Turbo or Supercharger
 

Hey Guys and Gals, if you will. I have been searching and searching and asking manufactures about quite a few aftermarket engine mods for the 4 speed auto. I was told by Greddy that the turbo was not made for the auto :shocking: I seen turbos on automatics?? Can someone point me in the right direction for a good turbo or Supercharger. Also If you are a experienced :Peace: street racer what should I be looking at for the very first engine mods. I am new at the RX-8. This rotary engine is a loop compared to my mustang cobra. Very Different in a good way of course.

wait, so you searched?

wow. you're saying/asking alot in those three sentences. also, you are not giving enough information for anyone to really help you. important info. like budget, what you are looking for (exactly), what compromises you are not willing to make, etc.

my advice...if you are unhappy with the way the 8 runs "out of the box" en toto, then you should've gotten a factory f/i'ed car. the 8, despite some successes and alot of arguments, is not what you'd call...an "ideal" candidate for f/i. most "tuning" bolt ons should be considered "fun-factor" or extremely slight gains for a lot of money. however if your pockets is a bursting, then you've a lot to do if you want to f/i your car. try searching under the "major horsepower" upgrades forums. there should be plenty on f/i.

hope this helps.

street racing is really frowned upon here. dont do it, its dangerous and stupid.

there are no kits currently out made for the auto. the pettit sc will be out it a little bit and they have a kit for the a/t. the greddy can be made to work but the greddy is just not that good though. you can try mazsport and see what they can do for you

how much are you looking to spend? the hp:$ ratio is really poor with the rx8 and dont expect big numbers anytime soon

actually if you are street racing go sell your car and buy some thing else. the rx-8 is not meant to go straight purely. id rather have you crash another car

The greddy turbo can be installed on an automatic car just fine.

Get THIS

LOL good find MM

nawwwwsssss

Make sure you read the fine print.

ha ha some good one liners in there "not for use while driving"

You went to a lot of effort there MM . Are you positive you covered yourself against legal proceedings ??

I want to buy It !!! Can we install it this weekend?
I'll give you a $1000 for it. :ylsuper:

SOLD! I can install it while we tune the other turbo. That should DOUBLE your HP!

Dude My ride is going to be so PIMP !

hahaha

Thats for the info guys. Let me be a little more detailed. I understand the $ to hp sucks. Umm, lets start with the intake and exhaust. I am really swinging toward the RB intake and RB exhaust. The guys there seem really deticated to the 8 and I heard from a few guy local that have both said that they would highly recommend RB. Any suggestions on RB or other. Street Racing is NOT what I want to do, so don't get me confused with those guys because I'm not rich. I am just looking to get very respectable power and make the car more like me. I have a starting budget of about $2500 USD.

You're not going to get "respectable power" from an intake and exhaust on the 8. I'd say start off with the RP Supercat. Decent power gains for price.

For 2,500 you can buy a used greddy kit. That's the only way you're going to get respectable power out of this car for that price.

Then after the the RP cat swap look at the Int-X Mazsport makes for the Auto.

I sure SprGrn did this to his A/T...



Post 600 !!

:rofl:

The 8 comes, stock, with "respectable power." If you want, "bow-down-before-me-and-my-awesome-car-power" then, you either bought the wrong car or will need more money. $2500 bucks will get you a nice suspension setup and a short shifter...or RB intake/ram-air/screens + a decent catback exhaust. These will not give you "bow-down-power." It will make your car sound nicer and give you minute HP/Torque gains. If you are a mechanic then you may be able to squeeze in a flywheel if you do all the labor yourself. The most bang for your $$$ may be a light weight flywheel, underdrive pulleys, and new final drive ratio/mechanical LSD. It's all up to you and how you want your car to run. The absolute cheapest bang for buck would be NO2 which would probably cut your engine life by a good percent but give you instant gains for a relatively cheap financial cost (up front).

Now, if it were me and my 8? If I had $2500, I'd go with mods that accentuate the things on the 8 that are ALREADY top notch--it's handling! For an 8, suspension is the way to go because you'll never, really, turn it into a "crap-your-pants-torque-monster!" It just wasn't designed to be "that" type of car. I've read of many people on this forum who have tried to make the 8 something its not, and its sad that they don't appreciate the 8's strengths and only want to modify it's weaknessess. If you take the same mods (torque and HP mods) and drop the same $$$ into and Evo, STi, or Mustang, then you'd have one helluva 1/4 mile car. However, if you drop a bunch of suspension mods in a Mustang (note the two AWD cars, previously mentioned, are omitted), it will not handle as well as a tuned 8. Work your strengths or buy a different car and work that car's strengths. That's how you should mod a car. The 8 has got enough balls to shoot in and out of hairpins really, really fast and fun.

Lastly, what do you mean, "more like me?" What kind of person are you? The 8 is a thinking person's car. Are you a sophisticated handling type of guy or a balls-out at the next green light kind of guy?

