Renesis Conversion, Would I? Should I? Could I? Options

[The Kelzer]

OK here goes....I got this idea. V8 conversions are great, I drove one and liked the power, didn't like the added weight or the required tranny work and the un-exoticness of it all.....did LOVE the sound though.

Now having owned several RX-7's I LOVE that rotary engine and have had over 200K miles on each with NO problems whatsoever. The new RX8 "Renesis" 13B puts out wonderfully SMOOTH horsepower and torque that are well within the apparent tollerances of the stock 901 tranny. Not to mention it's a VERY light motor that loves to rev and is more powerfull than a well built 2.0 4cyl.

Has anyone done a rotary (12A or 13B) conversion?

Does anyone know where to get a tranny adaptor plate?

I tried contacting Racing Beat who are the rotary guru's but they have nothing yet. So basically I'm starting from scratch and any info would be GREATLY appreciated.


Aloha,
Kelly

[MrsPnambic]

Far as I know, Kennedy Engineeringis the place to go for transmission adapters, specializing in the 901 for the Porsche/VW applications.

I think I remember someone mentioning an intention to do this months ago, but I don't recall reading if they went ahead or not.

Hope this helps a bit. (IMG:style_emoticons/default/beerchug.gif)

[seanery]

haha, Dan signed in as Leah again! (IMG:style_emoticons/default/biggrin.gif)

[Pnambic]

GGGRRRRRRRRRRR!!!!!!!!!!!!!!! (IMG:style_emoticons/default/rolleyes.gif)

[mudfoot76]

haha, Dan signed in as Leah again! (IMG:style_emoticons/default/biggrin.gif)

(IMG:style_emoticons/default/lol2.gif)
Good way to boost her post count
(IMG:style_emoticons/default/lol2.gif)

[Mueller]

rotaries in 914's have been done numerous times, reddawg racing (sp??) used to have a kit.....like mentioned earlier, KEP might have an adapter and flywheel to mate to the 914 gear box...I don't know if mazda uses the same bolt patterns for the engine and flywheel as thier older motors....once you figure out how to mate the engine to the transmission, the rest is fairly easy since you just follow what the V8 and other watercooled guys do... (IMG:style_emoticons/default/smash.gif)

there is a brand new 0 miles "Renesis" motor on ebay right now, bidding at 2K, reserve not met, I wonder what it'll go for????

[The Kelzer]

Thank you for the help.

I'll keep you posted on the transforamation.

Off to E-bay to look at that motor.

[soloracer]

There have been rotary conversions using both the 13b and 12a engines. If you search this forum you will find links to their websites. I'm not sure what all the fuss is about the new renesis motor. I good bridgeported 13b will make more power and cost signifigantly less. I'm with you in regards to wanting something exotic in my 914 - that's why I bought a 20b (3 rotor) and am keeping the turbos. Which I'm sure the guys here are getting tired of me spouting off about. (IMG:style_emoticons/default/biggrin.gif) I'm moving to an acreage with a 2400 square foot "garage mahol" with heated floors and plenty of room for my projects. As soon as I get settled in I'll begin my own 914 20B thread.

Kennedy Enginering would be the guys to contact for adapter plates, flywheels and clutch kits. I don't know if they have anything for the new renesis yet. I also don't know if the renesis engine will bolt up the same as the 13b. I don't think it does because my RX7 buddies haven't mentioned any transmission swap ideas yet.

[redshift]

(IMG:style_emoticons/default/lol2.gif)
Good way to boost her post count
(IMG:style_emoticons/default/lol2.gif)

(IMG:style_emoticons/default/ohmy.gif) oh my god i can barely contain myself..

[The Kelzer]

Thanks for the info soloracer. I went to Reddawg's site (which is embarassingly poor by the way) and also Kennedy Engineering (MUCH better). I sent them both e-mails asking about the conversion.

About your 20B motor where did you get it? How much was it etc.....

I'm open to all options as long as they are rotary related. I was drawn towards the Renesis motor for it's reliability stock over a built 13B (4 or 6 port). However, you're right regarding the cost difference. Maybe I should be looking at old 13B 6 port motors. Do they adapt well to carbs?
I'd like around 200hp or so and if I recall the N/A 13B is in the 145hp range.

Let me know your thoughts/links if you have any.

Aloha,
Kelly

[soloracer]

I got my 20b from a canadian JDM engine importer. I paid $3000 canadian for it. It will cost me another $2000 canadian to rebuild and streetport. I have the Kennedy adapter, flywheel, stage 2 pressure plate and clutch. I think those were around $1200 US all together. I bought the RH radiator for another $1200 US. My engine management (Haltech E11) was another $1500 US.

