RX7Club.com - Mazda RX7 Forum - Differences in FC-turbo and FD rotary engines...

Whats up guys? I'm new to this forum...where to start....

I've had 2 RX-7's before (81 GSL-SE w/ 89 n/a engine and an 88 TII), so I know a bit about these cars, but was thinking of doing a project car, and wanted to start to gather data before delving into this thing head first.

I have just gotten into doing my own wrenching recently (I couldn't afford my 86' 944 turbo otherwise), and am getting ready to sell my 90' celica all-trac to free up some funds and car storage space...but I will never get rid of the porsche...I want to be buried in it....

My idea for the project: 87-91 rx-7 turbo cab...errr...convertable (no porsche talk here ;) ). I would want to find a convertable in fair condition with a blown motor for cheap, and then find a suitable donor engine to go into it.

Now the questions...

Is there any difference between the 2nd gen turbo motor and 3rd gen turbo motor internally (by which I mean port sizing, port positioning, materials used for the rotors and rotor housings, apex seals, compression ratio, etc...I know that the induction system is completely different (simple single turbo vs. complicated as hell sequential twin turbo) and the FD engine obviously has more fuel coming into it, but internally) and could the 2nd gen turbo motor take as much abuse as the 3rd gen (i.e. lots of boost and CFM of air) if you had the fuel to match?

Does the n/a FC motor have a higher compression ratio than the turbo II motor? How is this accomplished with a rotary engine? It looks like you would have to change the geometry of the rotor (i.e. curve on the side) to increase compression ratio, but I am still trying to learn this stuff.

If I were to do this project, I would probably want to rebuild the motor before I dropped it into the convertable body. I have been told that the rotor housings on rotary engines have some sort of polished nickel/chrome plating on them that wears off with time, leading to blow by, compression loss, accelerated apex seal wear, etc...can this plating (if it does in fact exist) be re-applied? How expensive would it be to get done?

What is involved with installing 3mm apex seals in the rotors? How much more bullet proof would this make the engine? What is the pricing for 3mm apex seals?

Why are the turbos prohibitively expensive for 2nd gen rx-7's? I was looking to replace the turbo on mine with something "juicier", but the cheapest aftermarket turbos I found for the car were over $2000...I can get a nice T04E hybrid turbo for my porsche for less than $1000, and add $300 for ball bearings...how hard would it be to fit a turbo like that up to the stock turbo plumbing?

That is enough questions for now...my fingers are getting tired from typing...I am sure I will think of some stuff later. Thanks in advance for your replies.

Here's my car:
https://www.pelicanparts.com/ultimat...s/0709_001.jpg

https://www.pelicanparts.com/ultimat...s/0709_005.jpg