s475 I need help!

[obspsd]

Ok guys so I have 350/200cc injectors with all supporting mods and a s400 75/83mm with a 1.10 housing. My problem is I could only build 40lbs boost and after checking for leaks I put a backpressure gauge on it and found that at 40psi I am making 85-90 backpressure! So now i need to resize the turbo, and that's where I need the help. I was thinkin the 75/88mm with a 1.25 housing. What are yalls thoughts? Thanks in advice for the help

 

[DZL JIM]

Just add a waste gate.

 

[faster6.0]

75/87 with the 1.10 housing buddy.

 

[Powersmoker]

The best turbo I've ran was a s475 88/96 turbine 1.15 a/r with the T4i (hypermax mount). Made 62 psi. Not sure on back pressure. Iirc River City Turbo will build s475/88 t4's.

See he's only making 40 psi boost and the restriction is clearly on the turbine side.


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[Powersmoker]

Just add a waste gate.

That will reduce drive pressure , but won't increase turbine flow. He needs a bigger wheel.


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[TARM]

Yep you need that heat energy to get more boost. Bigger wheel and or higher AR housing. As you are already at a 1.10 the issue seems like the wheel as has already been mentioned.

 

[obspsd]

Does anyone have any idea how much just the bigger 87mm wheel would help? Would that be enough? Or would I still need to up the housing size

 

[Dieselboy.]

I dont thinkg you dont need a bigger turbo !

You need to have your tunes tweaked. FWIW one tuner I make 40/53 boost/BP. Another tuner I make 46/54 Boost/BP. Something is not right. I am in the process of upgrading my s471 with the 83mm exhaust to an s475 compressor wheel. I have the 1.10 housing. Something is not right if your making 40psi boost to 90psi BP.

 

[Marty]

Are you running an intercooler?

I run a comp475/83 with 400/400's and my boost to drive is as follows:

50/60 60/75

 

[Powersmoker]

Are you running an intercooler?

I run a comp475/83 with 400/400's and my boost to drive is as follows:

50/60 60/75

He is...


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[TARM]

Dieselboy,

That is interesting with the tuning. You also have 400% hybrids vs 200% B codes. Sound like something with timing of the combustion that can have to deal with the way the fuel is injected and or amount of fuel and timing.

I would like to hear more about this and what is effecting it.

 

[Dieselboy.]

Yes, that it is. Ive herd of guys getting live tuned and dynoing xxxHP at xx psi boost. And then with the live tune the dyno more HP with the same boost. Same thing could apply with the same HP at two different psi of boost/BP.

Like I said, one tuner just barely makes 40psi and the other one is closer to 50 both WOT. And both have relatively the same BP psi.

I will agree with the b codes vs hybrids. Both are similar size though. His 350/200 to my 250/200s. however I do know the injection ratio is different.

 

[Hotrodtractor]

Are you running an intercooler?

I run a comp475/83 with 400/400's and my boost to drive is as follows:

50/60 60/75

I was right at the 50psi boost and 60psi drive pressure area as well with the S475/83 setup I had on the red truck back in 07-08. It might have been 65psi drive, but right in the same neighborhood. 400/200 B-codes. I know I should have went bigger on the turbine..... I kick myself every time I think about it.

My bet would be something is up tuning wise, or a mechanical issue somewhere.

 

[TARM]

DB,

I was looking at Powersmokers injectors by mistake that was why I mentioned injectors. Jsut a wee bit dif in flow there. LOL

 

[obspsd]

Hotrodtractor, were you running wastegates with those numbers

 

[Hotrodtractor]

Hotrodtractor, were you running wastegates with those numbers

Nope.

I probably should add that was with ported heads, headers, solid lifters/roller rocker setup, and a custom camshaft....

 

[TARM]

What kind of valve lift were you running with that setup, if that is not guarded info, that is?

 

[Hotrodtractor]

What kind of valve lift were you running with that setup, if that is not guarded info, that is?

Over 0.550"....

 

[obspsd]

Ok well I ordered forced inductions 75/92 with 1.10 housing and billet wheel. Hopefully this should help me

 

[V-Ref]

I'm late to the show...and some pretty smart fellas have already posted up...

But how high psi-wise have you leak tested your system for?

You might have a boost leak that only manifests itself at higher psi's...something to look for I guess when you get the newer bigger turbine wheel turbo on :evil