1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

RX8 Engine into a 1st Gen RX7?

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Old Jul 5, 2007 | 08:14 PM
  #26  
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Thanks everyone for your inputs.
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Old Jul 5, 2007 | 08:28 PM
  #27  
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The Renesis may not be able to take as much boost as a lower compression 13B but look at the horsepower advantage it has over a 13B sans turbos. The TII was either 182 or 200 hp with a turbo. The Renesis only needs a few pounds of boost to hit 300 hp if set up properly. If you are doing a straight engine swap, you can use a standalone ecu. No need to make it complex. Full control. Even Megasquirt can control a Renesis now. If you have a standalone, you don't need anything else that the RX-8 does to keep the ecu happy.

Install a lightweight flywheel on it and go. You can use the stock transmission. Mazda has used the same bellhousing since 1972 or so. It bolts right up. The RX-8 transmission is really no worse than any other n/a rotary transmission. Imagine a high 13 second n/a 1st gen that could pass emissions if it had to!

True it's not the cheapest option. It isn't any more complex than any other rotary engine swap into the car. Use the 1st gen front cover. I have a Renesis here right now that I'm porting for a guy from Detroit. My spare GSL-SE front cover bolts right on. Problem solved. You can also use the crank angle sensor from a 2nd gen so no need to worry about the weird crank trigger the RX-8 uses. That means any standalone works. Bolt on a 75mm throttlebody from another car and you're done. Use the mechanical oil metering pump (or premix). Use a bicycle brake cable connected to the tb to control it. Make your own oil metering lines. These are cheap and easy. It's an easy swap. Far easier than a 20B anyday and arguably as easy as a T-II swap. The only reason not to do it is because you could get a TII engine in good shape for cheaper.
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Old Jul 5, 2007 | 09:45 PM
  #28  
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Sounds like a plan. I have a 1st gen with a bad motor right here, and as an 8 owner I am not afraid of using a Renesis.

I will have to get with MM and see if a 12a rebuild is more expensive than a previously loved Renesis.

How about cooling? I have 1980, would the oil cooler be large enough?
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Old Jul 5, 2007 | 10:05 PM
  #29  
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Originally Posted by jeffe19007
Sounds like a plan. I have a 1st gen with a bad motor right here, and as an 8 owner I am not afraid of using a Renesis.

I will have to get with MM and see if a 12a rebuild is more expensive than a previously loved Renesis.

How about cooling? I have 1980, would the oil cooler be large enough?
...did you read ALL of the posts previous to this page?

lol...

Save your money, save the headaches, fix the 12a (rebuild it yourself), learn something in the process...
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Old Jul 5, 2007 | 10:41 PM
  #30  
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Yep, I did. I have my pencil out and working it out now.

It depends on how cheap I can get the Renesis.

Where I live the 7 would have to pass emissions. And yeah there are ways to make that happen.

Looking at this option is a new thought and worth checking out.
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Old Jul 5, 2007 | 10:45 PM
  #31  
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Originally Posted by rotarygod
The Renesis may not be able to take as much boost as a lower compression 13B but look at the horsepower advantage it has over a 13B sans turbos. The TII was either 182 or 200 hp with a turbo. The Renesis only needs a few pounds of boost to hit 300 hp if set up properly. If you are doing a straight engine swap, you can use a standalone ecu. No need to make it complex. Full control. Even Megasquirt can control a Renesis now. If you have a standalone, you don't need anything else that the RX-8 does to keep the ecu happy.

Install a lightweight flywheel on it and go. You can use the stock transmission. Mazda has used the same bellhousing since 1972 or so. It bolts right up. The RX-8 transmission is really no worse than any other n/a rotary transmission. Imagine a high 13 second n/a 1st gen that could pass emissions if it had to!

True it's not the cheapest option. It isn't any more complex than any other rotary engine swap into the car. Use the 1st gen front cover. I have a Renesis here right now that I'm porting for a guy from Detroit. My spare GSL-SE front cover bolts right on. Problem solved. You can also use the crank angle sensor from a 2nd gen so no need to worry about the weird crank trigger the RX-8 uses. That means any standalone works. Bolt on a 75mm throttlebody from another car and you're done. Use the mechanical oil metering pump (or premix). Use a bicycle brake cable connected to the tb to control it. Make your own oil metering lines. These are cheap and easy. It's an easy swap. Far easier than a 20B anyday and arguably as easy as a T-II swap. The only reason not to do it is because you could get a TII engine in good shape for cheaper.

wow. you make it sound so easy
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Old Jul 5, 2007 | 11:33 PM
  #32  
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It is easy! It's simple. People make it sound too hard. Keep the stock oil and coolant system from the RX-7. It's fine. It's very straight forward. I have a Renesis here and I own a 1st gen. While the engine isn't mine, believe me, I've figured out what to do to make the swap simple. Don't think a TII swap would be any less of a headache. My money is on the Renesis swap being far easier to accomplish.

