Trimetal connecting rod bearings Honda K20A2 K20Z1 K20C1 K24

The Honda K20 and K24 four-cylinder engines

The K20 and K24 are the 2.0 and 2.4 litre 16-valve twin overhead camshaft four-cylinder engines of Honda's K family: the K20A2 and K20Z1 of the Civic Type R EP3 and Integra DC5, the K24 of the Accord, CR-V, Element, Odyssey, Stepwgn, FR-V and Elysion, and the turbocharged K20C1 of the recent Civic Type R. ACL and King list a single bearing set for these engines: same crankpin diameter, a single set covers the family.

From the factory, this engine is 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.

Trimetal connecting rod bearings

A trimetal bearing stacks three layers: a steel back, a copper-lead intermediate layer with high load capacity and an anti-friction running surface that protects the journal. The complete set contains 8 half shells, four pairs for a four-cylinder engine.

The original bearing relies on an aluminium alloy over a steel back, intended for low to medium loads, whereas trimetal is designed for high, sustained loads: an aluminium bi-metal takes around 8,000 psi, a performance trimetal up to 12,000 psi, 50% more. Hence better resistance and better durability on turbocharged, supercharged and high-revving engines.

Technical specifications

Technical guide

The ACL and King rod bearings shown here are trimetal bearings, designed for engine building and racing. Compared with an original bearing, they handle far higher loads: they cope with increased power, high rpm or the addition of a turbo or supercharger, where a standard bearing quickly reaches its limit.

The two brands

	ACL Bearing Company, an Australian manufacturer of high-performance engine bearings since 1949, offers with its Race Series precise trimetal bearings, available in many sizes and proven on built engines worldwide. Its Calico version (HC suffix) adds the CT-1 coating, a dry film lubricant that reduces friction and abrasive wear.
	King Engine Bearings, an Israeli manufacturer of high-performance engine bearings since the 1960s, offers with its pMax Black trimetal alloy, coated with pMaxKote in the XPC version, bearings designed for heavy loads.

Construction and advantages

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 (Race); Calico CT-1 (HC)	Yes, pMaxKote: polymer coating on the surface that limits wear when lubrication drops (start-ups, thin oil film).
Available sizes	Standard to +0.25 mm (+ increased clearance HX)	Standard to +0.50 mm (+ increased clearance STDX)

Vehicle compatibility

This connecting rod bearing set fits the K20 and K24 four-cylinder engines of the following Honda models: