Forged connecting rods Audi Volkswagen - 1.8L 20VT axe 20 mm for forged pistons

The 1.8T 20V EA113 engine

The 1.8T 20V, from the EA113 family, is a turbocharged inline four-cylinder petrol engine with five valves per cylinder (20 valves in total), displacing 1,781 cc (81 mm bore, 86.4 mm stroke). Introduced in 1995 on the Audi A4 B5, it powered a very wide range of Audi, Volkswagen, SEAT and Škoda models for over a decade, in both longitudinal (A4, A6, Passat) and transverse (Golf IV, Bora, A3 8L, TT, Leon, Octavia) layouts. Rated from 150 to 225 hp depending on turbo (K03, K04) and mapping, it is among the most sought-after tuning bases on the continent.

That popularity with tuners has a flip side: as soon as boost and torque are raised, the stock rods become the weak link of the bottom end. Fitting forged rods is therefore the decisive step to turn a 1.8T 20V into a durable high-power unit. The version shown here keeps the 144 mm stock center-to-center length and the 20 mm piston pin; it comes in several profiles and several brands, to cover every power target without needlessly over-sizing the set.

The forged connecting rods

Our forged 1.8T 20V EA113 rods are machined from wrought 4340 steel, the motorsport benchmark. The range spans several profiles (I, reinforced I-HD, I-3P and H) and four manufacturers, to suit every discipline: circuit, drift, rally, drag, time attack and hillclimb. Depending on the target (Stage 2, Stage 3 high power, Stage 4 and beyond), they lock in the torque and rpm increase without ever cutting corners on reliability. Each reference ships as a weight-matched set of 4, with its dedicated ARP bolts.

Against a factory rod sized above all for production cost, a forged 4340 rod offers a far greater mechanical reserve: around +19% yield strength, +8% tensile strength and +19 to +37% fatigue endurance. That margin lets the 1.8T 20V absorb cylinder-pressure peaks and inertia loads without breakage, whether the build stays a strong fast-road setup or moves to a track configuration.

Technical specifications of the 1.8T 20V EA113 forged rods (20 mm pin, 144 mm center-to-center)

Tightening torque and stretch

The torque and stretch relate to the ARP bolts supplied with each kit; refer to the technical sheet provided. Checking with a stretch gauge remains the most reliable and repeatable method to guarantee preload.

Technical guide

Forged 4340 steel: what is it?

The rod profiles offered

	The I profiles (ZRP in I and reinforced I-HD, Wössner in I) concentrate material on a light, stiff central web. They offer the best compromise between reduced mass and strength, ideal for a 1.8T 20V that likes to rev; the I-HD variant adds material in the loaded areas to handle more torque.
	The I-3P profile (Boostline) uses an optimised I web with three-pocket machining that finely distributes material. Designed for heavily built VAG blocks, it targets the best stiffness-to-weight ratio and suits builds chasing high power.
	The H profile (ZRP, Manley) has an H-shaped section with two flat sides that maximise stiffness in the bending plane. It is the profile of choice for high-torque, high-boost engines, when pure robustness is the priority.

How to choose your rod bolts?

The bolts are an integral part of the rod: they hold the cap preload under alternating loads. All our 1.8T 20V references are offered in 3/8"; depending on the manufacturer and build level, three ARP grades are available.

	ARP 2000: the all-round benchmark alloy, with a tensile strength of about 220,000 psi (1,517 MPa). Offered here in 3/8", it covers the vast majority of 1.8T 20V builds, from raised boost to high power. It is the default choice to make the bottom end reliable for good. It secures power of around 200 hp per cylinder and rpm up to 8,500.
	ARP L19: a very high strength steel (about 260,000 psi / 1,793 MPa), reserved for extreme builds developing the highest torque and rpm. More sensitive to corrosion, it demands extra care on assembly and protected storage. It targets serious turbo builds, up to nearly 250 hp per cylinder and rpm up to 10,000.
	ARP CA 625+: a premium stainless steel (about 260,000 to 280,000 psi) at the L19 strength level but immune to corrosion and hydrogen embrittlement. It equips the top Boostline version and targets competition engines seeking the ultimate preload margin.

Measuring bolt stretch

See the ARP stretch gauge

The brands offered

	ZRP (the Greek brand by Alex Drakos, in Athens) machines competition forged rods in 4340 steel, weight-matched to ±1 g. On the 1.8T 20V it covers the H, I and I-HD profiles, with ARP 2000 or ARP L19 bolts.
	Wössner is a respected European manufacturer of forged pistons and rods. Its I-profile rod for the 1.8T 20V (ref. KCR018A) ships with ARP 2000 bolts in 3/8" and targets high-rpm builds.
	Manley Performance, a renowned US manufacturer, offers an H-profile rod (ref. 14007-4) renowned for its robustness, supplied with ARP 2000 bolts in 3/8".
	Boostline develops a three-pocket I-3P profile designed for VAG blocks; on the 1.8T 20V the VW5669-787 reference is offered with ARP 2000 or ARP CA 625+ bolts for the most demanding builds.

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 1.8T 20V EA113 engine

Why is it the most economical solution?

On a tuned 1.8T 20V, a stock rod that lets go usually takes the block, crankshaft and pistons with it. Investing in a forged rod set from the outset costs far less than an engine failure followed by a full rebuild. You permanently strengthen the bottom end, preserve the value of your build and drive with peace of mind, in intensive use as much as day to day.