Alright first off I'd like to go ahead and say I searched, and found nothing more than a bunch of n00b "can I twin turbo my FC?" threads... Ok well here's a real idea for you to chew on... I was sitting around thinking of the ultimate twin setup for the FC, and this is what I came up with... Please do tell me if I'm an idiot...

Goal:
To design a sequential twin setup for the FC and control it via Megasquirt...

Hypothesis:
Ok so imagine if you will, designing a manifold that would allow you to run dual downpipes and dumping them just short of the front wheels (track use only)... So you would have a 2.5" downpipe for the primary turbo, and a 3" downpipe for the secondary turbo... That would promote more backpressure on the low end for quicker spooling, and less on the top end for obvious reasons... Building the manifold isn't my primary concern, as I have the resources to do so... I'm really just wondering if the Megasquirt would be capable of tuning it...

Conclusion:
This is up to you guys!

 

sounds realistic, but then again it might help if i knew what megasquirt was

 

It's a DIY standalone EMS... Costs about $250 for the whole setup I believe, and is comparable to Haltech or Microtech, except you gotta build it yourself... If you go to the engine management section, it has it's own forum...

 

Backpressure never equals faster spooling. The rotary has no trouble spooling even huge turbos in a reasonable amount of time. The FD turbos are only twin because Mazda used 20 year outdated turbo technology....

 

A bit more complex than that... First for sequentials, you need to obviously build a manifold that will mount both chargers, and feed both of them equally, but also, you must build a bypass to block exhaust from the larger turbo, so it directs all exhaust to turbo one, as turbo one spools, this 'gate' opens, allowing gas to pass through into turbo 2 (which starts to spool), and finally, as two is spooled, is opened fully.

 

Yea see I'm not an FD guy, so it's a little fuzzy for me on how the sequentials operate... So what would you suggest?

 

What exactly is outdated tech about the twins?

 

Explained above... If you're serious you're in for a LOT of rigging, especially to control the gas flow/wastegates of each. If you just want twins for the looks/some other reason, and don't mind that they're non-seq, check out the GT28R twin kits.

https://www.rx7club.com/single-turbo-rx-7s-23/twin-gt28r-turbo-kit-pics-387757/

 

I really want them for quicker spooling on the bottom end, and so I can run true duals... lol

Anyways, if it would be too much trouble, I'm not really in it just to say "hey I got a twinturbo FC", so I'll probably just stay with the single...

 

Well, they are twin ball-bearing, so they oughta spool nice! :p

 

It's covered pretty well in the Yamaguchi book (or however you spell it). Long story short is that if Mazda had spent just a little extra money on a ceramic ball-bearing turbo, they wouldn't have had to go through the trouble of developing the expensive and unreliable twins (with old fashioned bearings, oil seals that seem very quick to burn out, 7 million vacuum hoses and solenoids , etc.). The car would have probably had an entirely different reputation.

Mazda designed the twin system to provide good power with a smooth powerband (though that didn't work out very well) and nice response. If they had looked to more modern turbo technology, the wouldn't have had to do any of it.

 

True duals? so you were going to run one size pipe from one rotor, and a larger from the other... with a diff turbo on each? sounds like a bad recipe.

 

Yea but I'm not a rich man...

Who said anything about different runners on the manifold? Just different size downpipes dumping off the turbos...

 

How many production cars do you see with ball bearing turbos? Now how many had sequential twins? Seems like Mazda chose to go the route of following the competitor. It's bad enough the engine is so unique, imagine what people would've had thought comparing hmmm, single turbo, whats with these bearings things? oh this one has a bearing too, but it's got two turbos! I know, stupid people, but still. Also, what exactly was the cost on an OEM ball bearing charger that 12 years ago?

 

Wouldn't use a divided manifold anyways for an application like that...

 

Regardless you would need each turbo to be isolated to one rotor in order for it to be a true dual. Otherwise you're merging them before the turbos... merge = not true dual.

 

Well ok, "true dual" probably wasn't the best term I could have used there...

 

true turbo dual...

 

How about dual turbo-back

 

Agreed...

 

Nowadays? I think (though I may be wrong, and I can't seem to locate this information) the Mazdaspeed Miata as well as the SRT-4 both use BB turbos? Correct? It seems amazingly difficult to locate this information...

The Supra was sequential, right? Never paid much attention to those cars...Very ugly.

The cost was probably very high, but certainly must have been cheaper then designing the twin system considering how few FDs were produced.

The stock turbos seem to be the bane of FD owner's existence from my (limited) FD experience. It just seems like Mazda over-engineered where a simple solution would have been better (ie. FC's logicon).

 

I was referring to 12 years ago, back then BB wasn't quite as popular. (I can't think of one production car back then that had them) Now, though, the MS MX-5 has an IHI ball bearing, the SRT-4 doesn't. So does the Saleen S7, but that's a bit pricey. Back then, Subaru, Mitsu, and Toyota were playing with sequential twins, just seems a bit more logical to me to try to follow what others are using, but my real question was, how many production cars in the early 90's had ball bearing turbos?

Also, the R&D wasn't for the FD. The Cosmo is the first that I know of, which would've meant this was done in the late 80s. I don't blame them for sticking with technology they already dumped an assload into, versus more R&D for ball bearing which was rather limited back then (if it even existed, the closest I can find of anybody using ball bearing is garret from 1994)

 

I would assume none, but then how many had a rotary engine?

 

I have an idea for the exhaust manifold but my pic is to big to post. I will re size it and try again later.

 

Any ideas are welcomed...