If you are looking at carrying out an RX-8 motor swap we have done the research for you. Take a look at some of the popular options to bring some life back to your RX-8.
The Mazda RX-8
Remember the Mazda RX-8? (Read a road test here if not) It was really the last hurrah from Mazda, a bit of a swan song if you will. Of course, with rumours of a successor in the mix, it’s time to take a look back at what made the RX-8 so good, and what eventually condemned it. It was built to celebrate Mazda’s venerated Wankel motors and it immediately garnered high praise from various motoring journalists and critics.
Jeremy Clarkson, in particular, was infatuated, describing it as “a unique motor that will sing all the way to the redline.” He praised its well-designed chassis and the affordable price tag. It was even ‘honourably nominated’ for the (somewhat) prestigious 2003 Top Gear Awards for Car of the Year and Surprise of the Year categories.
Of course, the RX-8 is also a very quirky sportscar. It has an oddly jovial front fascia plus soft and circular lines that dull the sporty edge. It’s also oddly obsessed with the shape of its own powerplant: a Reuleaux triangle. You can find this emblem littered all over the vehicle.
For a sports car, it’s also peculiarly proportioned with a four-door configuration. The rear suicide doors (doors hinged at the rear instead of the front) open only from inside the cabin, which Mazda insists is due to safety concerns. In the era before seatbelts, if the door was opened accidentally, the wind would open it further and the passenger could be sucked out. Mobsters also used them to throw their enemies out!
Never mind these minor niggles. Drivers were too busy revving the RENESIS motor under the bonnet, which in certain trims went all the way to 10,000 rpm, and the chassis was very stylish. Yes, it’s not a direct successor to the revered RX-7 and does not have its sharp edge. But that’s missing the point. The RX series was never meant to be directly related. Think of the RX-8 as a sports car for everyday use.
Mazda realised that customers want a sharper, more performance-centric RX-8. That’s why they made so many versions. Even Mazdaspeed makes tuning parts for it. But the best thing? Like any other affordable Japanese sports cars, it quickly appealed to the fascinating world that pursues every drop of performance: the aftermarket.
The RENESIS was a new breed of rotary motor, but the performance sector caught on quick. Of course, intakes and exhausts are the entry level. Next, ECU tuning and remapping; eventually moving to turbochargers, superchargers, nitrous and motor porting. And nowadays, with many cheap used RX-8s available, they’re becoming an increasingly tempting prospect.
However, there is a good reason for that low entry barrier, and that’s because the RX-8 is notorious for unreliability, specifically related to its RENESIS motor. Horror stories of catastrophic motor failure and excessive oil consumption scared away interested buyers.
Initially, this was true to a degree. The early remanufactured motors had poor quality control and were put into RX-8s that didn’t need them. Early ECU flashes failed to supply enough oil for seal lubrication. After a few years, most problems were ironed out. It’s still a high maintenance motor by any stretch, but with dedicated owners, the RENESIS can be very reliable.
Now though, the big problem is inefficiency. Because of their design, rotary motors struggle with fuel economy and emissions. That’s enough to drive away potential customers. If nothing else, they are simply not powerful enough. The RENESIS is too expensive to generate much power and has a comparatively small aftermarket. There is a ‘solution’ to this – it’s counter-productive but put simply: do an RX-8 motor swap.
Why Do An RX-8 Motor Swap?
If you think about it, it makes sense. The RX-8 has one big advantage: it has a very favourable and popular powertrain configuration for performance purposes. FMR: front mid-motor, rear wheel drive. This means that the possibilities are extensive.
More importantly, it serves as a great base to work from. It has a well- designed chassis, normal variants aren’t too scarce yet, and there’s a big community behind it to guide and provide information.
That said, the RENESIS is a very small motor despite the long bonnet. That’s because Mazda seated the motor behind the wheels to preserve excellent weight balance. This is a bit of a double-edged sword. It means that you have more space to work with, but also that you’ll probably muddle the stock handling dynamics.
