," says Johnson, defin ing our task. We began by upgrading our basic street/strip deep-sump Moroso pan by installing a windage tray. Simply put, a windage tray separates the crankshaft-and its windage-from the oil in the sump. At the same time, it allows oil coming off the crank to drain back into the sump. Con versely, it also prevents the sump oil from getting tossed up into the rotating assembly. In theory, this cuts parasitic losses and frees up some horsepower.
In practice, we didn't see a horsepower gain or an appreci able loss; peak torque stayed the same, as did the average num bers. What we did see was a nominal 2-3 psi increase in oil pres sure over the course of our dyno pull. We were sur prised that Moroso's McLellan wasn't surprised. "By having a louvered windage tray installed too close to the rotating assembly," he explains, "the oil has a way of whip ping back up, causing a power and engine-acceleration loss. Installing the tray lower in the pan allows the oil to get farther away from the rotating assembly and will reduce the windage in the pan."
And that's where we ran into the street/strip pan's physical limitations. The windage tray was installed 1/4 inch below the rotating assembly, and that was as low as we could go. We would have liked to have seen a power gain, but the increased oil pressure indicated to Johnson that oil control was improved and our engine still benefited from the work. "The oil's not getting as aerated, which is better for the bearings" he observes. Dyno pulls are very brief, and the increases may look mini mal. Running on the street-or the track-and for extended periods of time, however, this improved lubrication will help engine longevity. We'll take it.