Boost problems

[Utah Blaine]

I put a little bigger turbo on the car (83 or so, can't remember what year the engine was, its only a little bigger) and can't get the boost lower than 3 lbs at idle. The new wastegate is back as far as it will go. It reads 9 lbs when I give it a lot of throttle. I don't have a tachometer and am afraid to drive it with the boost so high. If I get the idle boost down it should bring the wto boost down too, right?

 

[No disintegrations]

Not really possible to have boost at idle. The gauge must be wrong or damaged.

 

[Utah Blaine]

Tried two gauges and they show 3.25 psi out of the nozzle right where the foot goes into the intake manifold.

Will it hurt to drive at these levels of boost?

 

[dank GN]

Lol a 83 or so that's massive . I'm running ab6871 on my 4.6 stage block . Your boost problem is your wastegate . You will have to port the hole out if you haven't that's your problem. Hot air doesn't like making 90* turns so instead of going out the wastegate hole it's going to the turbine .

 

[NY Twin Turbo]

Tried two gauges and they show 3.25 psi out of the nozzle right where the foot goes into the intake manifold.

Will it hurt to drive at these levels of boost?

I still question your data. Boost at idle is impossible. Before someone jumps in and tries to convince me otherwise, don't bother. It's impossible.

 

[Utah Blaine]

I hope you know that I mean the turbo is off a 1983 Buick and not an 83mm turbo lol.
The advice sounds good. I don't know what the original turbo made (Boost) because I only had the original in dash gauge that just showed me if it was running economy or not. The new boost gauge is aftermarket.

Will it hurt anything to drive the car with these numbers until I have time to drill it out?

 

[Utah Blaine]

I still question your data. Boost at idle is impossible. Before someone jumps in and tries to convince me otherwise, don't bother. It's impossible.

I'll check it again tomorrow. Again I ask if it is ok to drive it if it has 3lbs at idle and 9 at wot with no load on the engine? What is the highest boost it should be driving down the road?

 

[NY Twin Turbo]

I'll check it again tomorrow. Again I ask if it is ok to drive it if it has 3lbs at idle and 9 at wot with no load on the engine? What is the highest boost it should be driving down the road?

It shouldn't make a single pound of boost if the motor isn't being loaded. It should cruise with zero boost.

 

[NY Twin Turbo]

Let me use an example.

If I'm at WOT and making 25 PSI, my turbo is spinning at 45,000 RPM, and I slam the throttle closed.

Even though the turbo is still spinning at 45,000 RPM when I shut the throttle blade, my boost level drops to vacuum nearly instantly! So you see, if this doesn't cause a closed throttle boost condition, than nothing will!

Also, how could a motor idle at boost? It wouldn't idle at all! It would continue to rev up as if you were introducing more air than it could use. Just like opening the throttle blade.

Engines idle because only enough air is let in to allow only enough torque to only overcome the parasitic loads of your accessories, converter and the natural drag of the engines rotating assembly. Add more air and you quickly overcome these loads and the engine begins to rev higher.

 

[Utah Blaine]

I understand. I'll recheck everything tomorrow. Thank everyone very much.
I'll figure this out!

Thanks again everyone.

 

[NY Twin Turbo]

I understand. I'll recheck everything tomorrow. Thank everyone very much.
I'll figure this out!

Thanks again everyone.

Maybe I still wouldn't drive it. But not because of the boost thing. More because if I knew something was wrong, but wasn't sure what it was, I'd like to play it safe till I figured it out.

Are you sure your not reading back pressure? Where are you tapping your gauge into?

 

[b4black]

Is the wastegate actuator directly connected to the compressor foot? Or do you have a boost controller/valve installed? The controllers can act like a check valve trapping pressure between then and the actuator. It need a tiny pinhole to vent pressure.

 

[Utah Blaine]

Maybe I still wouldn't drive it. But not because of the boost thing. More because if I knew something was wrong, but wasn't sure what it was, I'd like to play it safe till I figured it out.

Are you sure your not reading back pressure? Where are you tapping your gauge into?

Tapping into the bottom hole on the foot where it goes into the intake manifold.

 

[Utah Blaine]

Is the wastegate actuator directly connected to the compressor foot? Or do you have a boost controller/valve installed? The controllers can act like a check valve trapping pressure between then and the actuator. It need a tiny pinhole to vent pressure.

The actuator is mounted to the turbo with the rod going over to the wastegate lever. There is a rubber line that goes to the actuator controller (the hole above where the gauge goes). It's the same set-up as on the original 1979 set-up. I have the boost gauge hooked up to the bottom hole on the foot where the three bolts hold it to the intake manifold.

Where is the pinhole supposed to be?

 

[Utah Blaine]

By adding more rod to the actuator rod and closing it off more I can lower the boost to next to nothing and lower the boost of the revved up engine real low.

Contrary to popular belief, I do have boost at idle. I need to get the car to my house so I can figure this out. I'm going to have to creep it here I guess.

 

[WarWagon]

You have swapped out the turbo for an '83 model so you did not put a bigger one on. The wheels were the same in '78-'83. What did change was the turbine housing, a smaller A/R .63 in '82-'83 vs .82 in '79-'81.
Not enough energy to get boost at idle regardless of what a gauge says. Put a Vac/boost gauge on it!
Drive it as is you won't hurt it, if it bothers you lengthen the waste gate actuator rod.

 

[Utah Blaine]

You have swapped out the turbo for an '83 model so you did not put a bigger one on. The wheels were the same in '78-'83. What did change was the turbine housing, a smaller A/R .63 in '82-'83 vs .82 in '79-'81.
Not enough energy to get boost at idle regardless of what a gauge says. Put a Vac/boost gauge on it!
Drive it as is you won't hurt it, if it bothers you lengthen the waste gate actuator rod.

Thanks, I've got the gauge on it and it won't bother me at all. I'll have it home soon.

Thanks all.

 

[mikemcvaney]

I run 10 psi man on my car all the time. It is impossible to have boost at idle

 

[Utah Blaine]

I no longer have boost at idle. LOL, I no longer have boost. Turned it down, moved the distributor and wound up with15 vac at idle, no boost under acceleration and around 800 rpm at idle. If that ain't bad enough I went and hooked up a oil pressure gauge. I am surprised I have a motor. I have around 4 lbs at idle (800 rpm) and sometimes 15 at 45 mph. Needless to say this is my main concern right now. The new gauge is no good or I have been driving this car for the last six months with very little oil pressure. At least the oil pump seems like it will be easy to get to. Has anyone fixed this pressure problem before? Maybe I should start a new thread and call it "My Turbo Buick Problem".

By the way mikemcvaney, is your car stock? I had no idea what to run the than at anyway. I'll want to turn it back up after this next fix.

 

[No disintegrations]

dont worry about mph, for oil pressure. go by rpm. Have 30psi by 3000rpm? 40 by 4000rpm? etc.