rksti89

i know there have been threads for this and i know alot of people are going to bash but here is my reasoning for wanting to do a 13b-msp swap into my fc.

1) the engine is overall better compared stock to stock to any other 13b n/a engine

2) it will produce more power. as i've read in the other threads it produces less than the acclaimed 240hp to the wheels. but you have to include these gay factors that cause that. the computer is tuned to crap and restricts ****...it does make 200+ but its at the crank(Essentric shaft) compared to the wheels, and lastly this car is over 3k. fc weighs what between 2600-2900(s4 base, no power anthing except roof, ps and ac).

3) it will cost the same if not cheaper than a good 20b swap. sure you can get a swap done on a 20b for 6k but not in cali. if i do a 20b swap here is what i see vs a msp:
a) cost of 20b vs msp alone. as far as i know a 20b in nor cal is expensive, and i've seen msp engines go for under 3k
b)ecu is going to be same for either engine as well as getting mounts
c) rebuild on either engine. if the msp is still good dont need rebuild. 20b i will do one because it is an older engine and idk how previous owner treated it and i know a rebuild on 20bs aint cheap. im hoping to get a msp in good-perfect condition cause i know those rebuilds are pricey. :[
d) they both bolt up to t2 tranny and as far as i know you can still use the stock or after market design of the msp flywheel. wither way i have to get a t2 drive train to mount up.
e)the only disadvantage i see with the msp is no ps and different throttle set up but my friends and i can be handy to figure the throttle set up and no ps is not a problem...i like manual racks :]

4)the engine will be california smog legal if i leave emissions on it and im pretty sure its possible to tune a standalone to work with smog ****.

5)exhaust isnt going to be a problem, i know a good shop that will do a full exhaust for under 200 if i supply mufflers and i buy cats from them.

6) this isnt the greatest point but for the power over my s4 n/a ill be getting decent mpg on a rotary. if i build a 200hp s4 n/a my mpg will definitely go down.

any imput on pricing on the engines, or anything else, is much appreciated.

*TOUCH*

iTrader: (29)

dude, im not gonna bash you becuase im all for creative swaps, especially when you keep it roatry. with that said, this is my input, and again, this is not aimed at you, just at the topic:

1) no. simply no. ok, from an engineering standpoint yes. it gets better mpg, better emmissions, makes marketdly more power than its predecessor, all valid points, but no, not a better engine overall in my book. ESPECIALLY for performance (i realize maximum performance potential is not your main goal).

2) mazda quotes the 13bmsp at making 232hp at the flywheel. heres some ideas of what ppl had to do to break 200rwhp http://www.rx8club.com/showthread.php?t=77031

3) i really cant say since the msp swap hasnt really been documented enough (or i havent read about it) to get a ball park on the cost/difficulty of the swap. regardless, even if an msp swap does cost less, there is something called worth. worth is essentially the proportionality of one thing expressed in terms of something else. for instance: a 300hp n/a 20B or 500hp turbo 20B swap is worth the monetary cost to most ppl. im not sure if an msp swap is. im not sure if the two should even be compared. (my opinion)

4) very valid point

5) also a very valid point

6) actually, youd be surprised. not sure of the validity of this or not (someone with actual experience please chime in) but ive heard of ppl getting near stock fuel mileage from NAs making close to the 200 mark by just tuning with something simple like an safc.. i have never really tuned a stock fuel system NA before but apparently they come from the factory with plenty of room to tune out fuel. like i said, anyone with actual testimony, feel free to tell me im talking out of my ***.

in the end, i wouldnt personally do this (i'm a boost freak and those msps hate forced induction w/ their non-peripheral exhaust ports and high *** compression rotors (10:1 i believe??) but i guess it would be interesting to see? at the very least it might shed some solid light onto this much-talked-about-but-seldom-attempted swap. gl either way dude

walken

iTrader: (6)

there is a dude on teamfc3s selling a ren swap. it was like $4500 for everything you need. the guy had it setup up in a older car so you should just have to fab a few things and be good to go.

end of the day its still 200hp and you could probably do that for the same money with a s5 engine and a lot less headache.

