m477

Screw aftermarket turbo kits. You can't just slap a turbo on an NA engine. Go to a Supra or Z32 forum and ask (or better yet, search) about what a major PITA it would be to convert a NA car to a turbo one (I won't bother going into detail here about it). A good aftermarket setup will cost at least $10k in parts alone, not to mention installation. Personally, it would take me probably a few weeks to complete a job like that, or if I paid a shop to do it, it would amount to thousands in labor.

If it comes with turbo from the factory, it will take MUCH less time, money, and effort to reach whatever power goal you have.

fritts

Sorry to say but not all turbo kits cost 10 grand. With proper fuel management I'm sure a kit could be made for around 5. Yes it would be better if it was from the factory, but I seriously doubt that will happen unless they bring the seven back.

Red Devil

I would think a single turbo would be great in the RX-8 NA.

But...that is provided that the engine has low enough compression to safely accomodate it, the person installing it knows what they're doing (which can be a big problem sometimes), and the owner of the car doesn't want something insane like 25psi.

Just my thoughts

BlueAdept

I would think that most people wouldn't want much more than a 50-70HP gain without serious mods to the rest of the car anyway...

RedRotaryRocket

Sure you can. Lots of aftermarket performance manufacturers offer turbo kits for a variety of N/A cars. Just go to the Greddy website, http://www.greddy.com/products/turbo_frame.htm ,for example, and you'll see turbo kits for civics, integras, preludes, miatas, and 240SXs. And that's just Greddy...

I don't think it will cost anywhere near that much. Look at the Greddy page again and you'll see that the most expensive of the N/A-to-turbo kits I mentioned is $3449. The Civic EX kit LISTS at $1995.95.

The reason the N/A to Turbo conversions for Supras and 300ZXs cost so much is twofold. One, they are twin turbo setups, requiring you to purchase two turbos instead of one. Second, those guys are talking about using the factory turbos which are designed for lower compression ratio and higher boost. That means that on they risk damage to their higher compression N/A motor if they don't swap out engine internals and lower the compression ratio...that's what gets expensive.

An aftermarket turbo kit will be designed to work with whatever compression ratio comes on the stock engine...so the kit will be inexpensive and easy to install.

I will agree that time and effort are conserved if you start off with a turbo, but I don't think you are going to save any money. Let's say your HP goal is 350HP. You can buy an N/A RX-8 plus a mild $4000 turbo kit and reach that goal. Or, if you buy a Turbo RX-8 from the factory, you may be at that goal stock, but the MSRP for the turbo version would surely be $4000 higher than the N/A version. (As a real world example, the MPS Protege is ~$4000 more expensive than the regular Protege). Either way, it costs the same.

Now let's say you want really big power...the kind of power that Mazda will not sell on a stock vehicle...like maybe 500HP. If you start with a Turbo RX-8 from the factory, then buy a big single turbo kit for an additional $5000, you will reach your goal at a cost of roughly $4000 + $5000 = $9000 over the price of the N/A car. If you start with an N/A RX-8, you can buy the same big single kit for the same $5000, but you won't be able to bolt it on because the N/A car will probably have higher compression rotors....but wait! for about $4000 you can have your N/A engine rebuilt with lower compression rotors and then you can bolt that turbo on....it all costs about the same.

fuz

Well, you get a heck of a lot more on the protege than the turbo for that $4k

RedRotaryRocket

That's a good point, but then again none of those Greddy turbo kits really cost $4000 either.

Also, the MPS Protege is a limited production vehicle, which to me means Mazda is most likely selling it for the image rather than for profit. If it was for profit, why wouldn't they try to sell as many as they could? If they are being sold for image reasons, you can bet they have taken a decent hit on their profit margin.

It is pure speculation, but my guess is that if the MPS Protege was being produced in unlimited production, the price would be a couple of thousand higher.

m477

I said a GOOD SETUP, meaning beefing up other parts like the tranny, radiator, ECU, etc. Not just some cheap turbo kit. I sure as hell wouldn't just put one of those on MY car..

Funny, the big thing with Supras is installing a single turbo, but people don't start with an NA, they start with a TT and ditch the stock twins..

RedRotaryRocket

All those single turbo kits that are so popular with the Supra crowd (and the RX-7 crowd for that matter) ARE THE SAME turbo kits that are sold by Greddy etc. They ARE good setups. None of them come with ECUs or radiators and none of them cost $10,000.

You might spend $10,000 total if you buy extras like radiator, exhaust, ECU etc, but if you are going to use a big single you are going to have to buy those pieces regardless of whether the car started out life as an N/A or Turbo, so there is no advantage to starting out turbo.

