i was thinking of making a twin turbo setup using two s4 turbos just there intrnal waste gates and runing 5psi of each (10psi total), but i want to know what do u think i should do for the maifold (i was debating about having each turbo to each exhaust port or if i should make the mamifole branch into a single and back apart for each turbo.)

And if i should have them on at the same time or sincronise them with the engine rpm (run only one untill about 3k then let the other one kick on.)

thank you for your input.

 

I don't think you know what your up against.

First question: Do you have the ability to make this manifold? It needs to either be a very thick cast, or a very thick 321SS, with great welds.

Second question: How do you think your going to run them sequentially? The FD did it with about 100-120 vacuum lines...do you plan on hooking something up like that? I know I wouldn't want to.

And lastly..do you think it'll be worth it? 5psi on each? You might make 300rwhp. If your lucky.

Your MUCH better off getting a set of low-mileage FD twins, doing the full sequential mod, hooking them up, getting a custom downpipe-adapter made, some custom water/oil lines, custom heatshield/heat blanket, and getting a boost controller. It will be MUCH more "plug-n-play", and make a good 320-340rwhp.

 

I've always wanted to try the twin s4 turbos...

 

Well, i think personally if your not pushing alot of boost, stick with a single and go Hybrid or something. Makes things heck of alot easier. There are some turbos (single) that spool crazy fast and makes the whole setup easier to deal with. However, if you really want to go with dual turbos, there was a thread on here about someone who did 2 S5's but the piping was...very interesting at best. synchronizing them is not worth the effort (thats the sequential setup in the FD's and those were problematic if i remember correctly).

If you really want to do this, make sure you have enough room around everything and make sure you can make your DP fit both turbos with no interference. Dont have any hard angles on your piping (both out from the turbo and out to the exhaust). The manifold i think maybe better if its not divided by each rotor (but thats just my thinking). not sure if you have to think about oil cooling and all that since you have 2 turbos thus more heat (how much more, i dunno, but its something to think about).

Is there any particular reason why your going twins? maybe there is a better route for you.

 

i am a great welder and have ben doing it with all maner of welders (stick, mig, tig, O.A.) and i have a place in a town by were i live that can have any piping bent in any size, any angle, and kind of stuff. and the timing of the twin turbos sequentially would actualy be really easy. just T the vac line to the normal wastegate out to a silinoid of some kind then have the silinoid hooked up to one of the wires to the secondary injectors so that the second turbo and the secondary injectors kick on at the same time.

and as for the cooling aspect i could jest get 2 high pro coolers and stack themsome were in the oil line.

why i want to do this is because its just sweet to say "yea its got Twin turbos."
and with haveing two smaller turbos rather than one large one is to avoide lag during boosting.

 

Using a waste gat, the pressures are not added. If you had one at 5 psi and the other at 8 psi, the first turbo would just stop spooling after 5 psi, leaving the other turbo to push it from there to 8 psi.

 

maybe i'm not totaly sure on how the vac system works with a waste gate. but i was thinking that each turbo would have its own waste gate and vac regualtors to the waste gate. like dual manual boost controlers.

and with what u said about the twin turbos, the first would push 5psi then the second would only have to push 3psi to make the 8 total psi. but i would go probly 5 and 5 or 6 and 6psi.

 

To create a fully sequential twin turbo system, you will need something that mechanically diverts exhaust flow to one turbo and at a certain timeline, open flow to the second turbo.

From what you are describing, you plan to control the wastegates at a different interval. This will not keep one turbo from spooling seperately from the other with the stock wastegate spring rate.

Series 4 turbos have a wastegate spring i believe of 5.5 lbs (correct me if i'm wrong). And they will spool to that rate before the wastgate opens. In order for you to manipulate the second turbo to not spool until a specified time, i'd think you would need to run a very light spring to keep the wastgate open and then manipulate the wastgate via a boost controller. I don't think this would be a very good twin "sequential" setup.

Maybe look into A-spectuning.com for thier GT series twin setup. You would make much more power and with much more simplicity if you want the "cool factor" of a twin setup.

-Justin

 

Why not just skip all this madness, and get a variable-vane turbo? It's all the rage, and will probably end up costing less than all of this garbage. Either go with whats normal (good single, or FD twins), or go big (variable-vane).

 

Y would i not want them to be spooled up at all times so that the turbos are always ready for action, and doesnt the waste gate control the amount of boost a turbo makes, so if i set them both to spool but one to open and build boost right away then the other idle untill the set point is reached.

 

DUDE, the hole thing is for the me building it part so no one else can go online and get another one just like it.

 

Actually, there was a guy that fabbed up custom twins using stock turbos. He was also a damn good welder. If you can weld, then go for it. If not, its probably too much trouble. Search around and see if you can find anything about that guy for ideas.
Also, just run them parallel. From everything I can tell, it is very hard a complicated to get the sequentials to operate properly and smoothly.

