DriftWood

Well as the title suggests I'm new the the RX-8 community, but I am experienced in the RX-7 community and have owned a 3rd gen for about 6 years now so I am familiar with rotary terminology in general.

My question has to do with swapping a new (actually old) engine into the rx8. I would want to go two rotor to try and maintain the cars balance, but I want more power than an NA Renesis offers. I was thinking of going one of three paths and have questions about all three:

1. Swap in a 13b rew from a 3rd gen. I do all the work on my RX7 so I am familiar with this engine. Will the 13b rew bolt right up to an rx8 6speed? If so will the RX8 tranny support turbo hp? Does the 13brew drop right in or do you need custom motor mounts and subframe work?

2. Swap in a 13b re from a cosmos (I know it's actually a 13b rew also, I'm just trying to differentiate) Will this bolt up the the RX8 6speed? Does this motor drop right in? Does it need custom subframe and mount work?

3. Tear apart the 13b msp and replace the rotors with turbo2 rotors and install race seals, springs, and studs to strengthen it up and lower the compression. Then install a turbo kit. Will the RX8 tranny support this level of power? If not what transmissions can I mount up the the 13b msp (preferably without adapter plates)

Tell me your ideas. Let me know if there is something out there that I should be reading.

By the way I did search and found build threads, but they didn't have the detail I was looking for.

Thanks in advance

dznutzuk

All 13bs have the same pattern for the transmission, so yes both will bolt up. Now power wise everyone has their own experience and opinion. 13bre-you can modify your stock mounts like I did, 13brew(FD) will need new mounts. You can't change the rotors in the renesis engine.

BigTurbo74

Yeah you can make power with the renesis with some legitimate reliability upgrades. (i.e. proper ignition system, balanced turbo and waste-gate sizing, engine management, water and/or meth injection.... on and on.)

If you are set on a peripheral exhaust port 13b it will undoubtedly cost more for custom fabrication but gives you a little more options if you want to go all out.

Rotors are not inter-changeable but there is always a custom route.

The issue I have with and older 13b transplant is that the majority of the setups in my opinion need standalone engine management, but by doing so you will probably lose stock features that make the RX-8 unique within it's class. It's basically a compromise between dumb and powerful vs. smart and sophisticated. UNLESS you don't mind spending more than most...

The second you produce higher than intended torque levels, your stock drivetrain components are on a ticking clock towards failure. Even custom fitting a FD tranny is risky if it isn't at least had a good looking through, and then you have to decide what driving style your power levels will allow before something breaks or wears out too fast to make it worth the investment.

Sounds like you have had decent experience with your FD. I like to think FD owners eventually find out what it takes to go around the block good or bad. Good luck with your project.

Check out turblown.net they might have some useful things for you to investigate.

reddozen

iTrader: (1)

For the cost, if you don't already have another REW or RE block sitting on the floor, it would be cheaper to get a turbo kit, and tune it up to 300~450HP. If you're looking to make 500+, and with all the fab work included, you may as well pay an extra $1500 or so an get a 20b. They've come down in price a bit. I've seen them sell for as little as $2500 lately.

DriftWood

Yeah I have seen some cheap 20bs lately, but I would never trust them. Most of those are pre A series and have some problems. Plus rebuilds on 20bs are expensive and necessary when you buy one.

So from what I've read I think I might be able to work with the 13b msp. I'm only looking to make 350-375hp at the wheels, If I can get that (relatively reliably) without swapping I would rather go that route.

olddragger

iTrader: (3)

take a ride in someones rx8 that has a well installed fi system(turbo/supercharger doesnt matter). You may be satishfied with just a little less than 350 to the wheels.
If you can go ahead and put an 09 trans in when you build--i think you will like the ratios
OD

outinnowhere3193

iTrader: (2)

From my experience you drive like a old man...then the transmission will hold up....and even sometimes that's not enought it still dies. If you speed shift and do any hard shifting you can bet that 6 speed will die under hard power within a few months of abuse.


For the money lol Do like me and others...consider the v8 swap. it's cheaper if your doing the work and more reliable. My 383 stroker with 500+ na motor with the T56 trans is running me around 7 or 8 I haven't figured all my numbers but everything inside on all the 350 block is new.

DriftWood

There is no doubt that V8 power is good and reliable. I'm not interested in it for this build though. I will eventually get another 3rd gen RX7 and install an LS1 into it. But that is a few years off.

What I'm looking for out of the 8 is more power than stock to be able to compete with the STI and modded 350z guys on the street. I already have a track 7 with plenty of power, but it's not very streetable. I'm pretty much 100% sure I can get the car to handle as well as those other cars if I maintain the 2 rotor and because the 8 is lighter I think I can get by with 350hp. Because of the Cobb access port every STI owner now bumps their boost up to 20lbs and is rolling with about 360hp. I just want to be able to compete with them.

reddozen

iTrader: (1)

I feel your pain...
I'm hoping my custom supercharger will work out well for me. The first step is the bridge port... we'll see how that goes once I get it in hand. I'm just waiting on it to ship.