Moroso Pan TestWe decided to test a Moroso Sportsman road race small-block pan that would also fit the Chevelle chassis. This pan is slightly deeper than a stock pan and is fitted with kick-out "wings" in the sump that not only allow for more oil, but also incorporate five one-way swinging trapdoors designed to concentrate oil in the sump area around the oil-pump pickup even under high lateral g's. We decided to test the Moroso pan in the same backyard manner to see how good a job it could do in keeping the oil-pump pickup submerged at all times.
The Moroso pan is rated as a 6-quart pan with an additional quart for the oil filter, making the total capacity 7 quarts. To simulate one quart in the engine and another in the filter, we placed 5 quarts of solvent in the oil pan and subjected the pan to the same 45-degree tilt in both directions as we had previously done with the stock small-block pan. While the "wings" in the oil pan certainly help, the oil level was still very close to the top of the oil-pump pickup at 1 g but better than the stock pan because of the trap doors and the deeper pickup sump. Adding more oil would certainly help, but years of dyno testing has proven that raising the oil level in the pan merely positions the oil level closer to the crankshaft, which causes aeration and foaming, which quickly reduces oil pressure and may damage the engine. Not only that, but raising the oil level also costs horsepower since the crankshaft must swing through a heavier oil mist.
It appears that the best solution would be to make the sump deeper so the pickup could be placed deeper into the sump in order to keep it under the oil level at all times. Of course, this creates its own set of problems, since a typical Pro Touring car generally sits very low, reducing the necessary ground clearance for a deeper pan. Certainly, the Moroso pan is a major improvement over the stock oil pan, and it's certainly a reasonable compromise between depth and oil control for a road race-inspired street car.
It's also important to note that during a full lap at Buttonwillow or any flat road course, even a car capable of sustaining 1g lateral acceleration rarely achieves that level for more than a few seconds per corner. This means that about the time the oil reaches that 45-degree pitch inside the oil pan, the car has already achieved its peak lateral g and is rolling out of the turn and accelerating, pushing the oil toward the rear of the oil pan where the trap doors keep the oil in the sump rather than sloshing out.
Another variable worth mentioning is the sustained high negative g's created under hard braking. Many performance cars with big brakes and fat tires are capable of generating near 1g brake-deceleration numbers for several seconds. If you've ever attempted a serious braking effort, it's not unusual to witness the oil pressure gauge take a dive toward zero pressure as all the oil in the sump surges to the front of the pan. We simulated this with both our stock oil pan and the Moroso by pitching both pans forward for 4 seconds. Because this is so messy, we decided to measure how much solvent we lost out the front of the pan in that amount of time. The stock oil pan left barely 1 quart in the sump, leaving the pickup seriously uncovered, while the Moroso road-race pan displaced about 1 quart out of the sump, utilizing its trapdoors to secure sufficient oil in the sump to cover the pickup.
While this is hardly a scientific test, it does point to the improvements available with a trapdoor-style oil pan. Unfortunately, we couldn't install the new pan on the engine and back into the car in time for our deadline. However, we will do this and if the results are dramatically better, we'll tell you all about it.