The spur gear wet sump oil pump has been around for a long time. A very long time.
It works pretty well, and there have been improvements over the years.
But it also has its share of disadvantages. With an OEM-style pump, you’re forced to live with all of the factory pump shortcomings. Things like cavitation, pump chatter, scattered spark, broken pickup tubes, and so on. Yes, it’s true there are fixes for some of these issues, but there are some different ideas out there.
For example, the gerotor pump has gained some favor — even in applications that never had them. They work well too, but the big elephant in the room with a gerotor pump is the physical size.
They’re huge. Which means packaging a gerotor oil pump while using the original main cap mounting surface and drive shaft position pretty much ensures the oil pump will severely interfere with the oil pan. And since they’re triple-XL in size, they can also cause considerable grief from the windage perspective.
Some aftermarket pan manufacturers literally cringe when they hear the word “gerotor.”
Enter the oil pump experts at Melling.
These folks have been building wet sump oil pumps for decades and they’ve been the choice for performance applications for many years (keep in mind that Melling pumps are private labeled by others too).
Essentially, Melling figured there had to be a better idea. The main driving force for their new pump design was to provide an evolutionary change in the performance of the traditional spur gear pump without increasing or moving the operating envelope required by the oil pump. With their new design, the outward appearance of the pump looks more or less the same as a traditional billet wet sump pump, but the performance is greatly improved.
They did it by changing the design of the gears. Reviewing the gears inside of the new Melling pump design, you’ll see that they are helical.
According to Melling: “The new gears have been designed to provide the same volume of oil per revolution (volumetric displacement) as the traditional spur gears. The longer sealing lands on the helical gear teeth are more effective at reducing internal leakage which results in more efficient operation. The asymmetry of the involute improves the strength of the teeth and reduces the power required to turn the gear set. Asymmetrical gears are not new they have been employed in the designs of mission critical, power transmission applications like helicopter gearboxes and aircraft propeller drives.”
When you disassemble the Melling’s new “shark tooth” pump (the design has been patented), you’ll clearly see the differences between it and a regular spur gear pump.
For example, the body is nicely machined from billet aluminum.
Melling machines the basic pump housing and the pickup housing from 6061-T6 aluminum. These pieces are hard-coat anodized, which dramatically increases the surface hardness providing a durable wear surface for the internal components.
You’ll also see that the pump is compact. It fits in the same space that’s taken up by the original cast iron pump.
Melling notes that its billet pumps consume less power compared to other pumps built with thrust bearings. Omitting the bearing(s) wasn’t a cost-saving measure. Instead, Melling’s engineers saw it as a way to eliminate a potential catastrophic failure point. Makes sense to us. Remember: simple usually means good!
Melling incorporates an integral bottom oil pickup, which means there is no fragile tubular pickup to break or fracture. The pickup screen has been integrated into the pump body and features a stainless steel wire mesh, which provides for superior filtration along with improved pump efficiency.
By optimizing pickup and inlet points, they’ve managed to minimize the effects of cavitation.
The result is that the oil entering the pump is super-charged to provide improved pump performance at high operating speeds.
The length of the pump’s drive shaft was increased for additional support in the cover. Increasing the support eliminates shaft deflection, which in turn allows the gears to run true at high-rpm levels.
But the biggest breakthrough is the design of the gears.
When you look at a conventional spur gear pump setup, it’s easy to see the profile of both gears proves identical. With the Shark Tooth asymmetrical layout, the gears appear to have a helical twist in the profile. As pointed out earlier, in operation, the helix profile allowed Melling to reduce the clearance between the pump body and the gears. This results in improved pumping due to a reduction in internal leakage and according to Melling, this also has an effect upon oil temperature — it lowers it.
According to Melling: “The helix of the gear teeth allows the oil chambers in the pump to fill and discharge gradually allowing for smoother operation. This provides a significant reduction in the flow ripple and its resulting pressure ripple experienced in the engine’s lubrication system. This is accomplished by the overlapping pump chambers in the helical gears. One effect is the reduction in cyclic loading created by the torsional forces on the oil pump drive shaft. It has also been reported to us that spark scatter is reduced. The difference in performance can be felt by just turning the new pumps by hand.”
Bottom line: Melling has come up with a major improvement for SBC wet sump applications.
They’ve done it without creating a need for a new oil pan and/or windage tray. The new pumps are a direct bolt-in swap for a conventional pump.
The folks from Melling tell us a big block Chevy version is on the way as well.
Check out the accompanying photos for more insight. There are more features here than you might imagine.