RX-7 Swap (RX-8 engine into a 93 RX-7?)

[LexmarkX73]

didnt the renisis win international engine of the year award? and wasnt it the first rotary engine to move the intake and exhaust ports so it wouldnt kill itself as fast?

[Erkumi]

Forgive me for forgetting, but i forgot how many rotors the 12a has. I'm not the biggest rotory fan but i am a fan of rotorys. And i do know a few things about them. But i ocassionaly forget stuff since my heart belongs to my toyota(hehe, that was so *Censored**Censored**Censored*)

[Misthael]

I got everybody riled up huh?

[Infini IV]

A 12a is capable of 150-160bhp (120-130whp) assuming use of a suitable carb and unrestricted exhaust. A decent streetported 12a with proper intake and exhaust components should net near 180bhp (145-160whp). Bridgeported 12a's can see upwards of 220bhp (180-200whp). And finally, peripheral-ported 12a's can see upwards of 250bhp (210-230whp). It would take either a bridgeport or even a peripheral-port 12a to reach the same powerlevels as a stock Renesis. And to add to that, idle would be around 1500-2000 and it would be hard to keep the car quiet while still producing that much power.

Thing is...

An S5 13b (highest output n/a 13b offered to the U.S. for public consumption) makes 160bhp... around 130-140whp un-modified. A decently streetported S5 13b will make around 180-190bhp (145-160whp). Switching to a 4-port 13b using S5 rotors and bridgeporting could possibly net around 200-220bhp (170-180whp). Finally, a peripheral-ported 13b using S5 rotors has the ability to reach 300bhp (260-275whp). Knowing this, it would still take quite a radical port-job to get near the same power levels as a Renesis, while still not being able to keep the same civility that the Renesis offers (low idle, ability to keep quiet while making that much power, etc.)

Finally...

There hasn't been much info regarding porting a Renesis.. as in what type of gains are available. However, with a free-flowing intake and exhaust, there are large gains available. People have seen 10-20+whp increases from a full exhaust and about 5-10whp from a better-flowing intake. That means a Renesis is capable of flowing enough air to make 190-210whp with just an intake and full-exhaust. It also means that with just those mods, it is still a very civil motor, and is able to produce great hp figures without much more noise... *note: Rx8 owners have noticed a greater driveline loss than most find is average (average = ~15%)

Power talk aside... the Renesis uses a lighter rotating assembly meaning throttle response can be maximized through the use of appropriate intake and exhaust components.

I'm not saying the Renesis is a better motor than anything else(since people like different motors for different reasons)... but if you compare non-turbo rotaries offered from Mazda from the factory, the Renesis is quite hard to beat.

[Feint]

Originally posted by Erkumi
Oh and most of you people act like the rb26 is the best engine out their. Newsflash for ya. The 2JZ is just as good, the VQ35 is just as good(well as good as an n/a RB26), the nsx motor(dont know the name of that motor) is just as good(well as good as an n/a RB26). Anyways stop acting like the RB is the ultimate motor cause its not.

errr.....I wouldn't even begin to compare a VQ35 to an RB26 or a 2JZ.Ask Chris Foresberg why he has a SR20DET in his 350z.That invincible block blew up on a lot less boost than what an RB can take in stride.The C32B is a damn good engine,but then yet look at what it sits in.The NSX Type-R is completely over-the-top in the weight savings department,even down to the shifter boot.It's still a better engine the the VQ imo,but not better than an RB of 2JZ.I'm sorry,but those engines have proven the test of time and strength time over and over again.We've all seen them take 1000hp on a stock-bottom end without breaking a sweat.Then yet,the C32B,as great of an engine as it is,and even the VQ35(not as great imo,but you can make your own conclusions) can't do that.That's the truth.Those two engines were the bullet proof engines,which sat in 2 of the 4 Japanese supercars.The latter will never be able to fit the shows and create a legacy even near the same level as the RB and 2JZ have created.

The problem with the RX-8 is the location of the motor mounts relative to the new side ports,which replaced the peripheral ports on the 13B.This makes it very hard to create a good forced induction system for it.And even so,the RENESIS still has a high compression,We all know that if you want to run more boost,you need to lower the compression.

