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Discussion Starter · #1 ·
ok, here's the deal...

a friend of mine is working on a Twin Turbo project.... he's got a built engine and it was putting out 320whp with single turbo... now he wants to try the twin turbo deal with a 16g and GT30 for a sequential setup... oh by the way he is doing this on a i4

he has 2 questions....

1- How to do with the waste gates... does it uses only one... is it routed to the exhaust... whats the best way to go?

2- What would be the order of the turbos? We've been doing some research and the diagrams we've found seems to have the big turbo blowing into the small one... ???

info about this topic and PICTURES will be really appreciated.

PD: I tried searching but only thing I could find was a whole boulevard of broken dreams, not actual information based on facts or experience.
 

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Pretty sure the small blows the big as it will spool up faster.
 

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Are you going for both active all the time, or having one come up after the other, like the supra and gmc diesels do (If I just googled that correctly). If it's the latter, you're going to need some fancy valves. If it's the former, why not just use a single, bigger turbo? Lag time?
 

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That's gonna be quiet a journey you guys are going on. You can probably find your answers in a Supra or 300zx forum. They have sequential turbos to begin with. That should get you on your way to making them sequential, but as stated above, you're going to need some fancy valve work there and some time of EMS to controll it (Motec or something expensive).
 

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You may need a larger engine bay too - with all the piping and stuff to run two turbos is going to be very tight in a 4 cylinder engine bay
 

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Discussion Starter · #7 ·
MindaHacker

it will be one small turbo to spool faster the big one.

Wagtoda3rd

and where in the exhaust to I route the 2 wastegates? btw I've seen some TT setups in which either the small turbo has 1 wastegate and the big has none, or the big one has the wastegate and the small one has none. But anyways... where would be the best place for them?
 

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Actually after doing some more research you will only need 1 wastegate. Have the smaller turbo flowing into the larger. Use the wastegate before the smaller turbo. I am learning about this as I go because I am interested about learning some more about this setup, and also compound turbo setups but ill post up what I am finding.
 

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Found a pretty good post burried deep on NASIOC:

first off, [there] is no #2 wastegate. there is only one wastegate and it comes off #1 turbo because that turbo is always on line, therefore you always have a wastegate. there are 4 sets vsv's, actuators, and control valves for the sequential turbo system. each vsv is simply a solenoid that is either 100% open or closed, allowing manifold pressure to pressurize the different actuators that open/close the four different valves.
wastegate: when the manifold reaches 11#'s of boost, the ecu sends a signal to the wastegate vsv, this allows manifold pressure to build in the wastegate actuator which opens the wastegate.

exhaust gas bypass valve: somewhere around 3500 rpm, the ecu sends a signal to the exhaust gas bypass valve vsv, which allows manifold pressure to build in the exhaust gas bypass valve actuator which opens the bypass valve. this is a small opening inside the #2 turbine housing which allows some exhaust gas to go through the turbine of the #2 turbo which makes it start spinning, and dumps the exhaust gas out the exhaust piping coming off of #1 turbo. since it is a small amount of exhaust gas, it pre-spools the turbo and does not get it up to full operating speeds. this will smooth out the transition from 1 to 2 turbos. this valve is similar to a wastegate in design, but is located after the turbine wheel instead of in front of the turbine wheel like a wastegate would be. this is not a wastegate!

exhaust gas control valve: this valve is located in the exhaust piping downstream of the #2 turbo. when this valve is closed, all exhaust gas must go through the #1 turbine wheel to get out through the rest of the exhaust system. at around 4000 rpm, the ecu sends a signal to the exhaust gas control valve vsv, which allows manifold pressure to build in the exhaust gas control valve actuator which opens the control valve. this allows exhaust gas to go through #2 turbo and out the exhaust system which brings the #2 turbo up to full operating speed.

intake air control valve: this valve is located in the intake tract coming off of #2 turbo. it is closed below 4000 rpm so that boost pressure coming off of #1 turbo cannot backup through the #2 turbo and back out the air cleaner/suction of #1 turbo. there is also a 1 way reed valve within the same housing of the intake air control valve. as the #2 turbo starts to prespin at 3500 rpm, it will build some boost. if it builds enough boost, it will open the 1 way reed valve to allow this boost into the intake tract to join with the discharge boost pressure coming off of #1 turbo. at somewhere over 4000 rpm, the ecu sends a signal to the intake air control valve vsv, which allows manifold pressure to build in the intake air control valve actuator which opens the control valve. this allows the full boost pressure coming off #2 turbo to join in with that coming from #1 turbo and you are now fully on line. usually, the exhaust gas control valve will open first, which gets the #2 turbo spinning at full rate so that it is building good boost before the intake air control valve opens, allowing this boost to join in with that coming off #1 turbo
 

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Now you see how complicated it its to do a proper sequential turbo setup. Definitely not worth it on a little 2.0L engine. A much easier and cheaper set up for big power is a larger turbocharger like a GT35 or 40 and spray N2O down low to get that bad boy spooled up. Once its spooled kill the nitrous and run with da big boys!
 

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yea, if you cut off the smaller turbo, that will sequentially cut off the larger turbo (sort of logical). So by capping the small one at say 10psi, that in turn caps the large one to only taking in 10psi to spool it up (no more).
 

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Discussion Starter · #14 · (Edited)
Wagtoda3rd

great info! never thought it will be THAT complicated. thank you very much!

dmdicks

my friend already has the 2 turbos... but not all the other supporting hardware for this setup... how much extra cash would be needed to get all that stuff?

he wants to try this to have a unique setup and test the twin turbo efficiency. I already TOLD HIM about NO2 but he didn't like the idea... he's got a 350Z with a Greddy Twin turbo kit (parallel)... car is around 400whp, now he wants to try the sequential on his 2.0L Tib as a project.

Cheers!
 

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i have one question is it possible to use the boost from the first turbo to spool the larger turbo. not to get boost from the first but to spool the larger one to full spin sooner??
 

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Most add on kits for turbocharged diesels run the boost from the stock turbo into the compressor inlet of the new turbo and have a bypass for the turbine side. All exhaust goes to the stock turbo initially then it proportionally distributes the exhaust between stock and new and eventually all the exhaust switches over to the new bigger turbo once it's spooled. If you don't put in some sort of exhaust bypass system then you run the risk of overrunning the stock turbo and it blowing to pieces.
 

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i was thinking using the waste gate on turbo 1 to regulate spool not to over spool turbo 1
turbo 1 turbine side to compressor side of turbo 2 waste to atmosphere
turbo 2 only feeding intake (fast way to spool massive turbo)
is it possible??
 
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