Mazda had great success with the RX7 and proved a rotary engined car could be fun to get. The successor came in the shape the lovely RX8. It was leaps and bounds better than the RX7 in many respects.
The angular lines, edgy design and interior trim all won the hearts of RX8 all over the world. Mazda updated the 13b Wankel engine creating the innovative Renesis rotary engine.
Tuning the RX8 rotary engine is considered difficult by some but there are a few options that can transform the RX8 performance.
The key benefits of a rotary engine include the ability to provide high rpm tolerances and a silky smooth power delivery. Problems though include a lack of low down torque at low RPM but when driven correctly these cars have a lot to give. Standard power figures of about 200bhp from your 1300cc engine really pushes the envelope of what is feasible.
Your RX8 tuning should start off with some improvements for the brakes and handling. A big brake conversion kit will really pay dividends and offer a progressive brake feel. The car could be lowered around 35 mm. We would recommend adjustable suspension so you can set the damping and spring rates to fit your driver preference.
The engines need to be properly looked after and serviced regularly. Will not let the unusual rotary engine put you off. These are superior to early rotary engines and are every bit as flexible and reliable as a reciprocating piston setup.
The RX8 is just crying out for the turbo conversion and this is probably one of the few bolt on options although it can prove expensive. A turbo will raise the standard power to around 400bhp! Sadly in the real world there is a lot more with it than just bolting on a turbo. A whole host of other components will be needing uprating and strengthening along with the mapping should be spot on.
The 4 port engines will be more suited to turbo charging in comparison to the 6 port ones but both conversions require lots of work and planning and we would not recommend undertaking this unless you have obtained a whole kit and possess facilities to work a custom map. Obvious power mods for a turbo RX8 would include a larger front mounted intercooler. The intercooler can are afflicted by heat soak on long runs so channelling a great deal of fresh air through this will pay dividends. Power can also be increased with adding a larger turbo or a turbo with higher performing internals (a hybrid).
Engine heat build up is actually a massive problem when adding forced induction and a larger oil pan and even an oil cooler will help address this issue. It could also pay to get the exhaust down pipes coated or wrapped to contain the heat.
Further engine cooling mods will include an uprated water pump and thermostat, and use of a synthetic water cooler additive with a bit of high performance silicone hoses to prevent leaks from higher pressures.
When pushing larger power gains furthermore you will need to uprate the fuel delivery system to prevent the engine from running lean – if anything these engines prefer to run rich.
We have looked remaps for that RX8 and sport chips without much success. Hopefully RX8 remaps may become available.
The most suitable choice we could find is fitting a full aftermarket engine management system. This lets you fine tune the timing and fuel delivery for the maximum power gain and this will also allow you to factor in any other mods you have done. On a standard car by having an aftermarket engine management system you can see power gains of approximately 2-5%.
Tuning articles and tips
Porting the Renesis engines, if done properly, may have a big impact on the power delivery and torque curve. This is simply not a simple job though and is also only really worth doing should you be already stripping down and rebuilding the engine. Lapping the flat housings and adding high quality ceramic seals are considered important mods here, and dynamic engine balancing will also help you reach higher power gains retaining reliability.
A sports exhaust and induction kit may help provide power gains just a little, but in the opinion of TorqueCars members, the standard setup is pretty good and gains are only noticeable high up within the RPM rev range. There are very few 200bhp NASP 1.3 engines out there so you have something special within the RX8 and the nature of the way the engine works means it is ideally suited to hydrogen as fuel! (Perhaps this dream can get a reality some day but for now I suppose we have to stick to petrol! )
Adding a sports cat may also free up a bit more power, about the Renesis these little gains all tally up quite effectively.
Reducing the weight of the flywheel to around 9 lb’s seems to be a favorite choice and does modify the nature of the engine considerably, but we should add not really to the taste of drivers, try one fitted to an RX8 first before you commit yourself here.