13B-MSP swap
 

Hello everyone.. I was wondering if anyone knows anything about this if its been done before to a FC and what all do you need to do it.. Any info would be greatly appreciated.. also I when to the dealership and asked them how much for the engine and they gave me the standard, sports tuned, and mazdaspeed one which all cost the same.. and he couldn't really explain the difference (I'm a US Marine who lives in Japan so I didn't know that much Japanese to find out all the details from him)... he wasn't sure what engine harness would do too... hell he wasn't sure if it was possible.. but I told him it was.. hell any swap is possible... i saw a 20B go in a R33...

No, not really. Not practically, anyway. I am sure it can be done...but I am sure it would not be easy, and I am not sure it would be worthwhile. Here are some differences:

-the renesis motor mounts are on the bottom side edges of the block; there are no holes to mount your FC motormounts, and I'm not convinced there would be enough room to drill and tap them.

-the renesis pcm is a bitch...it is very complicated as compared to the control systems in the FC/FD/etc. Everything in the rx8 is setup on a serial bus communication system...for instance, I unplugged my rx8 gauge cluster while doing some work to the car, and later I got a CEL code because of it. :ugh2: It would be very, very hard to install this engine/pcm into a non-rx8 car. Some people on the rx8 forum are saying that if you do a simple PCM swap, that the dealership has to reprogram your pcm with a WDS machine to accept the other inputs from your car because everything was keyed to one single pcm. I do not know if I accept this or not.

-all the injection/variable intake/etc is controlled by the PCM mentioned above.

-the engine has no throttle cable....the throttle body is electric, drive by wire. None of the FC/FD throttlebodies will come CLOSE to bolting onto the renesis intake...so how are you going to control it?

-it uses a returnless fuel system so you'd likely need a higher pressure pump than the stock one in your car. I am not sure how a walbro etc. would perform in a returnless system.

-you can't put an FC/whatever other rotary front cover on the renesis; the renesis front iron is about half an inch thicker than all previous rotaries, and the front cover is made thinner to keep the overall length of the block the same. The renesis front cover also has the waterpump housing integrated onto it as one massive front piece.

-the renesis uses serpentine belts while the FC uses V belts for it's accessories. The renesis has no PS pump, so your swap would probably have to work without PS.

-one disadvantage to the renesis block: there is VERY little room to do any porting/smoothing of the intake/exhaust ports. There will be almost no gain from porting a renesis. Also, as of this time there isn't any aftermarket seal options for it...the rotors are cast so thin that you cannot *reliably* machine the apex seal slots for peripheral-style apex seals (what we use) or 3mm seals. you buy it for what it is, unlike rx7 engines that you make into what you want.

-another disadvantage to the renesis: when it breaks an apex seal there is no peripheral exhaust port for the pieces to exit...so they fly around until they eventually get out the side exhaust ports...when this happens they will wedge between the rotor and port, and most likely take the irons out with them. The typical rebuild parts bill for the renesis will be:

rotor, $250-400
rotor housing $500-550
adjacent irons to the affected rotor $350 x 2

On top of seals/springs/labor which is at least a grand-1500.

IN spite of mazda's early 247hp (flywheel) quotes and later revisions to 238, the "high power" 6 port renesis' have been making just at/under 190-200rwhp on the dyno.

Most standard FC NA ported engines with full intake/exhaust make about 160-170 at the wheels, and people have gotten 185-200 at the wheels with kickass tuning and standalone computers.

Bottom line, you're doing all the above mentioned head scratching and work to fit this renesis into your car to gain 15-25rwhp...and it will cost you a few grand for the engine plus fabrication. For that same few grand you could do pretty much any turbo rotary swap (13bt, 13b-rew, 13b-re, etc.) and make double the hp (assuming a few simple supporting mods) for the same money. Whereas the renesis pretty much "is what it is" these other rotaries can be modified to be whatever you want, and you have the potential for even more power later on.

To give you an idea, precious few are making over 300rwhp reliably on forced induction renesis' without them tearing up. I myself am strongly contemplating an engine swap to some other form of rotary in order to make any serious power in the rx8 platform.

hey thanks alot for the info then.. it sounds pretty convincing, I already have a turbo FC... I'll just stick with the plan I had going for it then.

Waitaminute...

You wanted to replace your 13BT with the engine out of an SE3P???


-Ted

Ha!

RotaryResurrection's post deserves applause -

There has been a full Renesis converted FB in Japan since 2004. It can be done if you're willing to put in the work and if know how to weld and fabricate. Not a worthwile swap in my oppinion becuase you can make way more power on a proven platform for much less work and less money. On the other hand I think it would be a great swap cause you'd be one of the few if maybe the only person with one. Many cool points...

I think the Renesis is pretty neat but I'm also a bit disappointed in it. The side ports are mostly for emissions. Everything else basically comes from shoving the best components around onto a rotary: most of which you can put on your FC's 13B anyway. It would be nice if Mazda mass produced the direct injected Renesis or at least invented one new thing besides "it passes emissions".

well, the intake manifold on the renesis is a pretty amazing piece too. I bet if it were bolted to a 6 port 13b block (and could be controlled properly), it would help the powerband a bit. It changes its length to try to produce a minor port pressure increase due to pressure waves, and from what i've read, is responsible for a bit of the renesis' hp advantage over other NA rotaries.

+1

most of the renesis' power comes at high rpm...it's ability to rev about 2500rpm higher than an s4 NA (and move extra airflow to match) is the most part of it.

It's my guess that a renesis with a peripheral exhaust would make even more power...but then it wouldn't really be a renesis any longer, would it?

The idea has also been thrown around to make a semi-pp renesis with both side and peripheral ports, but that'd call for really funky intake and exhaust manifolds.

ya.. i might try it after all.. I'm planning on trying to get a job as a mechanic at a garage or tuning shop in Japan after I'm done with my enlistment.. If i can pull this off to work well it might be my ticket...lol... Either way i know alot has to be fabricated but.. every engine swap there was had alot of doubts to start out first~ it does seem like ALOT of work.. but I'm obsessed about cars and its something i just have a "good feeling" about

Just getting the engine fitted in the car is not the biggest issue...getting the electronics wired up will be.

Isn't the renesis supposedly lighter and stronger?

Would FD rotors fit with standard apex seals?

Just wondering.

The renesis block would weigh the same...it is still iron and aluminum sandwiched. The intake manifold is simplified and half plastic, so you save a little bit there, just a few lb. There is no PS pump, bracket, or mechanical air pump, so you save a few lb there as well.

13b rotors will fit, but there is no cutoff ring at the oil control rings...the purpose of this is to prevent extra heat from deteriorating the oil control rings from the side exhaust. The side seal design and location has also changed, to accomodate the side exhaust ports and attempt to defeat carbon buildup and stuck seals.

One guy has experimented running the older rotors in a renesis (for stronger apex seals and lower CR) and tore the engine down and commented that he would not recommend them for long term use in the renesis, but did not give specifics.

Lighter?
Yes.

Stronger?
No.
That distinction still goes to the FD 13B-REW.

Gee, if you're planning on staying in Japan and messing with rotary engines, fuck 2 rotors - I'd be doing 20B's all day! :D


-Ted

If you want high RPM power, wouldn't a p-port offer that? While not so much the street car, it has the revs, no?

I'm gonna go with it... i found the engine with 23,000kms and the transmission for $3000 it looks clean as hell.. if i pull this off alone it'll be good resume material for getting a job with a garage or tuning shop in Mainland Japan... let you know how it works..

oo ya even here 20b's are hard to come by... and expensive to replace..