THough none of us have driven this thing yet, you know were all already thinging about it - Boost! From the few pics I've seen of this engine, it does not look very friendly to a turbo or supercharger setup. But beyond that does any one know how well it would take to a lil force feeding?

For instance, do we know what kind of air meetering system it will use? Is the fuel fed with a traditional return line system or is it the more recnet style of returnless? Do we know how big the fuel injectors are? Or what style?

Do we know anything about the strenght of this transmition or rearend?

 

I have not seen the engine bay, but from what I have heard there is no room for a turbo or supercharger.
That would really suck if its true.

Jason

 

But it would also mean that the MPS RX-8 would be NA :D

I hate turbos, and if I can avoid them I'd like to. NA rules supreme!

 

all motor! :D :D

though boost IS a very tempting proposition, like the dark side of the Force

 

I'm sure someone will boost it. RE amemiya perhaps... pan speed. Greddy; hks; blitz.. SOMEONE PLEASE!!!!

 

LIke Igoslow said, someone will FI the engine. The rotary has way to much FI in its history for some aftermarket not to. My thought on this is that the entire runner system will have to be eliminated for FI. Not to mention the dual throttle bodies. With the torque FI would add the variable exhaust length will not be needed. The question would be at what RPM the engine would start producing power over stock. This I'm sure will make the engine peaky to say the least.

I think the better bet is to get an aftermarket intake, headers, and exhaust, this coupled with some aftermarket cpu or ecu management system I am sure we'll see 300 hp. Though a low boost supercharger or belt driven centrifugal charger might be a viable option for performance.

 

I went to NAIAS, and the Mazda rep took the plastic covers off the engine for me so I could take a look. There seemed to be enought room to me.

The current prevailing rumor is that the base model 4th gen RX-7 will get a 1.5L NA engine. So then what will they put in the MPS version, maybe a turbo 1.5L? It's incomprehensible that the turbo rotary is gone forever, I'm sure we'll get another one someday, somehow...

 

Trust me...throw a low-inertia true ball bearing turbo, something larger than the Garrett GT25 used on the Protoge, say a 30 series and it'll build the bottom end and midrange quite nicely. Those turbos, sized properly with a divided manifold and turbine housing would EASILY make 12psi @2500 rpm on a rotary. I guess the issue is for me whether or not the actual rotors themselves are any weaker than the 13B-REW rotors. I know that SR Motorsports has the intention of purchasing a renesis as soon as one becomes available. www.srx7.com.

 

this issue with not having enough room in the engine bay... i thought the Renesis was more compact than 13B REW, and mounted further back and lower. and doesn't seem like the 8 has smaller front end than the 7, so shouldn't room not be an issue? personally, i'd like to see them do a similar sequential twin turbo system as in the 13B REW, but that's unlikely, i guess. or is it? bearing in mind that maz was the first company to apply such a turbo system in a road car, it'd be such a shame to see it gone

 

Maybe I'm off base here, but I think most FD owners would beg to differ. Most of the ones I've talked to and read about on the forums and lists prefer a single, ball-bearing unit.

 

A single turbo sound better. I wouldnt be concerned with engine room.

My cougar has the most cluttered engine bay ive ever seen (changin plugs is a knuckle buster) and they still managed to design a kit for it. The RX8 appears to have much more room.

 

One of the problems with the sequential turbo systems is that the manifold is very complicated and more importantly, restrictive. Restriction on a rotary is not a good thing due to hot gas reversion back into the combustion cycle. Since rotaries have a higher EGT than piston engines, it's very important to allow an easy path for the exhaust to exit. It's bad enough with a single turbo but very bad with the sequentials.

I do occasionally miss the instant boost of the twins. But I bought a single turbo that's waaaay to big for the street, especially with stock ports.

Like I said before though, the newest turbo designs with full ball bearing cartridges are just as responsive, flow more CFM, heat the air less, and give KILLER top end power. There's almost no reason to go twin anymore unless you have a vee configuration boinger (pistons).

As far as room, the 13B-REW and the Renesis are identical in size (at least the actual short block is). Clearance isues might arise if there's not enough room for a good turbo manifold design between the side of the engine and the shock tower aseembly. And possibly the firewall. It almost looks like we're going to have to put the car on the lift to change the spark plugs! It's bad enough on the third gen...

Michel
95RX7

 

There's no real need for sequential twin turbos anymore, you can get about the same responsiveness from a single, and believe me, you don't want the extra complexity or heat.

If I wanted to spend the money, I would definitely ditch the twins on my FD and replace them with a moderate-sized single turbo. Lots of power and response everywhere, I'm not looking to make big hp numbers, 330 rwhp is good enough for me. :p

The last of the Japanese sequential twin turbo cars (FD, Supra, GT-R) rolled off the assembly line last summer. Japan will never again produce another sequential twin turbo car, I'd bet my life on it.

 

at least they were cool at the time

 

If someone wants to buy a rx8 and bring it to my house, I can prove otherwise :DFitted with the proper turbo for the application, you could make more torque at low rpms. Thats what they did with the second gen rx7 turbo ii. The NA version is rather peaky where as its FI counterpart is making peak tq at 3300rpm and peak hp high 5000s/low 6000s.
The sequential turbos is what ruined the fd. A simple single turbo like the 2nd gen wouldve been better.

