MK Motorsport (Autohaus Krankenberg) modified both 320 engines (m10 4 cil and M20 6 cil) as well as the 323i engine, starting off by fitting faster camshafts:
BMW 320/4 MK: several setups possible using Weber carbs with engine powers 125-155 BHP.
BMW 320/6 MK: several setups possible using Weber carbs with engine powers 137-163 BHP. They even offered engine modifications to 2300 or 2500 cc with 175-200 BHP. Most common:
BMW 320 MK 60/3A: ‘affordable’ faster car with improved engine response based on 320/6 M20, faster camshaft fitted, modified intake manifold to accommodate three dual Weber IDF40 40 mm carbs. Uprated and lowered suspension and a modified exhaust system.
Specs: 148 BHP @ 6.800 RPM, 162 NM @ 6.500 RPM. Top speed 203 KMH, acceleration 0-100 KMH 8.6 sec.
BMW 323i MK 66/2: based on the 323i, reworked head and faster camshaft, uprated and lowered suspension using Bilstein shocks and MK springs, free flow exhaust manifold, 15” BBS alloys and a MK leather sports steering wheel.
Specs: 180 BHP @ 6.200 RPM, 222 NM @ 4.300 RPM. Top speed 216 KMH, acceleration 0-100 KMH 7.3 sec.
Upgrade to MK 66/3 was possible: displacement 2500 cc and 200 BHP.
MK also offered a wide range of tuning parts, engine and suspension upgrades as well as bodykits, all available separately.