*TOUCH*

iTrader: (29)

i agree w/ walken, you might not get the same fuel mileage/emmissions but you get 200hp out of a 13b for a fraction of the cost and no headache. ****, you could buy a nice TII for $4500. (again, i realize power is not wour sole/main goal)

*TOUCH*

iTrader: (29)

hey walken, could you link that f/s post? i couldnt find it and im curious (im sure the OP is too)

arghx

iTrader: (3)

The only way to make it smog legal would be to use a 12V smog pump (LT1 for example) pumped straight into the cat. The Renesis doesn't even do that, it doesn't have a split air pipe. All the emissions are controlled by the ACV.

What are you going to do for the intake manifold? You could use a modified stock UIM but you would have to attach a TB with a throttle cable on it. Then you would have to control the secondary shutter valve and auxiliary port motors with a Haltech. And you would of course have to premix.

you better have a lot of wiring and tuning knowledge if you want it to run anywhere near like it does from the factory even

rksti89

thanks for the imput so far guys i like what im seeing compared to the previous posts i read in the other threads.

Touch, you make some good points. yeah your right the engine isnt better tuning wise but, with a standalone over the factory system i could probably find a way similar to the factory settings but way better power efficiency(not saying i can do it now but i'd find a way over time with help from my friends ). Compared in a smog legal sense it does work better, but like you said its your opinion and it would be what your after in a swap. On pricing, yeah 20b, re, rew or tII is worth it but in my circle of rotary friends there is a gremlin with boosted cars. all of my friends with boosted rotaries never have a running fc. im the only one because im n/a, not saying im scared of this gremlin but i definitely dont have the money to deal with rebuilds, etc......in fact my only friend with running boosted fcs is brandon who is running a stock turbo and a wolf 3d turbo but he has been messing with rotaries for 15 yrs+. mpg wise i can probably get out of my s4 or even a s5 but im into this swap for the challenge/exprience/ and the knowledge to pass on to others

walken i would love to see that


arghx... i realize that the intake manifold will be a problem but its something i look forward to figuring out cause i love rotaries that much lol but seriously, i know about the custom throttle body cause it comes with an electric one but i have master engine n/a building friends to help me with that ;] lol (10 yrs of serious 240Z building aint for nothing lol) idk about the shutter valve but i have my rotary master friend brandon and my rotary brethren here at rx7club to help me when the time comes, same with the aux ports but as far as i can tell i might wire them open 100% or have them open up like they're supposed to from the factory.

edit: oh and what are you refering to when you say the only way to make it smog legal? the msp or when you build a n/a s4 or s5?


Now im really serious about this idea and im in the works of building up funding for it. i know in my sig it says i have a TII engine but its going to be a completely stock motor or full race tuned engine for a track car in the future. basically its my safety net engine lol I'm pretty much aiming for the MSP to be a DD and Long Distance, with the ability for a spirited sunday drive, engine. thats why im not too concerned about its power potential.

arghx

iTrader: (3)

you're not going to pass smog with a Renesis in a 2nd gen unless you have a working airpump. The airpump and ACV on the Renesis is complex and controlled by the factory ECU, injecting air right after the exhaust ports. You would probably have to ditch the OEM one and rig up a different type (as I said, the 12V electric smog pumps from GM LT1 v8's would work) and send the air directly to the cat.

leaving the auxiliary ports open and the secondary ports open will make the car a dog around town.

If you are actually serious about this, and I don't think you are because you don't have a budget set and you've done no research really--start studying the Rx-8 factory service manual here: http://isomerica.net/~fluffy/Ren/RX8%20FSM/

especially the vacuum routing:







and how about all the OEM timing maps:


Leading timing advance , rpm vs load as measured at the AFM (.9 - 1.0 on the X axis is approximately WOT)


split map in degrees between leading and trailing

and how about a list of all the factory ECU calibration tables and what they do:

http://www.geocities.com/arghx/Rx-8_AccessTuner.pdf


Now read all that a couple times, so you understand how the engine you want to swap in actually works. Get back to us in a month so you can tell us whether you are still going to swap the motor in and how you are going to eliminate or control all the stuff mazda spent a gazillion dollars designing.

jjwalker

Just in my opinion, if you are going to do a renesis swap, you need to swap the ECU and wiring as well. Swapping the motor and intake system without the ECU and wiring, and expecting it to work, is going to lead to nothing but disappointment and wasted money.