2 cents.

SC + Inter X + 2nd oil cooler + RB intake + exhaust + light weight wheels + ..........

Please continue....

that 2500 could go towards shaving some weight, and some sways and coil overs. I'd start there before going too crazy on the engine, I'm with phantom on this one, add to the cars strengths before going nuts and trying to attack its weaknesses.

+2 with Phantom.

I started with Springs =>sways => shocks => slotted rotors=> better brake pads => turbo.

With just the suspension upgrades, much more fun to drive and give a better feeling of handling..

even with just better springs/tires I can keep up with stuff I'm not supposed to be able to, just thought I'd throw that out there as well :D:

good post phantom

Phantom thanks for your thoughts. Greatly Appreciated! For my "2 cents" I am a more a thinking type of guy. What can I do to improve the 8 best all around? That is what I ask myself in general. Don't get me wrong I love hp and speed who don't, but I, like you said, want to focus on the cars strengths. I will take you advice; you seem to really know what you are talking about. I will focus on handling first. In fact, I will probably get most of my help from this forum. I am no mechanic, but I can do a lot myself. OK! What do you and anyone else recommend for suspension for step 1? I will build this car on this forum and give a list on what mods I will put on, along with other details including before and after pics, also installation pics on the mod before and after. All my decisions will be based on what I like off course and the recommendation and inputs of all of you.

if your looking for good handling all around, then your first step (personally) is tires. more specifically ones with low tread wear....120 or 140 if you dont already have so. (i really dont know what the stock tires for the AT Rx8 treadwear is, i've seen a lot of different models, different tires, it varies from model to model apparently) if you dont want tires, then sway bars are always a good choice. check out different websites for ideas for what different brands of suspension parts are. i know japanparts.com has a good overview of suspension parts. (just bare in mind that there parts are all for the right handed version of the 8). shocks and springs too.

Just my point of view:

. Racing Beat intake and duct, or Racing Beat ram duct, or Odula ram duct, or Mazdaspeed/AEM cold air intake
Note- Nobody knows which is better, but helps a bit. I have the Odula ram duct.

. R-magic air filter, if keeping stock box w/ Odula or Racing Beat duct

. ATF cooler and good AT fluid
Note- Why? Keeps tranny cool, helps it last longer, allows it to take 8,500 rpms if ECU flashed.

. 2nd oil cooler if 4AT

. Oil catch can and Breather mod
Note- Why? Pre-06 RX-8s are taking in oily vapor and bad air. 06 and up models "hide" the problem better by routing to the lower intake manifold.

. Throttle body bypass mod

. Agency Power Pulley, if staying NA
Note- Why? Faster revving. Should improve starts a bit.

. Structs
Note- Why? Better turns

. Sway bars
Note- Why? Better turns

. Exhaust
Note- Need to think about NA or FI in the future.

. Brakes
Note- Not a major issue, as RX-8 has good brakes, but something to think about.

. ECU flash
Note- Need to think about which direction you want to go, NA or FI. Cobb's AccessPort may change this thinking since you can flash whenever.... May find some HP, even on NA. Cuts speed/rev limit.

. Tires

. Supercharger
Note- Why? Boost is instant and AT needs it low because of torque converter issue. If turbo, needs to be tuned (if not made) specifically for Autos and provide boost starting at 2,500 rpms with little turbo/boost lag.

I heard it's only for the MT 6spd.

You heard wrong. It installs just fine on the automatic. I've seen it in person.

I wonder how it'd sound on a AT. Since the gears switch rapidly.. I need to this in person. But yes, I went to rotaryinsider.com, the forums, and on the Greddy Turbo kit thread, it said for 6spd only. But sure, I wouldn't see why it couldn't be installed on a auto.

hehe. Greddy's manual definitely says it's 6MT only. But I think it also says for offroad use only too ;)

Oh no, now someone else is starting the Supercharger vs Turbo charger crap again.

Please read this thread:
https://www.rx8club.com/series-i-major-horsepower-upgrades-93/supercharger-performance-110388/

and this thread might also be useful. Maybe:
https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/3-rotor-turbo-114646/

EDITED: To fix my horrendous grammar.

I have the Greddy install on my auto. Runs fine. The maps had to be re-tuned because of the 2 missing injectors. Right now I'm running 6 psi.

Thanks to MySql for his EMU :)

well, I'm bringing this crap back to life

so, which is it? supercharger or turbo, I am looking at either blitz supercharger or the Greddy turbo, 07Auto......

Thanks for bringing it back to life. You'd likely want to read this post for the definitive answer:

https://www.rx8club.com/showpost.php...1&postcount=33

ok, now it can die peacefully

Can't die too quickly just yet..

Anyways, so how's the turbo working for you on the AT? Btw, are you a 4spd or 6spd auto?

fine, lets hear it!

i'd be really interested in seeing a video with an auto + greddy turbo + WOT

I've seen 09factors in person, maybe we can get you a video of it working.

