hey everyone i have a fd with a blown engine and my buddy is telling me he can get me a cosmo 20b for $2,000 and i realize that that way is going to be mega $$ getting everything converted... my questions what a about a 13b cosmo... what is the difference between a cosmo and a stock reman from mazda... are theyre any fabrication issues.. or is it just bolt up and go... thanks!!!

 

the ports are bigger on a cosmo motor.. i intake is nicer as well...

there are a few first gen guys that are running around with single turbo cosmo motors these days.. they could probably be of some help here.

 

The 13B Cosmo engine has the same mounts as the 20B cosmo engine, so neither will fit without a custom subframe, although both will bolt up to the FD transmission. Due to the extra length of the 20B, it also has fitting problems with the steering rack and sway bar, and also with hood clearance.
http://www.rx7turbo.com/projectcosmo.htm
http://www.2751engineering.com/blackfc.html

 

I have a 13B comso forsale 1800

https://www.rx7club.com/forum/showth...hreadid=182356

 

I'm in the process of throwing a Cosmo 13BRE into my FD. A few things...yes the ports (all four) are much larger, especially the secondaries. I've heard that it's "possible" to make the FD secondaries as large however.

Pettit Racing makes custom motor mounts that will allow you to swap in the FD motor. I called Pettit last Friday to find out.

A few things you should change over if you get a Cosmo...go with the FD stationary gears. Also use the FD's oil pressure regulator.

I am using the FD intake manifold. I have been told by pro-level drag racers that the cosmo intake will make more torque than the FD. It's a plenium type intake versus the charge pulse of the FD's. You will need to port match the FD LIM if you use the FD manifold. You cannot use the FD top with the Cosmo lower. The Cosmo intake runners are substantially larger. Additionally, if you use the Cosmo intake, you'll need to fabricate an approx. 1" spacer to move the TB into the stock location. There are also issues with the fuel injection. Primaries are the same, secondaries are not (they're top feed). If you have a single (or fully modded twin setup) you can always go with 1600's. K2RD has a Cosmo-specific fuel rail. You'll only need it if you stay with the Cosmo IM.

FYI, I left my primaries fairly small. The secondaries, stock are larger than the FD's but I went ahead and ported them out as well. On the exhaust side, you'll need to pull the stock Cosmo exhaust sleeves and substitute FC or FD sleeves (identical). If you need to know how to get the sleeve pins out, PM me and I'll send you instructions.

I paid about $1600 including shipping for my Cosmo motor. $2K is WAY too much. Try and get a 95 model year (last year made).

Everything else swaps over...front cover, oil pan, etc...minus a few small details like the engine hoist brace on the front side of the engine. Use all FD ancilliaries, ie. alternator, etc...

Hope that helps a bit.

 

thanks for the posts!!! lots of stuff i didnt even know about!

 

One more issue...the oil pan (FD) has holes which allow the engine mount bolts to pass through. Those need to be welded shut. More info as I come across it :-)

 

Are the turbos used on the Cosmo 13B the same as that on the 3rd gen rx-7?

 

no they are different. the fd has 2 ht-12 turbos, the 13b cosmo has 2 ht-10's.

mike

 

maybe this will give you an idea of the size of the 13B-RE turbos. This pic is taken of the rear turbo.