Twincharging, Serious discussion.
 

Gday fellas,

Im currently starting a twincharge setup. It is a 1.6L with 10k in it, which already has an SC14 blower and W2A cooler, and going on it is a twinscroll equal length manifold, feeding a GTX3076r with a pair of Tial gates.

Its not a miata though, its a Suzuki Sierra (2nd gen, so its a katana in the US I think).

But I always said I would twincharge a miata with a serious super monstrous turbo and run high comp E85 setup with spastic cams and rev the tits off it.

I will. I promise.

So for now Ill use this as a progress thread for this Suzuki, and I want everyone to post links and ideas.

This car is just a job for me, I dont get a say how its set up, but for those wondering the guys mate is an automation engineer and is designing and setting up an interface for its adaptronic and he will run servo controlled 50mm gas stop valves to bypass the blower and turbo and swap between them etc.

Going for 400-500whp and eleventy torques.

So heres my miata plan And I have mentioned it before, but no one really took it very serious. Hopefully my actually building a monster twincharge setup on a different car will prick up some ears.

The miata build plan for me so far has been a low mount SC14 with a high mount GT35r or similar.

Here we go.

Now rip shreds out of me.

:)

https://www.miataturbo.net/attachmen...ine=1376788794

The 90mm above is a throttle body btw.

Dann

https://www.miataturbo.net/attachmen...ine=1376789981

This Suzuki already has a stroked supercharged twin cam GTi swap if I didnt mention that. :)

Dann

https://www.miataturbo.net/attachmen...ine=1376791113

Patiently await results..

Dont be that guy, elaborate.

One potential issue I see is that you are going to be running the turbo in a weird spot on the comp map, lots of flow without crazy boost.

Dann

Well the AW11 got twincharged decently often back in the eighties and nineties. However, the supercharger on the AW11 was actually clutch driven, like a A/C compressor. I think back then, the setup was done with a Hobbs pressure switch, along with a NC relay. Very simple, but effective.

I've always wondered, on a twincharge setup, why do people have the blower shut off? A few 350z guys have been twincharging their cars. I've seen it done with a roots style blower (Stillen), but no mention of a clutch setup to turn off the blower.

The one I found most impressive was the centrifugal setup along with a remote mounted turbo. However, it didn't seem very responsive (expectedly so) as the roots blower style. However, I don't know how much power the roots twincharge setup made.

Rotrex's suck in all but the best engineered setups.

This is using a toyota supercharger with a clutch and bypass and so will I.

Dann

You might have a better luck with a bottom mount turbo and the sc up high. For both heat and space reasons. You definitely dont want the supercharger wrapped in the turbos exhaust piping. Also twin screw or bust.. theres no point of going with a failtex.

I gave you props for this one.

Agreed, the heat soak is a huge issue with them to my understanding. But I believe the rotrex excels in low noise right?

Anyway, but do you know why the SC has to be shut off as the turbo spools? Is it an issue with blockage as the turbo starts making air (like fans on the highway begins to block air from flowing through)?

Rotex doesnt excel in anything... ok fine maybe low noise and a tiny bit more efficiency than a twin screw.

Not sure why he plans on shutting off the rotex as the turbo spools.. i'm guessing to prevent over spinning.. after all you run a sc to help with the lack of spool from a turbo.. why one would do a turbo and a centrifugal sc is unknown to me. Perhaps hes planning on running a very very small pulley on the centrifugal sc to increase low rpm power and then shutting it off to prevent overspinning the piece of junk?

my issue with twincharging is that you're either trying to overwork the turbo by sucking through a slow and limited supercharger

or you're trying to overwork the turbo by blowing through a slow and limited supercharger.

And if you use a Y configuration, you'll potentially have one blowing back through the other.

So the awesome thing to do in my no-experience-twincharging opinion:

put the turbo after the super and install a bypass on the super that allows you to switch it out of the system at some nominally low boost level where the turbo is happily spooling. A one-way valve that allows a fresh air source other than the super might also work but how, I do not know.

In any case, with a good control system and lots of pressure (and flow?) sensors, you can probably do this a couple different ways. I bet you could even run it on something like an arduino or something.

Well what is the plan here? To fix turbo lag at low low rpm or the opposite?

I assumed you want to increase low end and then get the benefit from the turbo at the mid and top end. IMO you're better off doing a twin turbo setup with one small and one large turbo.

The plan for the build Im doing right now is to have a car which has been 'Twincam swapped, cammed, ported, stroked, forged, supercharged, intercooled, twinscroll turbocharged 4wd.'

But if you were to put a practical application to it, yes the point is to spool the big turbo.

Neither this setup, nor my own planned setup will use a rotrex!

Y8s.

Positive Displacement superchargers like the Toyota SC14 being used in but this build and my proposed build work on a pressure ratio.

So lets say the blower alone is running 1 bar (15ish lb) boost, thats 2 bar absolute, which is pressure ratio of 2:1, it takes a 2 litre bite of air and compresses it to 1L with double the pressure.

If you feed it with a turbo making 1 bar boost (2 bar absolute) it takes that 2 bar absolute, compresses it to half the size, making it 4 bar absolute (3 bar of boost, 45psi).

If you feed a 30psi blower setup with 30psi turbo it outputs 100psi boost.

The issue at this point is you have 200* boost, and need a serious intercooling setup, which is why I propose alcohol injection for charge cooling between the turbo and blower.

This is interesting as it puts the turbo in a super high flow, not particularly high boost part of its compressor map.

Dann

That car is so stupid, look closely you will see the blower intake doesnt do anything.

Dann

Actually, it's the intake for the turbos- it's sealed off from the airbox below it, which feeds boosted air through the carbs and into the supercharger. Here's a video with a better look. Don't get me wrong, like all Pro Fairgrounds cars, is a ridiculous pile of wasted money, but in theory it would work.

Ah finally a video that explains that its sealed....but cant get enough fuel? lol.

Not enough fuel, what... do these plebs drip it in with a teaspoon?

Dann

Dan, you've pretty much got the theory in post 15. I would want an IC between the turbo and the blower though, even a small one. A 20*F drop between the two will be noticeable on the output, and if you feel the blower too hot of air you might run into blower cooling problems and reduce the blower life.

I still say this is stupid, but that doesnt mean I dont want to see it done.

And alcohol injection immediately after the turbo wont work? What if half the fueling happens there? What about all of the in boost fueling?

Also, for say, a daily driven miata, why is it stupid? 500tq for 6000rpm straight, why not?

Dann