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Ford 3.5L EcoBoost Engine Review

3.5L EcoBoost Engine

The 3.5L EcoBoost is a 3.5-liter V6 gasoline direct-injected and turbocharged engine firstly introduced in 2007 under the name TwinForce. The main idea behind this power unit was the creation of a solid alternative to a large-displacement V8 engine such as the V8 coyote sourced engine. The new turbocharged 3.5L V6 engine provides equivalent power and torque to a naturally aspirated 6.0L V8 with less fuel consumption and emissions of harmful substances to air. Since the start of production in 2009 and further extension of using this engine in Ford's vehicles, the popular platform for this V6 engine became Ford's top-seller - the Ford F-150. And this is not surprising, because EcoBoost F150s have a cheaper price with no disadvantages of small displacement, NA 6-cylinder engines, compared to V8 F150s.

The 3.5 EcoBoost is built around the Duratec 35 (Ford Cyclone V6 engine) engine block with the same bore and stroke dimensions. The EcoBoost block is all aluminum and an open-deck design with high strength steel sleeves. The engine is equipped with forged steel I-beam connecting rods and forged steel crankshaft with 6-bolt main bearing caps. High-strength aluminum and CNC machined pistons have low friction coating on the piston skirt and piston top shape specially designed for efficient combustion. The cylinder block got oil jets spraying oil on the underside of the pistons to keep them cool and strong. An oil pan is also aluminum.

3.5L EcoBoost cylinder heads are aluminum with four valves per cylinder, pent-roof combustion chambers, centrally located spark plugs (iridium spark plugs), and two overhead camshafts. GDI fuel injectors are placed below-center of the intake valves. The diameter of intake and exhaust valves is 37 mm (1.456 inches) and 31 mm (1.220 inches). The valvetrain has polished solid buckets - Direct-Acting Mechanical Bucket (DAMB). Camshafts are driven by a single primary chain. Ford also applied Twin Independent Variable Camshaft Timing (Ti-VCT) on this engine. The intake camshaft from the driver’s side has an additional lobe driving a high-pressure fuel pump of the direct fuel injection system. The pump delivers fuel pressures up to 2150 psi.

The key component that provides excellent performance is a turbocharger. The 3.5 EcoBoost uses twin parallel mounted Borg Warner K03 turbochargers for truck version and Garrett GT15 for other applications. They are smaller, variable-vane, high-pressure turbos allowing peak torque faster (at just 2,500 rpm), and reducing turbo lag. 90 percent of its peak torque is between 1,550 and 5,500 rpm. Turbochargers are attached to high strength cast iron low internal volume exhaust manifolds. After turbochargers, exhaust gases go through fast cat-converters to keep emissions low. The intake manifold, charge pipes, and stock intercooler end tanks are made of plastic.

The engine also features modern electronic components: Coil-On-Plug (COP) distributorless electronic ignition system, advanced Bosch engine computer unite, high accuracy knock sensors, IAT sensors, MAP sensors, wideband O2 sensors, and etc.

The Second Generation of the 3.5L EcoBoost Engine

In 2017, Ford has revised the design of the 3.5L EcoBoost and a new more powerful version became available for the 2017 F-150, 2018 Expedition, and 2018 Navigator. The upgraded engine received a number of changes, but the most noticeable of them is the addition of multi-port fuel injection and new turbochargers. The operation of multi-port fuel injection is combined with direct injection, what covers a raised fuel output needs but also prevents a carbon buildup on the intake valves keeping the engine on the same level of performance during a long mileage. New Borg Warner turbocharger has turbine wheel made of MAR-M-247 super alloy and electrically actuated wastegate reducing turbocharger lag even more.

New 3.5 EcoBoost is equipped with a two primary chain system (there is one separate timing chain driving each cylinder bank). The cam chain drive sprocket on the crankshaft is a double gear arrangement. New chains are also more durable and less prone to stretch due to an increased thickness of the side plates. Cylinder heads now have a roller-finger follower valvetrain and light hollow camshafts. All these changes are aimed at reducing friction and mechanical losses. And finally, the compression ratio was increased from 10.0:1 to 10.5:1 (excluding H.O.).

Engine Specs

Manufacturer
Cleveland Engine Plant No 1, Ohio, the USA
Production years
2009-present
Cylinder block material
Aluminum
Cylinder head material
Aluminum
Fuel type
Gasoline
Fuel system
Direct injection;
Direct injection + port injection
Configuration
V
Number of cylinders
6
Valves per cylinder
4
Valvetrain layout
DOHC
Bore, mm
92.5 mm (3.64 in)
Stroke, mm
86.6 mm (3.41 in)
Displacement, cc
3,496 cc (213 cu in)
Type of internal combustion engine
Four-stroke, turbocharged
Compression Ratio
10.0:1
10.5:1 - 2017+ (except on the 3.5L EcoBoost HO for the Raptor, which remains at 10.0:1)
Power, hp
320-647 hp (239-482 kW)/ 5,000-6,250
Torque, lb ft
350-550 lb-ft (475-475 Nm)/ 2,250-5,900
Engine weight
-
Firing order
1-4-2-5-3-6
Engine oil weight
SAE 5W-30
Engine oil capacity, liter
5.9 l (6.2 qt) – with oil filter
Oil change interval, mile
9,000 (15,000 km) / 12 months
Applications
Ford F-150, Ford F-150 Raptor, Ford Expedition/Expedition EL, Lincoln Navigator/Navigator L, Ford Transit, Ford Flex, Ford Taurus SHO, Ford GT, Police Interceptor Sedan, Ford Explorer Sport, Ford Police Interceptor Utility, Lincoln MKS, Lincoln MKT

3.5 EcoBoost Engine Problems and Reliability

The 3.5-liter EcoBoost engine has proven itself on the good side in terms of reliability. Many of these engines delivered hundreds of thousands of miles without a single breakdown and still going. But let's try to highlight common problems and failures that happening with these engines.

The timing chain is sensitive to the oil condition. Turbocharged engines are very aggressive to the engine oil and it is very important to not pass the recommendation of oil change intervals. Worn-out oil inside the 3.5 EcoBoost can damage the timing chain, guides, and its tensioner. The second gen engine got more reliable timing chain due to this factor.

The following problem is common to all engines with direct fuel injection - a carbon buildup on the backside of the intake valves and on walls of the intake ports. While port injection system injects fuel before intake valves and fuel also acts as a cleaner from soot and dust, direct injected engines suffer from lack of a natural cleaning process in the intake what causes restricted air flow, loss of power and increased fuel consumption. The upgraded engine already got an additional port injection which eliminates this problem.

As you can see, most of the engine problems are associated with the first gen 3.5 EcoBoost. Based on independent research, the engine has good longevity if owners precisely follow the maintenance schedule and use the recommended oil. Average trouble-free mileage for the 3.5 EcoBoost engine is about 200k miles, after that it all becomes individual.

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