As for tuning capabilities,the 13B is still the king.Maybe with some refinements and aleterations for the betterment of the RENISIS,it can one day step up from the shadows and take the place of it's older brother.But for now imo,the 13B/13-REW(for the technical ones) still is ahead of the game.Sure it may suffer from more overlap with the peripheral ports,it's still set records on the world stage,something the RENISIS has yet to do.When a RENISIS powered car smacks around a car with a 13B-REW,is the day the RENISIS is worthy.Until then,it's the redheaded stepchild of the RX family.

[Ghost of Duluth]

Well, as the destroyer of multiple Rotaries, I have to say I hate em. But even with all the hate, I understand that they are amazing pieces of machinery. As for the Renisis, I don't really car what kind of power it is "supposed" to put down, it won't take the place of a TT in my heart. I seem to recall a recall that Mazda put out because the Renisis was not making the claimed amount of power that it was supposed to be when they first came out. You could bring the car back and drop it off, no questions asked or you could get free services for the warranty period I think it was or a cash back option as well if I remember correctly. So that tells me that it was not the wonder boy motor that they made it out to be. With time, I do believe they can make it into a winner. But right now, it's too early to start wagering it's dominance over the tried and true TT.

As for making HP with less noise, what the poop is the fun in that? The main signature of the Rotary is the ominous wail as it comes down on you. Downright Headless Horseman type stuff. You find yourself wanting to make it to the bridge so you can cross some running water and maybe that demon will leave you alone.

[ToplessFC3Sman]

I just know id love to get a renesis in my S4 FC, quite a bit more power, better fuel economy (i get ~ 20 mpg right now... when taking it easy on the highway), and that its a rotary. I dont plan on doing any huge power upgrades... exhaust, intake... maybe fuel pump, and for being stock or close to it, you cant beat the power it provides given only 2 crazily spinning triangles, without any turbos. True, for serious tuning, going with one of the older 13B-REW's would be better, but how many people here are gonna be in the position to tune their rotary engine to 350+ hp?

Oh, and addressing the whole engine thing... i sense a bit of confusion... the Nissan Skyline's rb26dett wasnt the engine under discussion, even tho it is an awesome engine. it was the R26B, 4 rotor LeMans racing engine used in mazda's kick-*Censored**Censored**Censored* 727B racecar. Given the choice of any of the engines mentioned, the R26B would be mine in an instant. Just the 20B makes about 285 hp n/a, imagine what adding another rotor would do to that hp number... and a turbo or two? Yea, im going with the R26B, but more realistically, the Renesis.

Oh, and the tester-miata did appear in Road and Track and it was sitting on the RX-8's platform, wearing the RX-8's front end... but i remember reading in CAR magazine (british), that the RX-8 front was on there to fool casual observers to think it was the new rx-7 being tested. I also remember hearing about the new RX-7 having an electrically assisted turbocharger... its like an electric-motor driven supercharger at low RPM, until the exhaust gasses can spool it up enough on their own to produce boost.

[Erkumi]

Hehe I thought they said rb26.

[Infini IV]

Originally posted by Ghost of Duluth
Well, as the destroyer of multiple Rotaries, I have to say I hate em. But even with all the hate, I understand that they are amazing pieces of machinery.

As for making HP with less noise, what the poop is the fun in that? The main signature of the Rotary is the ominous wail as it comes down on you. Downright Headless Horseman type stuff. You find yourself wanting to make it to the bridge so you can cross some running water and maybe that demon will leave you alone.

Have you figured out why you are blowing your motors?

Well I had always thought we were on the discussion of N/A rotaries. If you had ever heard an uncorked stock ported N/A 13B, it's definately a sweet sound, but it's loud as HELL. It's definately loud enough to damage your ears. Add to that a bp or pp N/A motor and the sound gets sharper and much louder at the same time. Also, I was running an open downpipe on my car for some time. I can hear my car idling from the next street over. When I gassed it, my friends could hear me coming from over 1/4 mile away. I don't know if you live in SoCali or not, but if you do, you know how cops are around here What fun is not being able to get in your drive and drive it wherever and whenever you want? Isn't the whole point of having an Rx7 being able to enjoy DRIVING it?