Your best bet (still, this is just my opinion) is to do a very nice rebuild on the engine you have. Get rid of the exhaust diffusers, port the housings, and get some nice apex seals. All in all, a good rebuild will be cheaper, and I am sure more satisfying than trying to do a renesis bastard engine.

arghx

iTrader: (3)

you can't swap the ECU and expect it to work right. it will flip out and throw a gazillion codes because you won't have the ABS and traction control systems and all the stuff it expects to see, plus the anti theft system would be an issue I would think. it's a really complex unit man, the Rx-8 PCM is not some stone age piece of equipment like the FC factory computers.

jjwalker

Well, the issue still remains that it isn't going to work correctly the way the OP intends to set it up.

How did that other guy (he has a post in here somwhere) who put a renesis into an S4 do it?

*TOUCH*

iTrader: (29)

i dunno man, like i said, more trouble than its worth. the only thing positive about this swap would be originality. then again, putting a steam-powered engine into an fc would be original, but stuupid.

and arghx is absolutely right, the se3p ecu is VERY complex (like all modern ecus). its not an atari like ours...sadly

rksti89

arghx... thanks for all the info. i knew the ecu factor was going to be hard but your right i need more study time. ill definitely study up more while building up my money. if i decide to not do this ill at least have the money to go a different route. but right now im only in the birth process of this project which is just simply put, planning it out. i'll look over these with my friend brandon and see if its still worth it at this stage in my rotary life. if not right now its definitely something i really want to do later in life. idk why but i really wanna swap a MSP into an fc. lol

arghx

iTrader: (3)

Based on what I do know about the Rx-8, here is how I would control the stuff:

I'd run a Haltech and either use the stock Rx-8 CAS (if I can figure out how to get it to work) or put a 12A front cover on there (I've heard of people doing that) with an FC CAS.

I'd use some kind of GM throttlebody and TPS. I think I could talk to Black Halo Racing, which makes a throttlebody spacer for nitrous on that car, and see if they could give me ideas on how to mount a GM TB to the stock MSP UIM. I would block off the ACV.

Power/engine port stuff:

I'd use an FD vacuum chamber and 2 FD vacuum solenoids if I couldn't figure out how to get the MSP stuff to work.

SSV (secondary shutter valve, opens secondary port runners) -- switch that at whatever the stock RPM is, I don't remember off hand, using a vacuum solenoid. That would have to be switched from the Haltech.

VDI -- similar setup to the SSV I believe, just switch it at the higher rpm using a vacuum solenoid.

Auxiliary port motor--that's probably duty cycle controlled (would have to use a Haltech pulsewidth modulated output) or maybe just runs off +12V

VFAD (variable fresh air duct): this would have to be eliminated. It's a variable length intake (pre-throttlebody), which is pretty cool, but it wouldn't work right in an FC engine bay probably.

Emissions:

ACV -- even though it's really simple in the Renesis (one vacuum line), it's useless without the factory PCM. I'd just eliminate it and run an LT1 smog pump to the cat for an emissions test.

PCV -- catch can

evap system -- could run a charcoal canister or open vent depending on your preference.

OMP -- this is tricky. you would have to eliminate it because it would be impossible to control, but it would be better off with premix + OMP, because the oil injectors cool the side and corner seals as they pass over the exhaust port.

Idle Air Control -- unless you can drill holes in the LIM runners to mount one like on the s4 BAC valve setup, you'd have to run without an IACV and idle higher.

Engine mounts

that other guy who is working on the Renesis swap, I would get him to fab me some.

Then you would have to take some s5 n/a haltech maps and modify them, using the OEM timing maps as a basis to start.

arghx

iTrader: (3)

well damn, now i've got this renesis idea in my head a bit so I've thought more about how you could go about doing things.

the return fuel system conversion wouldn't be too bad. I think KGparts sells Rx-8 fuel rails for a return system.

The SSV for the secondary ports would have to be duty controlled based on throttle position. It's just like how the secondary ports butterflies open progressively on all the 2nd and 3rd gen TB's. So you would want to use say an FD wastegate or precontrol solenoid valve for that and a pulsewidth modulated output from the haltech.

