5.0 Mustang & Super FordsNews & Views
Ford Motor Company 6.2 Liter V8 Engine - Big Change
Sporting 379 CI, Ford's Newest Gas V-8 Packs Large Promise
Ford's newest gasoline V-8, the 6.2-liter, is an interesting development. Architecturally it doesn't much resemble other Ford engines once above the head gasket. Its production debut is in trucks and yet it already has a performance background on the dragstrip. But most interestingly, the more you study the new 6.2, the more potential you see.
Just to underscore that point-even though Ford certainly hasn't-the 6.2 is landing on dealer lots at 1.02 hp per cubic inch, in 5,500-rpm truck trim, no less. There's power lurking in this big engine.
Obviously designed to deliver the one thing modular V-8s can't-cubic inches-the 6.2 has an indirect development history. Originally codenamed the Hurricane and rumored to be a cool Mustang mill, the engine dropped off the radar for a while before resurfacing as the Boss. But now it's officially just called the 6.2 and, so far, is purely a truck engine.
What sets the 6.2 apart is its 115mm (4.53 inch) bore spacing. Modular V-8s such as the new Coyote 5.0 are limited to 100mm bore spacing by their production machinery. So to break the modular displacement barrier, Ford has gone to a fundamentally larger architecture. In the 6.2, that translates into a 4.02-inch bore.
We've come to think of the 6.2-liter as a big-block modular. Of course, the only modular architecture making it through to the 6.2 is the bellhousing bolt pattern. We suppose the deep-skirted block, cross-bolted mains, and gerotor-style oil pump are modular thinking, but it's best to remember the 6.2 as its own engine family.
What a Bore
That large cylinder bore does wonderful things for the 6.2. Most basically, it allows larger displacements with less friction, weight, and length than the modular method of adding cylinders.
Secondly, it allows large valves with reduced valve shrouding, so breathing is well supported. And while it may seem retrograde thinking to consider Two-Valve cylinder heads, the large bore allows good breathing with Two-Valve heads, which helps contain costs.
Other than the larger bore, we don't see anything fundamentally innovative in the 6.2's short-block compared to other modern Ford engines. The block is cast-iron for durability, the deep skirts and cross-bolted mains are typical modern practice, and the gerotor oil pump is also typical. We also like the piston oil squirters.
There is mention of improved bay-to-bay breathing in the 6.2. This is something Ford is big on, as it's mentioned by the company as a factor in the 3.5/3.7 V-6 family, the Coyote 5.0, and now the 6.2. In practice, it means the crankcase is ventilated, with windows through the main bearing bulkheads, so air pulses generated by piston movement can move more freely in the crankcase. Ford says there is good power from the technique; we guess it helps with ring seal.
About the only gamble Ford took with the bottom end was simply the large displacement. No one knows where the economy or fuel prices are going (well, they're going up, but how much and when are open questions), so the cross purposes Ford is addressing with the 6.2 are delivering a large-enough gasoline V-8 in trucks, while not spending too much money in case the engine is driven into obscurity by $7-a-gallon gas.
Where the 6.2 goes off on its own is in the valvetrain. Unlike any other Ford V-8 since you're granddad was buying muscle cars, the 6.2 uses a single overhead cam with splayed valves and shaft-mounted rocker arms. As we'll see, this is a cost-effective way of making good power, and it's definitely interesting in that it doesn't resemble any other Ford engine.
What reasoning led to such a valvetrain? Well, the overhead-cam layout is flexible from a manufacturing standpoint because different cylinder head layouts can be easily bolted to the same short-block. Much as Two-, Three-, and Four-Valve cylinder heads have been used with essentially the same 4.6 modular block, Ford engineers were careful to design the 6.2 short-block so it could readily accept twin-cam heads. And that's sounding interesting to us: a big-block V-8 with DOHC, Four-Valve heads? Tasty.
Overhead camming also frees up cylinder-head real estate because there's no need to accommodate push rods. That gives the cylinder-head designer more leeway in laying out the intake ports, exhaust ports, water jacketing, and head bolts. And sure enough, the 6.2 has large, symmetrical ports, the better to feed its large valves.
