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2.0L 16v - Cosworth YB N5
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2.0L 16v - Cosworth YB N5
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Set of 8 trimetal connecting rod half-bearings for Ford Cosworth YB 2.0 16V.
The Cosworth YB (2.0 litres) is a Ford 16-valve twin overhead camshaft four-cylinder engine, turbocharged, fitted to the Sierra RS Cosworth and the Escort RS Cosworth. ACL and King list the same bearing set for this engine: a single set covers the family.
From the factory, these engines are fitted with standard production connecting rod bearings, sized for the loads of the original engine: as soon as power, engine speed or boost pressure increase, they reach their limits.
Three layers make up a trimetal bearing: the steel back for stiffness, the copper-lead intermediate layer for load capacity, then the anti-friction running layer that protects the crankpin. This set includes 8 half shells, that is 4 pairs.
Where an aluminium bi-metal bearing, designed for low to medium loads, withstands about 8,000 psi, a performance trimetal bearing goes up to 12,000 psi: 50% extra margin. That is what keeps it durable on an engine boosted by a turbo or supercharger, or pushed to high rpm.
| ACL / King bearings Crankpin Ø 51.990 / 52.000 mm (King : 51.989 / 51.999 mm) Housing bore Ø 55.000 / 55.020 mm (King : 54.999 / 55.019 mm) Width 20.12 mm (King: 20 mm) |
| Reference | Brand and treatment | Size | Wall thickness (mm) |
|---|---|---|---|
| 4B2166H-STD | ACL Race - Untreated | Standard | 1.496 |
| 4B2166HX-STD | ACL Race - Untreated | Std, increased clearance (HX) | 1.483 |
| 4B2166H-.25 | ACL Race - Untreated | +0.25 | 1.621 |
| 4B2166H-.50 | ACL Race - Untreated | +0.50 | 1.746 |
| CR4440XP | King Racing - Untreated | Standard | 1.491 |
| CR4440XP STDX | King Racing - Untreated | Std, increased clearance (STDX) | 1.478 |
| CR4440XP0.25 | King Racing - Untreated | +0.25 | 1.618 |
| CR4440XP0.5 | King Racing - Untreated | +0.50 | 1.745 |
Between the crankpin and the bearing there is a small gap, the running clearance, in which the oil film circulates.
In operation there is no metal-to-metal contact: the crankpin turns on this oil film, which supports the whole load. The clearance determines its thickness. A clearance that is too tight hinders oil flow, heats the assembly and promotes seizure; one that is too wide lets oil leak away, weakens the film and makes oil pressure drop. The correct clearance balances oil flow and film strength.
| Size / grade | When to choose it | ACL Race Series | King XP |
|---|---|---|---|
| Standard (STD) | Standard journal, not reground | 0.055 to 0.065 mm | |
| Increased clearance (HX / STDX) | Wider clearance: high oil flow, high rpm | 0.080 to 0.090 mm | |
| +0.25 mm | Journal reground to 0.25 mm | 0.055 to 0.065 mm | |
| +0.50 mm | Journal reground to 0.50 mm | 0.055 to 0.065 mm |
Checking on assembly: lay a calibrated strip (Plastigauge) on the journal, torque the rod cap to spec, then compare the crushed strip against the gauge to read the clearance.
Designed for engine building and motorsport, these ACL and King trimetal connecting rod bearings carry much more load than an original bearing, whether the engine gains power, revs higher or receives a turbo or supercharger. They are available in several sizes: the standard size, +0.25 and +0.50 mm regrind sizes and the HX / STDX version with increased clearance for high-revving engines or engines needing a high oil flow. That makes it possible to put a reground crankshaft back into service without changing range and to set the clearance for the oil and use.
 | ACL Bearing Company has been making high-performance engine bearings in Australia since 1949. Its Race Series offers precise trimetal bearings, available in many sizes and proven in tuned and racing engines worldwide. |
 | King Engine Bearings, an Israeli manufacturer active since the 1960s, produces high-performance engine bearings. Its pMax Black trimetal alloy is designed to withstand heavy loads. |
| Criterion | ACL Race Series | King Racing |
| Cross-section |  |  |
| Type | High-performance trimetal bearing | High-performance trimetal bearing |
| Country of manufacture | Australia | Israel |
| Construction | Trimetal: steel back, copper layer, soft surface | Trimetal: steel back, copper layer, soft surface |
| Alloy | Race Series (copper-lead) | pMax Black (hardened copper-lead) |
| Protective coating | No | No |
| Available sizes | Standard to +0.50 mm (+ increased clearance HX) | Standard to +0.50 mm (+ increased clearance STDX) |
This connecting rod bearing set fits the Cosworth YB four-cylinder engine of the following Ford models:
| Brand | Model (chassis) | Engine code | Power | Years |
|---|---|---|---|---|
| FORD | SIERRA I Hatchback 2.0 4x4 | N5B, YBB | 204 hp | 1985–1987 |
| FORD | SIERRA II Hatchback 2.0 RS Cosworth / 2.0 RS500 Cosworth / 2.0 16V Cosworth / 2.0 16V Cosworth Cat 4x4 | N5B, N5C, N5D, YBB, YBD | 204–227 hp | 1987–1993 |
| FORD | ESCORT V (AAL, ABL) RS Cosworth 4x4 | N5F | 220 hp | 1991–1995 |
| FORD | ESCORT VI (GAL, AAL, ABL) RS Cosworth 4x4 | N5F | 220 hp | 1995–1998 |
When a connecting rod bearing gives way, the damage quickly spreads beyond the part itself: a scored crankpin, debris carried through the whole oil circuit, a crankshaft to regrind at the very least, sometimes a rod and block lost. A bearing set costs far less than a regrind and is nothing compared with a complete engine rebuild. It is the cheapest part of the rotating assembly, yet the one whose failure is most expensive.