No engine swap is cheap. At least not any swap that is done well. May as well use a current engine. Keep it n/a. That's about as reliable as you can get.
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Old Jul 5, 2007 | 11:38 PM
  #33  
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Originally Posted by jeffe19007
Sounds like a plan. I have a 1st gen with a bad motor right here, and as an 8 owner I am not afraid of using a Renesis.

I will have to get with MM and see if a 12a rebuild is more expensive than a previously loved Renesis.
If you have to replace any housings in the 12A, the cost of the rebuild will match what you can probably get a used running Renesis for. Don't fall for the budget rebuild bs that you see around here. Why is there never enough time and money to do it right the first time but always enough to do it again? You'll spend nearly $1000 in seals alone on a rebuild. You can go cheaper such as RA seals or Atkins but I personally only use Mazda seals. They're the best unless you can afford Ianetti. I wouldn't use anyone else's seals. Others do but that's their risk. If you have to choose between using what's proven vs using what's cheap, be safe. Use what's proven. Ironically it's usually the cheapest option in the longrun.
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Old Jul 6, 2007 | 08:50 AM
  #34  
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Originally Posted by rotarygod
The Renesis may not be able to take as much boost as a lower compression 13B but look at the horsepower advantage it has over a 13B sans turbos. The TII was either 182 or 200 hp with a turbo. The Renesis only needs a few pounds of boost to hit 300 hp if set up properly. If you are doing a straight engine swap, you can use a standalone ecu. No need to make it complex. Full control. Even Megasquirt can control a Renesis now. If you have a standalone, you don't need anything else that the RX-8 does to keep the ecu happy.

Install a lightweight flywheel on it and go. You can use the stock transmission. Mazda has used the same bellhousing since 1972 or so. It bolts right up. The RX-8 transmission is really no worse than any other n/a rotary transmission. Imagine a high 13 second n/a 1st gen that could pass emissions if it had to!

True it's not the cheapest option. It isn't any more complex than any other rotary engine swap into the car. Use the 1st gen front cover. I have a Renesis here right now that I'm porting for a guy from Detroit. My spare GSL-SE front cover bolts right on. Problem solved. You can also use the crank angle sensor from a 2nd gen so no need to worry about the weird crank trigger the RX-8 uses. That means any standalone works. Bolt on a 75mm throttlebody from another car and you're done. Use the mechanical oil metering pump (or premix). Use a bicycle brake cable connected to the tb to control it. Make your own oil metering lines. These are cheap and easy. It's an easy swap. Far easier than a 20B anyday and arguably as easy as a T-II swap. The only reason not to do it is because you could get a TII engine in good shape for cheaper.
Do you think it would be possible to get close to the Renesis's power with a standalone? I would think it is pretty difficult given the amount of time and research Mazda would have put into the tuning. But then again, they had to tune it for power AND emissions. If you could tune it without regard for emissions, you might to be able to up the power over stock by more than 20hp.
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Old Jul 6, 2007 | 10:49 AM
  #35  
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That shouldn't be a problem at all. Tuning isn't as hard as many make it out to be. Especially on a nonturbo. Everyone always tries to overly complicate things.
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Old Jul 6, 2007 | 12:07 PM
  #36  
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yark79-- from what i read werent the rx8s "deturned" once they reached american soil due to the emissions regulations? if thats the case with a stand alone you could gain power if you ignore emissions regulations.

i think the renesis swap would be the best swap you could do for reliable, streetable power. hell, i dont think itd be too hard to hit 230 or so to the wheels with a renesis. that in a SA/FB would be a fun car. mind you it wouldnt be the fastest 1st gen out there, but it wouldnt cost anywhere near as much either. itd alos be a **** load more reliable and wouldnt be a hassle to drive everyday.

rotarygod- what about things ive read about the renesis having some reliability issues? something to do with the oil supply i think? if everything you say is correct, then this swap really isnt as hard as everyone make it out to be. hell, if you could use any of the rotary trannys then you could keep all your stock gauges working correctly..except mayeb the oil pressure and temp.

i think youre on to something....
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Old Jul 6, 2007 | 12:12 PM
  #37  
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I wonder, where is everyone managing to find used rensesis engines? They've only been out since 2004, I wouldn't imagine there are that many wrecks yet....
This is definatly something I'm intersted in doing someday, if rotarygod is right it might not be such a big job after all, I wasn't aware that the standalones were compatible, I thought I read something about the RX8 electronics system being different than other cars or something....