What makes you think the Renesis is any more reliable than a 13b? Personally I think it might be LESS reliable than the older engines due to the newness of it all. I think it would take a year or two to get all the bugs out of it. The 13B had been around longer than dirt and anything that can be done to one has been done to one. For 200 hp all you would need to do is go with a large streetport or maybe a partial bridgeport. Most of the serious drag racers use carbs so that isn't an issue. This combination would be super reliable and cost around $2000 canadian including a full rebuild and porting.

[Brad Smith]

Thanks for the info soloracer. I went to Reddawg's site (which is embarassingly poor by the way) and also Kennedy Engineering (MUCH better). I sent them both e-mails asking about the conversion.

About your 20B motor where did you get it? How much was it etc.....

I'm open to all options as long as they are rotary related. I was drawn towards the Renesis motor for it's reliability stock over a built 13B (4 or 6 port). However, you're right regarding the cost difference. Maybe I should be looking at old 13B 6 port motors. Do they adapt well to carbs?
I'd like around 200hp or so and if I recall the N/A 13B is in the 145hp range.

Let me know your thoughts/links if you have any.

Aloha,
Kelly

Stock 86-88 13B 6 port (non-turbo in other words) is 146 hp. I picked up about 20 hp at the wheels (dyno confirmed) with just an exhaust and air filter change. (the stock stuff is VERY restrictive. ) That's with a 3" single exhaust WITH a cat, and a "cone" (i.e. K&N copy) filter. Losing the catalytic converter is probably good for another 5 and maybe even 10. (Stock 86-88 cars run about 110 at the wheels... I was putting down 130) NO other mods, although I was spinning it to 7800 RPM (right before the fuel cut.)

89-91 6 port motors have lighter rotors and more compression, and the manifolds are different. They're 160 hp stock. The "redline" is 8000 RPM instead of the 7000 rpm limit that I ignored on my earlier car. (IMG:style_emoticons/default/laugh.gif) They're actually good to about 9000 RPM in stock form, although it's not worth it as the power starts to fall off up high unless it's modded a bit.

Rotaries are finicky- yes, you can make good peak power numbers with a properly tuned carb, but the throttle response, driveability, and gas mileage will all suffer. (and as you know, rotaries are not "economy" cars to begin with!) Put an aftermarket fuel injection unit on there. A stock 89+ motor with a good tuneable fuel injection unit, header and free-flowing exhaust, and otherwise pretty stock should get you 180-190 hp with stock reliability, and lighter and more compact than a V8.

If you want to go turbo, I suggest staying with the earlier motors just because of expense. 275 hp at the wheels with a stock motor (not ported) is about the limit, and that will require a hybrid turbo. (stock hot side, perhaps clip the wheel a bit, and a T04 compressor section.) A little porting and a hybrid turbo will get you up to about 325 hp. (at the wheels) Beyond that you have to increase the cubic dollars quite a bit.

Brad

[Brad Smith]

I got my 20b from a canadian JDM engine importer.  I paid $3000 canadian for it.  It will cost me another $2000 canadian to rebuild and streetport.  I have the Kennedy adapter, flywheel, stage 2 pressure plate and clutch.  I think those were around $1200 US all together.  I bought the RH radiator for another $1200 US.  My engine management (Haltech E11) was another $1500 US.  

What makes you think the Renesis is any more reliable than a 13b?  Personally I think it might be LESS reliable than the older engines due to the newness of it all.  I think it would take a year or two to get all the bugs out of it.   The 13B had been around longer than dirt and anything that can be done to one has been done to one.  For 200 hp all you would need to do is go with a large streetport or maybe a partial bridgeport.  Most of the serious drag racers use carbs so that isn't an issue.  This combination would be super reliable and cost around $2000 canadian including a full rebuild and porting.

I disagree. Porting a 6-port motor is neither easy nor that effective. The secondary ports already have a lot of overlap when they are open. HOWEVER, replacing the sleeves in those ports with some that are contoured (pineapple racing has some) is good for a substantial increase (up to about 10 hp) and they only cost you about $50. A 89+ engine with those sleeves, a good tuneable fuel injection, and header/free flowing exhaust should get you to about 190 hp. You MIGHT make 200 if you are lucky- at the flywheel, not at the wheels.

The port timing on a 6 port and the size of the ports if opened up (ported) is such that you will LOSE power except at extremely high rpm. "All the drag racers" as you are referring to run 4 port (turbo) housings, not the 6 port housings... but use the rotors from the 6 port motor (more compression.) That means you have to buy either 2 different engines (one turbo, one non-turbo) or a lot of individual parts to build one. The flywheel and front counterweight MUST match the year of the rotors for balance reasons. Turbo and NA rotors for the same years are the same weight, but the 86-88 rotors are heavier than the 89+ ones. (Third gen rotors are the same weight as the 89-91 rotors.)