[Ghost of Duluth]

Well, that's a new concept. Here I was thinking that RX7 ownership was supposed to be filled with exploding engines, bad 5th gear synchros, swift kicks to the rocker panels and tantrums punctuated with heavy drinking and wild cussing fits. I didn't know you could actually Drive them.

Coolant issues, bad tuning, but mostly cooling issues have been the Achilles heel of my Rotaries.

[Velvet]

Me likey the 13B-MSP

I think the 13B-MSP is a good direction for the future of rotories. Unlike most companies that would scrap a product when it failed, the engineers at Mazda made it better. Look back to the 13B-REW was then and look at all the advances the 13B-MSP has made. Most of the power with the REW came from the twin turbos. We all know what happens when you force air into rotories: after 75,000 miles the engine goes !boom! if youre lucky to go that long. However, the MSP doesnt rely on turbos to get its power. Without the turbos the MSP can now go for 150,000 miles without going !Boom! Even without the turbos the MSP can still keep up with the REW with HP numbers at 238 and 255 respectively. Besides, if you want more power for the MSP, companies are working on turbos for them. Greddy/Trust had a turbo at TAS and I think it put out around 260hp!

Bottom line, the MSP is more reliable and stock puts out decent numbers. Give the big 4 (Trust/HKS/Blitz/Apex) time and the MSP will keep up with the REW!

[cloud7912000]

i know that blitz got a supercharger for the rx8, makin about 40 to 60 hp. i read it on some HK magazine. they also wrote something about a turbo kit too, but i forgot which company was it. but back to the topic, i think the renisis will fit better in a na fc or a first gen rx7. i think puttin a renisis in a fd will be kind of a waste, since the 13b rew is capable of achieving alot, maybe except reliability. but anyways, i think the renesis is just a base of something better, just like the 13b rew came after the 13b, there must b somethin that mazda is preparing.

but until then i will keep my unperfect na fc, or get the 8 if i can fit in to my budget.
peace

[nasty nate 7]

can someone actually tell me how much will this project actually cost? swapping an rx8 motor into an fc? if it goes beyond the price range over a 20b swap, forget it

[Feint]

Originally posted by nasty nate 7
can someone actually tell me how much will this project actually cost? swapping an rx8 motor into an fc? if it goes beyond the price range over a 20b swap, forget it

Yes it would.The engines are much newer,and would be more costly to obtain.Then you have to throw in all of the custom work on top of that.It's no drop in swap.

The RENESIS runs higher compression than previous rotaries,so turbocharging one is more risky,or challenging.

Also,for the ones that bring up realiablity and fuel consumption when talking about the !3b-REW and the RENISIS,saying the RENISIS is more realible,can go so many miles problem free,etc.Here's a piece of FYI.When you begin to modify your car,your realibility goes down the drain,same with fuel consumption.So when you stick on that turbo kit to that more sophisticated ECU,and higher compression motor,expect less reliability.Chances are,you'll get even less realibilty than a modified 13B-REW.Also,throw fuel consumption right out the window.The reason why the RENISIS gets better emissions is because it is not turbocharged.,and less overlap due to the new ports(the new ports is a trade off though).

[Velvet]

Originally posted by Feint

Also,for the ones that bring up realiablity and fuel consumption when talking about the !3b-REW and the RENISIS,saying the RENISIS is more realible,can go so many miles problem free,etc.Here's a piece of FYI.When you begin to modify your car,your realibility goes down the drain,same with fuel consumption.So when you stick on that turbo kit to that more sophisticated ECU,and higher compression motor,expect less reliability.Chances are,you'll get even less realibilty than a modified 13B-REW.Also,throw fuel consumption right out the window.The reason why the RENISIS gets better emissions is because it is not turbocharged.,and less overlap due to the new ports(the new ports is a trade off though).

You have a good point there.

Hmmmmm, I have a few questions for the more experienced rotorheads out there.

1. Setting the high costs aside, would it be possible to build a 3 or even 4 rotor engine using two 13B-MSPs and what parts would have to be custom fabed? I already know that you would have to custom fab the eccentric shaft but what else is there if any?

2. What powers the compressors in the aftermarker rotary superchagers?

3. What can someone do to lower compression in the 13B-MSP? Is it as easy as swapping the 13B-REW rotors and tweeking the electronics and all that other stuff?

Thanks for your input.