Yes I know...YOU were the one that brought up N/A Supra conversions...remember... I just responded to your comment:

The reason it's such a PITA is because there is no turbo kit in existence which is designed for the N/A Supra or 300ZX engine. Stock or aftermarket. It's always going to be a PITA to use a kit on an engine for which it was not designed. It has nothing to do with the fact that it is N/A. If the kit is designed for an N/A car to begin with, it WILL be easy to install.

Don't misunderstand me though, I am actually with you on the turbo option in general....I would rather see a turbo 2-rotor offered than a non-turbo 2-rotor, I just disagree with your assesment of price and ultimate power potential. I think it will be about even either way...it'll just be a little more work if you start with an N/A.

m477

Yes, which you NEED to do for reliability. Which is why I said a GOOD TURBO SETUP, not "kit", would be $10k. That was my whole point. Re-read my original post.

Turbo rotaries aren't something you can do half assed. You MUST make sure that it is running cool enough and the a/f mixture is just right, otherwise both the engine and the turbo will be needing a rebuild REALLY fast. Trust me, an RX-8 with just a turbo kit won't last more than 60k miles. You can learn from the mistakes Mazda (and many, many aftermarket tuners and vendors) made with the Series 6 FD, or you can pop your engine. Your choice.

Quote:

Yes I know...YOU were the one that brought up N/A Supra conversions...

Yes, and YOU were the one that incorrectly pointed out that you would need two turbos to turbocharge the Supra's I-6. What's your point?

RedRotaryRocket

Not always. If you are only looking for a small power gain, then a properly designed aftermarket kit will suffice....no extras needed at all. If you are looking for big power, then you will need the extras, but you will need those extras regardless of whether or not you start off with an N/A car...so it doesn't matter where you start.

I didn't mean to start a flame war with you...and I think the problem is that perhaps we are misunderstanding a couple of each other's points. Let me enumerate your points from your original post and restate my reactions to those points...hopefully this will clear things up:

My response: "Sure you can. Lots of aftermarket performance manufacturers offer turbo kits for a variety of N/A cars."

Possible source of misunderstanding: I think you are making the assumption that we're only talking about high power turbo kits. My response above is only meant in relation to mild turbo kits for modest power gains. I addressed the idea of a high power turbo kits later in my response.

My Response (Abreviated): "those guys are talking about using the factory turbos which are designed for lower compression ratio and higher boost."..."An aftermarket turbo kit will be designed to work with whatever compression ratio comes on the stock engine...so the kit will be inexpensive and easy to install."

Possible source of misunderstanding: I have seen discussions on those forums about people who want to bolt the FACTORY turbo setup to an N/A car. I made the assumption that this is what you were talking about, but it seems from your later posts you were actually refering to big singles, not a retrofit of the factory setup.

Either way, my point still holds: Using the N/A Supra or 300ZX as an example is not really valid because none of the turbo kits mentioned (factory or aftermarket) are designed to be installed on the N/A engines....It will always be hard to use a product in a way it was not intended to be used. An aftermarket kit for the N/A RX-8 will be properly designed as such and will be much easier to utilize.

My Response (Abreviated): "the most expensive of the N/A-to-turbo kits I mentioned is $3449."

Misunderstanding: Again, I think you are stuck in "big power" mode, while I am pointing out that modest power gains can be had for less.

My Response:"I will agree that time and effort are conserved if you start off with a turbo, but I don't think you are going to save any money."

I think this one was pretty clear to both of us. No matter what level of power you want, you are going to have to pay somebody for it, either Mazda or the aftermarket. In the end, the price will be roughly the same whether you start off N/A or turbo.

Now to your last post:

Turbo's period aren't something you can do half assed. Detonation and excessive heat will kill a piston engine too. All of the statements you have made above are NOT rotary specific. But you must understand that turbo kits for modest power gains are not half assed in any way. They come with more than just the turbo and manifold...they include methods for sufficient fuel enrichment and will not be the cause of premature engine failures if installed and used as the manufacturer intended.

Engine failures on the FD had nothing to do with the aftermarket being half assed in any way. My completely stock '93 lost it's first engine at 85,000 miles...and I'm far from the only one that has happened to. The cold truth is that any premature failures that are likely to occur on an N/A RX-8 with a turbo kit are just as likely to occur on a factory turbo RX-8.