I’m not underplaying the difficulty of the RX-8 motor swap It is not a simple job by any means, and the RX-8 is known to be tricky to work with. It may take a lot of late nights, fabrication and brainstorming and will be expensive, even if you do it yourself.
One major reason for this is that the RX-8 is a modern car, with CAN bus. You’ll need to sort out the instrument, electric steering, ABS, etc. The easier way, relatively speaking, is to ditch the stock ECU and choose a standalone solution with an aftermarket dash, but the electric steering won’t work without a CAN bus adapter. The other way is to keep the RX-8 ECU, and somehow retain the original sensors. Regardless, it’ll be hard, on both you and your wallet.
Also, it’s worth noting that the RX-8 was designed almost entirely around the RENESIS. This means that fabrication is almost always needed. Additionally, depending on the location, insurance will be difficult to acquire, and vehicle registration may prove challenging.
RX-8 Motor Swap – Brief Summary
Before we get into my own suggestions, arguably, the LS series is the most commonplace swap people have undertaken. Hence, that’ll be the most well-documented RX-8 motor swap.
However, the LS motors are difficult to acquire, except in America, so other motors, mostly Japanese, are an acceptable alternative.The legendary JZ motors and RB motors are both plausible and options popular for their limitless potential. However, not every garage wall cabinet contains replacement parts for this engines so if you’ll break any of them you will get in trouble.
Four cylinders are also swapped into the RX-8. The renowned SR20DET is a popular choice for the RX-8. People have even swapped other rotaries into the RX-8, either from the RX-7, or a custom made 3-rotor. Then there are some oddball swaps, which will generally require a lot more knowledge and skill to pull off.
Of course, I’m here to spark your creativity. By no means is this a comprehensive tutorial on how to put a different motor into your RX-8. The list will go from sensible, to plausible, but incredibly arduous.
RX-8 Motor Swap Option 1: 8-cylinder
Chevrolet LS motors
Possibly the most ubiquitous RX-8 motor swap candidate, it’s small wonder that the LS is amongst the first swaps to be conducted successfully for the RX-8. Not to mention one of the easiest, and well-recorded.
The LS family is broad, but the 5.7-litre LS1 and 6.2-litre LSx are ideal for the RX-8, but any LS will work. The LS motors enjoy the distinct benefit of being extremely prevalent, so parts are readily available. It’s also relatively powerful, at least 300 horsepower, but more importantly, has lots of torque down below.
Despite boasting a much larger displacement, the LS motors can be pretty economical, even more so than the RENESIS. 25 mpg is entirely possible with an LS-swapped RX-8. Of course, if you feel that it lacks zest, the LS motors enjoy a massive performance aftermarket. Of course, there are lots of different transmissions available for it, depending on how much power you want and what option you prefer. T56 is typical for manual drivers.
Depending on how much you’re willing to spend, 450-500 horsepower is realistic and achievable with basic forced induction or naturally aspirated build. But really, the sky is the limit for motors as well understood as the LS.
There’s also no need to cut into the firewall. With lots of insight to work with, it’s possible to build up your own kit. However, kits are also available for it. They may not be completely plug and play, but do cut down on required fabrication work. It also sits well back, but the motor does hang over the front wheels.
The LS motors will end up being heavier than the RENESIS, but not as much as you might think. The suspension geometry won’t be entirely stock, but most of the electronics like AC, electric steering, and instrument clusters can still work if you intend to reuse them. You’ll also probably need a custom fabricated exhaust.
You can expect the car to weigh around 1,450 kg after the swap, and the weight distribution to shift forward slightly. You may notice reduced agility, but plenty of gains in low-end grunt and speed. The heavier nose may also encourage a livelier tail. And of course, you’ll most definitely notice that distinctive V8 growl, as the giggles from the guys in the video below indicate.
