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ATT only 8 psi

H

heavychevy93

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Running an ATT turbo and only been getting 8 pounds max out of it... I dont have the injection pump turned up at all which is why im assuming why I'm not getting any more boost. Is this correct? and how much would the pump need to be turned up to get in to the double digits??? Thanks
 
Welcome to TTS....

I take it that you have first verified for any exhaust leaks pre-turbo. Also, I am presuming that you have a DB2831 pump in it. Were you using your new pump with another turbo before the ATT ? It is not uncommon for a drop in boost when swapping to a more efficient turbo. The mass of air probably is greater with less pressure. We run mechanical DB2831 pumps, and turn them wide open to achieve 15psi @ WOT.

Do you have any excessive smoke ? Might just be the pump is putting the motor on a diet and need to feed a little more go-juice....... if your pump is turbo calibrated as a 4911, you should have 3/8 to 1/2 of a turn left in it before the leaf-spring is in danger of rubbing on cam-ring. If you do not have smoke, you can turn it up. We like 1/4 turn increments, because I consider excessive smoke to be wasting fuel. Please don't jump up and do it, from what we tell you, wait, others will give their opinions also.

Have you contacted Dennis or Patrick, from what we've seen to date, they pride themselves on customer service. For sure they will be on here shortly.
 
Make sure the snorkel in the fender is gone.
Clean air filter?
Then 1/2 turn on the IP screw.

I would check the lift pump pressure and make sure it is running with the engine. Then check the screen in the FFM and loose the tank sock. The tank sock has caused me all kinds of grief. A prelift pump screen or filter you can service is the way to go. You loose 5 PSI of boost or stall the engine with restrictions.

Was the timing set properly? I set mine by ear. When the cold advance is on I get black smoke with the GM3 and it clears when the cold advance goes off - so a little advanced. Don't recall it smoking like that with the ATT.
Retarded timing, white smoke, will give you more boost but less power.
Advanced timing will give you black smoke but lots of power. (I would not get to crazy with timing without head studs and keep in mind the crack prone main bearings...)
There is a range in between with no smoke.
I assume the timing chain is new or a gear drive conversion? Chains stretch quickly - in under 30K miles - although still serviceable.
 
Just a quick tip on our wonderful lift pumps (or LP's), they are voltage sensitive. Translation, they require a full dose of electricity, so make sure that's its ground is extremely clean or you'll get robbed of fuel to the injection pump (don't ask me how I know, but trust me on this one)
 
sshewins said:
Just a quick tip on our wonderful lift pumps (or LP's), they are voltage sensitive. Translation, they require a full dose of electricity, so make sure that's its ground is extremely clean or you'll get robbed of fuel to the injection pump (don't ask me how I know, but trust me on this one)
Click to expand...

LOL. Thanks, Scott - all the inputs to our engines need to be clean and pure... solid grounds and connections (voltage), clear sock, FFM, screen (fuel), clear filter, path, and cool temps (air), and no leaks (xover), restrictions (DP), cat/trap (exhaust).

Amazing how much of our technical advice and Wisdom is built around those simple things... and everybody says 'don't ask me how I know, but trust me on this' LOL.

What's that old saying, 'Wisdom is what you needed just shortly before you got experience'?
 
JiFaire said:
LOL. Thanks, Scott - all the inputs to our engines need to be clean and pure... solid grounds and connections (voltage), clear sock, FFM, screen (fuel), clear filter, path, and cool temps (air), and no leaks (xover), restrictions (DP), cat/trap (exhaust).

Amazing how much of our technical advice and Wisdom is built around those simple things... and everybody says 'don't ask me how I know, but trust me on this' LOL.

What's that old saying, 'Wisdom is what you needed just shortly before you got experience'?
Click to expand...

An engine (any engine) is like marching an army somewhere to fight:

Without support lines, it's doomed to failure....

Everyone focuses on the engine and fails to realize without it's support systems, it's nothing.

Hence, fuel/grounds/etc/etc....
 
Thanks for all the input guys sorry I've been working alot and haven't had time to reply. I don't think its a fuel problem because im still blowing. alittleblack smoke at higher rpm. Also hit 10 yesterday on way home from work. I'm starting to think its a boost leak betwen turbo and intake manifold. Need to get better boots and clamps then what I have
 
I'm not saying don't check it, but I think you'd here a sound change if you had a leak between the turbo and intake. I've had a few of those silicone couplings come off - I have an IC so there's more possibilities. Every time it happened, it was immediately noticeable. The sound varied depending on how "off" the silicone coupling was, but there was no mistaking that something was wrong. It was EASILY noticeable in the cab.
 
How many miles do you have on the turbo? Mine took several miles to really "break in". If I recall, it took 5000 miles before the turbo was really settled in. I can see 10 psi if I stand on it empty. I do not tow anything so I cannot tell you what it would do with a load.

Brian
 
bshull said:
How many miles do you have on the turbo? Mine took several miles to really "break in". If I recall, it took 5000 miles before the turbo was really settled in. I can see 10 psi if I stand on it empty. I do not tow anything so I cannot tell you what it would do with a load.


Brian
Click to expand...

I've had it for about a year now. So 6-8k on it.
 
If you are indeed experiencing a pressure leak, make sure your lower intake manifold bolts are correctly torqued down, also. I've seen the manifold to head gasket leak, it's usually noticeable by pressure drop and unexplained oil leaks down the back of the block that look like either OPS or rear main leaks, but are actually oil from the CDR blowing out the manifold to head joint. How do I know this, trust me! :thumbsup:
 
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