This BMW S38B35 engine benefits from a recent rebuild by Henry Lawrence of The Power Plant. It now displaces 4.0 liters instead of the original 3.5, and it has a slew of upgraded internal parts to make it suitable for racing use.
The BMW S38 is an inline-six cylinder engine that debuted in 1984, it became the worldwide replacement for the M88 engine, which had powered some of BMW’s most impressive road cars – including the BMW M1 supercar, the E28 M5, and the rare South Africa only E23 745i.
The BMW S38 was partially based on the legendary BMW M88 engine. It would go on to become an icon in its own right, powering a number of BMW M cars.
At the time of its debut in the mid-1980s, the BMW S38 engine was used in place of the earlier M88 in some Canada, Japan, and US market models – specifically the E28 M5, the E24 M6, and the slightly later E24 M635CSi.
The S38 was based on the M88 to some degree, specifically the M88/3 variant. That said, there were a number of significant differences including a dual-row timing chain, a shorter camshaft lift duration, a simplified exhaust manifold, a lower compression ratio, and it was equipped with an exhaust catalytic converter to help bring emissions into line with North American environmental legislation.
The BMW S38 has a cast iron block, and aluminum head, double overhead cams, four valves per cylinder, electronic fuel injection, and power outputs that ranged from 255 bhp to 335 bhp from the factory. Displacements ran from 3.5 liters on the S38B35 up to 3.8 liters on the S38B38. Aftermarket companies have since further increased displacement options, resulting in additional power.
The engine you see here now has a displacement of 4.0 liters thanks to a rebuilt by the aforementioned specialist Henry Lawrence. The engine is now fitted with Wiseco 95 mm forged pistons, rings, and pins, Crower connecting rods, Supertech racing valve springs and retainers, and a custom-fabricated billet steel crankshaft with 94.5mm stroke.
It also has custom racing camshafts with 13.2mm intake lift and 12.5mm exhaust lift, 39mm intake valves and 33mm exhaust valves, adjustable camshaft gears, a custom timing chain sprocket, and a billet dry-sump oil pan custom-fabricated by Armstrong Race Engineering.
The S38 has an iron block, aluminum head double overhead cams, four valves per cylinder and a displacement of between 3.5 and 3.8 liters from the factory.
The engine is said to have been intended for a BMW 3.0 CSL race car but it was never fitted, and it hasn’t been run since the rebuild. As a result it remains in fresh condition, ready for the next owner.
It’s now being offered for sale out of Suisun City, California with no reserve on Bring a Trailer on behalf of the current owner. If you’d like to read more about it or register to bid you can visit the listing here.
Images courtesy of Bring a Trailer
Articles that Ben has written have been covered on CNN, Popular Mechanics, Smithsonian Magazine, Road & Track Magazine, the official Pinterest blog, the official eBay Motors blog, BuzzFeed, Autoweek Magazine, Wired Magazine, Autoblog, Gear Patrol, Jalopnik, The Verge, and many more.
Silodrome was founded by Ben back in 2010, in the years since the site has grown to become a world leader in the alternative and vintage motoring sector, with well over a million monthly readers from around the world and many hundreds of thousands of followers on social media.
