Sharper than from the factory A BMW M635 CSi with 350 PS

August 25, 2026 By Daniel

Schwarzer BMW M635 CSi der Baureihe E24 schräg von vorn links

The M635 CSi was already a special case from the factory: a grand touring coupé with the engine from the M1. This example goes a step further — an S38 block, with M88/3 technology on top, classic engine tuning, 350 PS.

Schwarzer BMW M635 CSi der Baureihe E24 schräg von vorn links vor einer Werkstatthalle — Black M635 CSi based on the E24 model line.

Why the M635 CSi stands apart

Between 1983 and 1989, BMW built the M635 CSi with the M88/3: 3,453 cm³, four valves per cylinder, six individual throttle bodies, 286 PS. The engine came from the M1 and was thus the opposite of a comfort-oriented unit — installed in a car that, on the outside, remained a grand touring coupé. This tension is what still makes the model line interesting today.

The Engine

The base is an S38 block, with M88/3 technology on top. Classic engine tuning brings output to 350 PS. The setup is clearly aimed at sporting use, not everyday comfort.

Reihensechszylinder mit M-Power-Ventildeckel und Einzeldrosselklappen im BMW M635 CSi — The M88/3 already had six individual throttle bodies from the factory. On top of these sits a carbon fibre air collector.

The carbon fibre air collector changes above all the sound: from around 3,000 rpm, the intake note becomes noticeably more prominent.

What looks at first glance like piping in the engine bay is a heat insulation for the tubular headers. It keeps the heat within the headers and thus slows the heating of the engine bay — no cosmetic detail on a high-revving six-cylinder in a tight engine bay.

Motorraum eines BMW M635 CSi von oben mit M-Power-Ventildeckel — The engine bay from above: M-Power valve cover, individual throttle bodies, carbon fibre air ducting.

Schwarzer BMW M635 CSi der Baureihe E24 auf einem Leistungsprüfstand — On the dyno.

Interior

The dashboard, door panels, and centre console front and rear are trimmed in high-quality Alcantara. This noticeably lifts the interior look without falsifying the character of the E24. The seats remain in their original, well-preserved condition. In addition, there is a sports steering wheel, also in Alcantara.