Jt-Imports

ANYWAY

BLITZ has the right to call it whatever they want in my opinion.

You can always go look somewhere else, no one stopping you.

PS--Is almost equal to HP, its so close that it doesnt matter too much.

HottRodder

I was trying to think through how I would define the various Supercharger, Turbo, Compressor mechanicals as I was reading the thread. Glad I read the whole thing first cause RG already did it and made it clear and simple.

RG- Have you heard of a roots type called PSI? Biggest blower I've ever seen. Supposed to be real efficient too. I think this car will benefit more from SC than turbo myself. I'm holding out to see what develops but may go with Canzoomers Stage 1 while I'm waiting.

JTI- What has Blitz done with the ECU. I presume their piggy backing something to it? Do you know any details?

speedy4500

New member here...no RX-8 yet, but I figured I could clarify something. Rotarygod touched on the different types of forced induction, but I can add a few things.

HotRodder - The PSI blower you are talking about is actually a screw compressor much like the Whipple design, which was first pioneered by Lysholm. Screw compressors are much different than a Roots type blower.

A Roots blower has 2 rotors of 2 or 3 lobes that both turn at the same speed. A Roots blower has very little, if any, actual compression within itself, it creates boost by forcing more air into the intake manifold than can naturally exist. It is also the least efficient method of forced induction. Not only does it heat up the air more than any other type of compressor, it also produces the most parasitic drag on the motor: some larger Roots blower can require 300hp just to turn them at speed.

A screw compressor, however, has male and female rotors within the housing, and they both rotate at different speeds. This produces actual compression of the intake air within the blower housing. I'm not exactly sure why, but screw compressors produce much less heat as they compress the air as well. There is often no need for an intercooler when using a screw compressor. Screw compressors produce more boost at a lower RPM and at cooler temperatures, there is very little downside except cost. I believe the new Ford GT uses a screw compressor.

The PSI blower you are referring to is actually designed for alcohol drag racing cars (funny cars, dragsters that run 5.5 sec 1/4 mile times at 250 mph, making 4000 hp). They are massive designs and would definitely not be appropriate for an RX-8. The Whipple Supercharger would be an excellent choice, however, as I am sure it would create much more torque down low than any other mod for the RX-8. So if I were an enterprising Mazda tuner, I'd definitely look at a Whipple before turbos. Whipples do not need oil lines, they don't need an intercooler, and they don't need custom exhaust piping. Turbos are much much more complex and costly than a Whipple, and for a street car wouldn't offer any forseeable advantage (except for maybe the ricey type guys who like the whooooosh of a BOV).

Jt-Imports

I dont have any actual details on the ECU. I was a little busy today, but I will talk to some peps tomorrow and see about some info.

luckee2bhere

Hello

I am new to this forum but am not new to the rotary. I used to own a 3rd gen rx7 and had done many many mods to it. I am currently involved in the auto industry but with german cars. I am thinking about picking up an Rx8 for fun but want to make sure that mods are available. I am interested in what aftermarket turbo options are in the works and who are the cutting edge companies to work with for mods.

Thanks in advance

Omicron

So far, only intake, exhaust, and suspension mods are available. An ECU piggyback will be out within a week or so. Also 1 company has developed a turbo (SSR Engineering) but it's not completely in production yet.

Rumor has it several major manufacturers are developing forced induction kits, Trust/Greddy being the most frequently mentioned. Blitz may have a unit ready to go soon too. But nothing has come out "officially" yet... probably not until first half of next year or so.

The RX-8 is so new, the aftermarket has not caught up with it yet. But's it's got an incredible following already, and this demand will definitely mean a plethora of parts soon to be had.

Hope this helps...

Dookie_Rx-8

its only been out for a couple of months already,just imagin a year or 2

XDEEDUBBX

wow...i would go for the charger..

luckee2bhere

either I am skitzo and dont know it or someone got onto my account somehow..........


I did not post this thread....

Sin

Skitzo...lets hope not

rexateher

probably need to seek help about this

NskGenakuDuckie

I love the RX8 in every aspect but the power, and I know since the RX8 is n/a it won't really respond to mods. So I had the idea of maybe getting my own parts and turboing the car. I think those "turbo kits" that greddy or hks makes are overpriced, and with less or equal the amount of money spent you can get more power out of it.

Ok here are some questions:

As I mentioned earlier instead of waiting for overpriced underpowered "kits" from greddy or HKS.... are there any companies similar to petite racing that specializes in rotories that make custom exhaust and intake manifolds for FI, or even individual parts for that matter? I could easily gather my own parts and end up spending half less than getting a kit. The only two parts that are not easy to fabricate are the exhaust and intake mani.

