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Discussion Starter · #1 ·
I just installed compound turbo's finally.
Stocker was sitting on the shelf for a while so I sand blasted both housings and checked for play and bored out the wastegate. It has minimal play within spec.
I haven't drove and listened carefully to any compound truck.

When I have the stocker at about 10-15psi I can hear what sounds like a vibration or a wheel touching the housing. Not a scraping by any means.
The best I could describe is a stiff piece of paper being touched to a spoke bicycle wheel spinning very fast.

I'm waiting on a guage to set the wastegate or I'll buy some longer hose to rig it up on the secondary real quick here.

Is this the 475 chopping up the sound coming out through the air filter?
It's louder driving next to a concrete wall.

I checked the cold side and it looks great.

The stocker wastegate is MPI's design that uses a regular spring on a bolt to push on the factory gate lever. Can those flutter making a similar noise?

Drives GREAT compared to a 63/68. Grinning ear to ear on the performance increase especially overall drivability. But the power increase is major also.
 

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Discussion Starter · #3 ·
So the whistle of both turbo's sound exactly the same as far as a whistle goes?
Of course the atmosphere 75 is much louder.
 

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White Collar Fabricator
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Ya. I am experiencing the exact same issue right now. Headed outside to pull it apart and see what is going on. I suspect its the atmospheric turbo making the noise on my truck, but not too sure.

On my race truck I had atmospheric comp wheel contact at some point and never heard a thing, but it was most likely at high boost levels or possibly during surge from letting off the throttle too quick and not having the bov turned on.
 

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White Collar Fabricator
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I don't know if this will make you feel any better, but neither of my compressor wheels are touching off. But I do have excessive thrust on my primary. I haven't put anything back together yet.
 
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With 2 turbo's you will get different sounds at different times!

I recommend that you temporarily disable the wastegate and then take the truck for a careful test drive.
If the noise is gone, then it is the wastegate.
 

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Discussion Starter · #7 ·
It was two sounds at different times as expected but one fluttered.
I found a small exhaust leak at a v band which maybe made the noise.
I just rebuilt the turbo because i had the parts and it's better to break it in now. It's hard not to step on the pedal now so do them both lol.

I'm warming up the truck now to test.
 

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Discussion Starter · #8 ·
I think I was just to concerned it's a turbo. The noise is still there but it's not a loud noise just a different one than I've ever heard. It could be accessory related for all I can tell right now but not as worried after seeing the smaller turbo. The 475 I suppose could be chattering just a hair pre spool but I seriously doubt that because it was never starved of oil and smooth install.

I'll mess with it over the next couple days, I did crank down the wastegate a little but got to a point where it barely could open and it was still there.
 

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Not to derail but did you find a kit for doing alignments? Did you get it figured what your tires were cambered at?
 

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Discussion Starter · #10 ·
Not to derail but did you find a kit for doing alignments? Did you get it figured what your tires were cambered at?
No I haven't even parked strait enough in a big flat parking lot.
I wanted to get these compounds installed and broke in before some races.

I need to order and install a drop pitman or remove my track bar drop so I haven't looked close enough yet. And another boost gauge, drive pressure check and some goodies are ahead of it.
 

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White Collar Fabricator
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I'm glad you have a grip on it, though I don't really know what guys are talking about when they mention two different sounds, neither of my trucks are like that.

I got mine back together and the few things I found wrong were not the source of my noise.

I found the IAT sensor was leaking dirty air into my intake tube. :shock: Put a length of silicone boot over the hole and clamped it down good, then zip tied the sensor to the air box. It won't be accurate anymore, but I don't think I care. Race truck runs just fine like this.

I also found a pinched o-ring in the cast elbow that BD uses on their super b.

I also found one boot that wasn't quite clamped as tight as I like it.

I'm pretty sure my 471 is experiencing some sort of metal to metal contact, but I couldn't make it rub by hand. I'll order a rebuild kit for both turbos, once they arrive I will tear into the truck and find the source of the noise.
 

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3 footin' through life
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I'm planning to ziptie my IAT nestled into a pleat on the primary filter. I'm glad to hear that's working well on your race truck.

Wayward, if you haven't already, do a boostleak check. They have made really bizarre noises for me before.
 

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Discussion Starter · #13 ·
Planning on finding some stuff to make a new bigger boost leak checker.
I did find a cut from the hose clamp on the air filter rubber so that may be it.
 
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