Future Build Planning/Cost analysis
02-22-21, 05:51 PM
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Future Build Planning/Cost analysis
Hi everyone, I'm currently in college, looking to graduate in engineering in about 2 years, and my fiancé is also looking to get her engineering degree. This means that between us sharing a mortgage and everything else I should have a lot of free floating cash which will be divided between some investment and of course obtaining my absolute dream car. Since I was about 12 or 13 I've always wanted to get into rotaries, especially the rx7. I have been doing a bit of research on them and found that as a p-car i'd be willing to put in the time and effort over a year to build the car I've always dreamed of. I've recently been looking into billet rotary engine clones, full billet internals for a 20b. Assuming fabrication and cost are really no value. How many horsepower would I expect out of a billet 20B and a semi-large turbo, another question I have is if it's possible to single turbo a peri-port 20b, and if it's been done before. As a "fun-car" I wouldn't mind if it wasn't possible to daily, (because honestly, I'd be afraid to considering the amount of hp people get out of the 20B) but would it still be possible (although bitchy) to drive on the street or would it potentially be reserved for the track? Another question that I have is what kind of transmission would I be looking at that could handle roughly 600-700 hp, because I'm not sure a standard manual from an fd or fc can handle that much power. And last question would be where I could find a full engine parts list for a 20B, so that I can start piecing together a parts list now so I'd be prepared. Many thanks from you guys for a reply, and hopefully eventually my build would make it onto here. 
Last edited by Sir Shiba Inu; 02-22-21 at 06:00 PM. Reason: Additional Question that I thought up
02-22-21, 08:55 PM
#2
welcome to the board.
at the end of the day, it's your money, but i have to ask ... if you're not planning to race/track the car, why do you need a 600+ billet 20B? when you say "fun" project car, to me, it's different from a race car. you're focusing on the deep end of the pool and you haven't even lived with an Rx-7 yet. if this is for fun (occasional street use, maybe sprinkle in a few races or track excursions here and there), then you simply don't need to build on the level you describe. if you want to drive the car on the street, then build one for the street. if you're stuck on getting a 20B, you can still find them. yes, they cost a bit, but if you're talking about billet housings and shafts, then cost is a moot point, but it should save you some coin.
a better course of action would be to:
1. get the Rx-7.
2.if it's not in good condition, then get it there. (perform whatever standard reliability mods along the way). you can start making basic mods here, too, but avoid overkill.
3. drive it! spend at least 6 months to a year with it and see if it's a good fit.
4. if you like the car, but remain thoroughly unimpressed with the 13B, then start making plans for your 20B stuff.
that said, i'll address whatever of the questions you asked that i am able to answer, the rest i'll leave for someone with more knowledge/experience.
this question can't be answered without details that you have not yet provided.
yes, and yes.
a 20B is just an engine (forgive me ). my point is, it can be as mild as you want it to be, or as wild as you want it to be. as far as what would be streetable goes, it really depends on two main things: (1) you, and what you can tolerate, and (2) whatever criteria the local law enforcement might use to harass you.
"handle" is a tricky term, but if you mean would you be able to drive the car, then yes. you can use the R-Type transmissions with it. however, if you plan to be beating on the thing, then people have upgraded with manuals from other cars or dedicated race boxes.
what parts list are you referring to?
the basic engine is the rotors, the side housings (front, regular intermediate, thick intermediate and rear), the rotor housings, the intermediate shaft and the tension bolts/studs. of course there will be manifolds, pumps, oil pan, etc., but those are the parts of the basic engine.
EDIT
keep in mind, that the "thick" intermediate housing is NLA, and on the used market, if you find one, then it might cost as much as a billet one. outside of that, you can replace the other housings with 13B parts.
at the end of the day, it's your money, but i have to ask ... if you're not planning to race/track the car, why do you need a 600+ billet 20B? when you say "fun" project car, to me, it's different from a race car. you're focusing on the deep end of the pool and you haven't even lived with an Rx-7 yet. if this is for fun (occasional street use, maybe sprinkle in a few races or track excursions here and there), then you simply don't need to build on the level you describe. if you want to drive the car on the street, then build one for the street. if you're stuck on getting a 20B, you can still find them. yes, they cost a bit, but if you're talking about billet housings and shafts, then cost is a moot point, but it should save you some coin.
a better course of action would be to:
1. get the Rx-7.
2.if it's not in good condition, then get it there. (perform whatever standard reliability mods along the way). you can start making basic mods here, too, but avoid overkill.
3. drive it! spend at least 6 months to a year with it and see if it's a good fit.
4. if you like the car, but remain thoroughly unimpressed with the 13B, then start making plans for your 20B stuff.
that said, i'll address whatever of the questions you asked that i am able to answer, the rest i'll leave for someone with more knowledge/experience.
another question I have is if it's possible to single turbo a peri-port 20b, and if it's been done before.
As a "fun-car" I wouldn't mind if it wasn't possible to daily, (because honestly, I'd be afraid to considering the amount of hp people get out of the 20B) but would it still be possible (although bitchy) to drive on the street or would it potentially be reserved for the track?
). my point is, it can be as mild as you want it to be, or as wild as you want it to be. as far as what would be streetable goes, it really depends on two main things: (1) you, and what you can tolerate, and (2) whatever criteria the local law enforcement might use to harass you.
Another question that I have is what kind of transmission would I be looking at that could handle roughly 600-700 hp, because I'm not sure a standard manual from an fd or fc can handle that much power.
And last question would be where I could find a full engine parts list for a 20B, so that I can start piecing together a parts list now so I'd be prepared. Many thanks from you guys for a reply, and hopefully eventually my build would make it onto here.
the basic engine is the rotors, the side housings (front, regular intermediate, thick intermediate and rear), the rotor housings, the intermediate shaft and the tension bolts/studs. of course there will be manifolds, pumps, oil pan, etc., but those are the parts of the basic engine.