 

This might sound weird but after reading the press kit I think the perfect engine to FI is the automatic lowpower version.

Its a 4 port!! NO DUAL INTAKES! no aux ports to deal with simple. just hook up a turbo, blower, N2O kit to the existing intake tract and you got your self a power engine.

The 4 port design is why the lowpower version has more torque.

If you put FI on this engine you wouldn't have to worry about removing any of the intake track.

 

It's not all that wierd. The automatic engines in Miatas, for example, have lower compression, which makes them better candidates for FI.

But you have to remember that the automatic engine in THIS car is also rev-limited, which kills any advantage from the 4-port setup. Still, we might see tuners take a 4-port block and make 9k revving turbo engines out of them. We'll have to wait until these guys get there hands on the car.

---jps

 

well, i thought the rev limit was because of the limits of the Torque Convertor... so unless your talking about a tranny swap as well, It sounds like the rev limit will have to stay for now...

 

It'll really depend on what tasks Mazda has assigned to the engine's ECU. A seperate ECU could be controlling the transmission and it may contain a rev limit function. The 6 port will be a bit more complicated to pressurize but it'll make substantially more hp at lower boost levels thanks to less restriction on the intake side, especially with a turbo. A roots type SC wouldn't see as much of a benefit down low due to increased volume and flow characteristics of the 6 port design. I'm sure that some aftermarket company will come out with a stand alone, whether it's Apexi with a PFC or AEM. Something will be released. But I suspect that the auto versions will have auxiliary ECU's which won't allow for total control from just one box, ie. it'll have to control or work around a seperate transmission ECU. The compression ratio for both versions is identical, is it not? I see that as being the largest hurdle to forced induction.

 

I think Mazda might actually be planning to throw some boost at the Renesis. I pulled a couple of quotes from Rotarynews.com

"All we can say here is: MazdaSpeed-8! We hear that a blown version of the car is in the works as we write. No confirmation of this going into production, but the car should just plain rock! The concept has already been shown at the Tokyo Auto-Saloon, and with a little boost from a turbo or super charger, watch out! "

And from the test drive impressions II

"I excused myself to the group for the technical questions, I was about to ask, that I knew they wouldn’t understand, and I started in. Obviously, one of my first inquiries was about porting the RENESIS. The motor will be able to be ported, but great care will have to be taken when grinding on the housing. Mazda has gone to great lengths to work with airflow and fuel atomization. There is a third injector per rotor sticking right in the intake port, as it enters the housing, which will have to be dealt with when cleaning up and porting the housings (see press kit information). Both the intake and exhaust ports can be cleaned up some and used for further power development in the new motor. The interesting thing is; the engineers said that doing a little port work down on both ports, might actually make a bigger difference in power than porting up, in a traditional manner. The RENESIS’ rotors are definitely lighter than previous Mazda rotaries. When picking them up, one can actually feel a big difference. Another question, that actually took me a drawing before the engineer understood, was did the 6-port sleeves have a radius in them to help smooth the air/fuel charge transition into the combustion chamber? The answer was a very pleasant; yes they do. The Engineer was actually quite surprised at our technical line of questioning, but he had been warned about the two Rotorheads who might be crashing the party. The time in the engine session flew by quick and soon they were booting us out of the room. We hadn’t noticed everyone else had been gone for a while, and they were waiting for us. Side note here: Almost all of my engine questions were under the assumption of Motorsport usage and didn’t take into account emissions and such. Overall though, the RENESIS is still a Rotary and I’m sure we are going to start seeing the Race and Aftermarket communities have it soon. Can you imagine, a 12000RPM RENESIS street motor, nice! Oh yea, before I forget, the engineer did mention one more important thing; the motor was built to take boost!"

 

yeah I remember that. Goddamn it! I want mazda to sell them as crate engines. Maybe just the shortblock but even then it would be easier to fab the manifolds and work with the motor.
With this being brand new it would suck to make some fatal porting mistake on your brand new RX-8 and who knows how much the dealers will charge to fix it or replace the engine is more likely. But hell who would want to get one just to play around with?

 

So their opinion was that the rotors, as they are, will handle boost? how are we going to lower the compression ratio without modifying the bathtub? I was under the assumption that was a no no? I too feel as though we'll see a boosted renesis.
Michel

 

apparently so. either that, or they have a lower compression rotor made for turbocharging.

 

I was actually (sarcasm) thinking a couple nights back about aftermarket turbo kits. With the complexity and the high compression ratio of the stock Renesis, I do believe I'll be waiting for a Mazdaspeed-boosted Renesis. The as is design is very much optimized to run naturally aspirated. As such, designing an aftermarket kit would be highly complex, limited, and probably wouldn't satisfy the hp junkie in me. I'd at least stay away from it in the first couple of years. The need for lower compression rotors alone would keep me away. The aftermarket is pretty ingenious however, so we'll have to see what they come up with.
Michel

 

has anybody heard when the mazdaspeed 8 is supposed to be released?