Tweak’D

Will this work(Youtube Vid Below)!?
What Issues will I have If so?

Times have changed since the excuses most of the post I've researched (over time randomly) had & it's much easier to make a Hybrid 13b engine with people giving RX8 engines away for free almost.
My research tells me there wont be a single issue, (Possibly Overlap?), but I'd like to be sure.
I'm mostly unsure, because CaNoT cOmPuTe & the other half is you rotards arguing more than coming up with solutions & confusing me.

To the Point... I simply want to
1. Heat up my Free Renesis Plates so they don't warp or crack 👀 (WHILST)
2. Pouring Iron or some other metal (lower than Irons melting, but higher enough than exhaust temps) into the Renesis Exhaust Ports to block them off completely.
3. Slap ported 1985 Housings on the engine that will open early & reap the benefits of both older exhaust/Renesis Intake at the fraction of the cost of what this street ported car would cost if I'd got it done after selling it.

I expect an "everyone would be doing it if it were that simple answer".... But it really does seem that simple in 2021 according to my possible delusion.

Examples:
I also know his car isn't running either for other reasons 🙃

GT35 With 1.06 A/R
RX-7 Rotors (Idk Yet whatev Pops Up that's not RX8 rotors bc I'm not dealing with milling for apex seals)
Limitations on RX8 parts? E-Shaft, Housings? etc I know the limits of anything rx7 I'll buy.

Side Notes:
I do have a street ported car freshly rebuilt I'm about to sell for profit that I bought for a Little over $2k (I beat everyone else too it refreshing marketplace for days on end & notifications on), but the guy needed the money.
I don't need the chassis or care for it like I do my engineless & much cleaner roller I am building up from top to bottom.
AKA boredem, free time, Resources.

TeamRX8

iTrader: (2)

compared to an REW it will never perform well

even the KMR/Mazdatrix results published to date reveal this (from almost 10 years ago btw)

my technical reasons for this are all detailed out on RX8Club if you care to understand them

in a nut shell; it all has to do with how Mazda phased the Renesis intake ports. The Renesis design is all centered around a zero overlap design principle. Which is not well understood, because pretty much no other reciprocating engine is designed around it and as a result it’s not very well understood by most people. You can throw a lot of standard intake/exhaust design theory out the window. Despite the obvious similarities, a Renesis might as well be an entirely different engine compared to the prior versions.

So once you add any overlap at all, the intake ports are immediately impacted/flooded by high pressure hot gasses as soon as the rotor moves past the exhaust cycle/BDC. In the case of adding a peripheral exhaust port it happens way early in the exhaust cycle. Bottom line is you will have little nothing below 6000 rpm and mediocre results from there, but like any high overlap engine it won’t require high boost because a lot of it is just blowing straight out the exhaust as well as into the intake. It’s even worse NA, but at least a turbo will get you something.

There is more to it than this, but I’ve grown tired of repeating it both here and at the other forum. Sorry there’s no free lunch here, because ask yourself this; everyone is doing it, nobody is posting results and what results there are; mediocre at best. They learned the hard way (the owner in that vid is too); if you go down this path … good luck.

Lastly; I’m not trying to sell something either. No skin off my back either way you go. There are Renesis engines reliably making 400-450 whp without all the gimmicky rigamaroll and gyrations this hybrid requires. So why even go there with a GT35 1.06?
.
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Tweak’D

I know little to nothing of the Rensesis, but thanks alot for the overlap info which is what seemed to be the part where I got lost at hearing what you'd stated about the Overlap.
Thanks Again & I just hear more bickering about don't touch the Renesis engine than good. I'd def Like to buy a JDM one for the $500-$600 they go for without the trans & run a conservative 300-350 Crank on the engine & call it a day.

dguy

iTrader: (8)

What you see as bickering, I and others see as statements of fact. Just because someone doesn't like the answers doesn't mean that they aren't true, and all through this you admit that you know little to nothing about the issue that you don't want to hear about. They're a poor powerplant for what you're trying to do. Period.

Dak

Sorry if I'm thread hijacking but tell me more about reliable 400-450whp from a Renesis? A 13B-REW would be my 1st choice for my car but with them currently being priced around $8k. $2k for a complete Renesis including trans( I've been kicking around swapping in an Rx-8 trans anyway) sounds a lot better. Also I'm looking to make around 350whp so your statement plus availability make the Renesis sound promising. I'll be installing a Fueltech ECU soon so I'll have a standalone to control it.

Slides

Can fueltech interact with the factory systems or it it the new Microtech lobotomy?