Other than that the 02 housing, downpipe, exhaust, IC piping can be easily fabricated. Just about any turbo would work with the right flange to mate it up to the custom manifold, and same goes for an FMIC, just about any universal core would work as long as you have custom made piping. Everything else needed such as BOV, wastegate, fuel/engine management, clutch can be easily obtained.

As I said I don't know much about rotories.... but how do you lower the compression? There aren't pistons so there's gotta be another way. And a matter of upgrading to bigger injectors and fuel pump. Would an FD or cosmo fuel pump be compatible with the RX8?

rotarygod

The problems with the prototype aftermarket turbo systems isn't that they are not capable of producing big power. The problem is that the cars ecu controls so much of the car that it is difficult to tune. While you can in fact save money and custom piece, fabricate your own turbo system, you are going to have some serious issues getting it to work properly. Yes you can get an ftermarket ecu and fully tune everything yourself but this will override many of the features that the car already has such as the traction control system. You will also have to figure out how to get all of the gauges back working as well as changing the throttlebody since the car is drive by wire. A Motec ecu can controll the throttle though. As far as the fuel pump is concerned, the fuel pressure is regulated through the pump by the ecu. There is no return fuel line. You will need a new pump, regulator, and have a fuel return line installed. By the time you do all of this, the car will no longer pass an inspection anywhere in the U.S. I'm not even talking about emissions testing.

The only way to lower the compression of a rotary is with either different, lower compression rotors, which they do not have for the Renesis, or to find someone to mill out the rotors and then rebalance the entire rotating assembly. Changing the rotors obviously requires engine disassembly. While you're in there you may as well do some port work, retrofit stronger apex seals, add a custom center bearing, etc.

Yes you can build a cheaper system that when properly tuned rivals or even exceeds others out there. But how are you going to tune it?

NskGenakuDuckie

Thanks for the reply.

About the tuning issues, if everything is controlled via wires/ecu, then all you need is an engine management computer of some sort. Well here's another question.... how are the aftermarket turbo kits different when it comes to tuning? With my own parts they're all going to be similar to what the "kits" have. From what I've seen those so called "turbo kits" are usually incomplete. You miss essential parts such as fp, injectors, fmic; so I highly doubt it would come with a fully re-mapped ecu. Regardless aftermarket or custom you're going to need to do something about tuning.

About taking apart the motor to lower compression, that's nothing new, with pistons engine you still need to swap to lower compression pistons and such. I personally think there's no point in spending thousands on a "turbokit" and running 6-8 psi of boost.

About the emissions testing, i'm not expecting it to pass (i have my ways), i'm planning on running catless anyways. As for the traction controls and such, i'm not sure what all the "features" are, but as for traction control I don't care for that either.

rotarygod

If you are willing to go the aftermarket ecu route then I say go for it! Obviously this isn't going to be cheap and probably comparable to an aftermarket kit in the end but you will have the advantage of added tunability and higher boost. Any aftermarket kits that come out will definitely need to address the tuning issue somehow in their kits. For cost effective reasons they will have to limit the total output at somehwere less than what many people would like to see. Others will love it. This is no different than the turbo kits for the RX-7's or any other car. The people that desire the most power always do some sort of fabrication.

The factory computer controls more than any ecu on any rotary before it. There is no fuel pressure regulator or return line. The ecu senses the engine needs and runs the fuel pump at the appropriate speed. The RX-8 is also drive by wire. No direct connection to the pedal. With some fabrication or a new throttlebody you should be fine. Traction control is something that you don't miss until you've had it and then lost it. The option of turning it off is very nice but it is a wonderful feature. If you don't mind having to find ways around emissions then I'd stick with the stock ecu hooked up to all of the cars features but then try to create "simulators" that hook in where other parts used to be connected. The O2 simulator plugs in to where the sensor used to be and fools the ecu so that no cel comes on. I would try to do the same with the fuel injectors and ignition coils too. Find a way to make the ecu think that they are still hooked up so that the gauges and other features still work but instead have the ignition system and injectors plugged into a new ecu. This could potentially work very well and the car would still have all of the other features.

I don't know of anyone who has yet to this date tried to mill out the rotors for lower compression. Hayes rotary in Washington state used to do this to the older rotors and they could take them down to 7.5:1 compression ratio. We don't know how much thinner the casting is on these rotors though since they weigh alot less than the 13B counterparts. High compression and high boost but severely retarded timing will not make for a very fast car. Until the compression issue is resolved the best option will be fairly low boost but the proper timing so as not to need to retard it much. This will make more power than the other setup. If you can get the rotors taken down 1 full compression point to 9.0:1 like the later T-II 2nd gen RX-7's and the 3rd gen RX-7's you could get sky high boost levels and even higher if you went lower on compression. Something else to think about is that the Renesis apex seals have gotten smaller than the older 2 mm seals. They aren't as tall and are a fraction thinner. While they may be stronger than the old seals, they have to be. I would still favor milling out the rotors for the older seals and then using an aftermarket set from Rotary Aviation.

