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May as well post these pics as It's highly unlikely I'll ever do this . But this was the major part of the concept I had for it . Also considered blocking off the siamese to the middle rotor which allowed two FULL sized side exhaust ports to the outer rotors.
Note that the PP intake for the middle rotor is controlled by opening the SSV valve which would help make the engine very streetable.
You can see how this could make 350whp, make good low end torque, be streetable and way more economical than any other 3 rotor.
if you want to ignore that it combines the principle of both overlap and zero-overlap design concepts, which require completely setups and are not really compatible in tuning design. Plus you have to get that manifold pieced together and functioning properly. Not saying it can’t be done, but not as simple as it seems ime in the custom metal fabrication business. It seems to me that whp claim is a bit of a stretch. That’s equivalent to the whp of the best Renesis 2-rotor engine not often seen yet does exist (233 whp) x 1.5, yet you don’t have that on the center rotor. Getting 140 - 150 per rotor with a PP intake/exhaust is doable, but the requirements are very particular.
Which as I attempted to explain in the other thread, a PP intake/exhaust requires the right combination of everything to make any reasonable power. Simply having one is not any guarantee of anything. I’m being sincere stating that I’m struggling to see that happening in a combination-hybrid setup like that. On the other hand, a short crank 20B PP engine based off the earlier 13B parts should be able to hit or exceed that target fairly easily with the right parts and not needing all that trickery (3 x 120+ whp per rotor).
I give you a lot of credit for ingenuity behind the idea, but have scratched off a number of ideas myself making the same kind of assessment.
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I agree It's a bit of a stretch to get 350 ...it requires everything to work in harmony with existing runner geometry and that's unlikely . Not impossible but unlikely. So best case the Renesis sides make more than a stock Renesis due to the larger exhaust porting plus a little intake port work and the middle rotor makes something close to what low power PP engine would make ...120 per rotor is a possibility so 360whp. Worst case it messes up all the intake dynamics and only makes 100 per rotor ........... 300whp wouldn't actually be THAT bad in a very streetable not to gas hungry combo.
As far as tuning goes ...it would be a challenge for sure.
And to your point re the 13b 20b ...yes but .......... will it be economical , street friendly or as cheap to produce as what I'm proposing ?
well you need a custom short e-shaft regardless and doing it PP that way eliminates the cost for the rare $$$ wide center housing and the other 20B specific plates and housings. It won’t require a large intake PP to hit 120 whp per rotor, but economical it won’t ever be. If economy comes into it, why even do that compared to a G25-660 on a Renesis 2-rotor with 350 whp? If anything it only makes a great selling point when your kit becomes available. The only reason to go there over 2-rotor FI is to have a higher power NA screamer. Thinking you’ll get that and good fuel mileage is a bit “fuelish” imo
well you need a custom short e-shaft regardless and doing it PP that way eliminates the cost for the rare $$$ wide center housing and the other 20B specific plates and housings. It won’t require a large intake PP to hit 120 whp per rotor, but economical it won’t ever be. If economy comes into it, why even do that compared to a G25-660 on a Renesis 2-rotor with 350 whp? If anything it only makes a great selling point when your kit becomes available. The only reason to go there over 2-rotor FI is to have a higher power NA screamer. Thinking you’ll get that and good fuel mileage is a bit “fuelish” imo
That's kinda why I went for the 2 rotor turbo project over this . But hey , it's not all about having the most practical or best solution ..... sometimes something like the exhaust note alone can be the biggest single drawcard.
I never meant to imply it would be economical ....just not ridiculously hungry like a normal 20b that makes that kind of power. Maybe around the same as the 20b Mazda made.
@TeamRX8, just because a 3-rotor Renesis is cost-prohibitive or not worth the $ doesn't mean it shouldn't be done. I'd argue that just having the data/results from such a build would be worth the endeavor. Sure, you can make heaps more power w/ a typical turbo 20B, but that's already been done many times the world over. Don't you want to see something new, especially w/ Renesis parts? I've only seen 1 example thus far of a 3-rotor Renny. Honestly, this is the kind of build where cost should more or less be disregarded. This is basically "dream car/build" territory. You don't skimp out on builds like this.
