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Check Out These California-Legal Engine Swaps That Are Impervious to Cops

If you’re looking for a quick and easy way to add more horsepower to your car, then swapping a newer and bigger engine can definitely do the trick. However, if you live in California, that easy engine swap can quickly become a headache. California’s smog laws are among the strictest in the U.S., which means that there are a lot of hoops to jump through if you want to swap engines in a car and legally pass an emissions test with it.

Of course, there are many different platforms to choose from and many types of engines to swap into them. But Hagerty recently reviewed a couple of popular engine swaps that are perfect California legal and impervious to the cops.

Why is it so hard to make an engine swap California legal?

The California Air Resources Board (CARB) and the Bureau of Automotive Repair (BAR) are the two groups in California that set the standards when it comes to engine swap guidelines. To sum things up, the typical requirements to completely swap an engine into a certain chassis requires that the engine be the same year or newer as the chassis that it’s swapped into along with all of the necessary emissions equipment to go with it.

For example, if you want to swap a 1997 Acura Integra engine into a 1995 Honda Civic, then you’ll have to swap over all of the related OBD-2 (’96-newer) emission equipment as well. It’s actually relatively easy to do when it comes to that specific engine swap, but it can get tougher depending on the type of engine and chassis that you’re working with.

A picture of a BMW E36 M3 with an S54 engine swap
BMW E36 M3 with an S54 engine swap | YouTube/Hagerty

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BMW E36 M3 with an S54 engine swap

In the video released by Hagerty, Matt Farah details one popular engine swap choice: An S54 engine into an E36 M3. According to Autolist, the E36 M3 was produced in the US from 1995 to 1999 and came with a 3.2-liter, inline-6 engine that put out 240 hp. That’s not bad, considering this iteration of the M3 was able to go from 0 to 60 mph in just 5.6 seconds, however, there’s always room for improvement.

For most, that improvement can come via engine modifications, but for the folks at Performance Technic, improving the E36 M3 equated to an S54 engine swap. According to BMW Tuning, the S54 engine is out of a newer E46 M3 and boasts a power output of 333 hp and 262 lb-ft of torque. That’s almost a 100 hp bump with stock engine reliability and smoothness, so we can see why they went that route.

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Flyin’ LS3 Miata

The second engine swap that Hagerty detailed was a first-generation (NA) Mazda Miata with an LS3 crate engine. You read that right, it’s a super lightweight, rear-drive roadster with a massive 6.2-liter V8 engine under the hood. That means, instead of pushing the stock 100 hp that the original Miata engine provided, this little monster now commands 430 hp and 425 lb-ft of torque at the flywheel.

According to that car’s owner, Zandr Milewski, the car was built by a shop named Flyin’ Miata in which he handed the keys over and let them do their magic. About a year, and probably over $10,000 later, he got the car back with the upgraded engine.

Fortunately, these LS3 crate engines have gone through the CARB emissions requirements and can now be swapped into any chassis 1995 and older, provided the proper catalytic converter length and emissions equipment are hooked up. Unfortunately, the LS3 crate engine packages start at around $9,285, so you better have deep pockets to make a project like this work.

Flyin' Miata with LS3 engine swap
Flyin’ Miata with LS3 engine swap | Hagerty/YouTube