European BMW 635csi


1980 Euro Spec BMW 635csi M90

Today we finish a engine for a customer’s 1980 BMW E24 635csi. Here are the specs on this build.


M90 Euro Spec
King Bearings
CP Forged Pistons 10:1 Flat Top


Stage 3 Port & Polished
Schrick Cams
Ireland Engineering Valve Spring, Rockers, & Guides
ARP Everything.

Powder Coat:

BMW Silver: Intake, brackets, oil pan, intake manifold & plenums, coolant flanges, etc…

Stay tuned to see this 635csi, subframe repair, steering, suspension, exhaust and custom header install.


1985 Article about the BMW 635csi

In many ways, the 635CSi is a superlative car. It produces prodigious speed thanks to its new 3.5-liter engine. The 635csi exhibits much better handling than BMW’s early 6-series coupes. It is put together ,vith rare care. Its ergonomics are generally excellent. And now it has Bosch ABS anti-lock braking equipment for help during emergency stops. All told, the 635CSi is a very accomplished piece of work.

Still, we’re talking 3.5-liter, high-rev­ving. seven-league boots here. BMW has punched out the 3.2-liter bore from 89 to 92mm, and the torque has increased from 195 to 214 pounds-feet. This single overhead-cam six is old. but it remains atop the pack in basic design. Its aluminum hen1i head is fed by Bosch Motronic fuel injection. Crossflow intake and exhaust ports handle the breathing. and a new, adaptive Lambda-sensor control sets the fuel-air mixture more precisely through a ,vider range of operation. ·ro allow maximum spark advance at all times, BMW has not yet resorted to a knock sensor, and the 3.5-liter motor compression ratio remains a impressive 10:1. The added dis­placement has bumped up, the horsepower only from 181 to well over 250hp. However, it is tuned instead for midrange response, the big six’s power peaks at 5400 rpm, 600 rpm earlier than in the 3.2-liter. A 3.45:1 final-drive replaces the 633’s taller 3.25 gear, boosting the throttle response throughout the rpm range. but a rev limiter clips the power smartly at 6200 rpm.