Unconventional triple turbo configuration

JoshH said:
Are you talking about the compressor side? Why would you want the 55 to outflow the 42s? The 55 is the secondary, it is being fed by the 42s. If it was able to outflow them, they would just be a restriction.
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I mixed those up. You're right
 
JoshH said:
Anybody else have any insight into this setup?
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I have no actual knowledge on this setup, as I have never run one.

But my thinking is, he cant fit a single charger large enough in the valley where the stock unit normally lies, so he is using two parallel to meet the airflow he is wanting to achieve before it gets to the big boy.

Is that the correct thinking?
 
Joesixpack said:
I don't see how there is enough spread between turbine flow. 2 week work binge has my mind mush too though.

Makes for a nice layout.
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IIRC, without looking at the maps, two GT4202's are around 190 lb/min. GT5541 was around 170-180 lb/min. Hardly any compounding. I'd imagine the two GT4202's would outflow the GT55 a bit on the turbine side of things. I'd be curious how it works, if its any better than running a single 55 or twin 42's alone.
 
Tate said:
IIRC, without looking at the maps, two GT4202's are around 190 lb/min. GT5541 was around 170-180 lb/min. Hardly any compounding. I'd imagine the two GT4202's would outflow the GT55 a bit on the turbine side of things. I'd be curious how it works, if its any better than running a single 55 or twin 42's alone.
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Agree with all. I am curious as well. I don't see how it could be better than if he ran either stage alone. The 42's have a very restrictive muffler behind them in the gt55 turbine, and the gt55 will be recieving cooled expanded exhaust gases.


What is really strang to me is how will the gt55 e able to do anything at all? As far as I can tell he is asking the gt55 to perform high pressure boost while receiving low pressure exhaust. even if the turbo's were sized normailly for compounding how can you expect the low pressure side of the exhaust to produce such a high overall PR?

My guess is the set won't last long and will be replaced by a more conventional set, but if I am wrong, cool. We will get to learn something new.
 
Todd W said:
Agree with all. I am curious as well. I don't see how it could be better than if he ran either stage alone. The 42's have a very restrictive muffler behind them in the gt55 turbine, and the gt55 will be recieving cooled expanded exhaust gases.


What is really strang to me is how will the gt55 e able to do anything at all? As far as I can tell he is asking the gt55 to perform high pressure boost while receiving low pressure exhaust. even if the turbo's were sized normailly for compounding how can you expect the low pressure side of the exhaust to produce such a high overall PR?

My guess is the set won't last long and will be replaced by a more conventional set, but if I am wrong, cool. We will get to learn something new.
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I think it would depend on the turbine wheel profile used as well. Does Garrett make a high pressure turbine like Borg's 83/74 wheel? I'm just kinda thinking out loud here.
 
murphy41 said:
I think it would depend on the turbine wheel profile used as well. Does Garrett make a high pressure turbine like Borg's 83/74 wheel? I'm just kinda thinking out loud here.
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I think any turbine that can receive 50 psi and power the compressor to put out 100 psi would be quite revolutionary.
 
Todd W said:
I think any turbine that can receive 50 psi and power the compressor to put out 100 psi would be quite revolutionary.
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I was actually reffering to the 4202's having a wheel similair to the 83/74 from Borg.
 
Im not saying it will or wont work but we normally gate around the secondary in a "normal" set of compounds. Who is to say without a little more knowledge on the turnbine/housings that there wont be enough heat/flow to push the GT55 hard enough. I see a lot of guys running a PR on the secondary that isnt all that high, so it may work by that line of thinking. Push the Primaries hard and leave to rest to the secondary(gt55)??? Just kind of thinking out loud

Edit: im curious how well the gt42s "push" air through the GT55 if they lite faster(which id think they would)
 
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mathews8pt said:
Im not saying it will or wont work but we normally gate around the secondary in a "normal" set of compounds. Who is to say without a little more knowledge on the turnbine/housings that there wont be enough heat/flow to push the GT55 hard enough. I see a lot of guys running a PR on the secondary that isnt all that high, so it may work by that line of thinking. Push the Primaries hard and leave to rest to the secondary(gt55)??? Just kind of thinking out loud
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This is more or less what I was beginning to think myself.
 
mathews8pt said:
Im not saying it will or wont work but we normally gate around the secondary in a "normal" set of compounds. Who is to say without a little more knowledge on the turnbine/housings that there wont be enough heat/flow to push the GT55 hard enough. I see a lot of guys running a PR on the secondary that isnt all that high, so it may work by that line of thinking. Push the Primaries hard and leave to rest to the secondary(gt55)??? Just kind of thinking out loud

Edit: im curious how well the gt42s "push" air through the GT55 if they lite faster(which id think they would)
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since we have never seen this type of setup everything is a guess and all we are talking about it theory, which is fun to me.

