Cant control boost

[Hotrodbuick]

So I have been trying everything to control my boost but can't seem to get it down to around 15 lbs. I have an external waste gate running to a manual boost controller. I know the waste gate opens because took my air compressor and blew some air through it an felt it open, blew through my controller so I know that works also. I have tried running line straight from turbo ad still can't get it down. Waste gate hole has been opened to same size as down pipe. Any suggestions?

 

[bison]

If you're attempting to use a compressor wheel that will support more than about 30% more mass flow than your engine is using and you have a late turbine design you will need to increase the wastegate bypass by a lot more than you would think. This is especially true if your ex after the turbo is very free flowing. Take the spring out of the wastegate and you will see how low you can get it. Bring the rpm up as high as you ever would and watch the boost

 

[pacecarta]

what spring are you running in the gate? , you cant run less than the spring

whose pipe and whose gate
what size gate
what turbo
you ported the turbo exhaust port to match the pipe to the gate.. what size was that opening?
on some (china) downpipes the opening in the downpipe flange is very small and needs to be opened up to the size of the pipe going to the gate

 

[Hotrodbuick]

Thanks for the reply. I will try taking the spring out and see what it goes to. If it doesn't bring it down as much as I would like anything else I could try? Or smaller turbo needed to bring the boost down? I'd like to keep it down as I will drive the car every day an dont have alky.

 

[Hotrodbuick]

Have a gn1 downpipe 3" with 46mm gate. Not the best but came With the car when I bought it and don't know what spring? I looked online at their website and just says to run a boost controller on it. Have the cpt66 ball bearing from cottons on the car. Ill have to pull off downpipe an measure the hole but I believe around an ich or so

 

[Hotrodbuick]

Car also has hooker headers on it, waste gate solenoid is not used. Has front mount with a blow off valve. Ported heads an intake. If anything else is needed to help let me know.

 

[dpasadena]

Have a gn1 downpipe 3" with 46mm gate. Not the best but came With the car when I bought it and don't know what spring? I looked online at their website and just says to run a boost controller on it. Have the cpt66 ball bearing from cottons on the car. Ill have to pull off downpipe an measure the hole but I believe around an ich or so

I have had the same boost issues with gn1 pipes. The hole that was cut where the wasted exhaust goes back into the 3" pipe was way too small. The wastegate pipe measured 1 1/2" and the hole that was cut into the main pipe was maybe 3/4" at best. Had to cut the pipes up and enlarge the hole to get the boost down. They work ok if you are at 25psi+ though.

 

[Chuck Leeper]

Post a pic of the dp/gate. Could be that the gate is in the wrong location/plumbed at a bad angle, etc...

 

[Royal-T-Ltd]

if i were to guess i would put money on the hole in the downpipe being way too small and impeding exhaust flow. i have some (extra) headers that i might use on a future build... and they are from a vendor (which i will not name) and the hole to the exhaust port which feeds the turbo is cut where half the port is covered up... IMO the ONLY way i will ever use these is to either cut an access hole and grind away the material or try and use a dremel extension and snake it through to take out the material.... You might find the same issue where half the hole isnt even functional and actually blocks the flow.

hth

 

[Hotrodbuick]

Ok so I took out this gigantic spring and took it for a drive and just seems like it bypasses so much it won't let it build boost?? Right around 2600 rpm the boost gauge starts to move then breaks up really bad an spits an sputters under load. But I'm counting on the spring pressure being way too much for what I want. I'm wondering if they sell different springs or if I start cutting off one coil at a time until It comes down haha

 

[Hotrodbuick]

Got it to come down finally. Had to use both the top port as well as the bottom port. Will make around 10 lbs like that wide open. So I can use my boost controller on my top port to shut off the vacuum going to it to get a little more boost out of it. Thanks for all the replies an help!

 

[nathanl70]

I have had the same boost issues with gn1 pipes. The hole that was cut where the wasted exhaust goes back into the 3" pipe was way too small. The wastegate pipe measured 1 1/2" and the hole that was cut into the main pipe was maybe 3/4" at best. Had to cut the pipes up and enlarge the hole to get the boost down. They work ok if you are at 25psi+ though.

Did you have to change the spring after opening up the hole?

 

[dpasadena]

Did you have to change the spring after opening up the hole?

Did not change the spring in the gate. I use a regulator style boost controller to raise the boost past the spring pressure

 

[Chuck Leeper]

As I said... The WG could be plumbed so as to cause the problem. It's in a position to do exactly that. [Directly under the turbo inlet, and at what looks to be a 90* angle.]

 

[nathanl70]

As I said... The WG could be plumbed so as to cause the problem. It's in a position to do exactly that. [Directly under the turbo inlet, and at what looks to be a 90* angle.]

I apologize for jacking the thread. Didn't see any sense in starting a new one with the same issue.
I previously had a TA-60 with the same setup with no issues. Had to crank in the regulator a lot to get the boost I desired. Now I installed the 6765 in my sig and boost jumps to 30 almost instantly with the regulator backed all the way out. The individual I purchased the DP from told me that if I put a lighter spring in the waste gate it "may" solve the issue. Just seems strange to have issues with one turbo but not the other?
Thank you in advance for the help.

 

[bison]

I apologize for jacking the thread. Didn't see any sense in starting a new one with the same issue.
I previously had a TA-60 with the same setup with no issues. Had to crank in the regulator a lot to get the boost I desired. Now I installed the 6765 in my sig and boost jumps to 30 almost instantly with the regulator backed all the way out. The individual I purchased the DP from told me that if I put a lighter spring in the waste gate it "may" solve the issue. Just seems strange to have issues with one turbo but not the other?
Thank you in advance for the help.

You went from a turbo that will flow about 53-55lbs/min if you're lucky to one that will flow about 80lbs/min. Common sense would say that you would need to bypass a lot more ex energy to run low boost. Whenever you try and run a turbo less than 80% of it's potential mass flow you typically have problems trying to run low boost. More turbo requires more engine speed or higher pressure ratios. Lighter springs won't be enough.

 

[nathanl70]

You went from a turbo that will flow about 53-55lbs/min if you're lucky to one that will flow about 80lbs/min. Common sense would say that you would need to bypass a lot more ex energy to run low boost. Whenever you try and run a turbo less than 80% of it's potential mass flow you typically have problems trying to run low boost. More turbo requires more engine speed or higher pressure ratios. Lighter springs won't be enough.

Thanks Bison.

 

[TurboTGuy]

I had problems with that same style DP and WG. I have a 6765 PTE turbo, too.

It worked OK for about 1000 miles and then the waste gate stuck closed. Wouldn't control boost at all. Had to take the pipe completely off the car to get it loose.

Tried a new but same style DP and WG from same vendor with no better results.

Got a new "Terry Houston" style DP with a huge puck from a vendor here and put an adjustable, stock type WG/actuator setup and a Hallman Boost Controller on the car. Regulates all the way down to 17lbs (I haven't tried to go lower) and it works like a champ! Runs like one too.

Not bashing anyone, just saying that particlar DP/WG combo wouldn't work on MY car and describing what does work on MY car.

 

[Chuck Leeper]

So, what brand of WG is it??

 

[TurboTGuy]

So, what brand of WG is it??

If it was the same one I had, unbranded, cheap Chinese Tial knockoff, came with the DP. Sure does look the same.