three rotor build.costs and other questions!
 

Hello, i would like to see how much my "Dream rx7" would cost to build and obtain.I would use this for mostly street/Drag racing, probably nothing around a track. Im pretty new to the rotary engine and would wonder what the end price for my rx7 would be.I think it would be easier to just type this out in a bullet format

• Three rotor cosmo engine
• tri plated clutch
• injectors+injector racks/ rails (forgot what they are called)
• turbo that would produce anywhere between 30-35 psi
• good street tires
• radiator
• rear axles
• o-rings
• spark plugs
• throttle body

I have more but I have specific questions about them. I was wondering what ECU would be best, i did some research and it seems like i would want an adaptronic and i really liked the 1280s but im not really sure what would be best. I was also wondering what exhaust would be best for my setup and how emissions work with a car like this. I live in North Carolina and apparently the emissions tests are pretty strict. there was also coils and coil overs. My last and final question which I have not been able to find out through research is what vacuum lines i would need to keep in place or if i need them at all. I would like to know an overall price for all of these combined plus the car and the new engine. I might of been wrong in making a new thread for this and if so mods please move me. And if i missed anything or if there is more that would have to be done please tell me, THANKS!:)

The base cost for a 20B conversion is about $35,000 not including the car, but would include the EMS, ignition, fuel system, tuning, and everything else needed just to get it running. With 30-35psi boost you will need to completely replace the transmission, driveshaft, and rear axle, and will need a lot of chassis stiffening, roll cage, and lots of safety equipment. All together you are probably looking at around $80,000 or so at minimum, probably more like $150,000 with premium parts, paint, and body work. This car will not be very streetable.

Contact these guys for a more accurate quote:
DEFINED AUTOWORKS | Service Repair Upgrades | Performance for Mazda RX7 | RX-7 | RX8

thanks for the response! for it to be streetable, what psi would i be looking at and about how much HP would I want/need? and how much would that lower the cost by?

i think he missed on the point that the factory block can't handle that kind of boost. in fact the 20B is a weaker engine due to torsional twisting than the 2 rotors are. fact is they break more easily and reinforcing them requires external modifications to support the internal ones.

the lower the boost the better, when still managing to keep your goals somewhat straight. going with a bigger turbo allows you to make bigger numbers with less pressure but at the cost of spool.

Better buy stock in transmissions, diffs, driveshafts, axles etc. Why not build a 2 rotor with a big turbo first and see if you need more? I wouldn't worry about emissions. Pre '96 there is no emissions test in NC. Safety inspection only.

The more power, the more it will cost and the more difficult it will be to drive on the street. It depends on what you are willing to give up for a given amount of performance, and only you can make that choice. We all have our own concept of what is worth the money and what is worth the trouble.

Also, I'm not sure why you are so obsessed with boost. Are you having a contest with a friend to see whose engine has the most boost or something? It would be a lot cheaper to see who can have the highest tire pressure.

Oh, I just remembered that Banzai Racing also does 20B conversions, so here is their contact info:
Banzai Racing Home Page

If you're new to the rotary, how is this your dream RX7?....it sounds like you're listing a bunch of "buzz word" items without much rhyme or reason. I'd suggest spending more time reading and learning so you can have a better idea of what you want, what is possible, and what it's going to take to get there.

If you have the kind of cash already mentioned, you won't be building this car, but commissioning it, in which case the shop you decide to hire will be making nearly all these decisions for you.

what would you do to reinforce a three rotor?

the typical method used is pinning. simply put, you machine the tension bolt holes around the perimeter of the housing and use extra dowels or use thicker bolts or studs. it's a lot of precision machine work and can be costly. the hardware can be costly, too.

it essentially decreases the engine's tendency to twist under load.

its not a contest but a few people suggested that in other forums. again im new at this and I love being taught new things

ive done a fair bit of research and im in no way saying that "I know everything" but after seeing what can be done and what could have the most potential, I decided to go with the three rotor. im planning on this car being my main project for quite a long time and I doubt i would regret getting the three rotor over the 2. And the reason i was trying to spew out words was because i was wondering what the overall cost would be.That being said I still love the responses, thanks!

i have given up on pinning, larger studs work as well or better and without distorting the block.



OP, the potential with the 3 rotor is only marginally better than the 2 rotors but requires a lot more preparation work in order to keep it in one piece.

displacement is not always a replacement. parts cost for the 3 rotor engines can be up to 10 times that of a 2 rotor, if you can find the parts. one could buy 3 brand new REW engines for the price of one rebuilt used 20B.

no, i agree with that 100%.

Jonathan (Goopy) and i spoke about it a few years back and that pretty much made up my mind. previous to that i had gone back and forth about pinning and could never really commit to it - even though i get the premise. when i found out that there are larger bolts and studs out there, it was much more appealing to me.

yeah, back when i started pinning it was more an experiment for us to make big numbers but it wasn't ideal. when you tore apart the engines you could see that the pins fit more sloppily into the block afterward and the pins were getting tweaked since they are hollow. add in that machining parts to match the already pinned set made it that much more difficult as the tolerances had to be exact and it just created an all around not ideal scenario.

i was seeing hairline cracks in the dowels, you start to really reconsider if something is a good idea. i haven't ever had any issues with oversize studding.

Here is my personal 20B build, with a mods list that you can add up and get yourself a ballpark. Banzai Racing 20B Conversion Suspension & Drivetrain Modifications

Just for anyone else reading in addition to you, you will want the new Adaptronic Modular lineup. The FD PNP can be used for a 3 rotor that is using up 2 injectors per rotor, or the M2000 wire in. Rywire is working on a new FD3S single turbo harness designed around the modular FD PNP that will be easily fit to a 20B 3 rotor with a few modifications. If going with 3, or more injectors per rotor then you need the M6000 wire in model.

^This.
Now on to something more realistic. How much would it cost to build my dream 4x4 with a 26b?