But see, the auxiliary port valve motor would be pretty tricky to control. I think it is a 2 wire stepper motor, and according to the Rx-8 FSM it reverses polarity to control the direction of it. you can't just use an RPM-activated deal for this, as the FSM specifically says not to apply 12 volts for longer than 3 seconds (FSM section 3 page 103). You can't make a custom auxiliary port sleeve motor setup. It's been tried, and the only people who have succeeded are Mazda itself. And if you have to remove the auxiliary port sleeves you might as well wire open the secondary shutter valve.

If you can't control the secondary shutter valve and the auxiliary port motor close to the way Mazda does it from the factory, then all you have is a big hole in your pocket and a street ported s4 n/a with no lowend and a little more topend power. whatever custom intake manifold you make would be inferior to the stock one for sure.

it's kind of a hopeless cause man. And I just gave you the technical reason why: besides wiring them open, you will never be able to rig up a way to control the secondary and auxiliary ports in a driveable way. it's beyond the reach of pretty much any home DIYer. The control logic is so sophisticated that you can't rig it up in your garage. maybe Haltech or Motec could figure it out using some expensive hardware but that's it.

I mean I know there's another guy working on it, but he knows what he's getting into and the engine control limitations.

rksti89

wow all i have to say is thank you so much for your imput. i've never gotten so much tips/help info from anyone on this forum before haha. thank you

honestly i would have never come up with any of that so quick..it would have taken me months, and i'm starting to see the problem with the intake manifold and how its the biggest problem to tackle with this swap. like i've mentioned before: mounts, exhaust, getting engine, getting supplies wont be a problem. the only problem i'll really run into is the ssv, aux and the mapping would just take a while to perfect.

do you know the other guy or any other people currently doing a msp swap on this forum or others?? maybe i can check out their progress and see if i want to do this now or down the road.

arghx

iTrader: (3)

just search for Renesis swap. there is a guy doing all the mounting and stuff right now. I don't think he's worked out the intake manifold.

Even though Rx-8's aren't fast cars, the Rx-8 intake system is the most sophisticated unit I have ever seen on any vehicle. It varies the length of the intake pipe (pipe before the throttle plates) based on engine load. It effectively varies the length of the intake runners based on RPM (VDI system). It effectively varies the rotary equivalent of valve timing and lift in 3 different stages (secondary shutter valve, auxiliary port valve motor), and you can't feel any of it because it's so smooth. All of these functions are dynamically controlled by at least half a dozen different maps based on whether you are accelerating or decelerating (hysteresis maps), and in some cases how much load the motor is under. It is a brilliant design and a testament to the millions of dollars spent on it.

Why do you think intake and exhaust mods do practically nothing in terms of power gains? They made the intake as efficient as possible, and all the restrictive exhaust from the older rotaries is gone. There are no restrictive precats on the Renesis (thus less power to be had from exhaust mods) and no accelerated warmup system, yet it still meets cold start emissions. All the oiling issues aside, the Renesis is the pinnacle of the naturally aspirated 1.3 liter street rotary, and that's why Mazda had to up the displacement for the next motor if they don't want to go turbo.

rksti89

well thats mazda....investing everything the have into a one of kind sports car. lol what you just explained is the reason why i love the MSP engine. i truly believe it is a fast engine its just in the wrong car...the rx-8 is too heavy imo vs the fc. and i wish i could just simply take everything i need off an rx-8 to make that engine run and leave out all the restrictive control systems. is there any way thats possible or is it going to a be a no way in hell. cause as far as i know...its not possible. correct me if im wrong

arghx

iTrader: (3)

you could make it run, you just have to remove the auxiliary port sleeves and wire open the secondary shutter valve and VDI system.

If you've ever driven an s4 n/a with the auxiliary ports open you would know what I'm talking about--Utterly gutless under 4000rpm, hard to go up hills without constantly shifting, etc. If a Honda could be stuck in the high rpm VTEC cam profile, that's how it would run.

the difference is, it would cost a significant amount of money and only do anywhere from 180-190rwhp with basically no torque whatsoever because the intake manifold won't work right. So you get the power output of a stock Turbo II with a catback but none of the torque.

rksti89

so your basically saying...wait to go all out with this motor instead of trying to make it run factory everything in my fc or not at all? lol my friend vince keeps asking if i can just swap everything that makes the MSP run in the RX-8 and drop it All in my seven and run it pure factory for now. i keep telling him about the intake and everything but he doesn't understand it. Guess i gotta show him this thread and the links :P