The cost will differ depending on how you plan to approach this project, but it should be achieved with around $10,000. Hinson Motorsports (US), Racefab (NZ), LS1RX8 (US), Ojimports (US), Brintech Customs (AU) and V8Roadster (US) are some professionals who provide kits or can perform the swap, and they have their own methods.
Referring to them will save you a lot of time and effort. By reading, researching and forum prowling, a Corvette-powered RX-8 should be a simple proposition. If you live in the UK, the V8-addicted blokes over at Dyno Torque can provide consultation too. (They have a video showing their own LS-swapped RX-8, see below:)
Toyota UZ motors
If you want to deviate from the norm, the V8 motor Toyota offers is a feasible RX-8 motor swap to make. The disparity between the UZ and LS family is that the UZ motors are DOHC or QOHC, rather than pushrod. This means that it’s a taller motor. While many believe that the UZ won’t fit inside the RX-8, people have managed to accomplish this, some even tucking the motor neatly inside.
The UZ motors, like the LS, span a long period, but have a much smaller family. While the 2UZ-FE will be easiest to find, it’s more suited to brutish SUV implementation due to its low-revving design with durable but heavy cast iron block. Therefore, either a post-95 1UZ-FE or a 3UZ-FE will be ideal. These are aluminium, with forged rods and high compression. Post-97 1UZ-FE received VVT-i too.
Nevertheless, the 4.0-litre 1UZ-FE will at least yield 256 hp and 353 Nm or torque, while the newer 4.3-litre 3UZ-FE should provide 282 hp and 417 Nm of torque minimum, before deterioration. Either way, Toyota was acclaimed for overbuilding motors back then, and the 1UZ-FE is especially rugged. Both the 1UZ-FE and 3UZ-FE are noted for their reliability. The original big Lexus LSs with these motors generally returned 20 mpg combined, so you can expect better figures for the light RX-8.
While performance modifications aren’t as broad for the UZ motors compared to the LS, people have commonly incorporated forced induction for extra verve. For extra headroom, you’ll want the 1UZ-FE with its smaller bore, which means thicker cylinder sleeves. With a mild supercharger with a modest boost of 6 psi, 350 horsepower is possible. Turbo and naturally-aspirated tuning is also common for the 1UZ. Generally speaking though, it’s going to cost more than the LS.
Unfortunately, information on this particular RX-8 motor swap isn’t readily available, so you’ll be performing it with blinkers on. From what I’ve seen, the firewall remains intact, but the front subframe will probably need modification. The RX-8 steering rack may also be too big for the UZ motors. That said, PMC Motorsports (EU) does make a bellhousing adapter that’ll marry the 1UZ and 3UZ to the stock RX-8 manual transmissions. No word on quality though, but they’re well-respected in Europe. Otherwise, for manuals, the Toyota W58 seems to be the go-to option.
For the conversion, some sources of reference are Yung Lee Auto (MY), SNJ Motors (UK) and KMS Motor Performance (PL). If you understand Russian, their forums may have something for you. This thread also contains some information regarding the RX-8 motor swap. 4 Spanner Mechanic on YouTube also has an ongoing series on a 3UZ-FE swap, so give him a look.
The 4.4-litre M62B44 and 4.0-litre M60B40, both pulled from older big BMWs have been swapped into the RX-8, with some success. That said, they’re going to be expensive to maintain, are harder to source, and are low on power. Still worth a look.
Then there are creative options that are quite impractical. The supercharged, fire-breathing M113 5.4 Kompressor which emits nearly 500 horsepower and over 500 Nm of torque (firewall cut), and the Ford Windsor 351 V8, which is the predecessor to the current Modular V8s. Photos of a Nissan 4.5-litre VH45DE powered RX-8 are also around.
RX-8 Motor Swap Option 2: 6-cylinder
Toyota JZ motors
Possibly one of the most exalted motors of all time, the JZ family needs minimal introduction. It’s also one of the more common conversions made to the RX-8. Keep in mind that with one of these, your RX-8 will most likely turn into a drag car or cruiser rather, than a time trial virtuoso.
