Associated costs and parts for setting up a GReddy turbo kit

Traditional bolt-ons do close to nothing for the car because it was so well tuned out of the factory. For example, cold air intakes can give you ~3 hp, aftermarket catbacks can give you 2-5 hp. Depending on what product you buy, the bolt-ons can even lower the amount of power your car puts down. Buying cheap crap from eBay is not recommended. To sum it up, you can expect to gain in the neighborhood of 20-30 hp with all imaginable bolt-ons. The cost is staggering for what you get in return.

While there are several turbo and supercharger kits "coming soon", the only one that currently has a wide install base is the GReddy RX-8 turbo kit. MSRP is in the 4k range. You can usually buy it for just over 3k.

You get everything you need to bolt the turbo and get moving. The problem with the RX-8 is that the car's computer (ECU) controls a LOT of things, and can't be easily replaced with a stand alone. Using the emanage blue has had many problems because of long term fuel trim (LTFT) making adjustments and "correcting" the changes made by the blue unit. There's been a number of fixes by members of the rx8club website, but honestly, it is not up to the job.

In recent days, GReddy has tried to address the issues with emanage blue by spending several months of R&D to take their newer unit, the emanage ultimate, and make it functional for the RX-8. The Ultimate can now force the car into open loop at will (Using the NVCS map), and can then adjust fuel injection directly, instead of trying to alter fuel by tricking the car into seeing less or more air. The Ultimate is now shipped with every GReddy turbo kit for the RX-8. Additionally, they offer a $600 upgrade kit for anyone who had the older blue kit.

The ultimate choice for fuel management is the Cobb AccessPort. It's a reflasher that changes how your car controls fuel directly instead of having a piggy back system. This means one less point of failure AND you can use your factory PCM, which is by far more advanced than any piggyback you can slap on the vehicle. MSRP is only $699.


The first thing someone wants to know when they start researching into getting a turbo on the RX-8, is what do I need to buy, and what is it going to cost me?

These are rough estimates for pricing (since prices change on a daily basis):

1. GReddy turbo kit (MAZDA RX-8 2003-on, 6-spd only, Turbo T618Z, Cast Manifold, intercooler type31). Cost is in the neighborhood of $3200 - 3500. REQUIRED.

2. The reducers/couplers/hoses that ship with the GReddy turbo are very poor quality. Many members have reported them cracking and breaking apart. It's even happened to me.. I recommend doing it right from the start, and upgrading them. New hoses will run about $100. Good thread about it here. HIGHLY RECOMMENDED

3. BOV (set to recirculate) or bypass valve. The pressure built up by the turbo needs to be released when you shift, or it will cause backpressure on the turbo. To do that, you'll need a BOV and have it set to release the air back into the car. If you later change the Ultimate (Or use the Int-x) to run MAP based (instead of MAF), you can set the BOV to vent to atmosphere. The problem with atmosphere and MAF is that the car sees X amount of air incoming, if you suddenly release it, the car doesn't know and still injects the same amount of fuel. Causing the car to run really rich. Most BOVs cost around $200. HIGHLY RECOMMENDED

4. Boost controller. The boost controller will give you better control over your boost, lower turbo lag, and can build pressure faster. It can also prevent you from over boosting, and save your engine from detonation, or even blowing. It's a good thing, though not required. The GReddy Profec B Spec 2 runs about $300. HIGHLY RECOMMENDED

5. Fuel management. There aren't a lot of people using the Ultimate right now. I highly recommend looking at the AccessPort. MazdaManiac offers premade maps that can work for NA or FI purposes. $699. OPTIONAL

6. Gauges. You'll want to monitor at a bare minimum your AFR (air fuel ratio). When on boost, your AFR should be less than 12 (I'm making general statements here, your application may differ), without a gauge to see, you could be running too lean and could destroy your engine. The AFR can also tell you if your system has other problems, such as a vacuum leak. I also recommend a boost gauge. It will let you know how much boost the engine is getting, if you're unable to maintain boost, and if you're overboosting. Also nice to have is an EGT gauge (reads exhaust temps), oil pressure, water temp, etc. The AFR gauge (wideband) will run about $300 (I use the AEM UEGO). Boost will run about $200 (I use GReddy's boost gauge). For $450 you can get racing beat's ash tray pod which tells you coolant and oil temp, plus oil pressure. HIGHLY RECOMMENDED

7. If you're sticking with the Ultimate, you'll want to get your wideband (AFR) readings to it. You'll have to buy a $20 A/F harness and splice in. OPTIONAL

8. Exhaust upgrades. The turbo sits between your engine and the exhaust. It is basically a fan that the exhaust is spinning. This means your exhaust has a harder path to exit the car. So anything you can do to help the exhaust will give you more power. An aftermarket catback is a good thing to have. The stock one is so heavy and restrictive that you can barely hear it when the car has afterburn (backfire). Another option is to remove the catalytic converter (cat) and replace it with a catless midpipe, or a high flow midpipe. This is usually illegal, as you're not allowed to change emissions hardware unless it's broken. So if you really want a catless midpipe, chances are, you'll have to do the install yourself. Don't worry - because the turbo is disrupting the flow of the exhaust, your car will not be super loud with a catless midpipe and aftermarket exhaust. Midpipe pricing is about $300, catback usually runs $600. Try to get pipes that are 3", it will flow better than 2.5" and your gains will be larger. OPTIONAL

9. Spark plugs. You'll want to run colder plugs on your turbo. The stock plugs run about $35 each and are too hot for this application. It's recommended that you get the NGK-5255 plugs. You'll need four. Figure $50 for a set. RECOMMENDED

10. Install costs. You can do the install yourself. Estimates using jackstands range from 2 to 4 days. If you get a shop to do the install, expect to pay $800 - 1200. RECOMMENDED

11. Oil change. If you tap the oil pan for the turbo return line, you'll need to refill your car with oil. Even if you do not tap the oil pan, you'll need to then plug the turbo oil return into the oil pan drain hole, which means an oil change too. $30 REQUIRED

12. Switch to synthetic oil. Redline or Royal Purple are brands people trust for rotaries. Go with a 5w30 or 10w30 weight oil. It will help in the longevity of the turbo's oil seals.