Anyway, my take on a "20B-MSP" would be to forgo the turbo that most 3-rotor builds include. I'd prefer a 3-rotor Renny to be either N/A or centrifugally S/C. Now, hear me out... the goal shouldn't be absolute maximum HP. That can be achieved via a traditional 20B or 26B build. Imo, I'd love to have a motor w/ the feel of a Renesis, but simply larger. Basically, it should rev sky high w/ a torque curve that just keeps on giving.
Does this mean you'd essentially be using center plates w/ blocked off exhaust ports? (Or REW center plates?) What are your thoughts on center bearing mod on a short-shaft setup? I've always wondered how that'd work w/o a
I was smart enough to have ignored this time-suck commentary before, and only point it out now for what it is. The “you don’t skimp out” hubris is a classic for all times sake just before blindly leaping over a wall not realizing there’s a 500 foot cliff drop on the other side straight down to razor sharp boulders at the bottom. It’s one thing to make the leap yourself, it’s something entirely different to be encouraging others to do it.
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With all the billet plates going on and how 3D printing has become more accesible, wouldn't a custom e-shaft and center plate matching the renesis side exhaust and apv, so you can get all rotors breathing the same, be something more practical? you'd have to compare the cost of buying/rebuilding a 20B vs the cost of a used renesis engine plus the one you'd have and these parts. It would be a thick plate but would also have place for a bearing to support the extended e-shaft. I'm sure it could be designed and built though, just don't know at what cost and if it is at this time worth it vs a 20B.
With all the billet plates going on and how 3D printing has become more accesible, wouldn't a custom e-shaft and center plate matching the renesis side exhaust and apv, so you can get all rotors breathing the same, be something more practical? you'd have to compare the cost of buying/rebuilding a 20B vs the cost of a used renesis engine plus the one you'd have and these parts. It would be a thick plate but would also have place for a bearing to support the extended e-shaft. I'm sure it could be designed and built though, just don't know at what cost and if it is at this time worth it vs a 20B.
Technically possible I suppose but the more I think about the complexity of the supporting parts .... the less desirable it gets . The design above is bad enough as far as getting everything to work smoothly and reliably - but certainly do-able.
Good luck getting a billet to work long term with a high temperature side exhaust port, something nobody has attempted and likely to prove more difficult than a side intake port.
A pure custom job too because nobody half way intelligent is going to stick their neck out producing any quantity of those for an unproven Renesis configuration. For which there’s no intake manifold to provide all the necessary runner valve sequencing configuration for either. That would be completely untested as well since the original intake was only designed to provide the proper resonance features for a 2-rotor on an NA application. Likely not as critical for FI though, but only serves to highlight how these things are so easily glossed over. Anyone who sees it happening for less than $20k USD is most likely not considering something.
The 20B Turbo RX8 in the FS area was purchased with the swap already done, but in need of work. Even after sinking money into a mostly new engine build it ended up stinging that new motor on the dyno due to not going all the way financially to make sure everything was in order. I still say most people underestimate the financial commitment required, yet attempting it with an unproven Renesis configuration elevates this to an entirely different risk level.
If somebody is willing to commit financially there will be any number of people willing to take their money and build it regardless of whether they think it will be a total bust or not. That’s a fact.
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A bit negative today huh, been lashing out all over other posts too. Anyways, this I guess, is merely a theoretical exercise. My point being that technology has become much more available at a reasonable cost compared with say 10 or 15 years ago. CNC machining, 3D printing, CFD software. Yes it's experimental and it won't be cheap, but because of these technologies available at a lower cost, a one off is certainly possible. The advantages N/A would be probably a broader powerband more than peak power, which in some applications is interesting.
Billet wise, I imagine different materials can be selected other than aluminium.
You can call it whatever you want; there are real world issues to overcome. Let’s be clear that I’m not offended by being questioned, challenged, or even being responded to by ridiculing opinions, but am not going to play games with people not doing their homework first, pretending cost doesn’t matter (99.99% because they will never have that kind of money to burn), trying to spoon feed illogical hubris, and so on. There’s 18+ years of that on here, but most people can’t be bothered with making the time to find it. A few people on here lived it though, including me.
There is a company in Australia that offers end plates in iron, but they’re a different style of 2-piece; inner 1/2 and outer 1/2. Regardless of whether it’s that or the other 2-pc type with aluminum housing and iron center, you still have a high temperature side exhaust port to deal with. A 2-pc with side intake port you can just seal easy with an O-ring, but for the 1700*F exhaust stream thats likely to be an issue. So it’s an easier proposition on a peri exhaust port like the earlier Wankel engines and I also don’t ever recall seeing a 6-port configuration version either.
So when you really sit down and look at it rather than just talking about if off the top of the head, there are some very real technical challenges to overcome. Yeah, anything is possible with unlimited cash flow (paging Jeff Bezos), but that’s another reality to face. I won’t call anyone foolish to propose spending 3x+ more seeking youtube glory boasting about building a Renesis version that will be lucky to last 60,000 miles before losing compression, because that’s not necessary. The obviousness of it speaks plenty for anyone with a sober mind, but given where our society is today wrt disposable income and the insatiable need to be the center of glorifying attention it wouldn’t surprise me at all if it were to happen. Yet here on Rx8Club, never mind that nobody will bother trying to improve upon the intake manifold for a 2-rotor Renesis; either NA or FI, but building one for a 3-rotor and working out the proper resonance for it is no big deal. Yeah, ok.
My position on it is still the same; it makes way more sense on every level to build a 20B using the earlier engine parts, and that’s still a $20k USD or more proposition in the opinion of most people who are informed. Again, there’s one FS on here now and my personal assessment on deciding whether to buy it or not is that I needed to be prepared to drop another $15k after the purchase getting it all square and up to reliable specification. Mostly because the freshly built motor lost compression after suddenly going lean on the dyno due to a fuel pump failure. There you go; a “stuff just got real” moment when that happened.
Go propose this over on RX7Club and see what they have to say. There’s no shortage of dreamers and yammerers over there, but my bet is that overall my comments here will look tame in comparison. Because over there they have a much clearer perspective on what’s required without the “you’re just being a negative meany” malarkey.
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You can call it whatever you want; there are real world issues to overcome. Let’s be clear that I’m not offended by being questioned, challenged, or even being responded to by ridiculing opinions, but am not going to play games with people not doing their homework first, pretending cost doesn’t matter (99.99% because they will never have that kind of money to burn), trying to spoon feed illogical hubris, and so on. There’s 18+ years of that on here, but most people can’t be bothered with making the time to find it. A few people on here lived it though, including me.
There is a company in Australia that offers end plates in iron, but they’re a different style of 2-piece; inner 1/2 and outer 1/2. Regardless of whether it’s that or the other 2-pc type with aluminum housing and iron center, you still have a high temperature side exhaust port to deal with. A 2-pc with side intake port you can just seal easy with an O-ring, but for the 1700*F exhaust stream thats likely to be an issue. So it’s an easier proposition on a peri exhaust port like the earlier Wankel engines and I also don’t ever recall seeing a 6-port configuration version either.
So when you really sit down and look at it rather than just talking about if off the top of the head, there are some very real technical challenges to overcome. Yeah, anything is possible with unlimited cash flow (paging Jeff Bezos), but that’s another reality to face. I won’t call anyone foolish to propose spending 3x+ more seeking youtube glory boasting about building a Renesis version that will be lucky to last 60,000 miles before losing compression, because that’s not necessary. The obviousness of it speaks plenty for anyone with a sober mind, but given where our society is today wrt disposable income and the insatiable need to be the center of glorifying attention it wouldn’t surprise me at all if it were to happen. Yet here on Rx8Club, never mind that nobody will bother trying to improve upon the intake manifold for a 2-rotor Renesis; either NA or FI, but building one for a 3-rotor and working out the proper resonance for it is no big deal. Yeah, ok.
My position on it is still the same; it makes way more sense on every level to build a 20B using the earlier engine parts, and that’s still a $20k USD or more proposition in the opinion of most people who are informed. Again, there’s one FS on here now and my personal assessment on deciding whether to buy it or not is that I needed to be prepared to drop another $15k after the purchase getting it all square and up to reliable specification. Mostly because the freshly built motor lost compression after suddenly going lean on the dyno due to a fuel pump failure. There you go; a “stuff just got real” moment when that happened.
Go propose this over on RX7Club and see what they have to say. There’s no shortage of dreamers and yammerers over there, but my bet is that overall my comments here will look tame in comparison. Because over there they have a much clearer perspective on what’s required without the “you’re just being a negative meany” malarkey.