 

You're a n00b.
You should learn how to search.
There was a GREAT thread a few weeks ago that went into exactly this subject.


-Ted

 

NO.


Boost is a funtion of resistance to the flow of air. OK?

You set one waste gate to open at 5 psi, and then set the other to open at 5 psi you dont get 10 psi. Assuming your wastegates can flow sufficiently you only get 5 psi. Its not a mathematical equation. Its an absolute.

If you want to make 10 psi then you set the wastegate with a 10 lb spring, or use a boost controller and set it to open the waste gate at 10 psi at both turbos.

Were you measuring airflow then that would be one thing, but you arent. You are measuring boost, so setting each to "only flow 5 psi" will result in you only getting 5 psi.

Further more, wastegates OPEN to release exhaust gas. if they are open you are diverting exhaust gases away from the turbine PREVENTING the turbo from speeding up creating more boost than you want. If the wastegate is closed all the exhaust gases pass throught the turbo, making the turbine spin, causing the compressor wheel to spin at the same speed creating boost. You seem to think that the wastegate is on the intake side of the turbo. it isnt.

Finally you cant have a turbo spooled up without it creating boost. "Spooled up" means that it is spinning fast enough to produce boost. So you cant spool both up and not have them both flowing air.


And those are the reasons why I, and I imagine others, have VERY little faith in you being able to pull off a sequential TT setup. If it was "easy" like you say then it wouldnt have taken so much work from the Mazda engineers. It is more than clear that you have only a VERY VERY basic idea of how turbos even work, let alone how to do something like this. So stop dreaming, do some research, and figure out that what you are wantng to do is very diffuclt and you do not have the ability to pull it off at this time.

 

Make a twin set up thats great but first do a little more research on how the turbo's work.

You wont have boost at all RPM levels. And if you want to make something nobody else has then I say you make your own manifold to run the 99spec FD twins or any set of FD twins. If you insist on having them stacked vertically on top of one another then you will be better off getting aftermarket turbos cause the S4 turbo's (though very cost effective) just wont fit to well in the engine bay with manifold and Downpiping. Not to mention the nightmare of working on the engine with that mess in there.

Has anyone used a Variable Vane turbo on a FC or FD??? I would like to see or hear more about that!!!

 

reTed i did see the thred on twin turbos.

and the thing that 5 psi off both turbos makes no sence at all if u have two compressors that have 15psi then at the point were the two are united in one area it would actualy make a little less psi because of the air compressing but still it should work, unless you have them run unequal pressure then they would fight each other and you would need to set up blow by valves to stop comressor surge.

 

then do it.

Posting on here won't make it happen, since you've seemingly got all the details worked out. Why don't you take you welding skill and your leftover S4 snails and build the damn thing!!!

Sorry, but Im just tired of seeing these multi-page, in depth discussions on the same topics where someone goes on and on and ON about something that - according to what they post - they can just build. WELL BUILD IT THEN!!

_________________

There some good info in the other twin turbo threads, as well as a few guys who actually made setups whom could be PM'd for technical questions. /thread

 

I've never seen a variable-vane on an FC or FD..let alone any other car. I've seen PLENTY on the local turbo-diesel trucks - a local is making 600rwhp and 1500ftlbs..

Porsche uses a variable-vane turbo.


Not to mention, their neat new "power boost" button! Hit the button for a 10-second blast of an extra 5psi? Sweet! :-D

 

Yep, the new 911 Turbo uses a variable geometry (I believe what they call it) turbo. It is the first such application I have ever seen. I'm going to have to do some research on how it works, as it looks very interesting.

 

Thats been around for a while the "power boost" thing. Its scramble boost. I know that the emanage can do it, it simpley closes the wastegate and hence more boost for a moment in time, or aslong as you push/trigger it. I am sure you can rig it up manually with a boost controller....maybe the Turbo XS dual stage (flick the switch for boost setting 2).... just a htought.

 

hey try to stay on topic here and could u guys help me on my other thred FPR AND PD DELETE. not many people had input to my questions.

 

I'm glad you were able to find that other thread.
There were at least two owners who are going that route that looked like they were getting favorable results.
I'd suggest to contact them directly through PM's.

And the FPR thing...
I'm going to repeat myself again - search!
I have a full FPR diagram on my website, and there are many references to that set-up.


-Ted

 

There is no topic here. Its over with. Opinions have all been shared and the universal statement is: do some research because you have no idea what you are getting into.


BC

 

okay this thread appears to be done. If the thread originator would like it re-opened, he or she can PM any 2nd gen technical section moderator with a very good reason.

otherwise... thread closed