Dak

That's a good question. From a quick glance I found this for the FT550 " • OEM CAN partial compatibility with: C6 Corvette, C7 Corvette, 5th gen Camaro, 2009 Cadillac CTS-V". So I gues it partially interacts with some GM stuff. Their core market is High HP drag cars. Since I've got an FC there's not much in the way of factory systems to interact with so I didn't even really take that into consideration. Its seems to be a competitor to the Haltech Elite stuff.

https://www.fueltech.net/products/ft550-efi-system

TeamRX8

iTrader: (2)

you misunderstand; for longevity and potential the REW is the better engine imo

if you have an RX8 then maybe swapping in an REW may not be an attractive option, whether it be for the cost, passing emissions, etc. then my response applies to that.

What needs to be understood about a Renesis is regardless of how cheap it may be to buy secondhand, if used you will need to buy new rotor housings and rotors right off the bat i.e. $$$, then machine the rotors for deeper 13B apex seals and associated supporting parts for that; more $$$. If you’re smart you’ll critically balance the rotating assembly too; more $$. Once you understand this and a few other things it’s not as cheap as it seems.

Because people again fail to understand why the Renesis is different and then why the sealing is much more critical and that critical difference being why you can’t just reuse those parts out of any old used engine. It’s the same reason why many Renesis NA engines end up only making 180 WHP and less. In the case of an NA engine, once you do make those mods and couple it with Iannetti ceramic 13B apex seals then you start getting multiple rebuilds out of those parts, but will likely still go through replacing them more often than a 13B. It will never make or exceed more than 240 whp NA if even that though depending on what it’s going into and the driveline losses. Some of the Mazda Pro Formula cars supposedly got near to that on Drummond engines, but they’re rear engine, direct coupled transaxle race setups with lower losses.


For turbo, with 10:1 compression rotors the fuel becomes more critical and unless you have ethanol or high octane options you can get into trouble real fast. It’s weaker, more likely to blow up, will never have the REW potential, and so on. Imo unless you have an Rx8, or trying to make some kind of point and have the money to burn, then it’s better to go REW/13B.

wrt the monstrosity known as the hybrid Renesis, it just makes way more sense to go 13B/REW than do that. Again, the Renesis engine cycle is designed entirely around a zero overlap exhaust timing cycle and then also depends entirely on the long intake cycle draw coupled with near perfect sealing to accomplish what it does. Once you add overlap, the long intake draw is now being polluted heavily by exhaust gasses and also it essentially creates similar conditions of a big intake PP without any of the advantages of why that can be made to work on a 13B. On the Renesis though, like a big intake PP you lose all the low end, but it never gains enough back on the top end to justify it imo. Then in addition to the output reality, there are now 5 exhaust ports to deal with, which in addition to destroying any hope of scavenging due to all the losses adding up from all those ports and different open and closing timing between them, it’s unnecessary complex, costly, and just an all around headache.

How big is the difference? The unported Renesis primary port opens at 3 deg ATDC, an unported REW primary port doesn’t open until 40 deg later. Yes, porting, the addition of BP, and such impacts all that, but that narrow BP eyelet opening is a lot different than the full side of the port opening up in one fell swoop and then again the Renesis multi-port exhaust was never intended for scavenging, will never offer scavenging, and only disrupts scavenging potential for the added exhaust PP. Another factor is the shared siamese exhaust port on the Renesis center iron. From a scavenging design concept it’s a total cluster. That’s not how it works, is why it will never work, but imagining your an F1 engine designer is a lot easier than actually being good at it.

but apparently Kyle Mohan, who’s been the big promoter of doing it, is supposedly building one now to show us all how it’s done. Unless he just never fully revealed the true results, I never saw anything prior from him or anyone else that was ever revealed publicly to justify all the cost and hassle of it. Which as a drift application nobody cares if it falls on it’s face below 5000, but even then I never saw anything that was all that impressive on the top end either, and that’s just comparing it to results we can find on this forum. Again, maybe he or others never revealed it all, but why promote and attempt to sell this and not publish impressive results, or for the people who spent the money, and a few have spent really huge amounts, you’d think that they would be bragging about it loud and clear. Yet to be fair, some racers might not want to publicize it, but we’d then see their competition results and what’s in the engine bay is not so easy to hide or disguise.