A single camshaft per cylinder head is less expensive than dual cams, weighs less, and is more compact than a twin-cam head. The downsides are you have to work harder to package anything other than inline valves with a single overhead cam, and there are fewer variable-cam-timing options available because the intake and exhaust lobes are in a fixed relationship to each other on the single bumpstick.
With a large displacement, low-to-medium-rpm engine such as the 6.2, variable valve timing is certainly helpful, but not as critical as on a high-revver such as the Coyote 5.0. So single-cam variable timing certainly has its place. We'll note the 6.2 uses Cam Torque Actuation of the variable cam timing to reduce parasitic drive losses.
Of course, inline valves are an inherent breathing limitation. Canting the valves outward is highly desirable, so Ford spans the distance from the centrally located cam to the splayed valve-stem tips using rocker arms. And to maintain rigidity, Ford opted for a stout shaft-mount rocker arm system. For a 5,500-rpm truck engine, the shaft-mounted 6.2 valvetrain should be absolutely bulletproof and stable. The medium rpm range of the 6.2 engine means the rocker arm mass isn't much of a bother, either.
One reason shaft-mounted rockers haven't been popular with overhead cams is dealing with valve adjustment. Shaft-mounted rockers in overhead-valve engines can employ a traditional hydraulic lifter, but overhead-cam layouts have traditionally called for mechanical adjusters. Because taking your F-250 to the dealer for occasional valve adjustments won't do, Ford got crafty, installing a tiny hydraulic-lash adjuster in the valve end of the rocker arm. Visually hidden, the adjusters are fed via internal passages in the rocker arm and shaft. Meanwhile, the cam end of the rocker arm uses a roller tip to reduce friction.
Thanks to its medium-speed rpm range and canted valve architecture, the 6.2 can employ some seriously large valves; right at 2.10-inch for the intake. These large valves obviously aid the 6.2's breathing, and considering both the canted intake and exhaust valves open into the combustion chamber, breathing should be excellent for a Two-Valve engine. That's borne out by the major-league power hot-rodded 6.2s have delivered when Ford took them racing.
One casualty of those big valves is the practical impossibility of a centrally located sparkplug. Ford's solution was to fit two plugs per cylinder. Coil-on-plug ignition is used, with the coil sitting on the top plug and a traditional ignition wire firing the bottom plug.
No doubt also to contain costs and in deference to the big-valves eating up the combustion chamber real estate, the 6.2 forgoes direct fuel injection for traditional port fuel injection. The injector does have a straight, vertical shot past the canted intake valve, however, so Ford is likely getting many benefits of direct fuel injection without the costly DI injectors and high-pressure fuel pump.
The combustion chamber shape, described as "Hemi-like," is mirrored by a flat-top piston with minor valve reliefs for good flame front travel, along with what seems like a complex-shaped chamber in the head thanks to the canted valves. Energetic motion of the air/fuel mixture seems assured. Of course, Three- or Four-Valve heads could deliver completely different chamber shapes.
A long-runner plastic intake manifold tuned for torque mates to the heads in typical modular engine fashion-via flat extensions of the intake ports jutting into the valley. The throttle body is electronic, of course, and is centrally located. So after decades of side-facing throttle bodies Ford has released two forward-facing throttle bodies for 2010 on the 6.2 and the Coyote 5.0.
Other details follow the latest Ford best practices. The crankshaft-position sensor is mounted at the rear of the crankshaft, and large separate cover plates are used to retain the crank seals. Numerous pips on the cam and crankshaft pulse wheels speak to high-accuracy engine management, and enhanced bay-to-bay crankcase breathing is cited. While the 6.2 was clearly designed for cost-effective horsepower, there is no overt cost cutting. Ford may have limited expenses with the 6.2, but it didn't do anything cheaply.
Built for Speed
Curiously for a truck engine, the first 6.2s seen in public were in racing applications. The first was the mysterious drag-race engine spotted in Don Bowles' yellow S197 in NMRA competition. A Ford/Roush collaborative effort, the mystery engine (with apologies to Chevy's Mark III 427 Mystery Engine of early 60s Daytona fame) kept the Ford world buzzing with rumors in 2007, as neither Ford, Roush, nor Don would give a word of explanation about it.
