Ok... I wanted a 20B, but I'm kinda interested in this. http://www.hitman.hm/damaged1.htm
I know the crank is custom, and one of the intermediate housings has been modified, the intake is custom, and the oil pan is. Where would I get a crank and maybe the intermediate housing of a 20B so I didn't have to make them (have them made)? Is this a logical way to build an engine since I already have a low mileage TII engine, and would be replacing the turbos and intake on a 20B anyways? What are your thoughts on this?
Thanks,
Don.

 

Check with the Aussies. Labor is too expensive in the US to make it worthwhile to order custom parts. You can get a good used 20B-REW for $3,500 from some US importers, and for as little as $2,000 if you keep an eye on E-bay. I just don't think it's worth the money and trouble to make your own when you can get a 20B at these prices.

BTW, the price of the 20B is nothing compared to the price of installing it in an RX-7, especially if you want to swap out the twins for a single turbo setup. I would plan on $20K for a stock-turbo 20B install in an FB or FC, about $3K more for an FD, an additional $10K for a single-turbo setup.

 

Thanks. I'm really not worried about the installation cost. I will be fabbing pretty much EVERYTHING myself. You have yours running yet?
Don.

 

No, too many issues keep cropping up, and it's taking forever to get some of the parts. I'm nearly finished, though. The main components I'm still piecing together are the ignition system, fuel system, IC plumbing, and transmission. I guess it sounds like a lot, but these are actually the easier issues to deal with.

You will save a lot of money by fabricating everything yourself, but you will still have a lot of costs unless you can fabricate your own EMS, ignition system, 2-disk clutch, 500ft-lb transmission, etc.

 

A computer of some sort is a given with any high HP rotary, so I don't really consider that a "20B" expense. As will the custom intercooler piping and exhaust. What kind of ignition problems are you having? I will probably just shatter some TII transmissions for a while. I have 3 to go through b4 I need to buy something. Not to sound stupid, but what's the problem with the clutch? Is there not a race pressure plate that can hold? Have you found a 2 plate that will work? I figure I have $600 in a convertible in decent shape w/blown engine, and $500 in a TII with 2700 mi that I'm gonna use the engine out of, but I was thinking to just slap another rotor on there and drop it in (sounds easy doesn't it? ). I was a RX7 tech and have a good bit of fab work on cars and other things. I have a tig and a plasma cutter, so that makes life easier. My lift and tubing bender is on the way. I'm about to have to build a bigger garage to keep my toys. Hey, IM me if possible. I'd like to discuss some issues.
Don.

 

there is a contact for Matt the Hitman's crank builder on the main rx7 page... warning it was NOT cheap, even in NZ dollars.

Try Australian rotary workshops for a 20b crank and the funky intermediate plate... plus the right thru bolts as well.
eg:
Dyson's
Dalton's
Selectmaz

or Mazfix (who run a 20b 3rd gen to 7.8's) or Pac Performance - I think they both have websites, sorry no links at my fingertips.

They will still not be cheap, as you will be needing someone who has the engine apart, and the reason for it being apart was not related to the crank or plate being trashed. They were never released here domestically, so all of ours are Jap import front cut or bare engine as well. For ECU, look up Microtech, as it uses all factory senders and while having less features than others on the market it is cheaper than Haltech - Microtech is the most popular ECU brand on the Aussie market, and by far powers more rotaries than any other ecu.

 

That's a good way to look at it. Actually, if you had a seriously-modified high-hp TII to start with, the 20B conversion would be much easier. All that equipment will help you, too, as I have to outsource all my milling and critical welding jobs.

I'm still waiting on my EMS software to see what options I have. I'm in the same situation with the fuel system, and I am getting estimates to see whether I want to add an extra rail or use a completely different throttle body. My EMS software should arrive any day now, so then I will have a better idea about what my options are.