The big question is whether to go for the 2.5-litre 1JZ or the 3.0-litre 2JZ. The 1JZ is a more realistic choice, being both lighter and more affordable. Both motors have similar potential, but in terms of brute force, the 2JZ is difficult to argue with.
Of course, there are different types of 1JZ and 2JZ, but if you’re not going for the GTE, it really is nonsensical to make the swap. You can expect at least 276 hp and 363 Nm of torque for the 1JZ-GTE, and 276 hp and 435 Nm of torque for the 2JZ-GTE.
But of course, these numbers mean little considering that the JZ motors are almost always modified to some extent. There are stories of the non-VVTI motors running routinely at over 400 hp, without breaking a sweat.
If you’re looking to perform an economical swap, the 1JZ-GTE can be adapted to match the RX-8 manuals. The 5-speed will be a better choice, with the same bolt pattern but stronger overall and with a better gear ratio for forced induction. Otherwise, a late model (~09) 6-speed can work. With an adapted bellhousing, you can avert a whole lot of fabrication and extra expense. More information can be found in this thread here.
However, if you’re being especially ambitious, the 5-speed R154 can sustain around 600 Nm of torque on stock internals. If you can afford it, the fabled 6-speed Getrag V160 is one of the strongest there is.
Regardless, it’s still a complex swap to attempt. It’s also a lot heavier than the RENESIS, so you’ll have to stiffen the front springs. There is a kit out there for this swap though, and it’s once again from LS1RX8.
For reference, check out Yung Lee Auto (MY). They have a video showing the swap too. LS1RX8 (US) should also be a good source to cite. This thread has a completed build with useful information, and if you are really interested, check out this Facebook page hosted by LS1RX8, made for like-minded individuals. This little article shows the potential one gorgeous drift RX-8 has.
There’s actually a lot of interest for a 6-cylinder powered Mazda RX-8. Narrow angle V6s can be installed and tucked away neatly within the RX-8’s motor compartment. Perhaps most intriguing, is the LFX swap, a 3.5-litre 54-degree V6 found in many Cadillacs. This guy is currently documenting his swap, which was supposed to be an LS-swap, then the VAG 1.8t 20v, before moving to the LFX. He is even swapping an Isuzu 3.5-litre 6VE1 into an RX-8 in his lengthy and heated (to say the least) thread. While it was interrupted, there’s a lot of useful information to glean from this.
The RB motors are an alternative to the JZ. That said, these may prove harder to find, and the swap is not as well documented. If you are interested, Slide Motorsport (UK) has done one before, see below. Enthusiasts have also managed to insert the 5.9-litre 6BT Cummins turbo engine into the RX-8, affectionately granting it the RX-Hate moniker. It makes no sense, but provides light relief.
RX-8 Motor Swap Option 3: 4-cylinder
Please note that 4-cylinder swaps for the RX-8 aren’t half as popular, possibly because the trade-off in labour and budget isn’t worth the meagre gains.
Nissan SR motors
Yes, it’s yet another Japanese motor, but there’s a reason for this. The Nissan SR motors are one of the most well-known performance 4-cylinders out there. For any small front-motored, rear-wheel drive platform projects, the SR motors will be given a thought.
The most prominent SR motor is probably the SR20. The most performance-oriented production variant being the SR20DET, perhaps most recognisable as the motivator of the Nissan Silvia. While there is technically a more powerful interpretation, the SR20VET, it’s exclusive to Japan and incredibly rare.
Depending on which car you sourced your SR20DET from, you can expect around 200 horsepower and 270 Nm of torque. But the well thought out design of the SR20DET means that it can be taken to 400 horsepower on a stock block, with good cooling and stronger internals. While it’s a full alloy motor, the DET is still relatively heavy.
For transmission, PMC Motorsport (EU) once again manufactures bell housing adapters to match the SR20DET to the RX-8’s motor. Otherwise, the SR20DET is often paired with the RB25 5-speed manual transmission, which can withstand mild modifications.
