For the moment I thought toykilla had an RX8! :D Even with the Z the power gain will not come easy without breaking your arms and legs.

 

I recommend reading Maximum Boost by Corky Bell. Great book about turbocharging.

 

I dunno. You could definately get 500whp with replacing the major weak spots of your engine and a killer turbo set up with an incredible intercooler. given, it will take alot of time and money to do, but its not impossible. My friend with a WRX has plans for his to get 500whp with not a rediculous amount of money. Just do your research (sorry, we cant help you there) and go from there. The more you know the less it will cost with time and money.

 

yes i am aware that it will take some engine work.. but FYI the TOP SECRET single turbo kit in Japan is pushing 450rwhp.. but they will not send this to the states.. it is a j-spec bolt on kit.. no internal mods needed.

forged rods/pistons and a headgasket will easily get 500+

 

So find someone in the JDM and get them to buy you the kit. I'm sure you could find a tuner in the states that would put it on for you. But again, buhbye warranty... altho for that kind of HP, it might be worth it :D till you blow up your engine

 

hehehe. yeah

 

On the topic of single vs twin turbos: Many people like to stick with singles because they are simple. One turbo, one set of oil lines, one wastegate, only one turbo to run plumbing to, etc. Many people get fantastically high numbers from just a single turbo. Twin turbos on the other hand require obviously the purchase of two turbos, the fabrication of two of everything from oil lines to piping, wastegates, etc. I personally like going with twin turbos despite their added cost but heres why. To get the big horsepower numbers you want, you will need a very big turbo. A big single turbo has a wheel that weighs an awful lot. It takes more energy to get it turning. This equates to more turbo lag and more exhaust backpressure. On a properly designed twin setup you have two smaller turbos. Each wheel weighs less and therefor is easier to get turning. This is less lag and less backpressure. Obviously in your case you will only have half of the engine breathing through each turbo but that is fine. It will not hurt spoolup time. There are too many things going on with the exhaust flow in the big single setup. You have the entire engine trying to breathe through a small hole. It sounds like you would just be splitting the engine up into two smaller holes and this is true to a point. When using a twin setup you actually need 2 turbos that are greater in total flow through them combined than the single turbo is. That my sound a little complicated so go back and think about that. You also have less pressure waves traveling back upstream into the engine and affecting its tuning. The result is that the twin setup has less backpressure and spools up faster than the single. However twins need to spin faster than the single so they heat up the air a little more. There is always a tradeoff. I still believe that the twins have the advantage though. The charge from the twins isn't that much greater but the reduced backpressure in the exhaust is quite considerable. As a general rule (not an exact rule) for every 1 psi of exhaust backpressure you free up, it is like adding 1 psi of boost pressure to the engine. The turbos may heat up the air more at the same psi as the single turbo but they can make more power at a lower psi so the heat loss is inconsequential.

Here are some things to consider. If you do a single turbo setup you need to fabricate one insane manifold that joins the pipes from each side of your engine together in front to run to one turbo. Are you up to this challenge? It will have to be built in at least 2 if not 3 pieces for you to get it on the engine. How much stuff do you have to move in front of the engine to fit a turbo there? The good side is that you only need one set of intercooler pipes. The twins can be tucked away next to the engine. Their manifolds can be small and easy to handle. The exhaust is easy to figure out since they can just run through where the factory exhaust was. However, you will need two sets of intercooler pipes to get to the front of the car. Alos consider that since the turbos are next to the engine that they are receiving a much stronger and more instantaneous flow of gasses from the engine. If the turbo is in front of the enigine, the gasses have slowed down some and lost some of their heat. Heat is energy too and this also spins the turbo.

As a comparison using a real system (a rotary!):
Marcus Williams used to have a 3rd gen RX-7 drag car. He had a bridgeport on it since he wanted some serious horsepower. He was using a big single turbo but kept hitting a power brickwall at about 20 psi of boost. He installed pressure probes to see what was going on. At 20 psi of boost he had 21 psi of exhaust backpressure. When he raise the boost above this amount his backpressure started to double that of the intake side and cancel out any more boost. He made more power at 20 psi than at 23 psi. He then switched to 2 smaller single turbos in a twin setup. At 23 psi of boost he only had 18 psi of backpressure in the exhaust! Remember that for every 1 psi of backpressure you free up you effectively gain 2 psi of usable power. The twin setup far and away out performed the big single turbo. He could actually crank it up to 26 psi and still keep going. Yes his engine was tough! He also had much faster spool times. The point of all of this is just to demonstrate the effects of backpressure between single and twin turbo setups. Both will work at low to moderate power levels but if you want some serious power get 2 single turbos.

