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3.8L 24v - S38B38
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3.8L 24v - S38B38
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Set of 6 forged 4340 steel connecting rods for BMW M5 E34 3.8L 24V S38B38.
The BMW S38B38 is the final evolution of the S38 inline-six, itself a descendant of the legendary M88 from the M1. Bored out to 3,795 cc (94.6 mm bore x 90 mm stroke), it crowned the BMW M5 E34 from 1992, producing around 340 hp at 6,900 rpm and 400 Nm of torque. Its 24-valve head, six individual throttle bodies and Bosch Motronic management make it one of the most accomplished naturally aspirated engines of its era.
Built until 1995, the S38B38 is still prized for its sound and its high-revving character. But its factory crankshaft and rods were sized for stock output: as soon as you raise the redline, build the engine or plan regular track use, the rotating assembly becomes the weak link to reinforce. That is exactly what these forged connecting rods are for.
Machined from solid 4340 steel, these rods replace the factory items whose strength tops out once the engine is pushed. Forging aligns the metal grain with the loads applied, giving far greater fatigue resistance than a cast or sintered part.
Each rod is shot-peened, inspected and weight-matched to ±1 g across the set, ensuring flawless balance at high rpm. Supplied with premium ARP hardware, they shrug off power increases, added forced induction or long track sessions.
| Reference | Brand | Profile | Bolts | Pin diameter OEM 22 mm | Small-end width | Big-end diameter OEM 52 mm | Big-end width | Center-to-center OEM 142.5 mm | Weight per rod |
|---|---|---|---|---|---|---|---|---|---|
| R-BMW-009H | ZRP | H | ARP 2000-3/8"-38mm | 22 | 52 | 24 | 142.5 | 535 | |
| R-BMW-009H-L19 | ZRP | H | ARP L19-3/8"-38mm | 22 | 52 | 24 | 142.5 | 535 |
| Rod | Bolts | Torque | Recommended stretch |
|---|---|---|---|
| ZRP (R-BMW-009H) | ARP 2000 | 61 N·m | 0.140 – 0.152 mm |
| ZRP (R-BMW-009H-L19) | ARP L19 | 67,8 N·m | 0.152 – 0.165 mm |
Manufacturers recommend the stretch-gauge method as the reference: the instructions supplied with the kit always take precedence. The torque figures correspond to assembly with ARP lubricant.
| 4340 is a low-alloy nickel-chromium-molybdenum steel, renowned for its rare balance of mechanical strength and ductility. Compared with the original sintered metal, it offers about +19% yield strength, +8% tensile strength and +19 to +37% fatigue resistance. In practice: a rod that deforms less, copes better with cylinder-pressure peaks and withstands the repeated stresses of competition over time. |
 | H-Beam profile. Its H-shaped, relieved-flank section delivers high rigidity for a controlled weight. It is the reference profile for high-torque engines and the most demanding uses, where bending resistance comes first. |
The rod bolt is the most heavily loaded part of the assembly: it keeps the cap closed on every cycle. ARP offers several grades depending on the target power and engine speed.
 | ARP 2000: high-performance standard with no storage constraints. Handles up to 200 hp per cylinder in 3/8" and 8,500 rpm. Ideal for circuit, trackday, drift, rally, drag and hillclimb — the balance of strength, reliability and versatility. |
 | ARP L19: designed for engines pushed to the extreme — very high boost pressure, sustained high rpm, elevated cylinder pressure. Up to 250 hp per cylinder in 3/8" and 10,000 rpm. Sensitive to corrosion and hydrogen embrittlement: store and fit it oiled. |
| In addition to torque tightening, measuring bolt stretch (with a dial indicator) remains the most reliable way to guarantee correct preload. Always refer to the instructions supplied with the kit: they take precedence. |
 | ZRP, a Greek specialist in high-performance forged connecting rods, machines its parts from 4340 steel and weight-matches them. For the S38B38, the range is offered in H-Beam profile with ARP 2000 or ARP L19 hardware, chosen according to the target power and rpm. |
 | 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 |
These forged connecting rods are compatible with the factory BMW S38B38 engine and its builds. Vehicles concerned:
| Brand | Model (chassis) | Engine code | Power | Years |
|---|---|---|---|---|
| BMW | M5 (E34) | S38B38 | 340 hp | 1992–1995 |
OEM reference: 11 24 1 401 358 (rod set).
When the bottom end of an S38B38 lets go — a spun or broken rod at high rpm — the bill climbs fast: rare parts, specialist labour, downtime.
For a budget comparable to tired second-hand rods, you fit a brand-new forged set here, calibrated and made reliable once and for all. No need to revisit it with every upgrade.
For the same budget: more reliability, a comfortable power margin and the peace of mind of a rotating assembly built to last. It is the most rational way to preserve an engine that has become rare.
