Single Turbo RX-7's Questions about all aspects of single turbo setups.

Fb turbo manifold 12a

Thread Tools
 
Search this Thread
 
Old Apr 8, 2026 | 08:35 PM
  #1  
Badfighterpilot's Avatar
Thread Starter
The most beautiful FB
Community Builder
Liked
Loved
Community Favorite
 
Joined: May 2022
Posts: 317
Likes: 46
From: Idaho
Fb turbo manifold 12a

Anyone know of any fb 12a turbo manifolds. I've seen maybe one or two but wanted to see if there was any sneaking around that you might not get a Google result for, like mtheory. T4 btw
Reply
Old May 18, 2026 | 08:42 PM
  #2  
peejay's Avatar
Old [Sch|F]ool
Tenured Member: 25 Years
Liked
Loved
Community Favorite
 
Joined: May 2001
Posts: 12,880
Likes: 577
From: Cleveland, Ohio, USA
A factory 13B manifold probably fits.

I found that nonturbo 12As and 13Bs used the same exhaust manifold casting, they just moved the bolt holes 5mm off center one way for one engine and 5mm the other way for the other. The exhaust ports in the manifold are larger than the ones in the engine so there is no port mismatch on either engine. If you look at the ears on the castings and see the carbon witness marks on a used gasket, this becomes plain as day.

When I was restoring my '81 and could not find a 12A exhaust manifold, I used a 13B manifold with the mounting holes elongated to fit. Worked just fine. If you go back a loooong ways you will find that they used to do this in Australia to stick FC turbos on 12As. Given the fragility of the 12A without a lot of work, I wouldn't worry too much about making more power than a stock turbo can provide.
Reply
Old May 22, 2026 | 02:32 PM
  #3  
Badfighterpilot's Avatar
Thread Starter
The most beautiful FB
Community Builder
Liked
Loved
Community Favorite
 
Joined: May 2022
Posts: 317
Likes: 46
From: Idaho
Originally Posted by peejay
A factory 13B manifold probably fits.

I found that nonturbo 12As and 13Bs used the same exhaust manifold casting, they just moved the bolt holes 5mm off center one way for one engine and 5mm the other way for the other. The exhaust ports in the manifold are larger than the ones in the engine so there is no port mismatch on either engine. If you look at the ears on the castings and see the carbon witness marks on a used gasket, this becomes plain as day.

When I was restoring my '81 and could not find a 12A exhaust manifold, I used a 13B manifold with the mounting holes elongated to fit. Worked just fine. If you go back a loooong ways you will find that they used to do this in Australia to stick FC turbos on 12As. Given the fragility of the 12A without a lot of work, I wouldn't worry too much about making more power than a stock turbo can provide.
so a fb turbo2 swap manifold would work pretty good just by adjusting the holes? Would an fd manifold also work, the turblown manifold looks very similar to fb manifolds ive seen. I want my turbo sitting right by the strut tower.

Last edited by Badfighterpilot; May 22, 2026 at 02:36 PM.
Reply
Old May 23, 2026 | 06:27 PM
  #4  
peejay's Avatar
Old [Sch|F]ool
Tenured Member: 25 Years
Liked
Loved
Community Favorite
 
Joined: May 2001
Posts: 12,880
Likes: 577
From: Cleveland, Ohio, USA
The aftermarket manifolds, I assume, wouldn't work well due to being designed to closer tolerances.

One thing I am remembering now is that they would also have to stack header flanges under the manifold to space the turbo away from the intake manifold. Anything designed to fit a close tolerance to a T2 or FD intake manifold would probably foul on any 12A intake you could find.
Reply
Old May 23, 2026 | 08:37 PM
  #5  
Badfighterpilot's Avatar
Thread Starter
The most beautiful FB
Community Builder
Liked
Loved
Community Favorite
 
Joined: May 2022
Posts: 317
Likes: 46
From: Idaho
There is a intake manifold made by jdl that is basically just an fd lower intake made for a 12a. But even then it sounds like it would be easier to make my own exhaust.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
JBR
Build Threads
6
Apr 30, 2022 12:22 PM
racerguy19
Race Car Tech
1
Mar 14, 2009 03:19 PM
yetterben
Single Turbo RX-7's
6
Jan 2, 2008 01:39 PM
FB II
RX-7 Audio/Visual Lounge
28
Oct 10, 2007 10:39 AM




All times are GMT -5. The time now is 05:34 PM.