Well I was browsing hte for sale forum and I saw that it looks like the intake , and TB and a few other parts seem to be desirable for the 7 , what difference is there between the cosmo engine , and the 7's ?

I have a shell and I'm looking for an engine to put in it . and than I saw that I know of a local cosmo engine in good shape but I shrugged it off since it was a cosmo engine insted of the 7's original one . so can someone lay it out for me ?


what differences I looked it up and it seems the cosmo's engine is 235 HP , vs the 7's 255 ?

 

I'm not 100% sure on the exact specs but i know a just because it's a 13B doesn't mean it has the same specs. Compression ratio coming from the rotors and port design are different. Im sure a search on this site could help identify the differences.

On the other hand, might want to double check if it's the 20B (3-rotor design) that's up for sale. This could lend you to a disgusting build!

 

no such luck on the 20b front LOL but I will check the compressions

I did a little wiki searching and apperantly its the turbos , the cosmo had a HT15/HT10 combo , and hte 7 had twin HT12's ..

 

dont do it, it will require a lot of fabrication, just get a FD engine that will drop right in.

 

^ the engine mount are not at the same place so you will have to make a custom subframe or engine mount. Probably a custom downpipe to if you keep the cosmo turbo!

Find yourself a good running FD engine

 

https://www.rx7club.com/single-turbo-rx-7s-23/cosmo-13b-re-vs-13brew-fd-148753/
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/swapping-cosmo-motor-2-rotor-153563/

 

13b-RE vs 13b-REW
differences are :
re has non hardened and 3 oil hole stat. gears
rew has hardened 9 oil hole stat. gears

re 90-94 has motor mounts only on middle plate, 95 had same motor mounts, but tapped rear plate for motor mounts.
rew has motor mounts on rear plate only.

re has massive secondary intake ports, people describe them to be a hair smaller then the largest streetport they've seen.
rew has tiny secondary intake ports...

re exhaust sleeves are pinned in place, are hollow, and are very restrictive.
rew exhaust sleeves are solid, and not as restrictive.

re was only mounted to automatics (prolly explains the restrictive exhaust sleeves)

at a minimum to get a re into a fd, you need to use the complete front plate from the rew shortblock, and either tap the rear plate for motor mounts (or get lucky with a 95 spec re motor), or buy a kit from some shop in FL (forgot the name atm) and use the rew oil pan. you really should do a rebuild to it and swap out stat gears, bearings, swap the exhaust sleeves and port exhaust to match how large intake porting is. This is what I will do next fall.

as far as differences in stock turbos
the 13b-rew came with double ht-12's
the 13b-re came with double ht-10's (also lower boost lvl then rew)
the 20b-re came with ht-15 primary and ht-10 secondary
the re cosmo turbos can not be used in an FD installation, however, you can bolt the stock rew turbos right onto the re block.
also if you do use the re intake setups, the lim requires a different sized secondary fuel rail.

 

thanks alot for all the answers , also I think the REW comes with the fan on it . while the re needs electric fans?

 

other way around, that's why u need the rew front cover for the re shortblock.
the re front cover has a mechanical fan on it, rew does not. you have to use the rew front cover. in an fd two electric fans are mounted to the radiator.

 

Does Mazda still sell 20B engines? It sounds like a business opportunity to me - lots of people still seem to want them, the way the muscle car guys want crate motors.

 

just because people ask about them doesn't mean they can afford them. almost everyone with a 7 talks about the 20B but few can afford the $15k to get one into their car and running.

and mazda no longer sells 3 rotor parts.