Tri-metal crankshaft main bearings ACL Alfa Romeo 3.2 JTS Opel Z28NET

The Alfa Romeo 3.2 JTS and Opel Vauxhall Z28NEL Z28NET engines

This main bearing set fits petrol engines from 2.8 to 3.2 litres: the Alfa Romeo 3.2 JTS (939 A.000) and the 2.8 L turbo V6 Opel and Vauxhall Z28NEL and Z28NET. They are fitted notably to the Alfa Romeo 147 GTA, 159, Brera, GT and Spider, as well as the Opel and Vauxhall Vectra C and Signum. All the applications listed below share the same crankshaft journal and housing dimensions: a single bearing set covers these engines.

The crankshaft of these engines runs on four main bearings. Each journal turns between two half shells, one seated in the block and the other in the main bearing cap: they carry the crankshaft. The ACL Race Series tri-metal set shown here replaces them on built engines.

Tri-metal main bearings

A tri-metal 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 covers the four main bearings of the crankshaft. The upper and lower half shells are different: each goes in its own position.

An aluminium bi-metal takes around 8,000 psi, a performance tri-metal 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 main 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 brand

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.

Vehicle compatibility

This main bearing set fits the following vehicles, by engine code: