yeah yeah, another thread about the twin turbos. Well an idea just came to mind about the stock twins and the rats nest. Why can't the whole system be controlled by a computer instead of vaccuum lines and control valves, solenoids, etc. Basically just set it up as a twin turbo system with one turbo running from 0-3500 or so RPM and the other one coming on later (how they function now). Basically eliminate anything that has to do with the pressure and just keep the exhaust and switching mechanisms. The computer can control the rest. Does this make any sense or am I missing something really big here?

 

I've thought of this a few times myself. I don't know enough about the sequential system, but I think it'd be possible. Hydraulic actuators, pump controlled by the ECU. It sounds simple.



And Mahjik, when you read this, if it could be done, I'd be on that like **** on velcro.

 

Anybody else?

 

That would be awesome, but who would figure it out to make it?

 

Well I'm working on it in the meantime...I'm just researching the stock system to see what can be replaced. I'm a technology person and somewhat mechanical with basic things, but the stock turbo setup is a mess...lol

 

I think you could do it using solenoids and an ECU like AEM

 

Good luck!!

 

The 99+ cars have a greatly simplified system using only a couple of solenoids. Perhaps it would be worth your while to contact Jesse Lau (www.4jspec.com) to get a 99+ "rat's nest". This will give you a good starting point if nothing else.

 

i dont think the 99 nest can be transplanted. i heard some ECU problems and the like. i heard the pettit 3 rotor also uses 3 solenoids?

 

I've got a 2000 Type R and is much more simple than yours. Not as many vacum hoses or mechanisms. It's very simple setup actually.

 

do a search and see if you can find Damian's Vacuum Hose simplification. It leaves only what is required for Sequential Twin Turbo (I believe all Emissions are removed) and he said he got a perfect 10-8-10 off it. It'd be well worth trying!

edit: damian not damon

 

Aha! Linkage

https://www.rx7club.com/forum/showth...=perfect+10810

Upon reading this time around, that's not what I thought it was. There is however, a simplification on rob robinette's site.
http://www.robrobinette.com

 

I've thought the same thing, but there's a lot of things that make the whole deal complicated.

First off, a lot of the complication with the stock system is to make a smooth transition to the second turbo. It isn't as simple as one turbo on at lower RPM, and the second coming on at a certain RPM - Mazda tried that . You get a big flat spot as the second turbo spools up. That's why the second turbo is prespooled, surged, then brought online.

You also have a number of flapper doors that are in a VERY high heat area - trying to control them with an electric motor might be tricky. That's why Mazda used pneumatic controls.

Basically, there are a number of inputs and outputs to the system pneumatically - they're from different parts of the system. Vacuum from the vacuum tank, pressure from the pressure tank, boost reference from the output of the first turbo, vacuum from the inlet to the first turbo...on and on. I think what Mazda did with the later refit (which actually was on the '96-up cars if I remember right) was consolidate a lot of redundant vacuum lines into single inputs to a single box. There's a number of vacuum lines that all carry the same "input" or "output" - why not just have one vacuum line taking that input or output to a control box? That's what they did.

Trying to fab something up would likely be quite costly and time consuming, especially trying to get it to work with the stock computer, live in a high heat and rather volatile environment, etc.

But, more power to you if you can pull it off .

Dale

 

...The beauty of the sequential system, is that the secondary turbo prespools between 3000 and 4500 rpm. If the secondary is not prespooled, you will have terrible secondary turbo lag. What's the point? You might as well get a big single turbo, if you still have lag. With a bigger single, you get cooler operation, and higher horsepower potential...

 

A rather simplistic viewpoint, IMHO

 

Exactly!

 

There are 5 valves that need to be controlled--two which need be held in position to control boost and three that are flipped open/closed at the transition. You could probably use something like a solenoid to move the two-position ones, but for the controlled-position ones, you would need something more like a stepper motor.
In the end you might end up with something that is more complicated than the basic vacuum system for the twin turbos (neglecting all the vacuum bits and pieces for emissions systems).