I wouldn't mind seeing that. :)

Its not about starting crap, its about finding an FI setup that might work will with the RX-8 auto.

Below, is a comparison from a new SC vs Turbo thread. As you can see the Pettit supercharger does well below 4,000 rpm and does a decent job overall. I would expect the AFSC to have a similar line. Maybe a little less below 4,000 rpm, but close to Pettit's SC and better higher overall HP because its more efficient. The greedy kit is no joke, but the HP come higher up the rpm range.

What the twinscrew and AF superchargers could mean for the RX-8 Auto:

. Help the torque converter/brake launch limit of 2,500 rpms and 0-60 for RX-8 Autos.
Why? The SC would give instant boost, where the Auto needs it at lower rpms.

. Help with exit speed on turns.
The RX-8 is already a monster on turns. The problem is the straights. When you make really sharp turns its hard to keep your rpms up and they usually drop. A supercharger may do a better job of helping you get back up to speed from the corner and your exit speed.

. Stop and go. Passing people in traffic.
Often your rpms are going to drop in this type of situation, a supercharger could do well here.

Its not just about overall HP. The DNA centrifugal supercharger is an example of that. Its power comes high up the rpm range. It will not do much for your 0-60, but may show up in the 1/4 mile and will with the time it takes you to get to your top speed. Problem is, the RX-8 can already go 150 mph. Not too many people complain about its top speed and few are brave enough to go that fast.

So then we are talking 0-60, 1/4 mile, exit speed out of turns, stop and go, etc.... That means you want a HP graph something like Pettit (but without that little dip up top and maybe a bit higher) that is giving decent boost in the lower rpms. Pettit, has yet to come out with stage 3.

https://www.rx8club.com/attachment.p...chmentid=98988

From- https://www.rx8club.com/series-i-major-horsepower-upgrades-93/dyno-comparisons-sc-turbo-115058/

I disagree - a supercharger is dependent on rpm. so if you're going slow around the corner, your rpms will be low and (depending on your SC setup) may not get back up to max boost till your rpms are up again. A turbo meanwhile can spool to max PSI at a wide range of rpms. With the greddy turbo, any rpm over 2800 will give you your full max PSI. So i I stomp on the throttle at 3k rpm, I will instantly get 12.5 psi, and it will stay at 12.5 till I let off the gas.

You're making a generalization that superchargers = torque, that isn't the case. There's many different types of superchargers, and you can set them up for power down low, with little to nothing up high, medium level with little at the bottom and top, or all the power up top, and little down low. The problem as you can clearly see is that you're tied to a pulley and can't dynamically adjust based on load, as you can with a turbo. Additionally as you can see with the DNA SC, the effect of the engine turning the SC over is drag on the engine, causing power loss. A turbo is more efficient. When you're not in boost, will net you just about the same mpg as stock, and little to no hp loss.


The greddy still appears the better choice:

Here's the only pettit dyno graph we have right now:
https://www.rx8club.com/attachment.p...chmentid=85970

You'll notice it doesn't make 200 hp till 6,000 rpm.

Now compare that to this overlay:
https://www.rx8club.com/attachment.p...id=99008&stc=1

Greddy makes more torque and more power sooner.

mysql101, don't get me wrong, I respect your opinion.

But below 4,000 rpms and above 7,500 rpms the Greddy turbo appears to have some issues.

Now, don't get bent out of shape, the Greddy turbo is smacking the hell out of stock. Turbo will have an overall HP advantage over Superchargers. Greddy does well within a certain range, but that range may not be all that is wanted.

There is still a lot that happens below 4,000 rpms and above 7,500 rpms on the street and certain tracks. Let us not forget that installing (stronger point) and maintenance issues (weaker point in comparison between the 2), which may tilt in favor of the supercharger, but I know turbo lovers will argue that point.

Also, I don't see any Greddy turbos posting their 0-60 and 1/4 mile times. If it's really all that, even in lower rpms, than people should be proud enough of their time to post them. If it's not showing up in the short distance, than I'm thinking there may be some lag and/or rpm range issue that's holding people back.

I guess RX-8s with Greddy turbos and Pettit superchargers are going to have to go "head to head" to clarify the issue. But, at least at this time RX-8 owners are starting to have some powerful choices.

I'm not taking it personally :) I'm also reserving judgement and graph updates till we see a real dyno sheet from pettit. Then we can see where their SC shines and do a direct comparison.


Argue what? SC install is much easier, but the turbo has less parts to maintain.


Damn right. Though somehow it doesn't seem like we have enough choices still.

btw, if people can post the dynojet .drf files, that will give us the best output for this..

Has anyone installed a twin turbo on the 8?

no. it doesnt really make sense for the most part.



also thank you for posting in this thread instead of making a new one

I don't really understand the whole concept of twin turbo? I thought RX-7's had them.