s475 I need help!

obspsd · May 5, 2012

I didn't have a regulator when I tested for leaks so I'm not sure on psi but i felt like i went high enough to discover any leaks but I will definitely check again with a regulator on it if the problem continues

blackbetty13 · May 5, 2012

Just curious I ran a gt4294 71mm and ran 40 psi. When I made the switch to a gt4202r 75mm I still made 40 psi can anybody answer why I didn't see a increase in boost.

obspsd · May 5, 2012

What injectors are you running

TARM · May 6, 2012

Remember that boost is only measuring resistance of volume. What was the temp of the air charge between the two 40 psi turbos. 40 psi can be a different air charge density depending on temp. What I do not like about going to the larger 42 from the smaller is they both run the same turbine wheel. It would likely be producing the same boost as lower shaft speed which means less friction and lower temp thus a denser charge.

haulin99sdp · May 9, 2012

Dieselboy. said:
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.

i dissagree that the turbo is the problem aswell..... i had simalier issues with my s366..... i could only see about 30psi or so and bp was through the roof at 68psi and would climb steadaily..... but my problem was my crank case vent was plugged up and building pressure......... run it out the side of the fender well, and it did help imsensly........

PowerstrokeJunkie · May 9, 2012

haulin99sdp said:
i dissagree that the turbo is the problem aswell..... i had simalier issues with my s366..... i could only see about 30psi or so and bp was through the roof at 68psi and would climb steadaily..... but my problem was my crank case vent was plugged up and building pressure......... run it out the side of the fender well, and it did help imsensly........

What does that have to do with the price of tea in China??

obspsd · May 10, 2012

Haha my thoughts exactly

haulin99sdp · May 11, 2012

because it sounds like a simalier problem i had that sounds like what he was dealing with and posted what my issues was and my fix..... it was pretty simple for me. hope it will be as easy for him as well to save him the trouble i went through......

TARM · May 12, 2012

How does crank case pressure effect drive pressure? I do not see where the connection.

V-Ref · May 12, 2012

haulin99sdp said:
i dissagree that the turbo is the problem aswell..... i had simalier issues with my s366..... i could only see about 30psi or so and bp was through the roof at 68psi and would climb steadaily..... but my problem was my crank case vent was plugged up and building pressure......... run it out the side of the fender well, and it did help imsensly........

Was your CCV still connected to your intake tube?

haulin99sdp · May 12, 2012

no it wasnt in the intake........... but me, carson and matt went over and over everything, i think matt's the one that acctually thought to cheak my ccv and the ccv being plugged up seemed to be the issue......

obspsd · May 29, 2012

Ok guys I'm still having a issue. With the s475/83 the truck made 40lbs boost and 85 drive pressure. I switched to the 75/92 and the truck still makes 40lbs and now 80 drive pressure. I have checked for leaks (boost and exhaust) and even did a compression test. John at swamps has doublechecked my tunes and says everything looks good. I can not figure out why this thing has such high drive pressure and low boost numbers. Does anybody have any ideas??? And the turbo has a 1.10 housing and I'm at sea level

Hotrodtractor · May 29, 2012

obspsd said:
Ok guys I'm still having a issue. With the s475/83 the truck made 40lbs boost and 85 drive pressure. I switched to the 75/92 and the truck still makes 40lbs and now 80 drive pressure. I have checked for leaks (boost and exhaust) and even did a compression test. John at swamps has doublechecked my tunes and says everything looks good. I can not figure out why this thing has such high drive pressure and low boost numbers. Does anybody have any ideas??? And the turbo has a 1.10 housing and I'm at sea level

?????? You have 80 lbs of backpressure on a 92mm turbine wheel????? Going from an 83mm turbine wheel to a 92mm turbine wheel only lost you 5psi of backpressure????

Time to start asking for pictures of everything and exact setup - what do you have after the turbo as far as exhaust? Anything restrictive? Where are you measuring backpressure at? Anything restrictive between there and the turbo? Pictures of everything would be great.

Are you sure that your gauges are working correctly? How does the truck run and drive? Maybe some video?

obspsd · May 29, 2012

I know it sounds crazy that's why I'm asking yall for help Haha. The truck runs and drives well it just doesn't seem like it has the power it should. It's still quick but not like it should be. The charger spools well but kinda levels out between 35-40lbs. The exhaust is 3in downpipe to 4in straight pipe and measuring drive pressure off the passenger manifold where the factory sensor was.

PowerstrokeJunkie · May 29, 2012

The reason it seems like it doesnt have the power it should is because you have all that restriction in the turbo system post-engine and it's not letting the engine breathe like it should. Something is up. You can get a 3.5" down pipe in a OBS with some work, i know because i have a truck in the shop now i made a 3.5" DP for last year, with a s472 on it. But still at that, the 3" downpipe shouldnt be causing THAT much restriction, but then again, the turbine wheel outlet is larger than the downpipe :shrug:

obspsd · May 30, 2012

I've been thinking it could be the downpipe too but I didn't think it would cause that big of a restriction but I guess it's possible

faster6.0 · May 30, 2012

There may be an animal residing in your up pipes.
Or maybe your bp gauge is broken LOL

obspsd · May 30, 2012

The bp gauge is brand new but the animal could be possibleLOL

mattman347 · May 30, 2012

I think your 40 PSI may be on the low side, I would think it would be closer to the 60PSI range with those injectors? Wish I could help more!

obspsd · May 30, 2012

mattman347 said:
I think your 40 PSI may be on the low side, I would think it would be closer to the 60PSI range with those injectors? Wish I could help more!

Me too!:shrug: