Hey everyone I am building a custom aluminum intake manifold to fit my 13b rew Rx8, I designed / fabbed up a 3 runner manifold and purchased 6 id injectors (2 for each runner) before I actually thought about the fact the im sharing the center runner between the two rotors so basically my first question is would running a single runner for the 2 primary intake ports and having injectors on that runner even work ? Or would this be injecting fuel into the opposite rotor when not needed?

I currently am using another custom aluminum intake manifold using the 3 runner design but there were never any injectors on the center runner.

Picture of the manifold im building,



If it is indeed a bad idea to put injectors on the center runner would putting 3 injectors onto each outside runner be fine or would this end up being to much fuel in those runners ?

Thanks for any advice.

 

are you going to be running alcohol or something? (just trying to figure out your injector strategy)

how will this eventually interface with the engine? is it going to be using the stock lower manifold or will you be fabbing the interface?

it looks good. in my inexperienced eyes, you've got great skills.

 

No alcohol just E85, I have 2 1000cc id injectors for primaries and 6 2000cc id injectors for my secondaries. Planning on mid 700's hp range. I honestly dont know why I didnt do 4 runners, I had 3 in my head like my last setup and just went with it. I was thinking 3 runners to the flange on the engine weld those up, weld on 2 injector bungs for each runner at a 45 angle up by the intake plenum (6 injectors total) then just have to cut and tap my fuel rail material and mount the rails using my cnc brackets I have.

Then one night it hit me that im possibly an idot and wasted all my time and money on parts so far building only 3 runners again lol.

Thats why I posted to see what other people thought would happen if i had injectors on the middle runner going to both rotors.. or if I need to build 2 smaller runners for the center and merge them together into the one velocity stack.

Couple pics of how it sits in the car.. Dont mind the turbo needs to be coated still.






Thanks.

 

Looks nice! I'm sure 3 runners would be fine as long as you are using the newer style injectors that spray a nice fine mist. Worst case, you can build this one and maybe sell it to fund the next one