13. Fix #2. (install a vacuum nipple in the outlet pipe of the turbo and plumb a line to the wastegate). This doesn't cost you anything (make sure the shop that installs your turbo does it), but is something you should not skip. HIGHLY RECOMMENDED

14. GReddy oil pan upgrade. This adds about a half quart of oil and acts like a heat sink under the car (It has fins to help cool down). The best thing about this pan is it has two oil drains, so you can perm plug in your turbo oil return in one, then use a quick drain plug in the other. This setup allows you to change your oil in a matter of minutes. $250 RECOMMENDED

As you can see, you can get your RX-8 turbocharged for as little as $3000, or as much as $8000+.

This is not meant to be an end all, be all listing. It's just a quick checklist for what items you should consider getting.

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User Comments


how much power can you make with a turbo?

Lizard on January 9th, 2009

The power you can make will be largely dictated by the flow characteristics of the turbo used. If you use the GReddy turbo, you can expect to make 230-270 whp (depending on how much boost you run). Generally speaking, you don't want to go much higher than 9 psi on that turbo since it's peaky and doesn't flow enough air to keep up with the RENESIS. I recommend looking into MazdaManiac's GReddy turbo setup - A custom 3071R that can flow to 400 hp and still spool as fast as the GReddy turbo.

Jason on January 9th, 2009

I'm not so much interested in the power as the torque, the RX-8 has a decent amount of power already but the torque is lacking. what would be a setup that yields MUCH more torque without compromising too much power, and is still reasonably cheap?

Colby on January 14th, 2009

Torque and HP are linked together. The ratio seems to be somewhere in the range of 200 hp to 150 torque. If you turbo it, you can double it, and both values increase - giving you 400 hp / 300 torque. Soo.... with the rotary design, you can't expect to see something like a diesel engine with 130 hp and 300 tq :)

Jason on January 28th, 2009

Generally when a car is turbo'd it loses a substantial amount of fuel efficiency. I'm just curious where the RX-8 doesn't have a whole lot to give in that area, and I know that it would vary between set ups, but do you know around where the fuel economy would sit at? Very helpful guide, thank you for your time!

Tyler on February 20th, 2009

Fuel efficiency is almost exactly the same as stock. I got 17-19 mpg stock, and made 17-19 turbocharged. The reason for this is that you cannot be in boost for long (unless you're living on the side of a mountain somewhere and going up hill), so if you floor it, you're only able to do that for a few seconds before you're over 120 mph... and since most of your driving isn't going to be in boost, your mpg tends to be similar to stock. I would say worse case you lose 1 mpg. Of course, if you're always on it, you will burn more fuel simply because you are injecting more air and fuel to keep the AFRs safe.

Jason on February 20th, 2009

Can we put a MisFiring system on that after the turbo is installed?

Zuriel on March 11th, 2009

what about fuel injectors? What size do you recommend to run with the greddy turbo kit and also do i need to upgrade my fuel pump if i get higher injectors

raul on April 27th, 2009

With that much of an increase in power how does the stock axle hold up?

Tyler2 on May 21st, 2009

The stock fuel injectors are good to about 300 whp. The stock setup is 230/320/320. If you want to go up to 400 whp, consider this setup: 320/320/720. Just pull the primary (230), move the secondary 2's to the primary spot, and drop in a 720. This allows you accurate fuel for normal use, and very large injectors that stage in later.

Jason on May 23rd, 2009

is there a gearbox upgrade as i have blown my gears up

stuart on May 26th, 2009

I just got my rx8 2004 is there any one in Calgary who can set these car up I don't quite understand this type of engine as yet are some where i can fine ather people that know about this car?.

Howard April 1-09 on June 1st, 2009

RX-8 comes with 100,000 miles warranty for drive-train. Check in with your local Mazda dealer. My used RX-8 had 3 syncros on the transmission broken by owner before. Cost $2,000 and the dealer covered all of it. I had 100,070 miles on the car at the time.

Soravia on June 5th, 2009

Where can I get that GReddy turbo kit with the T618Z turbo and all that other stuff you had in number 1 on your list for 3200-3500$?

Jake on September 9th, 2009

Will a turbo work on an automatic RX-8 4 speed? My car has such embarrassing torque. It only gets tough at about 3500 rpm in first. A second question is can I modify the RPM governor on an automatic 4 speed RX-8 so it goes past 8000 rpm or would I destroy it in doing so? I like the fact that it WON'T let me downshift into a redline, but I heard RX-8s can redline like mad before up-shifting. A third question is should i be using downshiftin in an automatic to slow myself down. It works great but i wonder if I'm wrecking anything somewhere that I can't hear or see. Fourth question - What modifications have you boys done to make your RX-8s start in the winter. I added a battery warmer (which helps a lot) and an oil pan heater. I was told they do NOT take block heaters. Any other ideas? Does an in-line coolant heating system work good? Synthetic 0w-30 oil?

Bilbo Boblo on December 12th, 2009

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