So let hypothesize that we want a total boost number of 80psi. We know that in general pressure into a turbine is close to pressure out of compressor wheel correct?

So if we gate around the 42's to get the necessary drive to the gt55 what we have is basically 80psi going into the gt55 turbine and 80 psi out. again this is all theory I know that drive and boost are rarely equal but close to equal is desirable.

It is also well established that we want boost into engine and drive out of engine at 1:1 correct? so intake manifold into engine sees 80 psi and exhaust manifold to 42's is also at 80.

we must gate around the 42's enough exhaust to get 80psi on the backside of them to the turbine inlet of gt55 so we can get the 80psi out of it into intake manifold.

And that is a major problem for the 42's because if the pressure is the same on both sides of turbine then they do nothing, they are stalled. And that yields no fun.

Anyway that is my thinking out loud, I have no first had knowledge with this type of configuration, hopefully it adds to the conversation.
 
You're assuming that 80 psi drive pressure into one charger is needed for 80 psi out of that same charger. Look at it in terms of pressure ratios. My twins generally run at less than a 2:1 PR on the secondary, be around 3.5-4:1 on the primary. So the 42's will be using the hotter, higher pressure exhaust to do most of the work building that pressure ratio. The GT55 gets the cooler, lower energy exhaust to produce the much lower 1.8:1 (hypothetical numbers) PR. This makes great sense to me. Put the energy to what needs it the most, the primaries.

Its the flow rates that cock it all up. The smallest housing Garrett lists for the GT42 is around 37 lbs/min. Largest is 44 lbs/min on the big housing. GT55 is 60 and 68, respectively. So best case scenario, the 42s still outflow the GT55 by 6 lbs/min, potentially as large as 28 lbs/min.
 
Tate said:
You're assuming that 80 psi drive pressure into one charger is needed for 80 psi out of that same charger. Look at it in terms of pressure ratios. My twins generally run at less than a 2:1 PR on the secondary, be around 3.5-4:1 on the primary. So the 42's will be using the hotter, higher pressure exhaust to do most of the work building that pressure ratio. The GT55 gets the cooler, lower energy exhaust to produce the much lower 1.8:1 (hypothetical numbers) PR. This makes great sense to me. Put the energy to what needs it the most, the primaries.

Its the flow rates that cock it all up. The smallest housing Garrett lists for the GT42 is around 37 lbs/min. Largest is 44 lbs/min on the big housing. GT55 is 60 and 68, respectively. So best case scenario, the 42s still outflow the GT55 by 6 lbs/min, potentially as large as 28 lbs/min.
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Totally agree with that.

I do want to discuss your thoughts further. In thinking in terms of PR I can see how it may be possible. I still am skeptical, but given that turbines work by a pressure differential before and after turbine perhaps it is possible.

In your typical compound set it is true the secondary may only run at a pressure ration of 2:1 but its compressor outlet pressure is quite high. In sticking with our 80psi example the secondary might do very little in terms of pressure multiplication to reach that number but it had 80psi driving the turbine to do it. Is that because compressing very dense air takes a lot of power to do or is it simply that the turbo is being gated around? maybe both?

If I am reading your post right it seems that you believe that a turbo can multiply pressures even with radically different pressures on the turbine inlet and compressor outlet. In our example lets assume that most of the work is done by the 42's and they are able to produce 40 psig feeding air inlet of gt55. In your opinion what would be drive pressure be in the manifolds going to 42's and what would be the drive pressure going to the gt55? assuming that a total boost of 80 psig is reached.
 
Not to mention that the compressor flow rates are basically equal when the 42's are in parallel, unless you can drive the GT55 to a higher PR...which is what is being questioned in the first place...

I can see it working, but I wouldn't exactly call it exceptional.
Chris
 
Regardless of how the turbos are mounted, exhaust into the GT55 first then the GT42's or through the GT42"s then the GT55, you will have the exact same volume of exhaust Gases and I don't think you will lose any heat. Will the turbos combo work, I am not sure, with the layout of the turbos work, yes. If Joe would have changed the intake and cold side, then you would of had problems, but that part of it is set up like any other set of triples.
 
Based on the level and quality of fabrication shown in the pictures, something tells me that he knows what he's doing.
 
newsmoke said:
Based on the level and quality of fabrication shown in the pictures, something tells me that he knows what he's doing.
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Winner Winner Chicken Dinner. Neither the owner of the truck, nor the person who did all the fabrication would agree to build something that hasnt been proven. Thats a guarantee
 
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