I am in the process of preparing an engine build to convert my series 1 929 (pointy nose) into rotary
Did a lot of reading and carb comparing and found that the oldskool Rotary Engineering dual DCD setup would be my favourite setup. IDA's are great for performance, but the lack of choke kills the deal!
Engine would be a 13B S5 4-port base with S5 N/A rotors and planning on a secondary half bridge, haven't decided wether i just clean up the primary port or add a streetport to that one.

The separated staged throttle on the dcd carbs means you can keep low-end torque on a half bridge port. Supposedly it should become pretty docile in low speed driving.
It will be a streetcar only, low speed driveability is key!

Now to the question:
The ancient RE carb kit uses 28/36 dcd carbs,
i will be replicating this setup and will probably make my own manifold

these carbs are hard to come by, but i found that there is a new version of this type readily available. It uses a 36mm primary stage instead of the 28mm

Do you guys have any input on how this larger bore would perform on the stock or streetported primary intake port. Remember, before 3/4 throttle, the engine will only be fed to the primary port!

Thnx in advance

 

Thread can be closed, found the 28/36 DCD so i will be starting the build very soon

 

FYI the RE kit came with 36 DCD rather than the 28/36 DCD.
I am running the RE setup on a streetported 4 port 13B.

 

It seems there were several options..

The majority was sold with the 28/36dcd, both for 12A and 13B
The 12A kit would have different chokes fitted

There are also 36DCD versions, they might have been later versions of the kit?
I like the idea of the smaller primary, because of the higher intake velocity and that would be perfect for my street-setup.
Power-wise it should be fine with either, i've come across a 28/36 setup feeding a 300hp semi PP setup and it worked fine.

Been working on it for a couple of weeks now, throttle and choke lever prototypes are almost finished
After that, i will be starting to fabricate the heated intake manifold

 

Wow! That's some beutiful work on that linkage, Heavy duty stuff!!

On the 28/36 DCD setup, I have stacks of promotional literature, instruction manuals etc on the Rotary Engineering intake products and have never seen any mention of anything other than 36 DCD setup so I am surprised to hear that a 28/36 setup was offered, interesting.

On the ability of the 28/36 to feed higher demand situations I agree that it will work fine, especially as far as driveability goes but I would worry that the smaller primary would limit top end power, especially with anything but the largest chokes.

I am running the 36 on a 4port 13 B with large streetports. I have experimented with choke size and have even turned my own custom chokes when I suspected that the largest chokes offered by webber were not quite big enough. Sure enough the larger custom ones helped the engine breath better at WOT. Driveability is still as good as a stoc intake setup.

I am very interested in your project. Please post pictures of the intake when you get it built.

 

Yeah, i really want to build everything just once, don't want stuff to break down after a few years

Odd that you don't know of the 28/36 setup, as it is referred to as such in almost all the threads regarding this setup..

Interesting...

Hope it'll work out, otherwise i would have to re-build everything with different carbs
On the other end, my goal was 200rwhp with a half bridge, with driveability as main aspect. anything more would be a bonus anyway.
I've been in contact with Defined Autoworks regarding my plans and explained how it should work. They also said it would work just fine.
They then translated this into port timing specs and will be providing me with custom porting templates. They are currently building me a header, calculated to engine specs.

 

nice setup! pj and i (and others before us i'm sure) have found that having vacuum on the ports with overlap = exhaust gasses in the intake = brap brap.

so if you have some adjustability with all 4 throttle plates this is good, can't wait to see the rest of the car!

 

Hey Furb

Just wondering can those carb supply youre engine the needed fuel demand in WOT, the carb fuel bowl isn"t that big they can run out of fuel.??

I have experience with them mounted in none rotory engine and they started to run out of fuel by 5500rpm

Rotary are thirsty

Good luck with the build

 

If those bowls drain empty its fuel pump issue, not the carb..
ive seen them fitted on 300hp rotaries, so should be fine

I want to redirect you guys to my build thread for more updates and chitchat
https://www.rx7club.com/showthread.p...6#post11339016

 

Okey !

I my case the fuel pump & lines wasn't the problem LOL

 

Its been a few years, but to finish the thread i would say it all worked out great.
Still need to work out some tuning, havent driven it much because ive been renovating my house for a few years and still a few more to go before i can spend more time and money on the car.

Havent taken the engine apart yet for the porting, since it is still running perfectly fine on the stock ports, 18 years since its been rebuilt...

Below a video of the car running through 3rd gear, 80-150km/h