How Much Does It Actually Cost To LS Swap the Mazda MX-5 Miata?

If you own a Mazda MX-5 and you’re planning on swapping the four-cylinder engine for a small-block V8, Flyin’ Miata has got you covered. From the first-generation NA to the latest ND, the conversion package costs $49,995 excluding the price of the vehicle but including labor.
LS Swap Mazda MX-5 Miata 12 photos
Photo: @lowla_smc and @claytonlillace on Instagram
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“Wait, so you’re telling me I could buy an all-new Toyota Supra with that money?” Rightly so, dearest reader; it’s not a cheap swap, but those on a budget have a few alternatives to choose from. The question is, how much cheaper than Flyin’ Miata can you go with a do-it-yourself approach?

Clayton of Slightly Mad Customs is much obliged to go through the expenses on his NA roadster, so let’s start off with the obvious. Costs depending on plenty of factors, including how many components you buy new or used and if you do the conversion in your garage or with specialized help.

“There’s a lot of people that get into this build expecting to be all done for $5,000 to $10,000 but end up much closer to $20,000.” In Clayton’s case, the car is running a 345-horsepower and 350-pound-feet LS1 with a tubular front subframe and a good ol’ 8.8-inch rear axle.

First off, a second-hand LS1 runs at approximately $2,500 in Canada, including the wiring harness. The clutch assembly is $500, and a few more parts add another $500 to the tally. A used T56 with a bell housing is about $2,500, the driveshaft was about $500, and the engine-transmission mounting kit retails at approximately $2,000. An oil pan from Flyin’ Miata or V8 Roadsters is $800, and frame reinforcements will set you back $50.

We’re currently sitting at $9,350 and the expenses don’t end here, oh no!

Remember the 8.8-inch axle mentioned earlier? Clayton paid $300 for his, the mounting kit is $400 if purchased from Monster Miata of California, the axles cost $750, the hubs are $200, and the wheel bearings cost $50. In other words, the rear-end section will cost you $1,700 in parts.

A limited-slip differential is $700 with the stock set of gears, headers run from $600 to $1,100 new, and used manifolds will cost you anything from $50 to $200 depending on the condition. The finishing touches – coming courtesy of an exhaust shop – should cost in the ballpark of $1,000.

A radiator and cooling fans retail at $750 new from Monster Miata, $50 is the price of the coolant overflow tank, and the water pump and thermostat boil down to $150 as a kit. Re-flashing the Miata’s original ECU to suit the LS swap costs somewhere around $100 while a stand-alone engine control unit starts at $700. The fuel and cooling fan relays are priced at $25 each, and getting the gauges to work right will set you back $135 or thereabouts.

The fuel system? Clayton suggests a budget of $225 on the cheap. Miscellaneous items like brake fluid, a sway bar, electrical tape, welding supplies, bolts, fasteners, and all that jazz run you at approximately $1,300.

Are you keeping count? If not, the grand total is $16,000.

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About the author: Mircea Panait
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After a 1:43 scale model of a Ferrari 250 GTO sparked Mircea's interest for cars when he was a kid, an early internship at Top Gear sealed his career path. He's most interested in muscle cars and American trucks, but he takes a passing interest in quirky kei cars as well.
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