Brettus 20B Renesis Hybrid thread
 

So , there has been a bit of talk lately on building a 20b Renesis and it got me thinking. If I were building one , how would I do it ? So I devised a concept which I believe will deliver 320-350whp in a fuel efficient/street-able/affordable package.

Assuming those goals are achievable, my question to the forum before I pull the trigger is:

IS IT WORTH THE TIME AND EFFORT BUILDING IT ?

I've been teetering over whether it's worth pursuing for a while now, as I know I can make more power/torque and have a more efficient street friendly engine on a turbo setup for less money. But we all know how cool a 20b sounds so ...give me your opinions please.

PS : this isn't meant to be a technical discussion on HOW .... more about the WHY ?

20 b in rx8
 

I am putting a 20 b turbo, half bridgeported in 08 rx 8 with sequential 6xd tranny, Starting to get into the wiring, does anybody know do I need the computer under the engine managementt one? Using Haltech everything. The tranny can do wide open throttle and blip for downshifting, just a street car. I still want to maintain, cruise, air, steering wheel functions, remote entry, etc.

My last 20 B
https://cimg7.ibsrv.net/gimg/www.rx8...cbcbe14eb6.jpg
https://cimg5.ibsrv.net/gimg/www.rx8...26442a154e.jpg

.no.

Team - I was laughing cause your response reminded me of Mel Brooks “Silent Movie” where Marcel Marseau (spelling?) the famous mime says the only spoken word - NO.

It would be interesting to see it done. I don’t agree with the whole electric car thing. Just feel they’re an environmental disaster looming. The mining of mineral nodules from the abyssal plain (deep ocean) is causing unknown havoc all to source battery material .

The green attitude of new owners grates on me. The tailpipe has been moved from the car to the coal fired power plant or gas powered plant.

Damn I’m getting to be a grumpy old fart

Did anyone else have a good laugh at my expense? I did and it’s ok to point fingers.

I guess I need to be less rabid when the word “hybrid” comes up. Sometimes it’s not another battery car.

Sorry for polluting your thread.

Brettus - ignore my crap and proceed. I’ve enjoyed and learned much from stalking your other posts.

Thanks Meathead, appreciate the response.

Team ...why not ? Please keep all comments about why it wont work out of this. Assume it will work............ and then tell me why it's a bad idea.

Not sure how this turned into an environmental discussion, but I'll just point out that while the above is true, it's not like sourcing petrol is environmentally friendly and not all electricity comes from oil. It's a matter of degrees.

As for why you would build a 3-rotor Renny: I can see a couple of pros:
- more torque
- potentially better top end bsfc than a twin renny
- more return on your turbo investment (if you're going to do all that work, may as well feed a bigger engine)

It sounds like some kind of endurance race car to me :)

Loki , I'll be keeping my turbo setup for track. This engine would just be for my street car, the blue one I put the PP Renesis engine into.That engine gets huge attention from the boy racer crowd due to the pulse ....but that's not really my demographic ...lol

It will costs as much or more than a regular 20B for starters and it will require a lot more work to achieve that power level target out of it as compared to one too.

What is the actual context for making that power though? 1-port (PP) per rotor 2-port (Std) per rotor, 3-port (High) per rotor, etc.? Because those details are going to matter wrt effort and cost even if we don’t get into the technical merits.
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You're right ... It should be in the general discussion area. My bad.
And ..... Thanks for the on topic comments you did make.

I'm not going to be lured into a technical discussion .... but will say ..... nope!

I'm not going to go into that.
I gotta say , I was going to delete this thread after no-one posted anything for a while because I pretty much had the answer I was looking for from the the Purely forum. But then I found I wasn't able to so had to leave it here.
We can just let it die a natural death ...

I wasn't looking for advice on the build ... I have that part figured out. I have a builder itching to do it (that has built plenty of 20b s and believes my idea could work) , I have a car to put it in , I have most of the parts I need already.
I was just looking for a reason to do it! If the general vibe was .... nobody wants to see a 300+whp Renesis based rotary that could work well in a street car . Then I would just forget the idea.

