For those who remember my 4 cylinder twin-cam micro engine, here it outfitted to a car (pros and cons in the comments) : r/legotechnic
LEGO MOC Inline 4 cylinder engine by BrickBuildingFox | Rebrickable - Build with LEGO
10 NEW LEGO Technic Engine Cylinder with Bottom Slots Light Bluish Gray | eBay
LEGO IDEAS - Working Four-Cylinder Engine
Exploring Piston Engine Design With LEGO | Hackaday
LEGO MOC Piston Engine Boxer Four by AKM-Sky | Rebrickable - Build with LEGO
LEGO Technic BMW M 1000 RR K66 - A massive motorcycle for ultimate collectors! [Review] - The Brothers Brick | The Brothers Brick
LPE car with a 4 cylinder boxer engine and remote controlled 3 speed gear box : r/legotechnic
LEGO MOC Custom 18 cylinder engine by C.LegoMaster | Rebrickable - Build with LEGO
Amazon.com: Yanscian 6 Cylinder L6 Engine Model Building kit Set Hobby DIY STEM Toy for Kids & Adults with Guide 500+ Pieces, Toy Building Set, Build Your own Engine That Runs, Mini
LEGO MOC Custom 4-cylinder engine for your Lego MOCs and models by ngotronghieu118 | Rebrickable - Build with LEGO
Moc Technical Parts Race Vertical 4 Cylinders Horizontal Contraposition 6- cylinder & V-8 Cylinder Compatible With Major Brands - Model Building Kits - AliExpress