Zepticon

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I came to wonder why there are not more options for improved OEM exhaust manifold designs? I mean with the current technology available in 2016, and even more in the future, redesigning and removing the faults of the Mazda manifold should not be to hard?

With the RX7 entering the "classic" era, i think people want to hold on to it as it was from factory, but also improve and fix the faults it came with. A new redesigned manifold with better materials and casting/machining would probably aid a lot in the issues the twins are seeing?

I know most people say "go single" but that is a huge change to the cars spirit and does not reflect the tech advance the twin-turbo system was in early 90s. Turblown have made an incredible piece of tech with their single turbo manifold, why would not something similar for the twins be possible?

ptrhahn

iTrader: (9)

Honestly, as someone who ran twins for years on track, I'm sure you could improve the manifold design, but turbo design has improved faster... in 1992, you needed twins to balance spool/power, but with modern turbos you really don't.... i can honestly say that the Borg Warner 8374 internal wastegate hasn't changed the character of my car really at all, it just makes a little more power, a little less heat, and has a little less weight and a lot less complexity.

Zepticon

iTrader: (1)

I ahve been drooling on the BW setup since it came out. But the only issue i have with it, is that the car looks modified the instant i put one on. And that ruins a big deal of what i like to do with my car hobby.

I mean, putting a Single on the car is not a problem. I store all parts i remove/modify so that i can put the car back to factory condition. But putting a single turbo on makes it stand out as modified instantly

ptrhahn

iTrader: (9)

That really depends on the execution. It can/could look remarkably OEM (unless you're knowledgeable about what the actual OEM setup looked like). You could even retain the EGR and air pump if you really wanted to.

That said, if what you're looking to do is be able to put it back to factory condition quickly, no that won't work.

For the OEM manifold, Ive heard of people hand porting it for better flow. It's so tight, that I think if you were to produce a replacement, you'd almost need to do it with 3D/Cad design and a casting or 3D printing (with metal) process. It would be a time consuming, highly technical, expensive proposition unless you're an engineer with access to all the equipment.

bajaman

Yeah...I get what you are saying, Zepticon but realistically, I don't know what would really be IMPROVED all that much by using "modern technology' in regards to the exhaust manifold. Meaning, one can't really change the design so that would leave perhaps FORGING the manifold rather than casting as one possibility but then again...it is much easier to cast the complex shape of the thing than forge it.
Interesting idea though.

photoresistor

iTrader: (5)

Has anyone swapped out the OEM turbos for more modern ones? I wonder how much performance you could gain if they were similar sizes (because of space restrictions) but were EFR's or something.. and make a custom cast exhaust manifold to mate up. Sounds like a "mini-20B"-type project.. anybody?

Carpe_Diem_7

iTrader: (6)

The OEM manifold is so tight that it is almost unavoidable to eventually crack due to the pressure created there. I think one guy in the forum tried to use external wastegate with impressive results on the dyno.
I also wish that an improved manifold existed for the twins, that would be an interesting project for anyone willing to put the investment in time and money it requires.

7-XR

iTrader: (7)

Hey, here is a link to that thread ^

https://www.rx7club.com/3rd-generati...-done-1000553/

AlienHack

I also keep my twins altgough the rest of the engine bay is modified (big intercooler biger water heat exhanger ,new cabling ,silicone hoses etc. )
I have thought a lot about making a better manifold for the twins but as soon as i took the twins & oem manifold out to study and start designing the new one i found out what the problem is.... there is actually no exhaust manifold in the fd. There is one small manifold that bolts on to the engine and then the rest of the "exhaust manifold" are actually the housings of the turbines themselves. What i mean is that in a normal 1 turbo car there is an exhaust manifold that combines all the gases to one flange that the turbo it self is bolted on . Well in our cars the manifold is actually the turbos themselves.. so you cant just design a new manifold... as that means that you should design turbo housings actually amd thats really crazy to do...



As you see the manifold is intergrated in the turbine housings. Its not seperate as in this example.



Here you see there is an exhaust maniifold with 2 wastegates (its a twin scroll one) and on the end of it the turbo is bolted . They are 2 seperate things, in our twins the manifold is the turbos themselves...

IRPerformance

iTrader: (41)

The 99 turbos, SP version of them, and BNR Stage 3s are all improved versions of the stock turbos. As said above, it would not be cost effective to make a better stock replacement manifold and it would yield little gain. Mazda's goal was to eliminate turbo lag and they were limited to the technology available at the time and by cost. Today a well engineered single turbo setup can outspool, outpower, and be more reliable than the twins.

SakeBomb Garage

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