auxilary Posted February 24, 2003 Share Posted February 24, 2003 Yesterday I watched my friend tear apart (and I mean, tear apart) a rotary motor in less than 2 hours. We're talking taking off the transmission, flywheel, waterpump, manifold and such. Then taking apart the 4 housings holding the rotors in, and take out the rotors and inspect them. All in 2 hours, he basically turned a fully assembled engine into a longblock, then a shortblock, then the shortblock was disassembled. Well, hard to say long/short block since the motor has no head Believe it or not, rotary is incredibly simple. 3 moving parts, and that's it. After discussing and evaluating the situation and given motor at hand (and knowing someone who knows how to rebuild them!) I am VERY tempted to do the 13b turbo rotary swap into the Z. We're talking about 300hp after rebuild, about 3.5k in parts including engine management. The motor is LIGHT. We're talking 200lbs just for the block, with turbo, manifolds and accessories plus transmission, it's about 400lbs. Heck, the longblock on the Z alone is about 500 lbs! Installed, the car would be truly mid-engined. The only concern is that the transmission is LONG. About 8 inches longer than the t56. The motor would still sit far enough back to require a support crossmember to be built for the Z, but it can easily be done. This would also allow TONS of room in the engine bay for electric fans, intercooler piping, etc. This has just become an easy contender for the RB25 (heck, and parts are available locally...but not cheap). Only other downfall is lack of initial torque. After watching him tear the motor apart, I don't have much fear of the rotary - it's very simple. Only complex parts are making sure that everything is within tolerable specs, and internals of rotors themselves are very complex. I also learned that a core motor from an 87-88 turbo rx7 can be purchased for about 600 bucks with transmission (bad motor, of course). It can then be rebuilt Input? Quote Link to comment Share on other sites More sharing options...
stony Posted February 24, 2003 Share Posted February 24, 2003 tearing apart is alot different then putting together. i to have watcged teh tear down and reassebling of parts. the most time consuming part is teh cleaning. you have to ensure everything is spotless or youll pay the price. I even have the fomula for parts. heres what i did on mine. i took a blown 89 T2 motor torn it down .. threw away the rotors and rotor housings bought new FD rotors and rotor housings had a pro shop assemble. wioth stock booste and to4e motor prduced 350whp!!!!. it lasted till i sold it (2 years) and a kid wrapped it around a tree ;< I say do it. should be an easy swap and should work well ;> Quote Link to comment Share on other sites More sharing options...
zgeezer Posted February 25, 2003 Share Posted February 25, 2003 Hey, I say go do it. My experience with a NA 13B in an R100 with some Racing Beat modifications made a believer out of me. No torque, but more RPM's than you'd want to believe. Great sound, louder than hell. gw Quote Link to comment Share on other sites More sharing options...
Guest Tht1KSguy Posted February 25, 2003 Share Posted February 25, 2003 Hey Aux, I say go for it too. It's on my list of future things to do. Mine will be a bit different though. I had a thread up here a while back talking about a 4 rotor engine. These things are basically modular, obviously it's not that simple or I'd have one put together right now. The biggest thing these engines lack for me is torque (which my version would have plenty of since it's basically 2 engines) and they're comparatively expensive to rebuild for their size. Depending on your skills they can last a long time but most I've seen pop one about every year or 2 in high output trim. But I love the smooth reving nature of the rotary engines. Quite the wonder of engineering to me. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted February 25, 2003 Share Posted February 25, 2003 Yeah I'd like to see it. I think you could be well on your way to a 2100lbs street terror. Throw some 4.11 or 4.38 (R180!) gears in the back and you'd be laughing. I think you could run the R180 without worrying about it actually... Quote Link to comment Share on other sites More sharing options...
auxilary Posted February 25, 2003 Author Share Posted February 25, 2003 I have a 3.54 r200 right now, actually. I don't think 4.11 gears would be a good idea for a turbo motor - it would run out of gear before the turbo would reach maximum boost Quote Link to comment Share on other sites More sharing options...
S30Z Bushido Posted February 25, 2003 Share Posted February 25, 2003 i think it's a cool idea, i'd like to see a rotory powered s30. you would definetly have tonnnnns of extra room in the engine bay. Quote Link to comment Share on other sites More sharing options...
Guest Rotary Racer Posted February 25, 2003 Share Posted February 25, 2003 Hello all, I am the person who started this crazy thought . I just need everyone’s help to push Aux to do it. I would love to put a 13bt in his car. I can already imagine the combo of parts I will use in his rebuild. This is also my first post so hello all. Quote Link to comment Share on other sites More sharing options...
fl327 Posted February 25, 2003 Share Posted February 25, 2003 do it. ive had three of those t2s, one of them had a third gen boosting +35psi?? dont know but it was FAST. why not? rotaries are a strange animal aux, 4.11s are good with the high boost, why you ask, cause you shift that thing at 9500 with the low cr rotars, lower numerical gear ratios really stink with the turbo rotaries-factory turbo 2s have 3.9-4.11 and the NA have 3.70. y. weird huh? we got a rotary guy if you need to get a rebuild or just about anything, hes really good. do it if rotaries are talking to you. Quote Link to comment Share on other sites More sharing options...