Yes, you can work out various combinations for a race motor... but you have to know what you are doing or you'll build a hand grenade that will shake itself apart.

You can also build a 300-320 hp peripheral ported motor (naturally aspirated.) It'll be hard to start, won't idle below about 2000 rpm, no power below 5-6000 rpm... but it'll scream up to 10000 rpm and beyond. Oh... don't expect more than 30,000 miles or so out of it either. Ditto on longivity for bridge port motors, which can get you up in the 250 hp range, cost less to build (but are a lot more work) and have better driveability.

To recap: Up to about 200 hp from stock ports, but that's the limit. Beyond that start with a turbo motor with rotors from a naturally aspirated motor, and port the housings. To make big power for less money, turbo is the way to go.

Brad

p.s. Solo- just so you know I'm not "blowing smoke..." you know me as "rx7_ragtop" from the RX-7 forum. (IMG:style_emoticons/default/smile.gif)

[soloracer]

You disagree with what? I never mentioned anything about using a 6 port engine. I just stated that you could build a streetported 13b that would make 200 hp that would be reliable and cost less than what it would cost to buy a Renesis engine. As far as parts goes I just bought a 13bt core engine with transmission for $400. I can buy S5 n/a rotors for $125 each. A rebuild kit would be around $1000. Add in a street port and labour and you aren't too far from the $2000 estimate - if you do it yourself. How much is a Renesis motor (if you can get one that is)? $4000? $5000? $6000?

As for longevity on bridgeport or partial bridgeport motors it depends upon who you talk to. BDC has been getting some good results with his partial bridgeports. I know of a person who runs a full on bridgeport making 280 flywheel horsepower that hasn't had a problem in over three years. But since he is only talking 200 hp a large streetport should get him there and the bridgeport reliability question is no longer an issue.

Good to see another RX7 Club member here. What brings you over to this forum? Do you also own a 914?

[J P Stein]

Dudes.
Get your stuff, put it in formation (showing us pics, of course) & go make some black marks on some asphalt.....*then* tell us how great it is. (IMG:style_emoticons/default/biggrin.gif)
Ya got all winter.........

[soloracer]

I plan on doing just that. Be on the lookout for my build thread in the not too distant future. I'm moving at the end of the month onto an acreage with a 2400 square foot shop. My progress won't be nearly as fast as Andyrew's but I'll be sure to post something when it does eventually happen.......

[Brad Smith]

I know BDC well. Look at the turbo thread- you'll see the description of the air-to-water intercooler looks familiar. (It should- it's how he set his up originally.) I've seen how he builds motors (very nicely done) and helped him install one in a car for a guy. (pics are on my website on geocities.)

He has some pretty cutting edge ideas and applies them well, even if he doesn't have the big name like RP or some of the other guys. He'll also be the first to tell you that a "hack job" on a turbo rotary (trying to trick the factory fuel injection when running high boost) is the fastest way to blow up a turbo rotary.

As for why I'm here... I'm shopping for a car for my soon-to-be 16 year old daughter. We've narrowed it down to a 914 or a 912, or MAYBE a 944. (I've tried to talk her in to an FB or FC, but she doesn't want any part of it.) SO, I'm trying to get a bit more info on what to look for in my shopping quest. I just couldn't resist chiming in on anything about rotary motors or turbos. (IMG:style_emoticons/default/biggrin.gif)

Brad

[soloracer]

You'll laugh because I have one of each: a 1987 RX7 Turbo 2, a 1973 Porsche 914 and a 1989 Porsche 944 turbo. Shopping for your daughter, eh? A cute chick with a hot car....interesting......have I told you that I'm still single? (IMG:style_emoticons/default/happy11.gif)

[The Kelzer]

You guys are killing me. How exactly did this topic go from Renesis installation (by the way thanks for all the help) to buying some guys daughter a hot car so soloracer can date her? All I can say to soloracer is, if that is really your picture.......we all know why your "still" single. I can say that cause I'm pretty damn ugly myself. Get a hair cut or SOMETHING. (IMG:style_emoticons/default/confused24.gif)

By the way, I've also owned a 76 RX-4 (13B) 78 RX7 (japan spec), 80 RX7, 93 RX7 TT and a 85.5 944........my point......I REALLY LIKE THE 914 BEST !!! (though the first gen RX7 was the most fun to hooligan around town with...I sure miss those thermal reactor backfires between shifts.)

[soloracer]

It's amazing how we all follow the same cars (RX7, 944,914). I just purchased a 1974 RX4 and hope to get it home soon. Here is what it looks like now: