Engine Swap 101

There are so many great resources for swapping engines that I don’t expect this to be a comprehensive guide to swapping an engine. Rather, I hope that I can share some basic tips that will help you make appropriate decisions when swapping an engine into your car.

Engine Mileage & Condition

One of the common misconceptions people have about used engines is that if you get a lower mileage engine you can swap it into a car and assume that it’s in good condition and you’re ready to rock and roll. The problem here is that there is no official way to know exactly how many miles are on an engine, and if you’re swapping in a performance motor like an RB series then you have to assume that whoever drove the car before the engine was removed beat on it pretty hard. There are standard tests that you want to perform on an engine before making a purchase if you are assuming it’s in good condition.

  1. Do a compression test. You’re looking for a consistent number in all cylinders. RB engines are in the mid-to-upper 100’s usually.
  2. Do a leakdown test.

If you perform both tests yourself then you know you can believe the numbers. I would not personally trust a sheet that somebody else has provided me showing that they performed the test on the engine, but that’s just me.

Rad’s Philosphy

Now… My philosophy on this is to remove the risk completely! Buy the cheapest engine you can find in decent condition. Don’t worry if there are problems with the pistons, rings, rods, etc. As long as the block and head are in decent shape you can replace and repair everything else. By building the engine you are setting yourself up for long-term success. For about $2,500 you can have a machine shop rebuild an engine professionally with forged pistons and heavy duty rods. At the end of the day you are essentially getting a 0 mile engine that is capable of withstanding a lot of extra HP. Why take the risk of putting a bad engine in the car just to have it blow a few months later and then have to do it all over again?

Blown RB20DET Engine

If you can’t afford to build the engine then I have to ask the fundamental question: Are you sure you are ready for an engine swap? This can get very expensive…

Engine Refresh Tips

However, if you want to proceed with the swap without building the engine then at least do the following:

  1. Replace all gaskets
  2. Absolutely replace the oil filter (don’t ask, I’ve seen this overlooked)
  3. Replace the water and oil pumps (If you’re going high performer consider N1)
  4. Might as well replace tensioner and idler pulleys.
  5. Replace all radiator and heater core hoses (they tend to rot with age)
  6. Clean everything up to the best of your ability.

Finally, RB engines like to overheat in engine bays, and this is possibly true with many swaps since you are often putting a larger engine in the bay than the car was designed for. When doing this, always do your best to upgrade the cooling system with a proper radiator and radiator fans. Keeping your engine properly cooled is a great way to ensure that it will last for years to come.


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