How loud is an S475 ?

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me2

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How loud is an S475 in a compound setup, with the compounds making about 50 PSI ?

I'm putting this setup in a truck used for towing and it would be nice if I wasn't listening to a loud turbo whistle all day long.

Do turbo covers make turbos quieter ? Does turbo whistle come from the exhaust side or the compressor side ?


Thanks.
 
As long as its louder than the wife complaining its just about perfect to me.
 
Also depends on the PR of each turbo. If the secondary is doing 45psi and the primary is barely moving i'd say it's not going to give that same s400 sound. Be more specific. $.02
 
My twin kit is much quieter than my single 66 was. I can hear the 475 come in, but almost stock sounding.
 
SethR said:
Also depends on the PR of each turbo. If the secondary is doing 45psi and the primary is barely moving i'd say it's not going to give that same s400 sound. Be more specific. $.02
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I hope that at 50 PSI that each turbo is running close to the the same pressure ratio.

PR Overall = 50 + 14/ 14 = 4.6

PR individual = sqrt (4.6) = 2.144

S475 pressure = 14PSIA x 2.144 = 30 PSIA = 16 PSI of boost.

Secondary pressure = 30 PSIA x 2.144 = 64 PSIA = 50 PSI of boost.

So that S475 will be operating at 16 PSI of boost if everything works out.

It should be pretty quiet, right ? Just loafing along ?
 
Chris Mallett said:
My twin kit is much quieter than my single 66 was. I can hear the 475 come in, but almost stock sounding.
Click to expand...

Thanks for sharing that.

I love how you have your 5.9 set up. How much were the QSB pistons ? How is it for power and how does it tow ?
 
I did a stock he351cw over an S475, and it was quieter overall with the twins then it was just as the stock charger.
 
dvst8r said:
I did a stock he351cw over an S475, and it was quieter overall with the twins then it was just as the stock charger.
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I have heard this before. Search Turbo whistle in the 2nd gen section on cumminsforum
 
Might as well drop a charger size if that's all the air you want from a primary.
 
If you want a quiet turbo, put a GTX in there. My GTX42 is way quieter than my GT42 was. Which I miss sometimes.
 
me2 said:
Thanks for sharing that.

I love how you have your 5.9 set up. How much were the QSB pistons ? How is it for power and how does it tow ?
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No problem. The QSB'S were comparable to stock pricing, maybe 15 bucks more a hole, the twins make it a champ for towing. The only flaw I am seeing is that I have to open up the exhaust housing on the 351cw a little more, temps climb quickly over 2800rpm and I believe it is drive pressure related. Once I get a different one on it I will test my theory.
 
I personally think my S475 sounds great in my twins set-up. Especially when towing through a tunnel. On the open road, unless there is jersey walls or another passing car you will barely hear it.
 
Lance@Alligator said:
only 16psi out of the S475 ?
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That is where it will run when both turbos have an equal load. 50 PSI isn't much from compounds, both chargers are loafing.

I think max boost will be 60 PSI, but I'll use 50 PSI when towing.
 
Chris Mallett said:
No problem. The QSB'S were comparable to stock pricing, maybe 15 bucks more a hole,
Click to expand...
How are they different ?

the twins make it a champ for towing.
Click to expand...
That is what I am striving for.

The only flaw I am seeing is that I have to open up the exhaust housing on the 351cw a little more, temps climb quickly over 2800rpm and I believe it is drive pressure related. Once I get a different one on it I will test my theory.
Click to expand...

I bet you are right and I would love to hear how it works. What size is the housing on it now ? What size is the turbine ? I'm hoping to make a S475 over HE351VE on a 6.7 with EFI Live. I'm probably going to plumb in a bypass valve around the '351. But I'd love to hear how your housing works out.

Do you have a drive pressure gauge on it ?
 
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