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-   -   What I need for 3-rotor conversion(250HP) (https://www.rx7club.com/1st-generation-specific-1979-1985-18/what-i-need-3-rotor-conversion-250hp-85210/)

Aico 06-03-02 02:38 PM

What I need for 3-rotor conversion(250HP)
 
http://www.hurleyrotary.com/mazda_12...ry_engines.htm

This 3-rotor kit costs around $7500.

If I buy this kit for a FB, what else do I need to modify? Driveshaft? And what would the extra mods cost?


I do NOT want a Turbo. A BP 2-rotor would cost around the same, because I live in The Netherlands so I have to order a complete engine in the US.

zyounker 06-03-02 03:01 PM

It would actually be pretty easy if you have a machine shop around that will do custom work for you..

All prices are US:
20B /w Custom crossmember
Haltech (Or your choice of EMS)
TII Tranny
TII Flywheel
Custom Driveshaft
20B header
Good radiator

THen just ditch the turbos and put an air filter on the intake..


Not the best but the cheapest probably.. or you could ditch the EFI for a custom webber setup. But that would probably cost more.


You could probably get it done for ~$4K-7K..


-Zach

zyounker 06-03-02 03:03 PM

Forgot you will want a good clutch/pressure plate too..


-Zach

Jeff20B 06-03-02 03:26 PM

Zach, do you think the triple SU carbs from HME is a good idea?

Edit: it doesn't look like it would fit a real 20B. Only probably fits HME's three rotor engines.

zyounker 06-03-02 03:33 PM

Um, I don't much like SU carbs.. but i don't have alot of experiance with them either..


The question is though, why go with carbs when the engine comes with all the Fuel injection stuff you need accept the ECU??


If you really want to go cheap pick up a distributor from mazdatrix and run a haltech F9..


I think carbs on a 3 rotor would be hard.. Because you would have to hack up the throttle linkage.. to make them open the same..


But if it is a 20B kit it might be ok..



-Zach

82streetracer 06-03-02 03:35 PM

did you see that 900HP six rotor.
imagine that in a fb

zyounker 06-03-02 03:46 PM

Well, You would probably have to sit in the back of the car to fit that bitch :)

Aico 06-03-02 04:38 PM

BTW it's not a 20B, but a 12A 3-rotor.

MIKE-P-28 06-03-02 04:38 PM


Originally posted by zyounker

You could probably get it done for ~$4K-7K..


-Zach

Uh Im at almost 4k now, getting ready to drop another 2.5k and Im far from done

REVHED 06-03-02 04:48 PM

Carb on a 20B is easy... 51mm IDA on a custom manifold. I saw a PP 20B with this setup and it was making some ridiculous horsepower. Though I guess the manifold would be pretty hard to make if it's not a PP.

peejay 06-03-02 07:07 PM

Why bother with the hassle and weight of a 20B if you're only going for 250hp?

moremazda 06-03-02 07:26 PM


Originally posted by REVHED
Carb on a 20B is easy... 51mm IDA on a custom manifold. I saw a PP 20B with this setup and it was making some ridiculous horsepower. Though I guess the manifold would be pretty hard to make if it's not a PP.
Was this a three barrel IDA?

MIKE-P-28 06-03-02 09:23 PM


Originally posted by peejay
Why bother with the hassle and weight of a 20B if you're only going for 250hp?
YEAH, true why?

Dyre 06-03-02 09:30 PM

The stock Comso 20b ECU doesn't work without the stock coils, wiring, and auto tranny, and even they you still have to trick it to run.
Plus the fuel maps will be all wrong without the turbos.

REVHED 06-03-02 10:29 PM


Originally posted by moremazda


Was this a three barrel IDA?

Nope, no such thing. It was just your regular 51mm IDA on a custom stainless manifold. The engine was in an 86 model 323 sedan which had been converted to rear-wheel drive. It was running mid 11's so obviously it was making plenty of power.

zyounker 06-04-02 08:29 AM

A 51 IDA is way too small for a 3 rotor.. That would be more inline for a PP 13B..


And If you price thing out right a 20B is not that expensive to do.. BTW the 5-7 was for the swap.. Not including car or other things.



Just so you all know, kurgan & i are droping a 20B into his FC right now.



-Zach

zyounker 06-04-02 08:30 AM

Mike: You say you are gonna be at $6.5K? are you going turbo or NA??? Because NA is alot cheaper.


-Zach

Directfreak 06-04-02 08:37 AM


Originally posted by zyounker
Mike: You say you are gonna be at $6.5K? are you going turbo or NA??? Because NA is alot cheaper.


-Zach

Mike is going Cosmo Turbo 13B.

REVHED 06-04-02 04:32 PM


Originally posted by zyounker
A 51 IDA is way too small for a 3 rotor.. That would be more inline for a PP 13B..
That's what I thought as well but I'm just telling what this car had and what times it was running. Obviously it can't be way too small if it was making enough power to run 11's in a street car. Probably not ideal though.

peejay 06-04-02 04:55 PM

If the carb was on a plenum manifold it would be big enough.

And it would have to be on a plenum manifold, for two barrels to feed three rotors :)

theNeanderthol 06-04-02 08:45 PM

Wouldn't a 3 rotor make way more than 250 horses? If you only want 250 horses I would put a big streetport on a 13b, or a halfbridge on a 12a and lighten the car up a little. Or maybe a TII motor. Or you could wait to hear from the guy who is supercharging his 12A (Sterling?) and get the specs on how from him.

theNeanderthol 06-04-02 08:48 PM

Or maybe go to a junkyard ang get a sixpack from an old pontiac. (three 2 barrel carbs) and do a custom manifold. 1 carb per rotor. That would be kinda cool.


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