There was nothing incorrect about my statement at all. I think we have just misunderstood each other, as I already stated above. As to "what's my point?" I took your comment as inflamatory, and my point was: You brought it up so don't flame me for making a comment about it. I'll admit that my response to your flame was also inflamatory. To keep this thread productive and interesting, maybe we should both try to lay off the flames and stick to the topic....agreed?

m477

Ok, let me be a little more specific about what I mean here -

I am speaking from experience from owning an FD, working on it, and reading everything about it I can possibly find about rotaries.

So, specifically for the RX-8, a rotary-powered car, I would not feel safe with just the turbo kit, even just for modest gains there will still be a significant increase in heat, and you will still need more fuel than the stock fuel system was designed to provide. I'd highly doubt the engine would make much past 60k miles without upgrading the entire cooling system and the entire fuel system, especially if you drive the car hard. In addition, you might as well upgrade the brakes and the clutch, since these will wear out faster due to the increased power so you're going to have to replace them anyway. If you do all these things, I would expect you could easily go 100k miles without any major problems.

Of course there's no kit because there's no need, Nissan and Toyota already make all the parts. Just open the hood of the turbo version, make a list of the parts that aren't in your NA car, and order them from the dealer.

Quote:

Misunderstanding: Again, I think you are stuck in "big power" mode, while I am pointing out that modest power gains can be had for less.

No, I am stuck in "paranoid that my engine will pop" mode, which even with is too likely to happen for my personal comfort level, with ANY aftermarket turbo on a rotary engine, unless you perform the rest of the upgrades which I am advocating.

Quote:

My Response:"I will agree that time and effort are conserved if you start off with a turbo, but I don't think you are going to save any money."

Well, yes and no, if you goal is 50hp over stock, then it's much cheaper and easier if you start with a turbo from the factory, than install one after the fact. If you goal is 600rwhp, then the difference is much smaller.


Perhaps, but Mazda has far more knowledge of their own engine, and any commercial product they release will go much more R&D time and testing than any aftermarket product. In addition, you will get a full warranty, so a factory turbo system is a much better deal.


Well, it depends -- if Mazda upgrades the cooling system, fuel system, and ECU and the aftermarket version doesn't, then the factory setup will be more reliable. For $3k the aftermarket kits don't give you these additional upgrades which IMHO are very important. I would, however, expect that Mazda would give you those additional upgrades, since they've learned their lession with the FD. That is why I'd prefer a factory turbo.

RedRotaryRocket

Same here....



Well, you will need more fuel, but remember those kits mostly come with additional injectors and a controller for them. While this is not as clean a solution (as compared to a stand alone ECU and larger injectors in the stock locations) it is just as safe. As for cooling, as you point out below, hopefully Mazda has learned a lesson with the FD, and if they have, the cooling system on the RX-8 should be robust enough to accomodate modest power gains.




The brakes on the RX-8 will be very good in stock form. I anticipate it will have one of the shortest stopping distances of any production car. With only modest HP gains there should be no need to upgrade them. As for the clutch, who knows....it may be strong enough stock, or it may not. I don't think we'll know the answer to that one until we get to drive it

Well, not just because they make all the parts, but because if somebody wanted a turbo, they should have just bought the turbo version to begin with :D But this "factory turbo kit" you describe doesn't work easily on the N/A because the "factory kit" is designed for an engine with a lower compression ratio than the engine in the N/A cars. Using Nissan as an example (since I have a 300ZX shop manual handy) the turbo engine has an 8.5:1 compression ratio while the N/A engine has a 10.5:1 ratio. The "factory turbo kit" is designed for the 8.5:1 engine. If you put that "kit" on the N/A engine, the boost pressure will be too high to use with pump gas and you will have a problem.

LOL! I think we're all in that mode ...unfortunately, my experience is that even with "the rest of the upgrades" you still are no safer than without. After I lost my first engine (stock), I decided it was time to upgrade. I accompanied my upgrades with the usual "safety" items; radiator, ECU, hose job (alas no single turbo for me yet ) J&S Knock Sensor, etc....and I STILL lost my second engine at 35,000 miles due to an injector that got clogged....and I was being REALLY safe. I never pushed it past 12 psi. Even without the mods, I still would have lost that engine. My opinion is that the only way a turbo rotary will ever have good longevity is if they can improve the design to be less likely to break when there is a ping, because I think no matter how hard you try to avoid it, if you are turboed, you are eventually going to ping.

If you think about it in terms of "50HP over stock" then I absolutely agree with you, but I think it's more appropriate to think of it in terms of absolute HP. "50HP over stock" is 300HP for an N/A Renesis, but might be 350 or 375HP for a turbo Renesis. If you keep it in terms of absolute power levels, then the costs will be about the same.

