Ford Barra 245T engine – Australian Car.Reviews

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Introduction

Ford’s Barra 245T was a turbocharged 4.0-litre inline six-cylinder petrol engine that was introduced in the Ford BA Falcon XR6 Turbo in October 2005. While the Barra 245T shared may attributes with the naturally aspirated Barra 190 engine on which it was based, key differences included:

A Garrett GT3582R turbocharger which provided peak boost pressure of 6 psi (0.413 bar);
Dished bowl pistons – with fully floating gudgeon pins – for a compression ratio of 8.7:1;
Increased fuel delivery pressure (4.0 bar, compared to 2.4 bar);
More heat resistant exhaust valves; and,
Heat shields to protect components such as the steering column assembly and the under floor area above the three-inch dump pipe and the catalysts.

Compared to the Barra 240T engine which it replaced, changes for the Barra 245T engine included:

The introduction of dual independent variable cam timing;
A revised camshaft profile; and,
The introduction of an additional knock sensor for more sophisticated ignition timing and spark control.

Furthermore, ‘transient’ rpm limits were introduced which momentarily allowed engine speed to exceed the prescribed rev limit during upshifting – this enabled wide open throttle upshifting to occur at an engine speed closer to the rev limiter than was otherwise possible.
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Model	Engine	Trans.	Peak power	Peak torque	Years
Ford BF Falcon XR6 Turbo	4.0-litre turbo petrol I6	6sp man., 6sp auto	245kW at 5250rpm	480Nm at 2000-4500rpm	2005-08
Ford SY Territory Turbo	4.0-litre turbo petrol I6	6sp auto	245kW at 5250rpm	480Nm at 2000-4500rpm	2005-11

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Block

Like the Barra 182 and Barra 190, the Barra 245T engine had a cast iron block with 92.26 mm bores and a 99.31 mm stroke for a capacity of 3984 cc. Similarly, the Barra 245T block had cross-bolted main bearing caps to increase rigidity and a cross-bolted alloy sump.

Cylinder head

The Barra 245T engine had a gravity-cast, aluminium alloy cylinder head which was mounted on a single layer steel (SLS) sheet metal gasket. The water jacket for the Barra 245T engine featured deflection vanes to squeeze coolant past hot spots – such as the exhaust valve seats – at higher velocities to achieve more even temperatures throughout the cylinder head.

Pistons and compression

Due to its forced induction, the tops of the pistons for the Barra 245T had a ‘dished bowl’ shape which lowered the compression ratio to 8.7:1 (compared to 10.3:1 for the Barra 190). Furthermore, fully floating gudgeon pins were used to connect the piston to the connecting rod.

Garrett turbocharger

The Barra 245T engine had a Garrett GT3582R turbocharger which provided maximum boost pressure of 6 psi (0.413 bar). The turbocharger consisted of two elements, a turbine and a compressor, which were both installed on a single shaft. The ball bearings were supplied with engine oil from the oil supply tube which was then returned to the oil pan via the oil return pipe. The turbocharger housing received coolant from the engine cooling system.

The turbine was mounted on the exhaust manifold and used the flow of exhaust gases to drive the compressor. The compressor would then feed air to the engine’s air intake via the air-to-air intercooler which regulated the temperature of the charged air to maintain boost pressure.

The Powertrain Control Module (PCM) used a boost pressure sensor (BPS) to monitor the boost pressure of the turbocharger. Based on engine load, temperature and engine speed, boost pressure was determined by the operation of a single by-pass wastegate valve which controlled how much exhaust gas was directed to the turbine and, therefore, the turbine’s speed. In turn, the wastegate valve was operated by an actuator which had a diaphragm and used regulated air pressure.

Intake air pressure was further controlled by a blow-off valve which would dump excess pressure into the low pressure side of the intake system when the throttle was closed. The blow-off valve was actuated by intake manifold pressure, via a rubber hose from the intake manifold.

Camshafts and valvetrain

The Barra 245T engine had double overhead camshafts that were driven by a single-stage roller chain. To minimise weight and improve durability at higher engine speeds, the camshafts were roll-forged and had bored centres. The four valves per cylinder were actuated by roller finger followers and a clip held the hydraulic lash adjusters to the rockers for durability. To limit in-chamber tumble and provide good seating, the valves had a domed head and no lip. It is understood that the Barra 245T shared key specifications with the Barra 190 engine (see table below).
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Barra 245T valvetrain specifications
Rocker arm ratio	2.04:1
Camshaft lobe lift (intake and exhaust)	5.39 mm
Valve lift (intake and exhaust)	11.00 mm
Intake valve diameter	35.0 mm
Exhaust valve diameter	32.0 mm

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Dual independent variable cam timing (DIVCT)

The Barra 245T engine had a vane-type VCT phaser – produced by Aisin – on each camshaft that provided continual variable adjustment within a 60 degree range (10 degrees advanced or 50 degrees retarded from the initial pin lock position). Each camshaft phaser was hydraulically controlled via an oil control valve that was mounted on top of it.

Significantly, the variable cam timing system for the Barra 245T engine was Ford’s ‘Dual Independent Phase Shifting’ (DIPS) which enabled the intake and exhaust camshafts to be varied independently of each other. In contrast, the Barra 240T engine had Dual Equal Phase Shifting (DEPS) in which the intake and exhaust camshafts could only be advanced or retarded by the same degree synchronously such that valve overlap was a constant 25 degrees.

Valve timing for the Barra 245T engine is understood to be the same as the Barra 190 engine and is given in the tables below. From these, valve overlap could be varied from -35 degrees to 85 degrees, intake duration was 256 degrees and exhaust duration was 256 degrees. Furthermore,

On low throttle openings, timing would be retarded by up to 50 degrees to improve fuel economy;
At idle, the intake camshaft was retarded by 18 degrees for improved combustion and a stable idle; and,
At higher loads, timing would be advanced for greater power.

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Barra 245T engine – valve timing: pin lock position
Intake	Open	27.5° BTDC
Intake	Close	48.5° ABDC
Exhaust	Open	78.5° BBDC
Exhaust	Close	2.5° BTDC

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Barra 245T engine – valve timing: 10 degrees advanced
Intake	Open	37.5° BTDC
Intake	Close	38.5° ABDC
Exhaust	Open	88.5° BBDC
Exhaust	Close	12.5° BTDC

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Barra 245T engine – valve timing: 50 degrees retarded
Intake	Open	22.5° ATDC
Intake	Close	98.5° ABDC
Exhaust	Open	@8.5° BBDC
Exhaust	Close	47.5° ATDC

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Injection and ignition

The Barra 245T engine had an electronically-controlled sequential fuel injection system with peak fuel delivery pressure of 4.0 bar; the injection and firing order for the Barra 245T engine was 1-5-3-6-2-4. The ‘speed density’ fuel injection system used the engine speed, intake air temperature and manifold absolute pressure sensors to calculate intake air mass and therefore the fuel required to be injected for combustion. This quantity of fuel was then adjusted according to feedback information from the Heated Oxygen (HEGO) sensor, providing close loop control of fuel injection.

The Barra 245T engine had distributorless, coil-on-plug ignition with individual coils mounted above the spark plug. The long-life spark plug was positioned in the centre of the combustion chamber roof between the four valves. For the Barra 245T, upgraded spark plugs were introduced which had a 0.5 mm finewire centre electrode (the smallest then available) and platinum pad ground electrodes. According to Ford, the spark plugs were optimised for idle stability and helped prevent misfire.

For the Barra 245T, the ignition system featured adaptive and variable dwell (the time required to charge the ignition coil) for more efficient ignition control. Specifically,

Adaptive dwell accounted for battery voltage and the temperature of the coil windings in the ignition system to provide a more reliable, consistent charge; and,
Variable dwell provided maximum coil energy when high voltages were required (e.g. wide open throttle) and minimum coil energy when cruising or at idle.

Knock sensing and spark correction

The Barra 245T engine introduced an additional knock sensor which, according to Ford, enabled a change in ignition timing strategy for more accurate spark control, improved fuel economy and greater refinement. Specifically, the Powertrain Control Module had four forms of spark control:

Individual/averaged spark correction: a performance mode which used 50 per cent of the individual cylinder correction and 50 per cent of engine average spark correction for more consistent performance at higher engine speeds and under heavy loads;
Individual ‘fast only’ spark correction: reacted to detonation noise and retarded the spark for the next firing event on the same cylinder. This method provided optimum fuel efficiency because spark was only retarded when detonation was detected by the system;
Individual slow/fast spark correction: applied in addition to the ‘fast only’ mode, slow correction recorded the spark advance used on previous combustion cycles and gradually reduced spark advance if knock was not detected for a few seconds, providing greater refinement; and,
No spark correction: used at low engine loads when detonation was not possible. As a result, optimum spark timing was applied.

Internal Exhaust Gas Recirculation (EGR)

The Barra 245T engine complied with Euro III emission standards and had an internal exhaust gas recirculation system whereby late closing of the exhaust valves – during the downward induction stroke – would cause some of the unburned exhaust gas in the extractors to return to the intake.