Good eveing everyone, just a quick question! I've recently acquired a 1994 JDM FD3S and I can say I've fallen in love with it! I'm also quite new to this forum and I can already see how much information and experience there is here! So, my question is what would be the procedure to convert a twin turbo rx7 to naturally aspirated? Currently my car is stock except for a titanium muffler, and I've noticed online a few people who have done the conversion but I have not seen how they did or what the procedure was, or the parts they had to obtain. I tried to search this but didn't get many promising results. Any help is greatly appreciated!

 

Why?

 

I noticed that RE-Amemiya did a similar build, and I was simply wondering what type of procedure that involves.

 

Are you talking about RE Amemiya's yellow 3 rotor NA car? 3 rotor na is much more common for obvious reasons than converting the 13Brew to NA. I would imagine you would need the obvious things like headers, and remove everything having to do with the turbo system. The 13brew would probably be gutless NA, so you would want higher compression rotors. But it is a 4 port motor, and all NA rotaries I think are 6 port, so you might be better off using a 6 port motor. If you kept the 13brew you would want to port the motor a lot. And you would need different engine management. I'm sure there's other stuff too, but I can't think of it all.

 

You are going to need to get a stand alone ECU also. But like mention above your car would be pretty slow. RX-8 would be faster.

 

The Pro7plus racing class (in NZ) runs a standard Series 6 motor (13BREW) without turbos (ie NA, standard ports and rotors). They make around 200hp (not sure if thats flywheel or wheel hp). But they have effectively no restrictions on exhaust, and use a Link ECU.

Or you could go bridge-port or peripheral-port, with high comp rotors. Should be able to get 250-300hp or so. But to get that sort of power your exhaust noise levels get pretty extreme, and wouldn't be the nicest thing to drive on the road :p

 

The intake manifolds, intake ports, etc are not optimized for naturally aspirated operation. The Rx-8 Renesis and the 6 port 89-92 model non turbo engines are much better for that but it would be a pain to swap. There were 4 port naturally aspirated 13B engines. They had carburetors. Mazda switched to a 6 port + variable length intake runner system for a reason.

The 4 port turbo engines are engineered for a turbo(s) and the 6 port naturally aspirated engines (2nd gen Rx-7 and Rx-8 Renesis) are optimized for no turbo. Trying to make these engines something they're not is an uphill climb.

 

the question is WHY would you want to do this for a street car?

its easy as cake to make 300hp with the stock twins and thats all you really need for a quick street FD

 

The only reason you'd do this is to take a quick car and make it very slow and gutless.

The only N/A FD's I'm aware of are running 20b engines and this is a whole different story. Don't run your 13b N/A, you'll just be very very sad.

-Geoff

 

i've seen a few in the japanese mags over the years... there are a few ways to go.

you could just pull the turbos and IC and put a header on it. power and especially torque will be down.

to get more power you're looking at pulling the engine and porting it, higher compression rotors probably too.