Forged connecting rods Opel - 2.0L 16V - C20XE / C20LET / Z20LET / Z20LEH / Z20LER 148 mm rod length for forged pistons

The Opel 2.0 16v C20XE / C20LET / Z20LET engine

The Opel and Vauxhall 2.0 16-valve comes from the GM Family II range. This 1,998 cc inline four (86.5 mm bore, 86 mm stroke) first existed naturally aspirated with the 150 hp C20XE “Red Top”, before the turbo variants C20LET, Z20LET, Z20LEH, Z20LER and Y20LET. They all share the same sturdy bottom end and the same standard rod, which allows them to be covered by a single forged part number. Built from 1988 to 2010, they powered nearly twenty years of sporting Opels, from the Calibra Turbo to the Astra OPC. The engine is still a much sought-after tuning base today.

The naturally aspirated C20XE is quoted at around 150 hp and the turbo versions range from 190 to 240 hp depending on the year: 204 hp for the C20LET of the Calibra Turbo 4x4, 190 to 200 hp for the Z20LET of the Astra G OPC, 240 hp for the Z20LEH of the Astra H OPC and the Vauxhall VXR. A strong crankshaft and block explain the success of this 2.0 16v in rally, on circuit and in drift. This listing covers the long-rod variant, with a 148 mm centre-to-centre length instead of the original 143 mm: a dimension chosen according to the crankshaft and the pistons used.

Forged connecting rods

Forged from high-strength 4340 steel and then machined to a 148 mm centre-to-centre length, this rod replaces the part that limits the 2.0 16v as soon as it leaves factory figures. Moving to forged rods is required with forged pistons, a higher maximum rpm, an increase in boost pressure or a gain in displacement. Intended for built engines, turbocharged as well as supercharged, it covers every discipline: rally, drift, drag racing, circuit and track use, hillclimb, time attack, and supports Stage 2, Stage 3 and Stage 4+ builds up to a fully rebuilt competition engine. The H profile used here, at 527 g per rod, favours big-end stiffness.

Technical specifications of the 2.0 16v C20XE / Z20LET forged connecting rods

Torque and stretch specifications

Manufacturers recommend the stretch-gauge method as the reference: the instructions supplied with the kit always take precedence. The torque figures shown apply to assembly with ARP lubricant.

Technical guide

Forged 4340 steel: what is it?

Rod profiles

H-beam profile. Made of two flat flanks joined by a central web, the H-beam offers high rigidity and excellent resistance to compression. It is the preferred choice for high-torque, high-boost engines where sturdiness comes first.

How to choose your rod bolts

On this 148 mm centre-to-centre variant the rod bolt remains the first lock of the bottom end: it limits the rpm and the cylinder pressure. The reasoning starts from the intended use, from torque used low down in rally to rpm held for a long time on circuit, up to the few seconds of full load of a drag run, then from the target power per cylinder. The bolts supplied with this rod are ARP 8740, in 7/16" diameter and 41 mm length; torque and stretch are respected on assembly, as given in the table.

The R-OPE-006H rods are supplied with ARP 8740 hardware, one of the long-standing references from US manufacturer ARP. Machined from 8740 chromoly steel, it delivers roughly 200,000 psi tensile strength (about 1,379 MPa) and around 180,000 psi yield strength, keeping preload perfectly stable and withstanding the fatigue cycles of a built engine. With a 7/16" diameter and 41 mm length, it provides high clamping force suited to the naturally aspirated 2.0 16v C20XE as well as its turbo versions (C20LET, Z20LET) run at high rpm. Fitting requires stretch measurement with a gauge (0.127 to 0.140 mm) to guarantee optimal tension on every bolt.

Measuring bolt stretch

Buy the ARP stretch gauge →

Brands offered

ZRP is a Greek brand of high-performance forged connecting rods created by Alex Drakos in Athens. Each rod is forged from 4340 steel, precision-machined and balanced to ±1 g for reliability at high rpm. Offered here in H-beam profile with ARP 8740 bolts, it is developed and controlled in Greece, proven in rally, on circuit and in drift.

Glossary

1) Small end 2) Small-end diameter 3) Rod beam 4) Rod bolt 5) Big end 6) Rod nut / bolt 7) Rod cap 8) Big-end diameter 9) Center-to-center

Vehicle compatibility for the 2.0 16v C20XE / Z20LET engine

These forged connecting rods fit the following Opel/Vauxhall 2.0 16v engines, both naturally aspirated and turbocharged:

OEM reference: 9117765 (set of 4 connecting rods).

Why is this the most cost-effective solution?

When a standard rod gives way on a C20XE or a Z20LET, the bill always goes beyond the part: the piston is lost, the block has to be checked and the crankshaft inspected. Going back to original parts therefore means buying rods and pistons, a heavy outlay for an engine that will find its starting limits again. For a comparable, often lower budget, forged 4340 steel rods combined with forged pistons bring reliability and a safety margin of another level, and above all real room to increase power, which makes full sense on a lengthened-rod configuration. This is how European engine builders have worked for more than 15 years on Opel 2.0 16v engines. For the same budget: more reliability, more potential, more service life.