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Oh my, what a rant. It's a shame because within all that you have some good points, it's just hard to sort out through all the other stuff.
Anyways, if you are talking off 35K to build a turbo 20B, it's not too far off what I would think building those parts for a custom Renesis 20B would cost. The main reason is that tools and cost for one off production has come down significantly in the last 10 years. Anyone has a 3D printer to test models (look at Turblown with their Renesis intake), they do CFD, why can't they do a CFD analysis on a custom designed intake? My point, tools and materials are available to do something correctly, there's so many examples on the restoration world of one off pieces that it's pretty clear. It would be cool to see it. I don't see the real world application other than doing it because it's cool. I mean, look at Brett and his exhaust manifold, 3D printed a prototype, did some corrections, then have it cast, 15 years ago the cost would be prohibitive.
About the exhaust temperatures, I don't think it's a problem with an insert. You would have to sort out how different the expansion rate from the aluminium billet center plate is regarding the other iron ones.
If this discussion is of no interest to you, you are free to ignore it, the way I ignore discussions that are not of my interest.
it’s not a rant, it’s me taking the time to spell it out in detail to help people avoid falling for a misleading and not well informed smack talker. I’ve been through this many times on various subjects on this forum before with someone like yourself.
You’re not really grasping the exhaust port dilemma wrt a 2-pc billet. The castings from Mazda; whether side or peripheral exhaust port, are fully sealed between the water jacket and exhaust port, then an insert is placed into into the sealed casting cavity. That’s not going to be the case in a 2-pc billet with a side exhaust port. An insert doesn’t solve the sealing interface between the iron side plate and the aluminum housing wrt a 1700 *F exhaust stream passing through there, just as I attempted to explain in the previous post.
The only real solution in my mind is going to be a full-on custom iron plate. I have no doubt it can be done, the extreme cost adder of that one part is only one of many financial and technical challenges to overcome though. I consider it fairly minor in comparison to the intake manifold resonance design with valve actuators that will be required to get anywhere near the 13B Renesis output per rotor. Mazda dumped a ton of money into getting that right for a 2-rotor. The flow dynamic isn’t going to be the same with an additional rotor added into the mix. It’s a lot of customization beyond what it takes to put in a 20B Mazda engine.
The video link below is from 3 years ago and the cost is quite a bit higher now,then figure 1.5x - 2x more for a Renesis version with all the additional custom stuff required beyond what’s expected for a non-Renesis 3-rotor, plus the risk factor of it potentially not panning out. Yet you don’t even acknowledge that possibility, but that’s what not so well informed smack talkers do.
Even a 3-rotor PP engine based on the Renesis plates is a fubar proposition due to the side exhaust ports not being easily dealt with as can be done with a side intake port. It’s an issue no matter which method is employed. To pretend like it’s no big deal and easily overcome, when after all this time nobody has still done it successfully yet, is neither honest nor prudent.
Lots of assumptions there smack talker. I have no intention to build a 20B Renesis, not my field, not my interest, this is just a theoretical exercise but you seem to have gone past that. What I said, and I will say it again, today software technology is widely available for anyone with the knowledge and time, to simulate all these challenges you see and come up with a solution if they so wish to. No need to build anything, 3D scan and simulate the coolant/air flow and do the necessary changes to the design without physically building anything. I mean, come on, manufacturers build less and less prototypes and simulate everything, this software is available at a reasonable price and the only thing that costs you is time. You are an automotive engineer or someone keen enough to acquire the knowledge, you are just software away to design the parts you need. And that is my point. I don't have the knowledge, don't intend to acquire it (to do it properly), since it's of no interest to me and I have other things to spend my time on.
What I do, is research whatever upgrade or change I want to do to my car to save me the head ache and money burning of trial and error.
By the way, saw that video and know that channel. Basically it's all common sense if you don't want to just through money at it, do your research then do it, I don't see any huge challenge if you do your proper research.
We can agree on it not going anywhere, because you’re not really interested in it going anywhere. You’re only interest is to hurl insults and think you’re going to somehow show everyone how to put me in my place doing that. You then offer up that unlimited resources being no object, anything is possible. When that infinite wisdom also fails, you fold like a wet paper bag and being blind to your own position, accuse anyone not in agreement with you of being in lala land.
Essentially what you’re suggesting is designing the proposed engine like a manufacturer. Which again I’m not saying it can’t be done. The effort and cost of doing that with zero payback is not something that can be easily dismissed. I’m just an old guy and maybe things have progressed more than I’m aware of, but my expectation is that rarely do they just design it on software and pump it out. It typically goes through an iterative process of prototypes being built, tested, and refined.
Maybe there is someone out there with all of the resources to do this. Because after all we have private companies working towards space missions to Mars and other similarly complex technical challenges. However, the average RX8Club member can’t even build their own basic turbo kit from scratch. So when we return from the clouds of heavenly possibilities back down to the sober realities of an earthly existence, this isn’t likely to be built in somebody’s garage anytime soon with a result worthy of the financial input being made compared to a non-Renesis 20B. Which is all I’ve been stressing from beginning.
Yet you state my position is lala land compared to your position of unlimited resources make it all possible. Clearly you don’t just think I’m stupid, but everyone else too.
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Anyhooo ............. getting back to the concept I had.
Some of what's being discussed now is why I started this thread the way I did ...... to build something like this you need a pretty big 'why' . I struggled with that , even though it was something I'd like to do just to prove the concept, that's not enough when you have to pour huge time,effort and $ into it.
The final nail in the idea was when I thought about how it would sound. I thought about how the sound from the Renesis side might not be as great as the PP portion and this would dull it down. I don't think Team has any appreciation of this, but to me that's half the reason you'd ever have a 3 or 4 rotor.
I would counter such an assertion by stating that it’s the lack of appreciation by the other person regarding why such an idea is very unlikely to pan out as is being supposed. Which is a different design configuration proposal than building a true Renesis 3-rotor configuration as has been bickered about for the last several days.
It would be more accurate to say that what I’ve been posting trying to explain why attempting to marry the combination of a Renesis zero-overlap design configuration with a 13B high-overlap configuration into the same engine and it not being likely to produce a satisfactory result with regard to cost & effort is either not being understood or being outright dismissed without attempting to understand it. Pretty much like all the other proposals & schemes about hybrid PP exhaust housings, other methods to add overlap to the Renesis engine configuration, how a rotary engine can make more power on less boost, and so on have all pretty much proceeded exactly this same way over and over again.
Which, just as in those other discussions I fully expect to be called a fraud and poseur who has no idea what he’s talking about, again.
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Well .... with this concept you have as much experience and knowledge of what the outcome would be as I do ... zilch. Your negativity about why it wont work have a marginally better chance of being correct than my optimism that It would. But that's only because things like this tend not to work as expected. The dynamics of what would actually happen are way too complex for either of us to accurately predict.
It's that uncertainty that is the driving force for me and would be the reason not to do it for you
It’s fairly easy to discern the end result for someone who has a good grasp of the two configurations. I’m confident enough to take a hard position on it. No different than on past similar concepts where it was incorrectly argued otherwise in a similar fashion. That’s the real cause for uncertainty.
They’re not directly compatible, which is why that intake manifold concept is never going to work. The same will apply to the exhaust. It’d have to be setup as two separate engines configurations, yet it’s not separate and can’t be separate. Trying to do this rather than a standard 20B is a fool’s errand. It could even be tried that way with a std. 20B, but hasn’t been because nobody is really foolish enough to do that just because they think it will have a cool exhaust sound.
That's what you think ... you THINK you understand the dynamics ....you can't know that for sure and your insistence that you do comes from a place of pessimism..... not experience. Yes,it would be a big risk to take ...but that's how good things happen ...sometimes.
As an example:
You continue to belittle my N/A pp experiment as 'not working' which according to my goals it doesn't. But I've got people approaching me wanting to replicate it ...just for the frickin' BRAPS! It braps better than any other Renesis can and I'm constanly getting attention from that (not the kind of attention I really want but still ...) . Who would have thought that would even be a thing that people would want ? Certainly not me.
Maybe this hybrid 20b wouldn't be a 350whp screamer as hoped...... maybe it would be a 300whp well behaved, good all round engine that doesn't use too much gas and happens to make nice noises ? Perfect for a unique road going rotary ...maybe.
04-17-2021, 03:40 PM
