For the longest time and more so of late, my boost is ridiculously low. I'm talking none at cruise and 4 lbs when I push it to redline. I just replaced the turbo with a new unit and it made no difference at all! I've looked at all the exhaust for leaks and all seems O.K. Please advise where to look next. Is it possible that the exhaust muffler is restricted?

Have you looked at your wastegate?

This is the non-wastegated Banks turbo. Anything else? (please!)

Did this turbo make good boost before, or is this turbo new to you?

I just installed a Banks unit on my 6.2 and I'm NOT impressed. The turbo makes 6psi when in on it, and 1psi at cruise at 70, smokes most of the time.

For me, I've got the wrong exhaust housing on my turbo. I need the smaller housing for my pickup (1/2 ton 2wd).

If you've got a 1.15 A/R housing, it's gonna suck like this.

Check for exhaust leaks, the pump can also be suspect if it's not throwing down the fuel...

It has never made alot of boost, but when I pulled a steep hill pulling a trailer, I could get it to 9 lbs, just not anymore. The housing on this new turbo is a 1.00 A/R, so I was kinda expecting better results. The only time it evens registers boost now is when I press it, right at the moment of upshift it will spike at maybe 1lb of boost. Oh, and now it really blows black like it is massively overfueled.

Do you possibly have the old turbo, you mentioned replacing the old turbo with a new one?

I had found a 1.00 A/R for my truck, still looking for another...

There are several things that can contribute, sounds like you're getting fuel if you're blowing the coals.

I really don't think that it's a clogged muffler.

You may be leaking the boost. Check the gasket underneath the turbo pressure chamber to see if it's torn or contaminated to where it won't seal. Also, as you already know, the gasket used with the Banks unit is not the paper type gasket that normally mounts to the intake manifold. If the paper type gasket was used during a service, etc. then it won't seal and you'll bleed boost.

Check your turbo connections on the boost side. The problem with the hardware provided with the Banks kit is that they use regular ol worm gear clamps. A T-bolt clamp is more appropriate (which I've upgraded to) that holds the clamping force and is able to torque down the hose onto the tube.

Lastly, check for any holes in the silicone connections at both the turbo and the boost chamber.

Any chance the air filter is plugged? They sure don't take much to fill up with these wimpy small filters...

Thanks to all those who responded. I got the idea today to have my son place his gloved hand over the tailpipe to force the exhaust out any possible leak. What I found is the crossover pipe that merges just beneath the turbo had a sheared bolt and had blown the gasket to smithereens and spit out the remains. Now if someone could offer me and easy way to get the exhaust manifold off......

Ouch!

No EASY way to remove the exhaust manifold... No way to get to it from underneath?

Glad you found what it was though.

they make .68 and .84 A/R housings of the same design, only difference will be 4 downpipe bolts instead of six. It's a standard P trim exhaust wheel....:)

Manifold isn't that hard to get off, as long as you can get the bolts broke loose. Several of the bolts need to stay in the manifold while it is removed if memory serves me. I would try removing the crossover pipe first and soak the broken bolt with a good penetrating oil, possibly drill out the broken bolt depending on where it broke(flush with casting or some protruding). Good luck.;)

Grape,

I had located a .84 in a six-bolt downpipe flange, but it was terribly expensive (~$260) just for the housing. I figure that the .84 would be tons better for in town driving, not so great for heavy rigs that pull (not me). It would also make ~12 psi boost with the 6.2 fuel system.

Yep, confirmed P trim wheel, so lots of configuration changes can be changed to meet the need. I prefer not to modify the downpipe to accept the 4 bolt flange. My exhaust shop's getting tired of seeing me week after week.

Grape,

I had located a .84 in a six-bolt downpipe flange, but it was terribly expensive (~$260) just for the housing. I figure that the .84 would be tons better for in town driving, not so great for heavy rigs that pull (not me). It would also make ~12 psi boost with the 6.2 fuel system.

Yep, confirmed P trim wheel, so lots of configuration changes can be changed to meet the need. I prefer not to modify the downpipe to accept the 4 bolt flange. My exhaust shop's getting tired of seeing me week after week.

that $260 doesn't sound all that bad, but you could try searching for Majestic Turbo in dallas and talk to Dave, tell him you need a "euro" .84 p trim housing. They call that configuration euro for some reason, t3 footprint on the entrance to the exhaust housing with a t4 p trim wheel......go figure.

Grape,

What about the Majestic In Waco? That's who had a 1.00 A/R for me, but rebuilt my current turbo.

Are these guys any good, I am starting to form other opinions.

Could you provide me with the contact info for the one in Dallas, you can do it via PM if you'd prefer.

Thanks!

the guys in waco i've had no experience with but they do seem shaky. Dave runs or owns the majestic in dallas and is a hotrod guy, www.dallasturbo.com (http://www.dallasturbo.com) is the dallas location.

As a followup, I want to first thank all those with suggestions/replys.
After taking the day off from work to properly cuss out the exhaust manifold and extricate the rusted bolts, I finally replaced the crossover gasket and added the rebuilt Banks turbo. I tentatively drove the the muffler shop and had them cut off the Banks muffler and straight-pipe me.
I will not suggest for a micro-second that this truck runs anything like a modern Duramax, but what I will tell you is that I had no idea that this truck could be this much fun to drive. It will now squirt around town all day on just 1/2 inch of pedal travel and I can make uo to 12lbs of boost at anytime. I had no idea how quiet and powerful this old 200k 6.2 could be. It makes me just that much more excited knowing I have a fully built-up 6.5 waiting in the wings! ( at the machine shop, that is!)
Thanks again to all.

Check fuel filter. sounds like you need more fuel. You did turn the fuel up?

DuramaxWannabe,

when do you make 12psi boost? AT WOT?

I got the 1.00 A/r on my truck now and I have to punch it to get 12psi, but it does make it.

J

CD,

I downshifted today from 4th to pass another vehicle on a two-lane road and I hit the 12lbs. Not bad for 4500 feet!