Most simply disappear, never to be seen or heard from again. The others out there publicly either failed, talked big doodley squat without ever showing results before swapping to an REW (you can’t make it up), and so on. You can pretty much thank the bastion of clueless noobs and all around dumber than dirt youtube smack talkers for keeping it alive despite it never actually accomplishing much of anything useful. Then again, in today’s virtual reality mindset you only need to imagine it makes big power, talk it up to get other people convinced and onboard, and whaa-laah … :face-palm:

I still say the only hope is to treat it like a turbo PP intake engine with big turbo and even bigger turbine housing to keep emap positive, but it then requires a bunch of other mods and still is flatter than Bonneville below 6000 with questionable high rpm potential compared to a 13B. If somebody can prove me wrong though, I welcome it if only for my own educational experience. Because I’m just not seeing it accomplish anything you can’t do with a 13B without having to go through all the rigmarole this hybrid idea requires.

Dak

Never mind. I think I'll just keep fanboying the REW and write the Renesis off as worthless for my application. In all seriousness I agree the REW is better I was just looking purely at the price/ availability of a Renesis. I also was thinking of using it with the ports in the stock configuration, no hybrid setup. I looked around on the Rx8 club and in my very short amount of time I spent there I gather that though a stock port Renesis will meet my peak power goal it won't have as broad of a powerband as a REW or even a 13b-t from a second gen RX7. Sounds like even a n/a 6-port from a 2nd gen Rx7 is a better starting point for a turbo build in an Rx7( which is what I have). Sorry for getting so long winded. Basically I'm planning to turbo my 6-port n/a engine in my S5 Rx7. I am only a front and intermediate housing short of a complete S5 TII( 13BT) engine that is if the rotors are usable, but they are pretty rusty. I was thinking ahead to the engine after the TII engine. With TII engines almost non-existent and 13B-REW's priced through the roof I thought the Renesis might be a way to stay rotary and not go LSX at some point. Sounds like it's not. Thanks for your detailed reply. It was really helpful.

j9fd3s

iTrader: (3)

Mazda still makes engine parts, even for the T2, and you're allowed to buy them , even for the T2

Dak

True. There is that option at the moment. I think I just remember the days when complete JSPEC 3rd gen engines were $2500 and 3 rotors were $5000 and I get sticker shock when I look at current prices.

dguy

iTrader: (8)

Yeah but bro you can't get them as $500 junkyard donors and make 123120387 horsepower!

TeamRX8

iTrader: (2)

that was a long, long time ago, grandpa …
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Dak

Seems like yesterday when you get old like me. I can't believe it's been eight years since I built my current engine.

peejay

You could also buy a Turbo II for like $3000 instead of $25,000.

rx72c

iTrader: (8)

Our Renesis builds are making 40RWHP more then factory with just a bridgeport and nothing else changed. With a throttle body upgrade we are seeing just over 60RWHP gains on stock as the engine starts pulling vacuum over 7000RPM. With the OEM throttle body we are pulling 3 inches of vacuum at 9000rpm.

We are seeing the same gains come accross in our turbocharged renesis builds as well.

There has been no need to machine the apex seal slots to the deeper counterpart.

Before all the endurance haters come out, we have the RX8SP which is turbo charged with an EFR8374 does around 6 hours of road work a week, 2-3 hours of racing every week for the last 18 months with 0 issues.

Yes they are a different engine, they need to be treated differently to work. People need to stop trying to make them a rew. We have seen 0 HP gains back to back with PP exhaust ports. Less down low power and nothing extra up top.

Something else to note, with higher boost levels the plates seem to be weaker then FD, we have seen them crack around the front stationary gear over 30psi of boost.

As far as engine efficiency is concerned, IMO they are far more efficient then a rew. The thin wall 10:1 rotors do pose an issue, they are super sesitive to detonation.

Brettus

Woah.............. , gotta say I'm highly sceptical .... please show us some dynos.

peejay

I find that really interesting. Some road racers here have completely given up on the side exhaust engines because they simply do not last in any kind of road racing environment, the side seals give up the ghost fairly quickly, and this is in naturally aspirated form. So, I am somewhat curious what different is happening here.

TeamRX8

iTrader: (2)

you pre-Renesis guys are so ingrained in what you’ve known for so long you can’t get past it to understand something different.

It’s not a 13B, despite the apparent similarities a Renesis is based on an entirely different intake/exhaust cycle concept. That being a no-overlap exhaust cycle coupled with a very long-draw intake cycle and a highly refined staged, critically helmholtz-tuned, intake manifold of which the performance is critically dependent on perfect intake cycle sealing.

There’s no exhaust scavenging and there never will be. It’s all about the intake side. Once the sealing starts going off; whether from wear, sloppy build tolerances, or the equivalent; intentionally adding overlap, it’s all downhill. Until you can get a hold of that in your mind then you’re never going to understand why the usual 13B techniques won’t work on a Renesis.

adding bridgeporting to a Renesis is the quickest way to ruin it.
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peejay

That's nothing "entirely different", it's just port timing, nothing more.