Don posted a 9.10/145 best with the unnamed, naturally aspirated engine in the 3,300-pound Mustang, which immediately tells you the combination was hitting in the 800hp range. What we now know is the beautifully detailed Bowles engine was a hand-built 6.2 prototype punched to an even 7 liters, or 427 ci. This was done by making a core change at the casting plant to get an extra 3 mm or so of bore diameter in the one-off iron-block, then over-boring the cylinders by the "organic" 2 mm allowed for field servicing. The resulting approximately 5mm-larger (0.194-inch) bore gave Don's engine about a 4.217-inch bore-call it a 4.250-inch bore among friends. If necessary, lengthening the stroke a bare 2 mm to 3.82 inch would have given the magic 427-inch displacement with a 4.217-inch bore.
Likewise, Don's cylinder heads were developed finding their limits. First they ported a set of stock castings as necessary, then cut those heads apart to see where they were thin. Some form of rapid prototyping fabrication was then employed to make special heads with the necessary extra metal. These castings were ported further. The eight-throttle, individual-runner intake on Don's engine was obviously a one-off and allowed excellent top-end breathing for the max-effort drag sprints. Ford insiders say burning E85 fuel, this combination was tuned to between 750 and 800 hp.
Closer to the real-world street is the 6.2 Ford ran in the 2008 Baja 1000. Bolted into the F-150 SVT Raptor R race truck-an amazingly showroom-stock Raptor with race-worthy suspension-this 6.2 was "production-based" featuring stock bore and stroke, but tuned to 500 hp. It completed the brutal off-road classic without a hitch. It is the basis of the "estimated 500hp" version of the 6.2 Ford has announced for the special FR F-150 Raptor SVT pre-runner. Only 50 of these trucks are to be built, and they won't be street legal.
Finally, there was also a 7.5-liter, 850hp version Ford developed for a Trophy Truck application. No doubt the extra half-liter of displacement came from a long-stroke crankshaft; we haven't heard how successful that engine has been.
Ford initially abandoned the 6.2 for Mustang production for unspecified reasons, developing the more compact Coyote 5.0 as the main Mustang V-8 instead. The Blue Oval could build the 6.2, or some variation of it, for at least limited Mustang use. But with the impressive Coyote 5.0 liter now hitting the streets and the near-certainty of a supercharged version of the Coyote to come, it isn't immediately apparent where a 6.2-or a 7.0-liter-would fit in.
Lack of a drop-dead obvious fit never stopped enthusiasm, however, and several good possibilities exist, including limited-run Cobra R or Super Cobra Jet specials using the FR Raptor engine. Or perhaps Ford has another limited-run Mustang up its sleeve. We just can't let go of what a highly placed Ford manager said to us: "You're going to see this thing hot-rodded in Mustangs." Was he hinting the factory has a plan, or simply that enterprising hot-rodders won't let this many cubic inches pass them by?
We don't know, but at the least the 6.2 seems a great Ford Racing crate engine candidate for crafty Mustang engine swappers. Hot-rodding started with durable, no-excuse, big-inch engines at moderate cost, and that's the 6.2 to a T. Sounds like a winning combination to us.
(as sold in 2011 F-250/350 trucks)
Type 90-degree V-8
Bore 4.02-in (102mm)
Stroke 3.74-in (95mm)
Displacement 379 ci (6,208 cc)
Horsepower 385 hp @ 5,500 rpm (411 hp in Raptor)
Torque 405 lb ft @ 4,500 rpm (434 lb-ft in Raptor)
Compression Ratio 9.8:1
Sparkplugs Two per cylinder
Valvetrain SOHC, two valves per cylinder
Valve Size 2.10-in, (53.5mm) intake, 1.65-in (42mm) exhaust
Camshaft 0.510-in (13mm) valve lift; 258/268 degrees duration
Cam Timing Variable with Cam TorqueActuation
Rocker Arms Roller, shaft-mounted
Oil Capacity 7 quarts
Fuel Grade 87-octane regular/E85 or any blend
Knock Sensors Dual
In Ford's Words
Those at Ford intimately familiar with the 6.2 emphasized several characteristics of the all-new V-8:
• Designed as a rugged workhorse specifically for truck applications.
• Excellent port-flow characteristics, especially at higher lifts, which lends itself to lots of tuning potential, as evidenced in the drag racing experimental engine and the Baja 1000 Raptor R race truck.
• With 115mm bore centers, the engine has lots of potential for increased displacement.