Engine Swaps

The attributes of the Renesis engine make quite a few people wish that there was a different engine in the chassis. Either one with more torque, more power, better economy, or better reliability. Many people start thinking about engine swaps, but it isn't as simple for an RX-8 as it is for other cars.

"Adding" a rotor to make it a 3-rotor:

Can you simply add another rotor to the engine to make it a 3-rotor? No, you can't. This is a piece written years ago by RotaryGod, an RX8Club.com forum moderator.

So much for there being too much to list. You can't do it unless you have lots of money to pay for some VERY one off custom work or you can do that very custom work yourself. If you have to ask if it can be done, the answer to these is pretty apparent. This isn't me being a dick. This is me being obvious. So let's take the time to explain it anyways.
First off you have 2 eccentric shafts at your disposal. They are machined. Each of them is 1 piece. For a 3 rotor engine you need lobes that are 120 degrees off from each other, not 180 degrees. This means you will need an entirely new eccentric shaft and can't use the ones you have. You might be able to machine each one you have into parts of another shaft but even then you don't have enough parts to finish the job.
You need an extra housing that doesn't exist that has the intake and exhaust ports for 2 rotors in it. This would require you to custom build one and no one has ever done that yet. One person has adapted a 20B eccentric shaft and modified an existing center housing to work in this place but the center rotor could not breathe as good as the outers due to the size of the ports. You would also have a different amount of intake ports on the center rotor unless you used a 4 port motor and even then it's not going to have the same port timing. I'd prefer not to get into this as well but trust me, it won't work.
You will need to custom make an intake manifold which is actually the least of your worries if you are content on losing lots of the benefit of the current design. You'll lose the VDI and auxiliary port functionality unless you do something really really trick. I'm not going to call this one impossible but rather highly highly improbable. Improbable to the point that we'll see a rotary climb Mt. Everest before it happens. But it's possible!
How do you plan to control the engine? The stock ecu isn't going to do it and one that does will be a couple of thousand dollars and require tuning from scratch. This isn't that abnormal since lots of people use standalone ecu's but it is a pain.
Cooling for both oil and water. Are you going to rely on the stock cooling system to handle 50% more load?
The exhaust. Prepared to replace the whole thing? Not unusual either but still more money to spend.
Even if you get all of this figured out, how are you going to balance the engine internally?
Just paying for all of the components without even doing the engine work itself will cost you several thousand dollars. A swap with a standard already existing 20B 3 rotor is a $20K plus affair and usually far more. Custom building a 3 rotor Renesis will at best double that and then there are costs that you won't ever expect.
Basically what I'm getting at is that a big pile of parts does not an engine make. A big pile of money on the other hand has a better chance. How much money do you have? Unless you can buy a Ferrari today, you probably don't have enough. That's a pretty direct statement but a very true one.

4-port engine to 6-port engine swap (covers AT to MT as well):

Two much text to post here. Read the first post from this thread as detailed by RotaryResurrection: RX8Club.com: AT to MT Swap

RX-7 13b-REW / FD swap

This is probably the most common engine swap there is, and it's still not very common. This swap has the advantage of having an engine that is pretty close to ours physically, and can be adapted to work with the RX-8's ECU, which means that much of the fabrication and wiring headache is a non-issue. It's still a long process and not cheap, as the engine is "pretty close", which means still not exact. The Renesis sits lower and farther back than the REW, and even a few inches can mean a surprising number of additional issues. Cooling is already a problem for the RX-8, so you need a completely new cooling system designed to take the REW's higher power (everyone that swaps pumps up the power). Expect that it will cost a minimum of $12,000 from a shop that is competent with both the RX-8 and the FD RX-7, and expect that it will still take 3-6 months to complete. Costs will likely climb higher however, with $15,000 to $18,000 more typical.

20b / 3-rotor swap

Similar to the REW swap above, although more-so in most dimensions. It can not run on the OEM ECU, so all the wiring must be completely re-done. The engine bay has to have significant fabrication changes to accommodate the engine in the correct location, and the parts themselves are rare, which means sourcing stuff (like the manifolds) can be a long and expensive process. Expect a minimum of $20,000 to start from a competent shop. If you go NA instead of Turbo, you can usually knock some money off that.

LS Swap

Often talked about, very very very rarely completed. The financial cost of failure is about as high as the financial cost of succeeding, and has been easily north of $30,000. There is nothing existing today that will make an LS swap easier. Every single last bit is custom. Even cars like the Miata where there are shops that do the swaps regularly STILL have a turn-key price of $30,000. For an RX-8 you can expect a healthy amount higher. As to who does them, the short, and nice, answer is that ZERO shops that can do this kind of swap advertise for it. None. Period. End of story. Someone once asked what parts he needs to buy for an LS swap...

  • engine
  • stronger and compatible transmission
  • stronger rear end
  • stronger rear axles
  • custom created driveshaft to the measurements in your car
  • ECU to run the engine
  • Several thousand feet of wiring
  • An entirely new front subframe
  • gauge cluster that works with the ECU
  • a steering rack that you can get to work (stock one won't be able to fit there any more)
  • entirely custom created cooling system for the coolant
  • entirely custom created cooling system for the oil
  • Completely custom exhaust built on your car after the engine is installed
  • lots and lots of fabrication work by SKILLED fabricators to modify every single structural part of the engine bay
  • lots of labor by someone that knows what they are doing with electrical work to re-wire every part of the car into the new ECU
  • If you want AC, your AC will have to be completely custom

Literally nothing in the engine bay that is there in a stock RX-8 can stay where it is with such a swap. Including things like re-locating the brake master cylinder, which means re-running hardlines for the brakes.

Set aside about $25,000 to start, and expect to need another $10,000 to $20,000 more. Expect to not have your car for a minimum of a year. Expect that the best price you can get won't be able to finish within a year and will have stuff wrong and jacked up. Expect that the 2nd best price isn't any better. Expect that the highest price you are quoted is probably from the only shop that can actually complete it, and for more than they quoted you.

Expect that once the engine is swapped, you will need to replace the suspension, wheels, and brakes to deal with the difference in the weight balance and dramatically different torque dynamics.

However, if you have the time, the skills, and the money, it is certainly possible to get the swap going: RX8Club.com: LS6 Upgrade Parts List and Paperwork
Note: The swap still isn't complete as of the time of this last article update, which says something about the difficulty of following through.

26b / 4-rotor swap

Take everything from the LS swap above and triple it. This is because there was never a production 26b rotary, so every 26b is completely custom created. There have been several 26b RX-8s built, and the usual price tag is over the $100,000 mark. No, that isn't a typo, no, I'm not joking.