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Discussion Starter · #1 ·
Ok so im sure yall have seen this a thousand times but... my plate is ground down to #0 and slid ff. I can hit 1600 on the EGT guage pretty easy. I have a BHAF but stock straight pipe. I really dont think that a 5" exhuast would drop me down 400 degrees to a safe zone lol. I can also run only 28lbs of boost at WOT. So i guess my question is is something wrong with my turbo? DO i need to upgrade? Or do i possibly just have other pump work that i dont know about? Thanks all help is greatly appreciated.
 

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Well a bigger exhaust will cool you down some and there is some pmp tunning you can do, read in the tech articles about turning up a p 7100 and you can pinch off the wastegate hose and you will get more boost but do not exceed 35psi, if you do get a boost elbow so you can adjust it
 

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why dont go over 35psi?
Anything over 35 is just waisted, hot air. The turbo is well out of it's range at 38+. Doing more harm than good, really.

Are you saying your PEAK boost is 28PSI? A lot of times WOT can be misunderstood. For example, are you talking about WOT in lockup, after the truck has reached top speed, or WOT while within the power band of the motor? Your boost number will fall off a bit after you've revved the engine out.

And yes, a bigger turbo will help your problem. High temps is just the nature of a #100 or #0. And sadly, 1600 is fairly easy to hit.. I might have done it once or twice myself :hehe:
 

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Discussion Starter · #5 ·
28PSI is the highest i have ever seen lock up, no lock up, highway, from a dead stop. Thats the highest it will go. I just wanna know why im not around 35PSI like everyone else
 

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Discussion Starter · #7 ·
idk how to check that. it makes kinda a popping or fluttering sound every once in a while when i let outta the throttle
 

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idk how to check that. it makes kinda a popping or fluttering sound every once in a while when i let outta the throttle
That's actually normal. Called turbo bark. Normal, but not good. What you're doing is spinning the wheel so fast in one direction, when you let out of it, you're slowing it down so fast it's actually spinning backwards. Try letting out of it a little slower.

As for the w/g, follow the lines off the turbo. I plugged mine with a bolt/hose clamp at the turbo. Others do it on the AFC side of the valve covers.
 

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What you're doing is spinning the wheel so fast in one direction, when you let out of it, you're slowing it down so fast it's actually spinning backwards.
Ummmmmm........I have a hard time swallowing that one. In order for the turbo to "spin backwards", you'd have to create a vacuum in the exhaust manifold, stop all the forward momentum of the turbine wheels, and reverse the direction of flow of the gasses. Now, I've only been mechanicing and running heavy equipment for about 40 years, trucks for about 35, and aircraft for about 30..... but that's something I've never seen happen just from letting off the fuel quickly.... or am I missing something here?:confused013:
John
 

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Ummmmmm........I have a hard time swallowing that one. In order for the turbo to "spin backwards", you'd have to create a vacuum in the exhaust manifold, stop all the forward momentum of the turbine wheels, and reverse the direction of flow of the gasses. Now, I've only been mechanicing and running heavy equipment for about 40 years, trucks for about 35, and aircraft for about 30..... but that's something I've never seen happen just from letting off the fuel quickly.... or am I missing something here?:confused013:
John
You're missing something.

When you let off the pedal quickly, the pressurized air past the turbo looks for an area, or zone, of lower pressure. In some cases, that zone is behind the turbo, thus the air moves backwards, through the turbo, spinning it in reverse.

Don't take my word for it. Search the term. Here are some other explanations that I found...

Turbo bark is common but it will kill a turbo, it happens when pressure on the manifold side of the turbo is greater than the boost pressure,(other wise know as drive pressure vs. boost pressure) usually on hard acceleration and then a quick let off of the go pedal(thus the turbo bark will happen). Usually its hard to do on a stock turbo but it can be done with a lot of fuel and like i said a quick let off after hard acceleration, easiest way is to try not to do it, after to long it can snap the shaft in the turbo. Adjusting the waste gate can help to

Read more: http://www..com/dodge-truck-cummins-turbo-diesel-forum/13402-turbo-bark.html#ixzz0eUXGKU1z
The exhaust turbine is being pushed really hard by the pressurized exhaust gases when running WOT on boost. When you lift the pedal sharply, no more hot gases are forcing the turbine to spin. But now you have the whole intake tract full of 30PSI compressed air. Normally the intake impeller is pressurizing this air, but without the turbine under load to keep it moving, it's free to release the pressurized air by trying to spin the impeller backwards.
 

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I'm not sure if bark actually spins the turbo backwards but it definitely can bring it to a dead stop.
Going from 150,000 rpm to zero in a split second couldn't be good for anything.
I've only heard of a couple cases of bark snapping the turbo shaft but many cases of excessive bark blowing the lid off the stock airbox.
 

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You could always just check for boost leaks. I checked a friend of mine's yesterday and found 4 leaks. Take a 3" PVC cap, drill and tap it so that you can screw an air chuck end into it. Pull the rubber intake boot off the airbox and push the cap down into it. You'll have to use some duct tape to "shim" the cap, but tighten the clamp down around it. Chuck your air hose up to it, with your regulator set low. Get some soap in a spray bottle and start hunting.
 
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