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Discussion Starter #1
Let's say there is two supra's, one with twin turbo's and one with a single, the twin turbo supra has a pair of 25G turbo's with .50 A/R turbine housings, the single turbo supra has one 25G turbo with a 1.0 A/R. Now comes where I get confused, does the two turbo's make any more airflow, then the one? or would it push the same amount of air, with more stabile boost? Both have same size compressor housings, wheels, etc.. the only difference is the turbine side.

(Please no bull shit "I don't know what I am talking about" replies, I just am curious and can't seem to figure out how to explain this to myself..)
 

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Discussion Starter #2
T.T. errr.. ehhmm. uhh... what was that last one.. oh yea.. T.
 

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There are to many variables to consider here. But I can tell you that the 25g with a 1.0 A/R will allow the engine to sing on the upper end. It's less restrictive, and less back pressure for the engine to fight. It may be a little more laggy compared to the twins turbo set up though. Other then that I'd say that the two set ups will probably flow the same. If you set boost to a max, thats what its gonna be no matter how many turbo's you have. The difference is that twins will probably split the load, and beat the air less (at higher boost settings), making less heat, and less pron to detenation.
 

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Discussion Starter #4
that's sorta what I was thinking.. but wouldnt they both have the same top end capabilities as well? because they both are allowing to flow the same??
 

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Supras are not twin turbos, they are sequential turbos. This is why they walk us beyond 110MPH.
 

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matt92vr4 said:
Supras are not twin turbos, they are sequential turbos. This is why they walk us beyond 110MPH.
I think he's talking about a moded Supra with Twin 25Gs, whereas they switch to a True twin converstion, like this one:



They rarely keep the Sequential setup when upgrading turbos, i think its because you can risk one of the turbos overpowering the other and start to spin it in reverse. Dat not too good!:D
 

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my bad.

I wish we could get our turbos up top like that for everyone to admire!
 

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Discussion Starter #9
jesus.. lol I was just using the supra as an example.. the real question is in the flow of the turbos.. I only used the word supra, because if I tryed to ask the question using the 3S, you woulda called me stupid for talking about putting a single turbo on a 3S.. I just want to know the differences between that single or that twin setup.. but if it makes you happy, yes I am talking about a twin, not sequential.
 

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matt92vr4 said:
my bad.
I wish we could get our turbos up top like that for everyone to admire!
TD-06 25G's






:D:D:D:D

and this engine below is using the same turbos as the Supra in the previous post (HKS GT2835s):



You gotta love the fact we could hide those massive turbos down there, and look totally stock, but Supras can't:eek: :D
 

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but wouldnt they both have the same top end capabilities as well? because they both are allowing to flow the same??
Well they might be close, but everything I ever learned about turbo A/R ratio's would tell you that the larger the A/R, the free-er flowing the turbo is. Turbo's are a cork on any engine, a source of restriction. Now they definatly are worth this extra restriction, because they boost the engines perfromance many times over making huge power gains. And mostly you'll notice this restrction on the high end, where an engine will have to fight this restrction some. So it makes sense that a turbo car equipped with a 1.0 A/R turbo (free-er flowing turbo = less restriction on the exhaust side of the engine) , should start to walk away from a twin turbo car running two .50 A/R turbo's, dispite the fact that they will both be making the same PSI in each set up. Think of it as you blowing air through a 1/2" straw. Now try a 1" straw. The 1.0 A/R turbo car will be breathing easier, but the same car will also have to wait around a little longer for the boost to come on.

Higher back pressure = quicker spool up time, but more restriction

Lower back pressure = slower spool up time, but less restriction
 

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matt92vr4 said:
Supras are not twin turbos, they are sequential turbos. This is why they walk us beyond 110MPH.
No. Supras are twin turbos - they both use the exhaust gas from the engine and both breath in outside air. In a sequential setup, the second turbo breathes the compressed gas from the first turbo - a very, very effective way to get high boost and used in competition tractor pulls. The Supra *operation* or spool up is sequential beacuse of the way the exhaust gas is routed - the turbos are not sequential..
 

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One turbo is on-line from idle to ~4000 rpm while the other one is gradually pre-spooled and then brought fully on-line at 4000 rpm onward. How is that not sequential? Yes the car is twin turbo (both are the same size) but they are not parallel twins as ours are.


Getting back to the point, what would flow better on the high end? The .50 AR twins or the 1.0 AR single? Indeed, would one setup be better or would they both be practically the same?
 

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Gatecrasher said:
How is that not sequential?
Technically, sequential turbos are when one turbo's output air is the input air for the second turbo. Sequential activation is quite a different thing. It's just terminology, don't let it bother you. You know how they work. :)

Actually Supra turbos are parallel in every sense. Look at the pics on the web page below.

http://203.97.216.253/mkiv/articles/turbos.htm

Each turbo basically feeds (or can at certain stages of operation) on 3 cylinders' exhaust. It's just that their 6 cylinders are in line and next to each other. Ours are seperated by quite a bit.
 
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