Forged connecting rods Citroën / Peugeot - 1.6L 16V - TU5J4 / TU5JP4 18 mm pin - long rods for forged pistons

The Citroën / Peugeot TU5J4 / TU5JP4 engine

Developed by PSA, the TU5J4 and its TU5JP4 version form the sporting family of the group’s 1.6-litre 16-valve four-cylinders. Naturally aspirated, this engine measures 78.5 mm bore by 82 mm stroke, that is 1,587 cc, and was produced between 1995 and 2007. Multi-valve head, compact architecture: the TU5 revs willingly, which explains why it is still found in the paddocks today.

Fitted to the Peugeot 106 S16 and 206 S16 as well as the Citroën Saxo VTS and C2 VTS, it built its reputation in rally, on circuit and in hillclimb. Very open to tuning (intake, exhaust, camshafts, forced induction), it quickly pushes the standard rod, with its 133.6 mm centre-to-centre length, beyond its capability. This is where a longer rod comes in: it changes the ratio between rod length and stroke, and works together with a specific crankshaft or specific pistons.

Forged connecting rods

Machined from high-strength 4340 steel, these long-centre forged rods protect the bottom end of the most heavily built 1.6 16V TU5 engines. Three lengths are offered, all for an 18 mm piston pin: 137.75 mm and 141 mm in the I profile and 139 mm in the H profile, i.e. +4.15 mm, +7.40 mm and +5.40 mm respectively over the 133.6 mm stock centre distance. This longer centre, combined with a light-weight design, optimises the rod/stroke ratio on forged-piston builds, displacement (stroker) increases or higher-rpm and higher-boost setups, where the stock rod reaches its limit. Built to absorb the severe loads of prepared engines, both highly tuned naturally aspirated and forced-induction, they cover every discipline (rally, drift, drag, circuit, hillclimb, time attack) and suit Stage 2, Stage 3 and Stage 4+ builds, up to full competition engines.

Technical specifications of the TU5J4 / TU5JP4 forged connecting rods (18 mm pin)

R-CIT-004-I, R-CIT-004-I-L19: Centre-to-centre length increased by 4.15 mm over stock; lightweight design.

R-CIT-005HL, R-CIT-005HL-L19: Centre-to-centre length increased by 5.40 mm over stock; lightweight design.

R-CIT-006-I, R-CIT-006-I-L19: Centre-to-centre length increased by 7.40 mm over stock; lightweight design.

Torque and bolt stretch

In competition use a bottom end is stripped often: that is exactly where the dial gauge becomes irreplaceable, since it lets you spot a bolt that is already stretched before refitting it. A bolt whose preload was insufficient has worked under alternating load: its parting face is marked, the matching shell is hammered, clearance has grown and the oil film no longer carries the same load. A bolt tightened beyond the range carries the other signature: increased free length, elastic reserve used up, a distorted bearing bore and an oval big end. The ZRP rods available for this TU5 do not all share the same fastener grade: the table below gives for each of them the fastener manufacturer's values, for ARP 2000 as well as ARP L19, and they are read row by row. Tightening is checked through stretch measured with a dial gauge, the reference method, with ARP assembly lubricant and the kit instructions as the authoritative documents.

Technical guide

4340 forged steel: what is it?

Connecting rod profiles

	H-Lite profile. A lightened version of the H profile, it keeps the two flat sides and central web of the “H” section while reducing the mass of the reciprocating assembly. ZRP designs it to help the engine rev up with proven reliability at high rpm, and recommends it for naturally aspirated engines such as the TU5J4.
	I-Beam profile. Its “I” section, thinned at the centre and held by two flanges, gives it high stiffness without excess mass. ZRP designs it for high performance and long durability, and it suits TU5J4 builds that look above all for a strong bottom end.

How to choose your rod bolts?

On a TU5 with long rods, the rod bolt remains the first lock: it caps the rpm and the acceptable cylinder pressure, whatever centre-to-centre length is chosen. The grade is therefore selected from the intended use, from torque used low down on a rally stage to rpm held high through a hillclimb or a circuit session, up to the few seconds of maximum load of a drag run, then from the target power per cylinder. The two grades below are offered in 3/8"-38 mm.

ARP 2000, quoted at ~220,000 psi (~1,517 MPa) tensile strength, covers most built TU5 engines, including those with a lengthened rod: up to 200 hp per cylinder in 3/8" and up to 8,500 rpm. It is the dominant grade in circuit racing, track days, drift, rally, drag racing and hillclimb, and it imposes no particular storage constraint before assembly.

L19 reaches ~260,000 psi (~1,793 MPa) and allows 250 hp per cylinder in 3/8" as well as 10,000 rpm. On a heavily boosted long-rod TU5, with high cylinder pressure or rpm held high, this is the grade that provides the margin, as on every big power level in drag racing, drift, rally and circuit. In exchange it demands discipline: the alloy fears corrosion and hydrogen embrittlement, the bolts are stored and fitted oiled, away from moisture, and never bare.

Measuring bolt stretch

Buy the ARP stretch gauge →

The brands offered

ZRP is a Greek brand of high-performance forged connecting rods, designed by Alex Drakos in Athens. Each rod is forged from 4340 steel, precision-machined and balanced to ±1 g to stay reliable at high rpm. On this TU5 application they are offered in H or I profile with ARP 2000 or L19 hardware, designed and inspected in Greece, and proven in rallying, 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 Citroën / Peugeot TU5J4 / TU5JP4 engine

These forged connecting rods are compatible with all vehicles fitted with the 1.6 16V TU5J4 / TU5JP4 engine. The table below lists the Citroën and Peugeot models concerned.

OEM reference: (set of 4 rods).

Why it’s the most cost-effective solution?

When a standard rod breaks on a TU5, the bill always goes beyond the part itself: the piston goes with it, the block has to be checked and the crankshaft inspected. Fitting original rods and pistons again is expensive and brings the engine back to exactly its initial level of fragility.

For an equivalent, often lower budget, forged 4340 steel rods and forged pistons give incomparable reliability and safety margin, and make it possible to look for more power afterwards. This is how European engine builders have worked for more than 15 years, including on TU5 engines with a modified rod length.

For the same budget: more reliability, more potential, more service life, with no compromise.