A 2.7-L gasoline engine in a full-size Ford F-150 pickup? Fuel economy is important, with challenging regulatory-dictated improvements to be met—but who would want to buy it? After all, isn’t the full-size pickup market all about V8 muscle, or at least diesel stump-pulling torque?
Ford hasn’t given up on the V8 for its light-duty trucks; the 5.0-L will remain in the lineup. But its game-changing move for 2015 to an all-aluminum body and cargo box gives it a significantly lighter platform for making engine downsizing a viable proposition. And it has tried to develop an all-bases-covered approach to make a convincing argument to truck buyers.
First, the 2.7-L (code-named Nano) is an EcoBoost edition: a direct-injected, twin-turbocharged 60° V6 rated at a healthy SAE certified 325 hp (242 kW) and 375 lb·ft (508 N·m). Peak torque is achieved at 2500 rpm, which is 3500 rpm short of the engine's redline. Its performance figures vs. vehicle weight are comparable with those of Ford's 3.5-L EcoBoost V6 that has captured more than half of 2014 F-150 customers, according to the company's sales.
Ford has yet to announce fuel economy numbers for the 2.7-L-powered F-150, but officials are informally promising the truck's fuel efficiency will impress the customer base. The last U.S. domestic nameplate model 2.7-L V6 was by Chrysler, a naturally-aspirated engine for compact sedans; it was discontinued in 2010. Toyota currently uses a 2.7-L naturally-aspirated inline four to power its Tacoma midsized pickup.
CGI cylinder block in aluminum structure
The 2.7-L is based on an all-new V6 architecture; it's not part of the 3.5-L family. Bore and stroke dimensions are a "square" 83 x 83-mm. Bore spacing is 95 mm/3.74 in, and the cylinder bank offset is 35 mm/1.38 in.
The dohc, four-valves-per-cylinder engine employs twin-independent continuously-variable valve timing (TI-CVT), with the phasers operating in a range of over 30º. Ford is able to use TI-CVT to eliminate the need for an exhaust gas recirculation (EGR) valve. Compresson ratio is 10:1.
The linerless cylinder block is compacted graphite iron (CGI), Ford's first application of this material in a gasoline engine. Proven on the latest generation diesels and some racing engines, CGI is a high-strength material with excellent heat transfer properties. Compared with grey iron, the CGI cylinder block offers approximately 75% higher tensile strength, 45% greater stiffness and roughly double the fatigue strength, with excellent dimensional stability, durability, and NVH damping characteristics, according to Ed Waszczenko, Ford's V-Engine Design Leader. He noted that Ford also used CGI in the 6.7-L Power Stroke V8 diesel (which influenced the design of the 2.7-L's block, offset I-beam connecting rods, reinforced-plastic oil pan, and pistons) as well as in the 2.7-L light-duty diesel co-developed by Ford and PSA for European applications.
CGI's strength properties allow for thinner-section cylinder block walls and narrower main bearing saddles. The CGI block is actually one of two main structural elements of the new V6's lower end. The other main element is a die-cast aluminum ladder frame which envelops the lower portion of the CGI element and bolts to thick flanges on each side of the cylinder block. Heavily ribbed on its exterior for added rigidity, the ladder frame also supports the precision-fractured main bearing caps.
The bearing caps, also in CGI, are laser-etched at an angle, Waszczenko explained. The specific angle creates a wedge effect that when the sections are merely set together, the engine actually would be able to run without the cap bolts.
The small (top) end of the con rod does not contain a piston pin bushing. Instead, the rod's pin bore is slightly convex, to allow for flexing of the pin, and is silicone-coated. Eliminating the bushing permits a slight reduction (3.0 mm) in deck height of the engine, which is 218.3 mm (8.60 in). The exhaust manifolds are cast integrally with the cylinder heads, which produces a compact overall structure and improves heat transfer—necessary for fast catalyst light-off. At the front, the accessory drive pulleys are mounted to a single, rigid aluminum casting.
The cooling system is a reverse-flow: Once the thermostat opens, the coolant flows from the pump through both the heads and the exhaust manifolds, and then down and through the block.
The twin-turbo configuration, which uses low-pressure BorgWarner turbochargers, is similar to that of the 3.5-L EcoBoost V6, with peak boost of 29 psi (200 kPa).
Efficiency upgrades, payload performance
Idle stop-start is standard on the 2.7-L for 4x2 and 4x4 applications. However, it is disabled when the F-150 is in tow mode or four-wheel-drive is engaged.
Other efficiency upgrades include a variable displacement engine oil pump and active grille shutters on the truck. The shutters and idle-stop system not only provide Corporate Average Fuel Economy credits, but also may improve the truck's window sticker numbers.
To help sell the 2.7-L and the downsizing strategy to the F-150 customer base, Ford is announcing some significant performance numbers, specifically that the new F-150 will have a 15% better power-to-weight ratio than the 2014 model, thanks to curb-weight reduction of over 700-lb (342 kg), based on a comparison of 4x4 crew-cab models with 18-in wheels.
F-150 engineering is putting its focus on payload: 2250 lb (1021 kg ) with a 4x2, and 2160 lb (980 kg) with a 4x4, which tops both GM's 5.3-L V8 and Chrysler's Ram 3.0-L Ecodiesel V6. The long-advertised peak flat towing capacity is lower, at 8400 lb/3810 kg (4x4) or 8500 lb/3856 kg (4x2) than on those competitive makes.
But Ford also tested the 2.7-powered F-150 against those competitors to the SAE J2807 towing standard, pulling a 7000-lb (3175 kg) enclosed trailer up a 6% grade (at the Colorado River's Davis Dam in Arizona), and is claiming it outperformed both. (See related article on the Ford vs. Ram towing-claims battle and J2807: http://articles.sae.org/13365/).
Further, the new F-150 will continue to offer the 3.5-L EcoBoost and 5.0-L V8 for buyers looking for higher flat towing capacity. Ford is anticipating a roughly even 28% market share split for those three engine choices, with the remaining 16% estimated share taken by what is now the base engine: a "new" 3.5-L naturally-aspirated V6 based on the 3.7-L V6.
The 2.7-L is produced at the Lima (OH) Engine Plant, into which Ford has invested half a billion dollars for tooling and processes related to the new engine
6.2-L V8 dropped
While the 6.2-L V8 has been dropped from F-150 duty, the 3.5-L V6 EcoBoost was a 2014 towing leader at 10,300 lb (4673 kg). The available 5.0-L V8 also had a high number, at over 9000 lb/4082 kg. But Ford said its surveys show that up to 85% of F-150 buyers' towing needs would be satisfied by the 2.7-L V6.
So Ford Truck engineers are confident their new, mass-efficient pickup will retain its competitive towing capabilities, and its market leadership, even as it faces increasingly stringent fuel economy regulations.
Senior Editor Lindsay Brooke contributed reporting to this article.Continue reading »