Some Geniuses Are Stuffing Jaguar Engines In Mazda Miatas And Going Crazy Fast

Question: If you want a Mazda Miata with more power than the stock four-cylinder engine can provide, what would you do? You could go with an LS and make an overabundance of power and torque, but need to beef up the driveline to handle the sheer output. You could turbocharge the stock four-cylinder engine, but even the best turbocharged applications still have lag, and a turbo engine that pulls hard up top typically compromises on low-end response due to compressor sizing. You could go with a Honda K-Series inline-four, and while that will rev to the moon and make good power, sometimes you just want more combustion pulses than a four-cylinder can offer.

Happily, there is another tantalizing off-the-shelf option. Rocketeer Cars has been building Mazda Miatas with Jaguar AJ-V6 engines for nearly a decade, and not only is the horsepower figure similar to what you’d get from a stock 5.3-liter or 4.8-liter LS-based truck motor, there’s a whole lot to love about this V6 beyond its output on paper.

While the donor engine can be found in the Jaguar S-Type, its lineage is actually more complicated than that. See, Ford didn’t have the capacity to work on an overhead cam six-cylinder engine for its front-wheel-drive cars, so it contracted Porsche to do some of the engineering work. From there, Ford used Cosworth’s sand-casting method to make the cylinder heads, and the Duratec V6 was born. Jaguar, then owned by Ford, saw this V6 and decided that with its own cylinder head design, direct-acting tappets, and variable valve timing, it could be good enough to use under a leaping cat hood ornament. Thus, the AJ-V6 was born.

In stock three-liter form, it pumps out a tidy 240 horsepower and 221 lb.-ft. of torque. Crucially, it’s oversquare so it loves to rev, it comes with a standard redline of 6,800 RPM, and it’s actually 11 pounds lighter than the 1.8-liter engine in later NA Miatas. An interesting candidate for swapping into a Miata, made a little more interesting by a few tweaks Rocketeer Cars has made.

See, Rocketeer has designed its own carbon fiber intake plenums to not just fit nicely under a stock Miata hood, but help bump the V6 up to 280 horsepower. That’s 143 percent of what a 1.6-liter Miata made when new, all in a car that weighs roughly the same. Translation: 7.9 pounds per horsepower, slightly better than a Porsche 718 Cayman GTS 4.0. Back in 2017, Evo had a go in a Rocketeer development car, and while the plenums and tune weren’t ironed out yet, the results sound spectacular. As per the magazine:

The V6 takes a moment to catch and in this pre-production phase it’s a little unhappy when cold or on very light throttle openings. But damn does it sound good, with a rich, throaty note.

Every slightest movement of the throttle pedal, once past the initial stutter, results in instant response. Tom says the plenums may dull this slightly, but the trade-off will be perfect manners at low revs and more power at the top end. Today’s limit is around 6000rpm but even that’s enough to give the growling MX-5 ample pace, with one of the best soundtracks I’ve heard from a car in years.

Admittedly, the swap is not a cheap kit, but it is comprehensive. For £5,995 or just under $8,000, you get a whole new subframe, new engine mounts, a throttle bracket, special accessory drive parts, an electric water pump, a full exhaust system including manifolds, a baffled oil pan, the adapter plate, clutch and lightweight flywheel needed to mate the V6 up to the Miata transmission, carbon fiber intake plenums, an oil filler tube, throttle bodies, basically everything needed except the engine itself and the electronics.

Should you wish to not piece the electrics together yourself, Rocketeer sells a kit with the full harness, brand new pre-tuned standalone ECU, all the necessary sensors, and idle air control valves for £1,995, or about $2,653, and they’ll even help you with an engine for additional cost. Oh, and if you want to do the driving but not the wrenching, turn-key conversions start at £16,662 (around $22,170 at current conversion rates), or you could go really nuts and have them build you a restomod, a ground-up refurbishment and personalization of a V6-powered Miata.

In essence, Rocketeer Cars can get you the parts to build a much quicker Miata, or build you something like a Singer-modified Porsche 911 or an Alfaholics GTV for far less cash than some of these ultimate mega-dollar restomods that have been gripping the car scene. It’s a properly fascinating endeavor, giving the best-ever copy of a British sports car a British dose of extra performance, all while keeping the Mazda DNA largely intact. After all, a variant of the three-liter Duratec V6 with variable cam timing was used in the Mazda 6.

Top graphic credit: Rocketeer Cars

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