That's patently false, as you as assuming that the exiting exhaust isn't pulling the chamber under a vacuum before the port closes, just like what happens in negative-overlap piston engines. The blowdown effect is real and the exiting exhaust has inertia to go along with its velocity.

TeamRX8

iTrader: (2)

It’s simply not, and even Mazda clearly recognized this. Otherwise they wouldn’t have left it on the table.

If exhaust scavenging theory is truly understood then it should be clear why that’s not possible. It has to be viewed in entirety, not just one small piece as stated above. One of the main reasons being that the exhaust port closes in a progressively bleeding manner at the closure point rather than abruptly. There are physical constraints of the side port configuration that dictates this and are not easily overcome in the standard 13B dimension geometry. Which is partly the reason why the Gen2 version was moving to a revised geometry 16B. Further, the siamese port is only 3/4 the size of the end ports and split in half with an abrupt divider wall in the center; which relegates it to down to 3/8 size per rotor.

16 years and I’ve seen way more engines lose power than gain, but go ahead and be the first to demonstrate otherwise … because again; show me, teach me, expose the error within me that I may grow and learn. I have a lot of respect for your insight and experience on the pre-Renesis engines, and no disrespect is intended by claiming that those words only demonstrate a lack of familiarity with the zero overlap concept. Because again, it’s extremely unique, not well studied, or understood. It took me many years to get where I am on it now, but I first recognized back in early 2006 that exhaust scavenging isn’t possible on a Renesis. Then built my first non-tubular exhaust racing manifold for it.

Yet a few years later I was on the same boat as pretty much everyone else about a hybrid Renesis with 13B rotor housings, but then came into a better understanding of why the idea can’t and doesn’t deliver. Because it’s not based on physical reality once you sit down with the Renesis SAE paper, understand all the changes Mazda made and why they made them; which not everything is revealed in full detail. However, once you get deep into the assessing the details and conditions with sound logic and understanding, then it should be obvious why it’s not going to play out as might be supposed when glossing over all those things. Be honest now, if it was really that simple, then after all these years where are all the outstanding results and proof of it?

Those who believe it’s possible to pull a vacuum on a closed chamber with a progressively slowing port closure and then carry that vacuum over to the intake cycle are in error. No, it’s not being thought through properly.

peejay

"Zero overlap" is not unique in the slightest. There are literally millions of piston engines on the road with zero overlap. To believe that it is something unique and new that Mazda invented from Yamamoto-on-High is like drinking the kool-aid that shoving the engine back three inches is somehow a brand new drivertrain layout (the "front mid engine" bullshit).

Mazda the manufacturer has production constraints that the aftermarket performance engineer does not have to consider: NVH quality, and emissions. Emissions is more or less zero if yo have a catalyst and closed loop fuel control, except for cold start emissions. So Mazda's goals are primarily to get the engine to run stoich under as many scenarios as possible, and to get the cat lit as soon as possible. The side exhaust's port timing allows the engine to run at idle and low load at stoich, something peripheral exhaust engines fail to do. Close coupled catalysts light off quickly and preclude the use of a tuned header. Such is the reality of the modern production world.

j9fd3s

iTrader: (3)

interestingly the Skyactive cars have a functional header with a close coupled cat, i guess it costs them $$ and a lot of space (it sits between the engine and driver)

the Rx8 though has a cat under the car, and its probably further from the engine than any other Rotary. its actually far enough back to melt the gas tanks peripheries. its not an engine fire like the old cars, but still fire, so compromise?

TeamRX8

iTrader: (2)

No, we're specifically addressing the Renesis engine and that's just a bunch of talk. So again, 18 years later and there's nothing specific to the Renesis to show otherwise. When you have something to actually show me, I'm all eyes and ears. I'll built this back in 2006 and will put it up against any other Renesis exhaust manifold/header, any day. There's no tuning; just as free flowing as possible to minimize back pressure. That's it.

peejay

What is interesting about that is that someone took a NASCAR engine, which is probably the most highly developed type of two valve engine ever made, and replaced the ultra-tuned headers with some 8" stubs dumping at right angles into a 4" "collector" kind of like what you had done.... and the power was almost the same.

Something a ways back thatcis tickling my memory is that on a peripheral exhaust engine, the first four inches of header design are the most crucial, and if you get that right the rest is mostly irrelevant. I always kinda wanted to make a 4" long standoff and bolt a stock manifold to the other end, to test that theory. Left hand drive means no steering box in the way!