Motor Vehicle Maintenance & Repair Stack Exchange is a question and answer site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

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?

share|improve this question
It'd help to know what kind of car it is. – Evan Parsons Dec 30 '13 at 14:08
1968 Fiat 850 Coupe (rear engine, rear wheel drive). Considering using something like a Volkswagen Beetle engine. – Andrew Dec 30 '13 at 18:01
VW Bug would work, especially if you use the engine and transaxle. Something better yet would be the drivetrain out of a Porsche. Turbo pancake six cylinder? Awesome! Whatever you get, go with the entire engine, transaxle, and get the PCM/ECM to go with it. Seeing as you being from OR, I would bet your state law says you have to have a newer year engine than what the car is. It is going to take a lot of measuring as well as machining and ingenuity to get it to work, but it can probably be done. Also search for anyone else who has swapped something into a Fiat like yours. I bet it's been done. – Pᴀᴜʟsᴛᴇʀ2 Dec 30 '13 at 19:47
up vote 2 down vote accepted

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.

share|improve this answer
That was helpful. Thanks! – Andrew Dec 30 '13 at 18:03

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.