Call Turbonetics. If you tell them your engine specs they can recommend sizing for you. Understand that if you intend to change anything in the engine later that you will require a different set of turbos. Turbos by themselves can go for as little as $400 apiece up to $2500+ for a really large one. Intercoolers can be made or purchased. I built mine with cores from a junkyard that I welded together. I have less than $150 in it an d it is insanely huge. Piping you can make for relatively cheap but you'll need to find engine flanges. Don't forget fuel and an ecu. It may just be worth the effort to wait for a good kit unless you know how to do all of this. Luckily I do but I drive an RX-7 not a Z.

Anyways, there are several avenues to go down. Single, twin, supercharged, both centrifugal or positive displacement, nitrous, etc... Each has its own advantages and disadvantages.

Good luck.

 

Woh, and I thought my post was long. Great info tho Rotarygod!

Now not to hijack the thread, but have you spoken with Turbonetics about the RX-8? If so, what did they recommend? And do you know if they are working on anything? Inquiring minds want to know...

 

well, i haven't, but i will recommend for all "high" power (6 port) RX-8 owners out there that you don't try to boost your engine unless you're really, REALLY sure you want to, and willing to open it up and do a few clever things to it (not the least of which would be lowering the compression ratio).

 

Agreed. My plan is an engine rebuild/strengthening etc after Mazda's warranty runs out, then adding FI at that time... see this thread for details: https://www.rx8club.com/showthread.p...threadid=14703

 

thanks for the info everyone.. my quest for power is indeed a great one..so i definitely take my time...

 

I will second the vote for the supercharger installation over the turbo. There was an AMAZINGLY OEM looking intercooled supercharger installation at SEMA by a South African company called "Alpine Developements Inc." They have a U.S. office here in California and I would give them a call and at least get the full details on who to contact about it here. I dug out their card: 714-379-8066.

Unlike the crappy Stillen kit this Alpine kit used a custom aluminum intake manifold to hard mount the Eaton supercharger on the engine with integrated twin air/water intercoolers in the custom manifold....looked 100% factory and does not require cutting the hood like the Stillen kit does.

Brian Goodwin
Good-Win Racing

 

Nice, Brian! I don't suppose that card had a email address on it...?

Oh, wait a minute, you're talking about a SC kit for the 350Z, aren't you? D'oh. Got all excited there for a second, thought you meant there was one for the RX-8. D'oh.

 

Yep, talking 350z supercharger.... I talked with them about doing an RX8 kit. They are happy to do it....but development cost estimate is 40k. Given how nice their 350z setup was I could hardly debate the costs but I am not about to foot the bill.

Here is that link: http://www.alpine-developments.co.za/index.html

Their 350Z kit was brand new for SEMA and I don't see it on their site yet.

As for our RX8, there are several U.S. companies looking at forced induction for us...but the impression I got was that it will be a while before anything is done.

Brian Goodwin
Good-Win Racing

 

Not to worry, I can (and will) wait, but I'm interested in following the development of these kits as they come out. Thanks for the info.

 

Since you arent that knowledgable of FI and are newbie to these things, supercharger kit would be the way to go, that is just my honest opinion. Its realitively 'safe' in the choices of FI, but you can always have problems, just research the kit before you get it and have it installed AND TUNED by a professional that has done kits like that before in your car and is familiar with aftermarket FI parts and the industry. My short by sweet recommendation.

 

Just like people said that the Supra was coming about in 2004? Haha... hmm it must be lookin like that Camry Solara they remade.

 

Wait a minute turbo!

A S/C kit can be just as hard to tune as a turbo kit! Although a S/C might put out more reliable FI, it still requires a delicate amount of fuel tuning on the car. Even with electronics to adjust fuel, you might need a new Fuel Pump, and a new FPR.... oh wait... our cars are Returnless (like new Audi 1.8T's), so there can even be a higher degree of tuning either way!

Why would a S/C be a "short sweet recommendation"? Either way, each option will require new (at a min) 3D maps, and you will have to most likely interface with the ECU to attain those maps (Remember DBW Drive By Wire), no thottle cable.

Just keep that in mind when all the expert tuning doesn't work, as a lot of the experienced don't have exp with DBW system (and I've been fighting DBW since 1999)

 

update??????

 

Yes, please?

 

No kidding

 

check this post. I made it a few weeks after this one.
https://www.rx8club.com/showthread.p...threadid=13763

I haven't been back there reciently. I'll try to find the time to stop by and ask if there's any updates.

Last time I was there cam said to check their website for any updates, but they don't really update their site regularly. Anyhow, if you're interested their website is www.pettitracing.com.

 

no kidding they dont update
last update was july of 03

 

Hmm, that isnt too far from me. I'll try to drop in on them sometime next week and see if there is any news.

 

Genom, please post what you find out when you do, ok?