Having trouble controlling boost
Thread Starter
Joined: Sep 2007
Posts: 4,188
Likes: 292
From: woodbine, md
Having trouble controlling boost Having trouble lowering boost-5.3, VS 83/75, 4" down under the car to 2-2.5 pipes, JGS50 WG.
I bought the WG second hand, but it was new, only had the red spring, the weakest. I orig plumbed
it from the comp. to the top port, and tee'ed into it to the controller, and controller to
lower port. My thinking was I could add pressure to the lower port and offset the upper pressure. Boost
was higher than I wanted, even with the controller open, so I swapped the lines, which is now like
most are plumbed. Took it out today, with the controller closed, boost is still high, I think around 14
at 75% throttle opening, 5K RPM, surely go higher. Trying to get to max of 12. Could there be a back
pressure problem. This is how I had my Buick setup using the silver spring, same type WG, and it was fine.
Looking for ideas.
I bought the WG second hand, but it was new, only had the red spring, the weakest. I orig plumbed
it from the comp. to the top port, and tee'ed into it to the controller, and controller to
lower port. My thinking was I could add pressure to the lower port and offset the upper pressure. Boost
was higher than I wanted, even with the controller open, so I swapped the lines, which is now like
most are plumbed. Took it out today, with the controller closed, boost is still high, I think around 14
at 75% throttle opening, 5K RPM, surely go higher. Trying to get to max of 12. Could there be a back
pressure problem. This is how I had my Buick setup using the silver spring, same type WG, and it was fine.
Looking for ideas.
Manual boost controller Im guessing? Take the line off the dome completely and try it. Excessive drI’ve pressure typically results in lower boost because you’re blowing the gate open or the compressor is struggling to flow air.
I agree remove the line from the top port, plug the line of course, and see what it does.
Also does the gate have good flow into it? Like it needs more of a 45 degree instead of 90 if that makes sense. Back pressure would be blowing the gate open earlier instead of later
Also does the gate have good flow into it? Like it needs more of a 45 degree instead of 90 if that makes sense. Back pressure would be blowing the gate open earlier instead of later
Teching In
Joined: Apr 2018
Posts: 29
Likes: 0
+1 on the comments above
By adding any type of pressure to the top port, you're automatically going to raise the pressure at which the gate opens, thus allowing the turbo to build more boost pressure.
When you say you have the boost controller "closed" do you mean the screw was all the way in or all the way out? The idea behind a manual boost controller is to restrict the air pressure going to the bottom port of the gate, in effort to delay the gate in opening to build more boost. With a boost controller maxed out, your maximum final boost pressure can only be double what the wastegate spring pressure is, assuming the gate works and is sized properly for your application. So essentially if you left your boost controller "open" meaning the screw was backed all the way out, you'd be running just off of wastegate spring pressure.
By adding any type of pressure to the top port, you're automatically going to raise the pressure at which the gate opens, thus allowing the turbo to build more boost pressure.
When you say you have the boost controller "closed" do you mean the screw was all the way in or all the way out? The idea behind a manual boost controller is to restrict the air pressure going to the bottom port of the gate, in effort to delay the gate in opening to build more boost. With a boost controller maxed out, your maximum final boost pressure can only be double what the wastegate spring pressure is, assuming the gate works and is sized properly for your application. So essentially if you left your boost controller "open" meaning the screw was backed all the way out, you'd be running just off of wastegate spring pressure.
Thread Starter
Joined: Sep 2007
Posts: 4,188
Likes: 292
From: woodbine, md
Its a Hallman man. controller, with the kit to make it adj. from inside.
The waste gate Is plumbed right at the curve where it turns up to the turbo mount.
The way I have the lines now, comp. to the bottom port, tee off that line to the in fitting
on the controller, out to the top port. With it turned all the way in, should be no pressure to the
top port, allow low boost to open the gate with the weak spring, maybe 5-6 PSI. Maybe the top
port cant bleed off enough to take the pressure off the top?? so I will pull that line. There is
a bleed hole though. Everything is the same way as I ran on my Buick, it had the stronger spring, but was a 6.0.
Also fighting a back fire out the exhaust problem when going into boost, datalog shows nothing.
The waste gate Is plumbed right at the curve where it turns up to the turbo mount.
The way I have the lines now, comp. to the bottom port, tee off that line to the in fitting
on the controller, out to the top port. With it turned all the way in, should be no pressure to the
top port, allow low boost to open the gate with the weak spring, maybe 5-6 PSI. Maybe the top
port cant bleed off enough to take the pressure off the top?? so I will pull that line. There is
a bleed hole though. Everything is the same way as I ran on my Buick, it had the stronger spring, but was a 6.0.
Also fighting a back fire out the exhaust problem when going into boost, datalog shows nothing.
Teching In
Joined: Apr 2018
Posts: 29
Likes: 0
Its a Hallman man. controller, with the kit to make it adj. from inside.
The waste gate Is plumbed right at the curve where it turns up to the turbo mount.
The way I have the lines now, comp. to the bottom port, tee off that line to the in fitting
on the controller, out to the top port. With it turned all the way in, should be no pressure to the
top port, allow low boost to open the gate with the weak spring, maybe 5-6 PSI. Maybe the top
port cant bleed off enough to take the pressure off the top?? so I will pull that line. There is
a bleed hole though. Everything is the same way as I ran on my Buick, it had the stronger spring, but was a 6.0.
Also fighting a back fire out the exhaust problem when going into boost, datalog shows nothing.
The waste gate Is plumbed right at the curve where it turns up to the turbo mount.
The way I have the lines now, comp. to the bottom port, tee off that line to the in fitting
on the controller, out to the top port. With it turned all the way in, should be no pressure to the
top port, allow low boost to open the gate with the weak spring, maybe 5-6 PSI. Maybe the top
port cant bleed off enough to take the pressure off the top?? so I will pull that line. There is
a bleed hole though. Everything is the same way as I ran on my Buick, it had the stronger spring, but was a 6.0.
Also fighting a back fire out the exhaust problem when going into boost, datalog shows nothing.
The way it should go is like this, compressor housing to boost controller inlet, boost controller outlet to lower port on wastegate. With the boost controller backed all the way out (counter clockwise) you'll be running purely off of wastegate spring pressure. As you turn it "in" you'll slowly increase boost until you reach double the wastegate spring pressure, that's where it will max out.
Thread Starter
Joined: Sep 2007
Posts: 4,188
Likes: 292
From: woodbine, md
Found my problem, when I switched my lines around, thinking I was now comp. to bottom port,
controller to top port, I mixed them up, still had the comp to the top port, the tee off that ended up
going to the outlet of the controller, and the inlet to the bottom port, lol so it wasn't controlling anything.
After swapping them around, comp. to bottom port, controller to top, it is working as it should. Controller closed,
3 lbs, controller open, 6 on the weak spring. I noticed I had to open the controller more than I had it before,
so I may swap the lines back as orig., now that I know its wide open, see what max boost is.
Sure is gutless on 6 lbs, lol.
controller to top port, I mixed them up, still had the comp to the top port, the tee off that ended up
going to the outlet of the controller, and the inlet to the bottom port, lol so it wasn't controlling anything.
After swapping them around, comp. to bottom port, controller to top, it is working as it should. Controller closed,
3 lbs, controller open, 6 on the weak spring. I noticed I had to open the controller more than I had it before,
so I may swap the lines back as orig., now that I know its wide open, see what max boost is.
Sure is gutless on 6 lbs, lol.
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