EDIT
keep in mind, that the "thick" intermediate housing is NLA, and on the used market, if you find one, then it might cost as much as a billet one. outside of that, you can replace the other housings with 13B parts.
Last edited by diabolical1; 02-22-21 at 09:00 PM.
02-22-21, 09:14 PM
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Yeah, I agree with your course of action as well with getting a 7 and seeing if it's a good fit. While I am finishing up graduate school here in the United States, I don't honestly plan to live here much longer, thus moving to the netherlands or another european country. This rises some issues with the 7 because it's emissions are a joke in europe and on top of that, modifying basically anything on the car will just be a confiscation of the keys. The reason I wanted to overbuild as soon as I got it was to get as much fun as possible, and then while moving to europe, reserve the car purely as a track car that I can just simply let loose on the track. When it comes to the parts list however, I'm finding it difficult to account for the rest of things. All 13b builds online show the motor assembly, which I got down, but when it comes things such as the intake, turboing, mounting etc. , all of which I know get affected by most types of power gain, I'm not sure what I can do.
Other questions I've been wondering about however:
1. Would a full periport 13b be "impossible" to drive on the road, I understand it gets rid of lowend torque, but I already drive a car that's dying so starting at 3-4.5k is not something I'm unused to. The sound is something I don't really care about, I drove a straightpiped 4age mr2 for about 9-10 months and never had and issues, (had to sell it because of moving back to europe.)
2. Would it be possible to get the 10k+ rpms with a single turbo in a billet 13b?
Clarifications:
1. Why billet?
a. I've always thought of a "0-Milage" rotary engine as possibly one of the coolest things in the world possibly.
2. Reason for such a built car.
a. I've always been the person to maximize whatever I could get once I had the money for it, for instance I built a pc that was as powerful as it could have been at the time I built it, even though I was only 16, which I saved up a fuckton of money to afford it, and for all the joys that it gave me, it was 100000% worth it.
3. Future-Future Plans
a. After working as an engineer, one of the only hobbies I have are cars, so ironically at one point I want to make a dummy overpowered car that has absolutely no reason of existing except for the fact that it's what I want, whichever way I decide to take it, other plans I have are to recreate a group-c car with a 6 rotor in it built completely out of my engineering experience (except for the engine.)
Obviously I have lofty goals, and whether those final plans happen is likely gonna be a no, but for me it's still something that essentially a poster car for me, I've always wanted an rx7, and i've always wanted to make my dream car, as I've gotten older i've realised more and more that if I want something, if I put the effort in, I can do it.
Other questions I've been wondering about however:
1. Would a full periport 13b be "impossible" to drive on the road, I understand it gets rid of lowend torque, but I already drive a car that's dying so starting at 3-4.5k is not something I'm unused to. The sound is something I don't really care about, I drove a straightpiped 4age mr2 for about 9-10 months and never had and issues, (had to sell it because of moving back to europe.)
2. Would it be possible to get the 10k+ rpms with a single turbo in a billet 13b?
Clarifications:
1. Why billet?
a. I've always thought of a "0-Milage" rotary engine as possibly one of the coolest things in the world possibly.
2. Reason for such a built car.
a. I've always been the person to maximize whatever I could get once I had the money for it, for instance I built a pc that was as powerful as it could have been at the time I built it, even though I was only 16, which I saved up a fuckton of money to afford it, and for all the joys that it gave me, it was 100000% worth it.
3. Future-Future Plans
a. After working as an engineer, one of the only hobbies I have are cars, so ironically at one point I want to make a dummy overpowered car that has absolutely no reason of existing except for the fact that it's what I want, whichever way I decide to take it, other plans I have are to recreate a group-c car with a 6 rotor in it built completely out of my engineering experience (except for the engine.)
Obviously I have lofty goals, and whether those final plans happen is likely gonna be a no, but for me it's still something that essentially a poster car for me, I've always wanted an rx7, and i've always wanted to make my dream car, as I've gotten older i've realised more and more that if I want something, if I put the effort in, I can do it.
02-23-21, 09:07 AM
#5
well, again, they can be driven on the street. i have seen it with my own eyes. the notion that they will fall completely on their face is arguable, but from guys here on the board who have PP cars, and drive them (not daily), it sounds like that may be a little exaggerated. i don't know because i don't own one. however, there are quite a few guys that you can look at their posts, some even have build threads, and get a better sense for yourself. you probably won't be looking at a daily driver, but you already stated that that's not what you want in the first place, so that's not an issue.
they are loud though. i don't think your 4AGE experience can be considered proper preparation for a peripheral ported rotary. i've had the occasion to be around a few 4AGE cars (mostly Corollas) back in the day, some of them were pretty loud, but the PP doesn't just assault your ears. it's different. it assaults your whole body. again, you have to make the decision for yourself though.
is it possible to get 10k with the turbo? yes. i don't think it's recommended (and in my opinion, not particularly wise) to do so though. choose your turbo in such a way that it gives you the power you need at a lower RPM.
they are loud though. i don't think your 4AGE experience can be considered proper preparation for a peripheral ported rotary. i've had the occasion to be around a few 4AGE cars (mostly Corollas) back in the day, some of them were pretty loud, but the PP doesn't just assault your ears. it's different. it assaults your whole body. again, you have to make the decision for yourself though.
is it possible to get 10k with the turbo? yes. i don't think it's recommended (and in my opinion, not particularly wise) to do so though. choose your turbo in such a way that it gives you the power you need at a lower RPM.
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