With all due respect to every opinion given here, but here in UK a bunch of wannabe's managed to build a 3 rotor out of renesis housings and plates and it worked.
Any engineer in his right mind would have looked at that engine and said this is not going to work since the mid rotor would not breath as well as the others, is it ideal ? Hell No, but then again what exactly is ideal about a bloody rotary??!!
it worked and they have videos of it in an rx7 drifting and ripping wheels.
​​​​​i am not sure what the design would be but judging by your documented work, I believe it will be you that pull this off purely based on success statistics.
best of luck.

my 20 b dyno sheet
 

You were giving advice based on what you think is achievable . I asked what you thought putting all that aside. You can't do that and that's fine. I don't need to hear anymore from you. Byeeeee !

You are the only person that didn't understand what I meant... because you can't look past your current paradigm of what's possible and assumed it couldn't work.
Childish ? You do remember that you banned me from your sandpit (aka turbo thread) because you couldn't take the criticism?

Wow ...that's one hellova power curve ! Got any links to your build ?

Assumed what wouldn’t work? We haven’t even established that yet. I don’t assume it won’t work. I don’t see how it makes sense to put that time and effort into a Renesis 20B just to get a lesser result from a real 20B, as per the that dyno graph. Or go choose an NA 20B graph if you think that matters.

I did get frustrated and asked you to leave back then. It’s not the same thing at all. That was when I was in the peak of the chemo and radiation treatment. I’m content enough to say I’m not the same person now either, even if you refuse to recognize it.
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Ok ... that's the kind of answer I was looking for ! Thankyou.

Have you ever driven a PP rotary 13b or 20b? If you have ...how was it for driving around town ? Stopping in traffic , taking off from the lights slowly behind traffic? Crawling along the freeway ? How was the fuel consumption ? I don't know the answer to these questions myself BTW ....but i'm sure you can see where i'm going with them.

Also ...did you know : a STOCK Mazda 20b makes around 230whp?

I already told you that in my second reply to this thread.

The factory stock 20B intended for a luxury car ... how many years ago was that? I guess all those details matter now. You’re something else. :)

Doesn't really matter ...no . But what can a normal 20b make and still be a practical street engine? Again ...I don't know .... but that's what we would need to compare the Renesis 20b to. If a normal 20b can make 320-350 and be a practical street engine then my proposal is a waste of time.

I agree 100% ,and I'm not thinking of doing anything like that.

It might be you whose mind explodes when you do see what I have planned though ...lol

good, I look forward to that day then

but to answer your question, 20B NA can get about 300 whp 200 ft-lb streetable, addition of staged ITB semi-PP can get 350 whp helping flow more at high end without hurting lowend, higher if you’re will to sacrifice some driveability.

With PP it just depends what you call streetable. I’m not convinced it will work well with side ports because they only support so much hp/flow. You could see that with the one aviation PP motor that was built compared against a well built stock port; it made an ok number within the side port limitation, but only for a 1000 rpm range and suffered a lot below and above it. Which the 20B Renesis center rotor will be limited siamese only exhaust ports. A staged semi-PP might be ok to a point. The biggest hurdle is the intake system. Without the S-DAIS it will suffer at lower rpm. The semi or full PP might help it make a peak number, but torque on either side of that will suffer.

So I stand on my claim that it won’t be worth it even if it makes that output range in comparison, but based on the basis of my general understanding since I’m not clear on what you’re plan is. A standard 20B engine is quite expensive. A Renesis 20B engine might initially cost less, but you have to spend money in other areas since there was never a factory version, like intake and such. Even if you position the PP to not have overlap, I don’t think it will be able to handle the exhaust flow requirement, but maybe. Overlap is not a solution to anything, but again based on all the configurations I’m familiar with.

I can see how thinking the addition of a PP to a 4-port would help it transition to 6-port like power and the addition of the 3rd rotor help to offset the mid-range TQ loss of not having a staged SSV, though you can stage all that with enough $$$, but the effort and overall cost still has me in the “no” category.
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Going off those numbers ,I would expect it to do better that a ported 20B down low and equal to a ITB semi-PP up top, with better driveability, better fuel consumption and a lower all up cost than either of those two engines.

Does it dispense gold coins out the tail pipe too, lol.

