Introduction
The Boss 260 was a 5.4-litre 90-degree V8 engine which was introduced in the Ford BA Falcon XR8 in January 2003. The Boss 260 V8 engine was a member of Ford’s Modular V8 engine family and closely related to the5.4-litre Barra V8 engine that was also introduced in the Ford BA Falcon. Developed for top-end performance, key features of the Boss 260 V8 engine included its:
- Cast iron block;
- Forged steel crankshaft; and,
- Aluminium alloy cylinder head with double overhead camshafts and four valves per cylinder.
Unlike the Barra V8, the Boss 260 V8 engine omitted variable intake cam timing (Ford’s ‘VCT’).
| Model | Engine | Trans. | Peak power | Peak torque | Years |
|---|---|---|---|---|---|
| Ford BA Falcon XR8 | 5.4-litre petrol V8 | 5sp man., 4sp auto |
260kW at 5250rpm | 500Nm at 4250rpm | 2003-04 |
| 6sp man., 4sp auto |
260kW at 5250rpm | 500Nm at 4250rpm | 2004-05 | ||
| Ford BF Falcon XR8 | 5.4-litre petrol V8 | 6sp man., 6sp auto |
260kW at 5250rpm | 500Nm at 4250rpm | 2005-08 |
Block
The Boss 260 V8 engine had a cast iron block with 90.2 mm bores and a 105.8 mm stroke for a capacity of 5408 cc. The Boss V8 had a deep-skirt design whereby the block extended below the crankshaft centreline and enclosed the crankshaft – this enabled the fitment non-structural, low-profile oil pan with a single plane oil seal and fully enclosed, one-piece rear main bearing seal. This oil pan was shared with the Boss 290 V8 and included a front well to clear the cross-member and to provide adequate ground clearance; it was also tested for oil starvation when cornering.
Crankshaft and connecting rods
Unlike the relatedBarra 220 V8 engine which had a cast iron crankshaft, the Boss V8 engine had a forged steel crankshaft and cross-bolted main bearing caps. The six-point main bearing locations consisted of two cross-bolts, two vertical bolts and two vertical locating dowels for each main bearing cap – these provided greater rigidity and more precise location than a conventional six-bolt mounting.
The Boss 260 engine had sintered connecting rods with fracture-split big-ends.
Cylinder head and valvetrain
Shared with the Ford Mustang Cobra R, the aluminium cylinder for the Boss 260 V8 engine was cast by Ford USA and machined by Cyl-Tech Manufacturing. The Boss 260 V8 engine had hollow double overhead camshafts (DOHC) per cylinder bank that were chain-driven and had a hydraulic chain tensioner for each timing chain. The camshafts actuated the four valves per cylinder – two intake and two exhaust – via roller finger followers, with ball tip hydraulic lash adjusters used to maintain zero valve clearance.
The Boss 260 engine had a unique inlet camshaft profile to match the high-rise inlet manifold and exhaust header system. For the Boss V8 engine,
- The intake valves had a 37.00 mm diameter;
- The exhaust valves had a 30.00 mm diameter; and,
- Intake and exhaust valve lift was 10.00 mm.
For the Boss 260 V8 engine, the cam cover was made form magnesium to reduce mass and was isolated from vibration by rubber grommets. For rigidity, reinforcing ribs were cast into the cam cover and a structural baffle plate was fitted in the underside of the cover.
Intake and exhaust
Whereas the Barra 220 V8 engine had a variable length intake manifold, the Boss 260 V8 engine had a ‘high-rise’ alloy intake manifold which featured tuned-length intake trumpets to match the straighter inlet port. The cast alloy plenum cover was manufactured in Australia and profiled for optimum breathing, while the high volume conical filter was shared with the Ford Mustang Cobra.
The fabricated stainless steel exhaust headers for the Boss 260 V8 engine had a 1 7/8 inch diameter.
Injection and ignition
The Boss 260 V8 engine had sequential multiport fuel injection via eight solenoid-operated fuel injectors. Compared to the Barra 220 engine, however, the Boss 260 engine had a unique fuel rail, upgraded fuel injectors and upgraded fuel lines. A constant fuel pressure drop was maintained across the fuel injectors by the fuel pressure regulator which was positioned upstream from the fuel injectors on the fuel injection supply manifold.
The Boss 260 V8 engine had an electronic ignition system with eight ignition coils and a compression ratio of 9.52:1; the firing order was 1-3-7-2-6-5-4-8.
Lubrication
The Boss 260 V8 engine had a positive displacement internal gear oil pump with top seal rotors – commonly known as a gerotor pump – that was mounted on the front of the cylinder block. The Boss V8 engine required 10W30 GF2 engine oil.
