The Jeep 4.0-liter engine uses a cast iron block and cylinder head. It comes in both an inline-6 and inline-4 cylinder version and the specifications vary, depending on the vehicle.
The first 4-cylinder 4.0-liter engine produced 125 horsepower and replaced the 2.5-liter GM engine because it produced an increase in power. As development continued, the 4.0-liter Jeep engine produced 180 horsepower and was designed for fuel injection, completely replacing the fuel pump and carburetor.
The Jeep 4.0-liter, 4-cylinder engine has the same bores as the 258, but provides a shorter stroke. The engine has a displacement of 241.6 cubic inches but it kept the same-sized connecting rod length. The 4.0-liter, 6-cylinder engine provides 190 horsepower and Jeep built the engines to be able to travel at least 300,000 miles without a rebuild. The 4.0-liter engine was the last of Jeep's inline engines.
When shopping for a Jeep, opt for the 4.0-liter engine rather than the 2.8-liter motor. Older Comanche and Cherokee models come in both variations and the 4.0-liter engine is much more powerful and fuel efficient than the 2.8-liter engine. Remember that the 4.0-liter engine is an inline 6, not a V6, meaning the cylinders are arranged in a straight line, not in a "V" shape.