Welcome back to another installment of our 2018 Mustang GT build for drag racing, known as Project Magneto. From the very beginning, our intention has been to add boost to the Gen-3 Coyote, which, as everyone knows, is hampered by weak factory oil pump gears. While the overall engine package is robust, the Coyote oil pump gears are brittle and prone to failure when subjected to high-RPM and boost. Thankfully, Melling has complete drop-in replacements from the gears for those more budget conscious to an entire oil pump assembly in standard, high-volume, or high pressure. If you aren’t scared of reassembling the oil pump, then the Melling chromoly billet oil pump gears are the way to go.
For a quick refresher on the overall oiling system and the Coyote oil pump gears: all generations of the Coyote use a crank-driven gerotor-style oil pump like most late model Fords. Because the gerotor pump is driven directly by a gear on the crankshaft, the pump turns at engine RPM.
Gerotor pumps build pressure by meshing the inner and outer gears together. With the elevated speed of the pump, it’s easy to surpass the design parameters of the original material of the gears once the aftermarket upgrades start. Considering how the completely stock rotating assembly in these engines holds up reliably at over 1,000 horsepower we’ll take this one Achilles’ heel any day of the week (notice I said reliably, LS fanboys).
Melling’s Billet Oil Pump Rotor Assembly (P/N: 11396) is made of AISI 4140 Chromoly steel, measuring 89.0mm in outer diameter, and 14.2mm in thickness. It was designed as a drop-in upgrade to the OEM powdered-metal rotor set.
“Melling has been providing billet steel rotor sets since 2006,” states Mike Osterhaus of Melling. “The billet rotors were created as a solution to withstand the additional forces applied when power adders were installed onto the 4.6- and 5.4-liter engines. For material, 4140 chromoly is used due to its toughness, resistance to fatigue, and impact and abrasion resistance. The rotor profile has been optimized to provide efficient performance.”
“Melling does not heat-treat the rotor sets, as they need to provide what we call ’embedability’ to foreign material,” Osterhaus continues. “Since the oil pump operates with unfiltered oil, the rotor set needs to allow contamination to be passed through the oil pump during operation. This means that the gears still need to be ‘soft’ to allow foreign material to embed into the rotor surface, instead of locking it up. A hardened rotor set has a greater tendency to lock up when foreign material is present in the oil. So the design of the rotor set needs to be balanced – tough but still soft.”
Getting To The Coyote’s Oil Pump
Technician Mike Russell at CCC Motorsports in Santee, California is our faithful companion on the latest automotive journey with Project Magneto — namely, installing our billet oil pump gears. We got started by draining the radiator and oil. Russell then began work on the air intake system, unplugging all attached sensors and emissions plumbing before pulling the intake tube, air box, and filter. Next, he turned his attention to the battery, which needs to be completely removed along with the surrounding heat shielding to gain better access to the rear coils and spark plugs on the passenger side. Occasionally, Russell does remove the windshield wipers in order to get under the cowl to remove this piece. But, they were being a little stubborn and he managed without it this time. The coils and plugs were next on the agenda.
Removing the fans provided better access to the accessory drive, which Russell removed, starting with the water pump before progressing to the harmonic balancer. This gained access to the timing cover, which was promptly removed along with the timing chains and oil pump. Russell also dropped the oil pan a few inches for better access to the oil pump pickup, which is unique to the Gen-3 Coyotes.
Installing Billet Oil Pump Gears
Reassembly was straightforward. Melling’s billet oil pump gears were easily installed into the factory oil pump housing. It’s best practice to pack it with grease and then secure the oil pump housing with Loctite on the bolt threads. Since the crank gear and chains appeared to be in good shape, we decided to reuse them.
Getting the engine back in time was not as challenging as one might expect. It took a few attempts, but Russell quickly dialed it in. As components were being disassembled, Russell made sure to inspect them, such as the timing cover, which required replacing the gasket and front seal. He recommended applying a dab of RTV at some of the corners, but cautioned against using too much, as it would make removal of the cover more difficult if necessary.
After reinstalling the cam covers, Russell took the opportunity to upgrade our plugs for boost. We switched to NGK 6510s, gapped to .028 inches. These plugsare considerably colder than the stock plugs. The factory plugs are not suitable for boost, and after 89,000 miles, they had worn significantly and were due for retirement.
Well, it’s time to reveal the exciting news — that is, if you haven’t seen it already on social media: we’ve partnered with VMP Performance to showcase the true capabilities of the 5.0-liter engine, using the same Eaton TVS2650 supercharger found in its big brother, the GT500’s 5.2-liter Predator.
It was tempting to try other methods of boost to better manage traction, but the 50-state legality and the chance to work with VMP was too great to pass up. After speaking with Steeda, we feel we have a few tricks up our sleeves in managing traction. However, we also have the option to work with VMP on a track-only tune to get out of the hole softer, and are already plotting some trips to quarter-mile tracks with stickier surfaces. Stay tuned for the supercharger install.