An endeavour on the level that you are willing to go to will take a considerable amount of money. The turbo kit can be done relatively cheap and I can attest to this as I have personally built my own kits as well for both my RX-7's. The money starts to add up in engine strengthening and ecu. Also it will take considerable time to integrate everything in properly with all of the needed wiring changes. I'd actually like to see more people try stuff like this on their own. That is how you really learn how things work and you also learn how to improve upon what you have as well.

Go for it! Take lots of pictures too!

neit_jnf

N/A Rotaries respond very well to mods like intake / exhaust and fuel / ignition maps. Even more so with some porting work. It wouldn't surpise me if someone gets 250whp or more in N/A form. Of course if you want to go higher then the turbo would be an option.

-=Zeqs=-

Ya, I can forsee a N/A getting 250whp in the near future. The only variable I would still be concerned with would be the low-end torque. Traditionally, the more high end one gets through simply port work as opposed to increasing displacemet, they sacrafice a bit of lowend. Combined with the 3000 pounds of the RX-8, one may very be better off with forced induction, especially for daily drivability.

Either way, 250 at the wheels is a respectable number.

wakeech

bull. know what you're doing.

it's not tradition, it's fact: the more you trade to optimize operation at high engine speeds the less efficiently the engine will work at low rpm, and thus you're not going to get much low rpm horsepower. it's not just porting either, it's manifold design, ignition timing, fuel ratios, etc... all the same things you'd have to worry about in a turbo motor.

250 rwhp, all motor?? hmmm... yeah, sure, maybe with a huge bridge, no emissions, perfect tuning, etc... if you want all low-end power, you can tune it that way. if you want the most horsepower you can make, you gotta take the hit.

i don't think that 3000 lbs is undriveable with a highly tuned motor... not as much fun as the surge of power you get with a turbo, but even then you still have the boostless dead zone off of idle.

but yes, i'd rather have a medium tune turbo engine over a highly tuned all-motor engine, too. but if i was gonna go to all the trouble (and cost), i'd use the 4 port and do it right.

PetersonPeleRx8

Hey guys!! I'm kinda new to the forum so just wanted so say "hey" and that I'm glad to be here.

So, as I've been reading through all these threads, I've noticed lots of information about turbo's being worked on for the 8, and haven't seen anything about a supercharger. (If there has already been a post about this: I apologize)

It seems to me that a supercharger would be a much more logical upgrade for the 8 than a turbo given the low amount of torque this car puts out. Now, I could be completely wrong, but from my limited understanding of cars and racing, superchargers provide a lot more torque, while a turbo's effect is obvious.

So, just wondering if you guys know of any superchargers in the works... or if they're not being worked on for a reason.

Thanks,

Brit

rotarygod

You can't claim that any particular type of forced induction has more torque than another without first stating the variables. At what rpm? At what boost level? Etc... Different types of superchargers will provide different amounts of boost at different rpm's. A positive displacement supercharger will have much more low end torque than a centrifugal supercharger at the same boost level. Quite easily. For all intents and purposes a positive displacement supercharger produces the same amount of boost regardless of rpm. There is leakage around the blower rotors at lower rpms though which cause less boost until the engine gets spinning. A centrifugal supercharger poduces boost exponentially in proportion to rpm. Little to no low end torque gain over not having a supercharger. A turbocharger can have very good low end torque or none at all. Turbo lag is also not necessary. A smaller turbo will spool up much faster and have fantastic low end but suffer on the top end. A big turbo will have less low end but fantastic top end. The key with any type of forced induction is determining what your ultimate power goal is as well as determining if you want a race engine or street engine. A 400 hp rotary that has fantastic low end power and not too much boost is almost impossible. The engine is too small. Everything has its limits and the key with any system is to find the best overall compromise for your application. There are many books as well as threads on here about how different forms of forced induction work so I invite you to search around.

