I'm interested in restoring an old car that has a relatively underpowered engine. I'm curious how difficult it would be to replace it with a different (cheaper, more common, more powerful) engine. What sorts of considerations do I need to make before undertaking a project like this?
The details of preparing for an engine swap will vary greatly with the make, model, and sophistication of the vehicle. It will be easier if they are from the same make and the engine was originally available as an option. If it is an older non computerized vehicle than it may be a bolt-in using factory designed parts. Concerns may also include, will the original suspension support the added weight (4cylinder vs 6 cylinder vs V8). Will the original drive train, transmission and differential mate to the new engine and handle the additional power. Another often overlooked area is the brakes. Many older vehicles came with drum brakes on standard models and discs on high powered models. Computerized vehicles bring additional issues as the ECM (engine control module) must match the engine and transmission. Then there is the issue of getting the vehicle to get a passing grade from the government enviromental department in your area as it will now be considered modified. If the swap involves matching different brands it will involve considerable design and fabrication of unique mounts, brackets and wiring harness.