Hehehe, sounds like a plan to me. The TII transmission seems to work OK with the 300-400hp 13BT engines, so I think it would be fine for a stock-turbo 20B. For my single-turbo project, I am too concerned about exploding a TII transmission, even with the scattershield. I don't mind ruining a transmission, but exploding one is another story. OK, so I'm a paranoid helicopter pilot.

Besides overheating, the few people with 20B RX-7's that I have talked to say that the clutch is the next biggest problem. I will be using the Quartermaster 5.5" 2-disk clutch, which 3 out of the 4 pro racers I have talked to think will work great. The one who didn't think it would work (he is by far the "lesser" of the bunch) thought that a 7.25 2-disk clutch would be needed. I personally like the low-inertia 5.5" clutch better, so I'm going to try it out, and if it slips then my 84 RX-7 will inherit a really nice clutch.

No, but I'm not a mechanic.

Feel free to send me PM any time. However, please post in public if you think that others will benefit from the discussion.

 

Jeff Bruce is the mans's name

$1NZ = 42 cents US

3 rotor e-shaft $1900nz
3 rotor thru bolts $180nz
modifications to centre plate to accept bearing $600nz

4 rotor e-shaft $3000nz
4 rotor thru bolts $250nz
mod to centre plate x 2 (you need two of these) $600nz

 

Like I said. I have a 2700 mi TII. I think it's probably in better shape internally than a pull out 20B, that I'd probably want to rebuild and put new housings in anyway. That's another reason I want to go this way. And I'm thinking that I can put another rotor in the front and keep the stock mount location if I remove the fan and make some room up there. I'm not scared of work... obviously...
HWO,
Is that crank price the price of a 20B crank or a custom unit? If it's custom, how does it compare with the factory 20B unit in relation to power handling? I don't think I'll ever hit 1100HP, but if that one is better than stock...
Don.

 

they are custom made cranks for usage in 3 rotor applications using 13B parts, they are a slightly shorter motor than a true 20B. they are stronger than factory 20B cranks, he can also make up 20B cranks from the same 'billet' style, these are machined up 'billet' cranks definilty not 'off the shelf' mazda cranks

 

HWO,
Is the modified center housing as strong as the 20B center housing? Is this something that I should even be concerned about?
Don.

 

Am I understanding that the guy in NZ is also making cranks to create 4 rotor motors too? From 13b parts.

 

I have set aside ~15K for the project on my car right now. but im sure I will run over.

im hopping to have it running in the car around 1st week of april but you never know........

 

if you read my post you'll even find the prices for those parts

 

You know I don't think I'll ever make a wankle with that much power, but if I were to spend that kind of money I'd step on up to the bat and do the 4 rotor. What kind of ign and management system would that thing require? You wouldn't have to turbo charge it. It would probably a beast NA.

 

Of course I also realize that is easier said than done.

 

Repu,
I agree with the comment about 4 rotors. I like the idea, but since you can make almost unmanagable street HP with 2, I fugure 3 will be overkill, and make more power at lower boost than I'll ever need. 4... I'd kill myself, and I'd think the packaging problems would be immense. I think it's going to be hard enough for me to fit a 3 rotor in. I'm just weighing the costs of doing this VS a true 20B. What do you guys think considering that I already have a very low miles 13BT?
Don.

 

Any aftermarket EMS which will run a V-8 will run a 4-rotor.

 

Would one system run leading and trailing?

 

Yes, but not split timing, so you would probably need two systems if you wanted to comply with emissions standards.

 

HWO do u know how much hp/torque that 4 rotor shaft can handle? just curiosity

 

the 3 rotor ones can handle well over 1000HP 0 i aint sure on the exact numbers, they dont have the problem of breaking at around 1000hp like the stock 20B cranks do, so i'd imagine the 4 rotor wold be around 1300HP or so - more than enough HP

 

sounds good thanks

 

Does Jeff Bruce have any web info on his e-shafts

 

I thought he did, or had something in the works a few years ago, but I haven't checked since then. Do a google search?