Tom Wilson
February 16, 2010
Photos By: Dale Amy, Courtesy of Ford Motor Company

Coyote Slim
Anyone who's lived around coyotes knows just how thin they can be. Apparently some of that has rubbed off on the Coyote engine, which at last count was just 430 pounds. This is the shipping weight from the Essex assembly plant and includes the water pump but not the alternator, AC compressor, or starter.

This also the same weight as the Three-Valve 4.6, which is commendable considering the Coyote's larger displacement, two extra camshafts, extra valves, four cam timing phasers, extra crankshaft counterweights, beefed block, and other niceties. The engineers say they saved weight with the plastic intake, hollow camshafts, composite valve covers, five-core head castings, and plenty of attention to detail all over the engine.

Coyote Oiling
Considerable work went into prepping the Coyote's oiling system for its 7,000-rpm redline and high-g Mustang home. It begins with thin 5W-20 mineral oil for reduced oil-pump-drive requirements, less internal drag, and quicker cold-start lubrication. Oil capacity was increased to 8 quarts, both to ensure adequate supply at high engine speeds and to increase oil change intervals to 10,000 miles.

The oil pan shape and baffling was aided by computer modeling to check sloshing behavior while braking and cornering. Testing also showed oil drainback out of the valve covers while cornering (and drifting!) proved inadequate with the initial design, requiring slight but vital revisions to the drainback channel shape in the side of the block.

At 1g cornering, the oil was accumulating in the valve cover and flinging into the PCV system via the camshaft-timing wheels. These "pip wheels" make great oil paddles at 3,500 rpm, so Habib Affes Ph.D., CAE technical expert, modeled the situation, disclosing that down in the block's oil drain passage there was a curve or bump. At 1g cornering, this bump-physically angled at 45 degrees-was sensed as flat by the oil, so it would not drain past it. Straightening the curve lowered the oil puddle depth around the pip wheel from 11mm to 3mm, curing the PCV problem.

Interestingly, one item needing less oiling are the VCT phasers on the camshafts. Thanks to the cam torque actuation strategy, the phasers do not require high-pressure oil from the pump, but are instead fed bleed oil from the front cam bearing. Had CTA not been used, the oil pump would have needed enlargement to keep a relatively large volume of pressurized oil ready to go next to the phasers in the cylinder heads. And that would have cost horsepower.

Crankcase ventilation and oil drainback are major oiling improvements in the Coyote. Crankcase breathing has never been particularly good in high-rpm modulars, and early testing showed the Coyote's high volumes of drainback oil at high rpm were air-locking the crankcase from the top of the engine. In other words, the gush of oil trying to drain down at 7,000 rpm was blocking the pressurized crankcase air trying to find its way up, effectively choking the PCV system and inhibiting drainback.

The cure was to separate the drainback paths from the crankcase breathing chimneys. Thus, Coyotes have three large oil drainbacks on the exhaust or lower side of the cylinder head. They mate to corresponding passages on the outer side of the block that downspout the oil into the pan-similar to the dry-sumped Ford GT block.

For PCV gasses, passages are placed at the top of the crankcase, about where the camshaft would be in an OHV block. These passages connect to corresponding flues on the intake side of the cylinder heads. Thus, the oil drains and breather vents are completely separated and probably approach double the combined area of previous modulars.

Consideration was given to an external oil cooler, but ultimately it was decided not to penalize all Coyote buyers for the occasional antics of a miniscule fraction of owners. Oil temperature rises precipitously when the Coyote is revved more than 4,500 rpm for extended periods, and then an external oil-to-air cooler is vital. But those conditions can only be reached on a road-racing track, so the expensive cooler was ditched and engine management strategies were used to protect the engine during hot idles. However, the mounting area for the cooler was "protected" during the 2011 Mustang's development. That makes it easier for the open-trackers among us to fit a cooler (highly recommended by Coyote engine designers), and tells you something about Ford's intentions for special editions of the Coyote-powered Mustangs.

And don't worry about the occasional open-track without an oil cooler. The engineers say the oil cools quickly as soon as you take your foot out of it, and the engine management will limit the torque output if the oil gets too hot.