I’m obviously not envisioning the same thing you are. It must be as wild as you claimed, because I can’t comprehend how you’re going to accomplish that.

I'll look into that as an optional extra :p: .

FYI, Defined's ITB semi-PP made 476 WHP.
CLR has a full PP making 486 WHP

I would personally take the 10hp less for more drivability.

As far as a 20b renesis, if I was going to do it... I would have to insist on 6 port base design, and all 9 ports staged like the factory renesis, and probably semi pport setup similar to what Defined did with their setup where the p-ports have a slide throttle to close them off at the housing until they're needed. Also, the thick iron would have to be 100% port matched to the stock renesis porting. Exhaust setup would be the big unknown for me, so not going to get into the theory crafting in all that nonsense. you guys do that enough hahaha.

I'm kinda with team though... after you go through that whole laundry list of things there's just no point, as nothing really justifies the cost. Event an original 20b will cost you 6k for a # - C series block. D blocks are 15k used now. 3k for the rebuild kit, the eshaft will most likely be bent limiting you in RPM range (Defined number required 10k rpm, and CLR did it at 8.5k), labor, etc. You're taking a 10-15k engine just to start, and that's an off the shelf engine, and stock. i would imagine this hybrid could easily cost you 20~25k in just the engine. gets hard to justify those numbers for under 500WHP. I know I'll be well over 30k into my 20b swap alone. I'm at least 15k into the block already, and I don't even have it in my hands yet. With a D block I would be pushing 21k into the block alone already. I fully expect the # - C blocks to come up to the D block price over the next few years. New OE thick irons from mazda are 6k, and new eshafts are 9k. The prices are getting scary. I only paid 2k for my first 20b....

If you have the cash to burn, give it a try... would be interesting to see results.

I have had a quote to build the engine for around (edit) 10k $NZ ($6600US) using mostly parts I already own. I also have a mock up of the lim and the uim which have cost me just time and 0$ so far. They will require some machining and welding to complete ... not a whole lot.
I've said it should make 320-350whp, be very streetable and even relatively economical to run and I stand behind that statement 100%.
I see it more as a cool alternative to a turbo Renesis rather than trying to duplicate what a semi or full pp 20b can do. That's because power will be in that sweet spot where the existing drivetrain can manage it without destroying itself.
However ...I have not pulled the trigger on the project yet . My biggest concerns are around the costs of modifying the chassis to accept the engine .

Not to mention ...... I already have a well sorted fast spooling 400whp turbo Renesis plus a very strong N/A 6 port sitting in the gge so I'm struggling to find a good reason to do it.

Since there is no room to shift engine backwards, I'm also skeptical what it would do to the handling. Then again, a 350WHP engine that can take more or less all abuse you throw at it, does not sound that bad.

Throw out backseats and make a mid engine 4 rotor RX8?:D

It would be a short crank 20b (no mazda 20b parts involved)
so not so heavy as the wide Mazda 20b . Battery in boot will mitigate the balance somewhat.

it will still be 130mm longer and require a short-crank 20B 2-pc e-shaft (typically $4000-$6000 USD new) with either custom studs or custom tension bolts

how were you planning to address it extending into the front of the subframe?
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A company here makes the 2 piece shafts for a lot cheaper than that ! ............... 3 rotor short crank , centre plate bearing mod,20b counterweights , through bolts, dowells and seals ............all for less than the above.

Re the subframe .......... I don't know ...my engine builder seems to think it wont be hard to do along with a power steering setup ... I'm a bit nervous about that aspect TBH.

seems like it must be Green Brothers then, I have one of their 2-pc 13B shafts I bought 2nd hand unused for pennies on the dollar

These guys : Rotary Parts | Precision Engeneering

I have a universal flaming river steering rack. Some guys have used FD racks. You have to either extend the subframe, or make a new one. I'm going to make a tubular subframe, and use the MR2 Spyder electric power steering pump.

Jeff Bruce is a better choice for sure, surprised it’s that low though

Looks like that is Jeff's company.

Weight distribution front/rear yes, but inertia is increased. I think inertia is a good part of the "feel" of the car. I believe relatively little change in inertia is detectable, and often overlooked.