Absolutely. That's one of the reasons I said I would also prefer a turbo from the factory. That still doesn't mean you will get your power for less, it just means it will come with a convenient warranty....certainly the more preferred option.

Let us all hope that they have indeed learned their lesson and overengineer the critical systems, whether it is on a turbo or an N/A car.

Red Devil

I think a moderate turbo is no big deal. My experiences with FD's have me a bit worried, but as I said in another post, anything below 10psi in a single configuration should be fine. My biggest mistake before was sticking with the sequential setup, and relying on what was probably a questionable A/F mixture. (I didn't know any better and was torched by both mistakes.) I will be much more cautious this time around, and because of that I would want to upgrade the radiator and other misc. measures before going to a turbo.

...One more thing. There are aftermarket turbo kits for NA Supra's. NA Supra's are actually much better for handling turbo upgrades than the Turbo version from the factory. The stock, factory engine with NO INTERNAL UPGRADES can handle up to 20psi, and still be reliable.

TuRb0n3ticS

#2:RX-7 (take off the rear doors and seats, remove trunk, add hatchback, add additional rotor, shorten car a foot-foot and a half)

dang if the rx-7 is gonna be a hatchback......


i dont like the idea of tainting the rx-7's image with a hatchback.
dont get me wrong hatchbacks can be fast and stuff but an rx-7 was not built to be a hatchback.... hatchbacks go on hondas if it does go hatchback ill just get me a third generation...
theyll look way better ne way and stick in a 3 rotor renesis motor from the silly hatchback in it....

Sputnik

Dude, each of the previous generations of RX7s were hatchbacks.

---jps

RX8-Rob

Cool! My first post.

Anyways, I think that Mazda should take a look at archrival Nissan for a solution to the single turbo problem. The jist of the problem is that a big single turbo spools slowly and therefore you get big power, but lots of lag. Mazda tried to solve this problem on the FD using a sequential system, but that was very complicated to operate, and somewhat unreliable.

A lot has changed in 10 years, however. The best rumor about the upcoming Nissan GTR has it being powered by a twin turbo V6 with electrically assisted turbos. Say what?

Well, basically, there will be small electric motors with one way clutches attached to the impeller shaft. Under low exhaust pressure situations, the electric motors will engage and spin up the turbine blades to create boost where otherwise there would be none. Once there is sufficient exhaust flow, the turbines can freewheel faster than the electric motors can spin. Basically you have the best of a supercharger (instant boost whenever you need it) with the best of a turbocharger (non powersapping big boost capabilities in the midrange and topend). This tech is being used in other industries, so it has been done before, just not in an automotive application.

I think it'd work really well on a single turbo RENESIS application. 350hp with no lag. Wouldn't that be sweet?

zoom44

ooh and once the turbo kicks in then the electric motors could act as generators to recharge the battery or run some accesories!

zoom44

uh rx-7's are/were hatchbacks

N1XRR

NOTE: The application of ball-bearing turbo's has releaved most of the lag problems as we know it! The Mazdaspeed Protege is suposed to have NO lag(partially due to a T-25...but also ball bearing)

Michael

RX8-Rob

That's not entirely true. Ball bearings or not, if you run a big enough turbo, you will get lag. Even if there is no friction acting on the impeller shaft, you still have to overcome the inertia of the turbine wheel itself. Thus, a big turbo on a small motor will still have lag. The electric motor spins up the impeller, thus completely eliminating lag.

N1XRR

Yes, you are right, inertia still has to be account for, but as all the turbo rotary guys already know...THIS ISN'T A SMALL ENGINE in terms of air. Its like having a small V6 or large I4...2.4-2.6L(about that much, I know its not exact). So a small turbo, like the HT-18S on the TII's could actually spool pretty quickly...and would have been almost not even noticable if it where ball bearing.

Michael

Sputnik

Even a small BB turbo on the small motor will still have some lag (I have such a turbo on my Miata). Don't get me wrong, lag has been reduced dramatically over other turbo cars that I've owned/driven, enough that it is now more of a "characteristic" than a "hindrance", but it is still there.

But don't forget, depending on how an SC is installed in a car, you can even have boost lag with that too. Take for example the Jackson Racing SC kit for the Miata, which still has a long enough intake path that you can install a small IC on it. It still has to pressurize that intake path when it gets under boost, so there is a delay. It's so short that it's considered by most to be "throttle response" issues instead of "boost lag", but it's still there. Electrically driven turbos will suffer from this too.

---jps