If you are interested, this thread here is a good read and should provide you with useful insight. Again, Yung Lee Auto (MY) has attempted this swap before. Powerfab Automotive (US) can also be a useful resource. Another thread with good material, albeit abandoned halfway.
Other than the SR20, the Volkswagen AG 1.8t 20v, and Cosworth YB 2.0-litre turbo are both common options for the RX-8. Both have their own motorsport pedigree, and a big cult following with the results to show for it. They’re not cheap to modify, but well respected for their abilities. If you live outside of Europe though, it may prove trickier to acquire one. This thread here records a Cosworth. Here’s another thread with a build stopped halfway through, but with a 1.8t adapted to fit the Mazda transmission.
Another more unorthodox choice is the 2.0-litre naturally-aspirated F20C VTEC, pulled from the Honda S2000. This won’t be an easy motor to find. Even the traditionally transverse Honda K20 has made its way into the RX-8 before. Otherwise, the third generation MX-5 has a similar underpinning to the RX-8, so it’s also an interesting prospect, if a less logical one.
RX-8 Motor Swap Option 4: Rotary
In the end, the best option may be to stick with what you’ve got. While the RENESIS and the 13B-REW may have the potential to generate impressive power figures, if you can find the 13B-REW that came from the original poster child, the RX-7, you can swap that in.
The main advantage is that it enjoys a larger aftermarket appeal than the RENESIS. Of course, the 13B-REW needs no introduction. It’s the sequentially-turbocharged 2-rotor found in the third-generation RX-7. Emitting 255 hp and 294 Nm of torque, it was one of the first rotaries to put Mazda on the map.
With stock internals, the 13B-REW is known to have gone well over 400 hp. If you have seen videos of a fully-fleshed out 13B, it’s usually running a turbocharger that’s nearly as big, if not bigger than the motor itself.
There is a lot of useful information out there, with even a swap kit offered by RX-8 Performance. While it’s technically the same powerplant configuration, there are a lot of differences between the two. You’ll probably have to convert to a single turbo, since the twin won’t fit. The oil filler neck on the 13B-REW won’t fit, and you’ll have to shrink the lower intake manifold, using a power tool.
If you want to maintain the spirit of the RX-8, combined with the soul of the original, here are a few threads you should take a look at: This one is powered by a big BorgWarner S466, currently producing over 500 hp, and this one has a more humble, everyday 300 hp build.
It’s not going to be cheap, but if you want to go for broke, consider a three-rotor, known as the 20B and of course, the four-rotor. It’s not an off-the-shelf motor, even though the scarce Mazda Eunos Cosmo has one. If you are interested, Promaz (AU) has developed a kit for a 20B swap. If you are considering a 26B, you probably know what you’re doing already.
You can either make a three-rotor of your own from parts provided by Mazdaspeed themselves or purchase one made by a reputable builder. Give Defined Autoworks (US) a look, Precision Motoring (NZ) is also famous for their work, along with Promaz (AU). Of course, they can make a four-rotor too. For 20B information, this thread is particularly informative. Being very rich will also help here.
RX-8 Motor Swap Verdict
Before any RX-8 motor swap, it’s prudent to research before you begin. Of course, no motor transplants are going to be easy on the RX-8, and it can be argued that swapping out the RENESIS is sacrilegious.
However, if you love a challenge, and want something more unique, you can do a lot worse than the RX-8. With many professionals figuring out its quirks, attempting your own swap isn’t as daunting as it used to be.
Never underestimate the challenge you’re going to face, which is a big obstacle to any project. Budgeting is also a concern, as many end up forsaking or selling their projects simply because the cost is too extortionate.
Otherwise, if you do your homework, an LS-powered RX-8 is certainly one of the easier options. Perhaps it’s not the most creative, but its popularity and results are hard to dispute. Regardless of your intended ambition, it’s crucial that you can enjoy whatever you end up with. That’s really the joy of any automotive adventure.