As to whether a turbo or a supercharger is better for the Renesis again all comes back to what the car will be used for. A supercharger almost always produces more charge heat than a turbo but not always. An intercooler should always be used as well. Anyone serious about a power boost will use an intercooler. The issue with the Renesis is the high compression ratio of 10:1 and the extreme control that the ecu has over all of the car. With a high compression ratio we need to either limit boost to a low amount, use higher octane gas, use an efficient intercooler, strictly retune the ecu, but probably all of the above. we are getting too close to a detonation prone engine to not take precautions. A good turbo system will have little backpressure, be efficient within the desired boost and rpm range, use an intercooler, and be tuned properly. This is easy to do since the intake manifold doesn not need to be touched. A turbo that meets all of these demands will be hard to beat in the efficiency department and therefore provide less heat and more power. Many supercharger systems utilize roots type of technology that is less efficient. Then to make matters worse many companies don't add an intercooler. This is a disaster waitng to happen with the Renesis. Either that or the intention would be to just get more average power at low boost with very little to no ultimate top end gain. The roots blowers just aren't that thermally efficient. The also really need to replace part of the intake manifold and move the throttlebody to in front of the blower. That is alot more work. The ecu still needs lots of attention. A centrifugal supercharger only provides adequate boost at or near max rpm. While their efficiency is that of a good turbo system and are easy to use with an intercooler, they will do little to nothing in the way of adding low end power to the Renesis. depending on the setup a turbo may develope more or less torque than a comparable supercharger system, whether it be at high or low rpms. Proper design is essential.

There is currently one known company working on a supercharger for the RX-8. The company is Blitz out of Japan. They are using one of the most inefficient roots style superchargers that you can even get anymore which is puzzling me. They do have kits for other cars that use intercoolers but it is unknown whether or not this kit has one or not. Their current power level for the supercharger system is only 210ps at the wheels. That is hardly worth it but they are still working on ecu tuning. Compare this to Greddy and their turbo kit that so far is producing 260ps at the wheels. They too are facing tuning issues. I think if properly designed systems come out it won't matter too much whether or not they are turbocharged or supercharged. Ultimately you can get more power out of a turbo but this is at the extreme upper limits of engine life and drivability. For the gains that most people would like to have, it can be accomplished with a good turbo or supercharger. There are so many variables that I have not discussed. I suggest finding some good reading and doing some hoework on the subject.

Here's a picture of the Blitz supercharger kit as it is still in developement.

Lock & Load

ROTARY GOD

Since canzoomers stage1 kit seems to kick in at around 5000rpm what is required is a system that gives the rx8 more oomph down low up to 5000rpm .

WHATS THE BEST SYSTEM TO DO THAT AND STILL BE AN EVERIDAY FAST CAR?

thanks

michael

wakeech

...or give me a shout. one question at a time i can handle right now...

wakeech

huzzah, no best system. it all (my favourite word) depends. depends on what you ask?? well, of course, it depends on what you want.

in the end, if you want better low rpm performance, increase the size of your combustion chamber. presto, more displacement = more power (especially effective at low rpm). if you're talking about modifying the 13B-MSP you already own, well, this will get long :D

because of the way roots chargers do their positive displacement thing, they're good for low speed flow, but as RG and PY and many others say over and over again, they're extremely inefficient (thermally speaking). this is bad for serious high performance.

turbos, well, same difference as a supercharger, but exhaust gas driven rather than belt driven. there are plusses and minuses which i really don't give a damn about right now. because it's a centripital compressor (works like a fan sucking air in, increasing its velocity immensly and thrusting it into a smaller volume than what it started in) it's inherently more thermally efficient, which is a good thing. but off the line performance isn't quite as spritely with a turbo as a super for lotsa reasons (no, not just because the compressor has to spin up to speed and all that... it's a factor, but there are others) and doesn't seem to jive with what you're after.

but that's all moot: in the end, what you'll find is that there are no absolute answers. there is no "best" solution all the time, only what's optimal given certain conditions.
if you want low-end performance, be prepared to sacrifice upper end (meaning overall) performance, and for the highest performing top end you're not going to have so much of a bottom end.

it's all about comprimise: what you want and what you're willing to trade for it.

because you're saying "low end" in a supercharger thread, i'm worried. i think it's fair only that (if you really want to) you find out all the nasty reasons i think superchargers (especially in the application for which i'm assuming you're thinking about) are just junk when you're thinking about performance, considering the engine we're talking about. but 'cause it's fairly late and i'm still working tomorrow (yay), i'm just gonna see if you're really interested in sifting through another one of these technical triste thingies some of us mega-nerds (y'know, the ones who always get the babes ) seem to be writing up right and left these days (well, most of mine are very very very old now).

g'mornin'.

Lock & Load

WAACCHEK

TA, for your revealing posts , i will do some homework on superchargers / tubochargers and then post more ideas.

michael

XeRo

god wakeech your annoying like my little brother...

Freakin' nerd goes to Case Western Reserve (interns at NASA) and says the same **** you do...

"all the girls think i'm sexy"...."geeks rock"...he even has a shirt that says something to that effect but uses an algorithm...what a retard...well he is smart...what do i know...im just a programmer...