Compound S400s?

[SSchmi5519]

Wondering what you guys think about the viability of a set of compounded S400 turbos...maybe something like an s465/s483. Thinking as long as I can get the turbine sides it could work well.

I sold my s472 because anything big enough to properly pair it with is wayyyy more air than I will ever need.

Basically what I want to do is run a small s400 frame T4 charger in the valley, since I already have everything set up to do so, and hopefully twin over it with a big AR T6 s400 frame charger. Don't want to have to go s500 or a big overpriced (aka can't afford) Garrett.

 

[MarkBroviak]

Hell yes you can do it and I've done it before and was happy with it! 64/87 with a Stainless 485/96 would be a great combo!

 

[IOWA LLY]

Hell yes you can do it and I've done it before and was happy with it! 64/87 with a Stainless 485/96 would be a great combo!

I assume the 64/87 would have to be waste gated correct?

 

[kiwilml]

And what if the valley charger is a 64/83? What kind of difference would that make?

 

[MarkBroviak]

If you ran the 83mm turbine then I would gate it but the 87mm turbine I wouldn't waste my time with a gate.

 

[SSchmi5519]

Mark, at what point would you start to worry about overspeeding a 465/87 .90?

 

[MarkBroviak]

With it being compounded you don't run that risk unless you go out of your way to try and do it. In a compound setup the high pressure charger spins quite a bit slower because you are force feeding it. Usually the exhaust housing of the high pressure with be the choke point of the setup and you would have to run the rpm through the roof to get the efficiency down low enough to over speed it. Good example for you, my 72mmvgt as a single would see 120-140k rpms at 850hp range. Throw a S485 over it and that shaft speed drops to 75-90krpms and power jumps 300hp and boost jumps from 45psi to 80psi. Now take the twins off and put triple S300's on it and the speed drops down to 60-65k rpms and power jumps up another 150-200+hp along with another 20+psi in boost. Now I am running Triple S472's and the shaft speed stayed about the same but boost is up to 120psi and power is in the 1400hp range and I still do not run a gated setup. Hope this helps.:hug:

 

[Awenta]

That's a lot of good info. Thank you Mark.

What about a max effort 467.7/83/80
Would you gate it or not?


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[Chevy1925]

With it being compounded you don't run that risk unless you go out of your way to try and do it. In a compound setup the high pressure charger spins quite a bit slower because you are force feeding it. Usually the exhaust housing of the high pressure with be the choke point of the setup and you would have to run the rpm through the roof to get the efficiency down low enough to over speed it. Good example for you, my 72mmvgt as a single would see 120-140k rpms at 850hp range. Throw a S485 over it and that shaft speed drops to 75-90krpms and power jumps 300hp and boost jumps from 45psi to 80psi. Now take the twins off and put triple S300's on it and the speed drops down to 60-65k rpms and power jumps up another 150-200+hp along with another 20+psi in boost. Now I am running Triple S472's and the shaft speed stayed about the same but boost is up to 120psi and power is in the 1400hp range and I still do not run a gated setup. Hope this helps.:hug:

Mark, this may be a question that cant be answered willingly as i have not seen anyone answer it when it has been asked buuuuut....

How do you determine turbine shaft speed? are you using a sensor or calculations? i have often wondered that and from the little research ive done, most say you need a sensor but i cant see why you couldnt build an equation for it.

if im asking for more info that wished to share publicly, i completely understand. :hug:

 

[MarkBroviak]

That's a lot of good info. Thank you Mark.

What about a max effort 467.7/83/80
Would you gate it or not?


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I'm not a big fan of gates cause they seem to cause more issues than good most of the time. If it was mine I wouldn't bother with a gate. If you needed more power then step up the compressor size.

 

[Awenta]

I'm not a big fan of gates cause they seem to cause more issues than good most of the time. If it was mine I wouldn't bother with a gate. If you needed more power then step up the compressor size.

That certainly solves my dilemma. Thank you


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[MarkBroviak]

Mark, this may be a question that cant be answered willingly as i have not seen anyone answer it when it has been asked buuuuut....

How do you determine turbine shaft speed? are you using a sensor or calculations? i have often wondered that and from the little research ive done, most say you need a sensor but i cant see why you couldnt build an equation for it.

if im asking for more info that wished to share publicly, i completely understand. :hug:

I have a Garrett Turbo Speed sensor and gauge setup in my truck for testing purposes and it's pretty freaking cool to watch also! It's not cheap but it is the only way to get this info when testing turbos in the real world not on paper. It is a real eye opener to see where when and how they actually operate in the day to day activities. Would love to put one in my atmospheric turbos to show the comparison on them! Shaft speed on the turbo will also help show you where the volumetric efficiency of your motor setup is. Really cool nerdy ass technical shit for sure!

 

[Chevy1925]

I have a Garrett Turbo Speed sensor and gauge setup in my truck for testing purposes and it's pretty freaking cool to watch also! It's not cheap but it is the only way to get this info when testing turbos in the real world not on paper. It is a real eye opener to see where when and how they actually operate in the day to day activities. Would love to put one in my atmospheric turbos to show the comparison on them! Shaft speed on the turbo will also help show you where the volumetric efficiency of your motor setup is. Really cool nerdy ass technical shit for sure!

Nice!! I'm right there with you on knowing that stuff. Really puts reality to what your working with instead of guessing. I spent the better part of a week trying to figure out the right sized turbo for my 2.5 v6. And when it all finally "clicks" it's like a moment in heaven and yet you haven't put the turbo on yet! Lmao

 

[IOWA LLY]

I don't mean to hijack this thread, but since were discussing how slow shafts speed on the high pressure charger is common in Twin or triple setups...

Would 3 S475's all with the 96mm turbine work on a fairly high RPM duramax? (Keeping RPM's between say 3200-4500) Could a guy use a tighter exhaust housing on the high pressure turbo?

Or would a smaller turbine work better on the high pressure turbo?

Reason I'm curious is it would be a very inexpensive 3 turbos to purchase.

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[SSchmi5519]

I don't mean to hijack this thread, but since were discussing how slow shafts speed on the high pressure charger is common in Twin or triple setups...

Would 3 S475's all with the 96mm turbine work on a fairly high RPM duramax? (Keeping RPM's between say 3200-4500) Could a guy use a tighter exhaust housing on the high pressure turbo?

Or would a smaller turbine work better on the high pressure turbo?

Reason I'm curious is it would be a very inexpensive 3 turbos to purchase.

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The 96mm wheel is sub-par for a high pressure turbo. Would act lazy and come up slow. Flows a ton though if your RPM is through the moon i guess :spit:

 

[MarkBroviak]

For the valley yes, for the atmospheric's I think it would be too big. Brett's combo originally was a Billet 475/96 1.0ss gated in the valley with a pair of TCT 475/87 1.0SS housings and there was no spool up difference on the 87 vs 96 in the valley. You'd have to have some serious rpms and gated valley charger to get the 96mm atmos to come to life but it would be rowdy when they did!