Owen Posted February 26, 2003 Share Posted February 26, 2003 Everyone of my friends I've talked to say "NO" to the rotary motors. Why? Because they say they're unreliable or too peaky or the apex seals go so fast. But what I want to know is, are all these rumors true? I personally think a well built and ported 13B or 20B could last as long as any piston engine - as long as the engine was built properly. Maybe we should find a rotary web board and locate a builder with experience and see what he thinks. You could always get an RX-8 engine, wasn't there a shakedown test of a modified RX-8 at Laguna Seca recently? Owen Quote Link to comment Share on other sites More sharing options...
stony Posted February 26, 2003 Share Posted February 26, 2003 a stock rotary is very dependable if you take care of it. It is a higher maintenance motor then others. It is also a good motor to modify but like you said owen it has to be built to exact specs. More importantly you really have to have the tools to tune it. egt a/f ratios are very important in a rotary. if you get lean and detonate 9 times out of 10 the motor is done and will need new apex seals. If the apex seal breaks off a big enough chunk it will mor then likely damage something on the way out. turbine wheels dont like metal chunks if you are going to modify a rotary here are some suggestions. go with a mild port that will make it breath better. go with bigger primary and secondary injectors instead of sub inj controller. and slap the bigest turbo you can fit on it. it seems like rotaries like big turbos. and again tune it on a dyno and make sure y0our margin for error ( a/f ratio) is thick. my 2$ Quote Link to comment Share on other sites More sharing options...
Tim240z Posted February 26, 2003 Share Posted February 26, 2003 Back when my Dad was racing rotaries in standard saloon class (RX7), he went whole seasons without teardowns, and that car was a winner, almost every time. Like what was said above, if it's built right to start with, and kept clean during assembly, they'll run like clockwork! I want my next project to be a Opel GT with a turbo rotary.....fun, fun, fun!! Tim Quote Link to comment Share on other sites More sharing options...
Mikelly Posted February 26, 2003 Share Posted February 26, 2003 OK, this has already been done, and it is a VERY good combo... Zdr. of Roanoke, Va. had one of these in their stable and the car was the SCARIEST streetcar I had ridden in until I built my own V8Z, and quite honestly, I'm not sure his still wasn't faster... I tried to buy that car from Rob at Z Dr., then from Z Doc's brother, but could never get them to budge... VERY potent Vehicle! Mike Quote Link to comment Share on other sites More sharing options...
Guest Rotary Racer Posted February 26, 2003 Share Posted February 26, 2003 With the rotary being a motor not a lot of people know about there are always misnomers that follow it. One misnomer being that they are a lousy motor susceptible to breaking all the time. This mostly comes from the people that blew them up them self because of improper maintained, and tuning. Let me explain, I will not discuss how the rotary works and all the specifics (that makes for along post that could be done on another day:)). The rotary is (I will admit) more temperamental than your standard reciprocating piston engine. This is due to the fact that there is a smaller margin for errors. Where a piston motor can take detonation a rotary can not. With the tolerances being so tight there is no slop in the motor and the apex seals suffer. The rotary engines can and have been reliable. Looking at the non turbo motors for a second I have dealt with motors that have lived in the 200 and even 350k mile range (mine has 173k miles on it and race about ¾ of it’s life). Turbo motors on the other hand get more abuse and do not last as long, the longest I have seen one run is about 180k or so. I have said, and will always say, a true rotary enthusiast is just a little more anal about upkeep and tuning. Having a proper built motor is a great first step in making a reliable rotary powered vehicle. But it does not stop there. Proper selection of intake, exhaust/turbo, ignition, and fuel have to be just as carefully selected as the internal parts of the motor. One mistake that people make is not having a plan/goal for their project. This results in mix matched parts, and a unstable/not happy motor. Third is after all your components have been selected and installed (properly) tuning the motor has to be done. Your best way of tuning is going to be in a controlled environment where you are not worried about outside factors (like Cops ). So proper tuning should be done on a dyno with a wide band O2 sensor and display. All these take time, some cash, and a lot of research/planning/patience. So having a rotary powered car makes you take a step up and beyond the call of duty. But I feel these obstacles are outweighed by the rotary’s clean smooth power delivery, high peaking HP, and light weight. Go for it bud you know I would Quote Link to comment Share on other sites More sharing options...
Owen Posted February 27, 2003 Share Posted February 27, 2003 Hmmm, I almost feel like abusing my current engine and blowing it up, just to get a rotary! OWen Quote Link to comment Share on other sites More sharing options...
Moridin Posted February 27, 2003 Share Posted February 27, 2003 The new rotary design places the the exhaust port on the opposite side of the motor. In the 13B and other designs by Mazda up until now (as I understand it) placed the exhaust port right below the intake. With the older apex seals, sometimes the extremely hot exhaust gasses were pushed through into the intake area. The intake charge was heated and detonation occured. This was perpetuated with a turbo added. As far as I know, a new style apex seal has been created to help tremendously with the exhaust in the intake (Which also explains the poor emissions of the these motors). I think Mazda, Apexi, and other companies sell these. Again, I'm not sure, so someone please correct me if I'm wrong. These new style seals in conjunction with the new placement of the exhaust port should lengthen the life of these motors. Placing a turbo on one won't be as much of a problem as it has been. Again, I could be wrong, and I'm definitely open to someone who knows a lot more. Quote Link to comment Share on other sites More sharing options...
stony Posted February 27, 2003 Share Posted February 27, 2003 im thinking selling teh rb and going rotary ;> Quote Link to comment Share on other sites More sharing options...
auxilary Posted February 27, 2003 Author Share Posted February 27, 2003 stony, if you're gonna do that, I'll buy your RB! Quote Link to comment Share on other sites More sharing options...
Moridin Posted February 27, 2003 Share Posted February 27, 2003 I forgot to mention that the new rotaries are the ones that will be supplied with the RX-8. The sport models will have a 6-speed and 250HP NA. Slap a turbo, monster intercooler, some HPC coatings, a huge radiator, and your set. I don't think you'd have the heat problems of the old rotary. Quote Link to comment Share on other sites More sharing options...
auxilary Posted February 27, 2003 Author Share Posted February 27, 2003 I don't think a turbo would be a good idea on a renesis motor due to its rather high CR. That would be begging for detonation and grenading of the motor Quote Link to comment Share on other sites More sharing options...
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