Putting a LiFe battery under the hood isn't the end of the world either, and removes the weight instead of adding weight with heavy cabling and moving weight around. Some people fight it to the end of the earth but I'm curious how many of them do so because of experience..

so much fail in one thread should never happen

Just weighed a rotor/housing/plate and eshaft which should approximate the added weight (less from the eshaft more from lim and uim etc).... Came to 28kgs . X-member may add a little more ...maybe 35kgs all up heavier.
That's less than half of one person ... and it mostly down low .

One thread?

Yes, you guys posting about inertia effects of battery location, or added cable weight of moving a battery that doesn't like heat exposure to the trunk for that protection, and other such nonsense.

My extra-length battery cables added maybe 2 lbs if that to my 10 lbs of battery and mount weight, which has a 1000+ CCA capacity, and it was all routed down low on the passenger/RH side to help offset the usual driver/LH side weight bias, but let’s not fuss over the particulars like your car not cranking on a regular day or flooding on a cold 32*F day and other such nonsense because the battery is too small/low in capacity or on it’s way out due to excessive heat exposure. Which I’ve dealt with all those things since 2006 except fortunately never flooded because I was fortunate to have a battery jumper box on standby. Trust me, some extra weight for some extra protection is worth the hassle and inconvenience of every time that happened in the past before I finally wised up and paid the price to do it right. I obsess about weight as much or more that anyone, but do also appreciate and understand the give and take nature of it; cut it where you can, concede it where you must.

otherwise the weight addition Brett mentioned is expected and not really the issue. If you understand the subject at hand then the issue is more about the engine management mods, custom internal engine mods, custom intake, custom engine brackets/mounts, custom subframe mods, custom exhaust manifold, custom fuel system mods, and so on in total, yet is still supposedly economical. It’s still basically a full engine swap, which in other threads is proposed as the opposite of economical by the same person without all those same consideration or to a lesser degree. Of course I can speculate on multiple scenarios and assess how it could possibly have good fuel economy and hit the projected whp target, but would prefer to wait and see what Brett specifically proposes to accomplish such a lofty goal.

not that any common sense should prevail ... because some of the commentary represents the wild @ss speculation Brett speaks out against, but then he also doesn’t fully appreciate the difference between those kind of comments and someone who may have the experience to wield it properly and make accurate assessments. Then again he assumes what is known without having any clear understanding to the sources of the knowledge based on what may or may not be posted on the forum. I share plenty in due time, but not necessarily everything for my own good reasons. The recent 4-port ported thread discussion as one of many such examples.
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When I say 'economical swap' I mean that as a relative term, as in ; by comparison to a traditional 20b. Same goes for fuel economy.

And yes I do realise all that needs to be done ..... I would have just done it by now and not procrastinated for so long otherwise.

I don't discredit your experience or choice. I do know, however, that at least some lightweight starter LiFe batteries can handle years of track use in an Rx8. Maybe these cars that use them (mine included) are not stock cars nor do they see climate extremes or daily use, but that doesn't discredit them all together.

Without getting into specifics of how this will be achieved (shouldn't be too hard to guess) I may as well divulge the basics of the engine setup proposed. It's kinda looking like I wont do it anyway so may as well discuss the merits or otherwise of such a setup.
Here it is:

2/3rds Renesis 6 port with full s-dias .................1/3rd semi pp intake (staged) with pp exhaust . No Siamese ports.

Obviously it will require ability to tune each rotor separately but if that can be done .... it should meet or beat the whp goal no problem while still being fuel efficient (for a 20b)

I like the way u think, and thx for linking me to this thread.:ylsuper:

@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 "thick" center plate. Btw, why are you no longer pursuing such a build?

P.S. I really wish aluminum/billet Renesis plates were a thing...:(

Nope .... Renesis centers with one side blocked and other side dedicated to an outer rotor.
We have a firm here that does the center bearing mod. How good it is ...:dunno:
I decided to pursue the turbo manifold instead because it worked so well. The 3 rotor project would be a huge undertaking and I wasn't ready to go down that rabbithole.

I won’t waste time any further here to even post something condescending :suspect: