Tom Wilson
July 8, 2011
Photos By: Ford Motor Company

In fact, EPAS just debuted with the '11 Mustang, so the Boss program gave EPAS specialist Steve Ferrari a second shot at fine-tuning the system. "Between the dampers and the EPAS, that's one of my favorite parts because you have five adjustments on the dampers, and you can drive it as your daily driver and the EPAS goes along with it. You have Comfort, Sport and Standard settings, so you can dial back on the shocks and dial back on the steering and relax." Or go all out.

Because the EPAS' electric motor is so tunable and the feedback each driver likes is so subjective, there's real artistry in harmonizing the steering with the shock settings.

"The neat thing about the system we use," Steve said, "is you can tune the damping independently like a shock absorber, so turning in versus turning out. You typically use more damping turning out; just like hydraulics, we're able to make it emulate the feel of the hydraulic system. We have aggressive tires and high levels of caster and camber, and it gets really snappy if you don't have control over the steering system."

Obviously the chassis guys gravitate to the track-oriented Laguna Seca. As Kevin summed it up, "[I] think what we achieved, especially with the (optional) Torsen, is reliable consistency throughout the track day. It's a 444hp car, right? And they can be nasty. But we worked hard to make it approachable and docile, yet still fast and give the experience of being fast." Just the way we like it. Thanks, Ford! 5.0

Horse Sense: It's impossible to discuss the Boss 302 engine without understanding the Coyote 5.0-liter engine it is based on. If you need to brush up on that engine, see our March 2010 issue for the 19-page "Coyote Beautiful" article. If that issue escapes you, or your friend "borrowed" your copy, we are re-running it as part of our 2011-2012 Mustang Performance special issue, which is on newsstands June 21, 2011.

Slick Stuff

Lubricating the high-rpm Boss called for detail changes from the already fast-rotating Coyote baseline. Interestingly, a new oil pump was not one of them. By deleting the piston oil squirters, the Boss oil system effectively closed eight bleed holes, thus gaining pressure and slightly restored volume to the bearings. Furthermore, the oil was thickened to a fully synthetic 5W-50 from the Coyote's 5W-30 dinosaur squeezings. Together these changes gave the pressure needed to force oil out to the rod bearings at 7,500 rpm.

Another boost came from the synthetic's better aeration qualities. Ford says they need to be under 10 percent aeration; the Coyote posts 8 percent aeration, and the Boss, 5 percent. Inevitably the high-speed RoadRunner heats its oil a little more than the Coyote, and indeed the engineers say they let the Boss's oil temp run a little warmer under extreme conditions, something synthetic oil is entirely nonplussed by.

Regular readers may recall an oil-to-water oil cooler was considered for the Coyote, but didn't make the cut because it was only necessary after about 20 minutes at speed on a road-racing track. Well, if the everyday Mustang GT doesn't really need an oil cooler, the race-car-with-license-plates Boss 302 demands one. The unit is fitted between the block and oil filter, and is fed coolant from the lower radiator hose. As in the Mustang GT, it's only needed for on-track action, but it's there because the Boss 302 is designed for just such fun.

More hardware changes were required when tuning the Coyote oil pan, not only for the Boss 302 engine's higher rpm, but also the Boss 302 car's increased cornering and braking loads. At high rpm, the issue is oil drain-back. The Coyote's horizontal baffle is a step for the river of draining oil to loiter on at high rpm, so the baffle was trimmed back to route the oil more directly to the pan's sump. Naturally this had a negative effect on keeping the oil in the sump when the Boss was maneuvering hard, but extensive work gained a compromise between drain back and retention.

Another pan detail, the Coyote baffling is stitch-welded in sections to the pan. During hard Boss braking, the oil fountained up between the baffle and pan, so the welds were made continuous in the RoadRunner. Tim Vaughn says that even if it's run a quart low, the Boss engine still keeps adequate oil trapped around the oil pump pickup.