project e21
Classic BMWs • Designing Parts • Building Community
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AJ's M42B18 ENGINE SWAPPED E21
Building the Baby M E21.
This 1981 BMW E21 represents years of thoughtful development and refinement. At its heart is an E36 M42B18 paired with a ClassicDaily standalone ECU, combining modern reliability with the unmistakable character of BMW's twin-cam four-cylinder. Every aspect of the chassis has been upgraded—from Bilstein B8 dampers, H&R springs, ST sway bars, and Powerflex polyurethane bushings throughout to Hartge and Alpina suspension components—creating a lightweight, confidence-inspiring driver's car. Finished with subtle period-inspired details like the E30 325is rear spoiler, the goal has never been maximum horsepower, but rather to build a balanced, engaging classic that rewards every drive.
BUILD HIGHLIGHTS
Engine: E36 M42B18 1.8L DOHC 16V
ECU: ClassicDaily Standalone ECU
Suspension: Bilstein B8 • H&R Springs • ST Front Sway Bar
Chassis: Powerflex Poly Bushings Throughout • Hartge Front Strut Brace • Alpina Front Brace • Rear Strut Brace
Exterior: E30 325is Rear Spoiler, Front clear turn signal housings, Enkei 92 15" rims
Focus: Lightweight, balanced, driver-focused build