I agree, that amount of power would be a fun car, I don't think too much more would be needed in a SA/FB....
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Old Jul 6, 2007 | 12:21 PM
  #38  
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Originally Posted by aws140
except mayeb the oil pressure and temp.
http://www.racingbeat.com/resultset....rtNumber=11803
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Old Jul 6, 2007 | 12:23 PM
  #39  
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^^ ohh you sneaky little bugger

if thats the case then most aftermarket oil pedestles would work. even the respeed one i have....hmm....you guys are getting close to making me rethink my bastardly swap ive been wanting to do for some time.
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Old Jul 6, 2007 | 12:59 PM
  #40  
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The biggest hurdle I see in trying to do this swap, is the exhaust. Remember, the renesis has 3 exhaust ports. No readily available headers for a renesis in a 1st gen chassis.
Of course, I know someone with a laser cutter, that happens to also be a car guy. Tubing benders are pretty easy to get ahold of.
Dammit, why do I have to be too stubborn to give up the simplicity of a carb/dizzy? I don't know of any carb intakes for the renesis, yet.........

One more thought. I know the stock FB trans will bolt up, but what about clutch and starter? Aftermarket flywheel for the 79-82 or 83-88 and an auto counterweight for the renesis *should* solve that, I would think.
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Old Jul 6, 2007 | 01:15 PM
  #41  
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Originally Posted by 82transam
I wonder, where is everyone managing to find used rensesis engines? They've only been out since 2004, I wouldn't imagine there are that many wrecks yet.....

car-parts.com shows two pages of engines for sale.
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Old Jul 6, 2007 | 01:45 PM
  #42  
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Hmm, I always seem to forget about that site..... As you say there are plenty of them to choose from, cheaper than 20b's too, not much more than a 13B REW too......
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Old Jul 6, 2007 | 01:45 PM
  #43  
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That seems like a lot of money to spend for 230whp.
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Old Jul 6, 2007 | 01:49 PM
  #44  
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Nice ... 3G Canadian would net me a renesis that's only 6hrs drive away from here.

Damn, this swap is looking more and more inviting.

Jon
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Old Jul 6, 2007 | 01:52 PM
  #45  
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Originally Posted by daemonjosh
That seems like a lot of money to spend for 230whp.
230hp and stock reliablity. That's more than a 100% increase over a stock 12a, yet has the same reliability and driveability. Getting over 200hp from a N/A 12a kills it's ease of driveability.
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Old Jul 6, 2007 | 01:59 PM
  #46  
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Check this out.

I especially like the part where they converted the throttle body to accept a 1st gen throttle cable using a rod from a stock nikki carb.

http://www.yawpower.com/renespic.html

Jon
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Old Jul 6, 2007 | 02:25 PM
  #47  
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The nice part about a new engine is They are new, 90 K miles before you start worring about them.

I have a guy that buys at the insurance sales, Can have him pick up a whole car any time I want.
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Old Jul 6, 2007 | 02:48 PM
  #48  
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Cool link Jon, very interesting stuff.
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Old Jul 6, 2007 | 02:54 PM
  #49  
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Originally Posted by Rogue_Wulff
230hp and stock reliablity. That's more than a 100% increase over a stock 12a, yet has the same reliability and driveability. Getting over 200hp from a N/A 12a kills it's ease of driveability.
I just don't understand why it's ok to spend this much on swapping in a Renisis, but swapping in a 302 is wrong when it gives you more power and better reliability for less money with a proven swap.
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Old Jul 6, 2007 | 03:15 PM
  #50  
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Originally Posted by daemonjosh
I just don't understand why it's ok to spend this much on swapping in a Renisis, but swapping in a 302 is wrong when it gives you more power and better reliability for less money with a proven swap.
It's not about bang for the buck. It's about keeping a rotary in a rotary powered car. A 302 is not a rotary! I'm still waiting for someone to do the coolest swap of all and I guarantee it would **** off alot of American V8 loving people. I want to see a supercharged 3 rotor in a C6 corvette.
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