Forced Induction


Regardless of which option you go with below, keep in mind that you should probably have a spare engine ready to swap in at all times, because it's likely that you will need it sooner than you think.

Nitrous

Nitrous is a cheap way of getting bursts of power, though if you pursue nitrous as a power adder, make sure you do your homework on the considerations. It's still easily possible to destroy your engine with it and it has continuing costs over time.

Nitrous oxide systems, particularly the Zex #82021 system, work quite well whether your RX-8 is stock or modified. Most of us are using a 55 h.p. shot. A couple people have been able to get the 65 h.p. jettings to work, as well, but we don't tend to suggest their use. For those who wonder; the Racing Beat and MazdaManiac's Cobb AccessPort tuning work well alongside the nitrous and either one actually enhances the effect that the 55 h.p. shot of nitrous has on the Renesis. With the right modifications those who drive the reputed "Kings of the Street" platforms will be surprised to find the RX-8 to not be as slow as they have been told.


First, you must make sure ...

The quote is deliberately truncated, the full read is here: BHR: Rules for Nitrous Use

Any research you do should start with this thread: RX8Club.com: Power Adders (FI) For Dummies (Turbo, Supercharger, Nitrous)

Supercharging

There aren't many options here, and by that I mean 'virtually no options'. There have been a number of different supercharger kits produced, Pettit's being the most widely used and the highest production count, but they are not currently being produced. Pettit hasn't completely pulled the plug on the kit though, so they may return for a time. The kit is relatively well put together, but has a high initial cost ($7k+) and still requires some changes for smooth and reliable operation. Used kits are exceedingly rare.
There were 10 S/C kits produced by Hymee in Australia (the website is no longer active), but they had problems, worked out to around $10,000 USD for the kit, and the designer ran into major health issues that permanently halted further development. Only 2 of those 10 made it to the US. There have been a few other aborted attempts from other manufacturers as well.

The main reasons for preferring a supercharger over a turbocharger is going to be because of kit quality and completeness. The supercharger kits cost more up front, but have less on-going tweaking, changing, and maintenance. There are also fewer possible hardware failure points than on a turbocharger setup, so less chance of something going wrong and taking out your engine. You also can't just casually reach over and turn up the boost, so once a supercharged rX-8 is tuned, it tends to stay at that boost level and on that good map for a long time. Turbocharged cars tend to keep moving the boost around, which can cause problems if you aren't cleanly tuned at each boost point.

There is only 1 correct reason for the belief of "superchargers are easier on the engine" vs a correctly tuned and set up turbocharger, and that is the nature of the turbo manifold and how it extracts energy from the exhaust stream means that there is more localized heat buildup on the exhaust ports, meaning side seal failure is accelerated faster compared to an equal power supercharger. Power = heat, so it's still relative. More power from a supercharger can mean shorter side seal life than a lower power turbocharger. Exact setup can make this statement move around quite a bit.

Any research you do should start with this thread: RX8Club.com: Power Adders (FI) For Dummies (Turbo, Supercharger, Nitrous)

Turbocharging

There are no complete "kits" for turbocharging. Some kits get closer than others, but all require modifications to work properly and safely. The most popular is variations on the GReddy kit using a 3071R turbine. These kits are for sale regularly and often cheaply. Even if the kit is cheap, you should expect to have a cash pool on hand of $10,000 before you start buying parts, and if you can get a 2nd engine as well, it's recommended, since you will probably be using it.

Any research you do should start with this thread: RX8Club.com: Power Adders (FI) For Dummies (Turbo, Supercharger, Nitrous)

This thread is a must read if you are planning on a GReddy kit. Read the entire thread, not just the opening posts: RX8Club.com: Definitive GReddy Turbo Fixes