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well i have a 22t swapped 96 legacy with a stock vf11 having over boost issues.

 

i run no ebcs, i hit 12-14 psi (un-safe boost for tiny vf11), w ebcs hooked up w low boost set at 4psi and high boost setting at 8 will still hit 12-14psi.

 

it did this w catless dp and stock catted dp and about a month after i did the swap.

so i dont think dp has anything to do w it

 

i have a good jdm vf8 laying around off my jdm ej20 and the wastegate actuator is way easier to move then my vf11 which should move way easier then the jdm one. i would think since it supposedly a 5lb spring

 

 

car breakdown

96 legacy ls

ej22t

06 wrx tmic

ebc

bellmouth catless dp

full 3"exhaust

fancy gauges

fancy wheels

fart cannon

etc etc etc.

yup its my daily poor man turbo build

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  • 1 month later...
So, I have gone from overboost to underboost! I pulled intercooler to test due to finding very small leak. I welded it closed. I did a boost test from the intake tube at 10 psi and no leaks. The only thing I found was the bov wouldn't hold boost when bench testing the intercooler but i also didn't have pressure on the vacuum line going to the top of it. Im not sure if it should leak without pressure to vacuum line? bcs not controlling? It's holding about 13.5 when it should be at 17cryotune. It's holding 13.5 when should be at 16 cobb stage 2+.
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  • 1 year later...
First test drive i blew the stock intercooler due to not putting in top bolt and intake tube coming off.

 

then I leaned against the air vent over the radiator and broke the fitting off the radiator that goes to the turbo coolant container! FAIL

 

Test drove after a ghetto radiator repair.

 

test drove again after hooking up a hose I pulled off by accident.

 

going to try to swap with my blown turbo.

 

So looks like the problem might be the ebay china turbo the junkyard sent me

 

:lol:

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wait I thought overboost happens when the wastegate is fully open but still can't bypass the turbo so the turbo is still building pressure? for me when my car was running I had a catless.. everyone said that if I got a catted DP the issue would no longer be the case? I'm not sure if I could overboost with a VF-52 and a catless DP?
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wait I thought overboost happens when the wastegate is fully open but still can't bypass the turbo so the turbo is still building pressure? for me when my car was running I had a catless.. everyone said that if I got a catted DP the issue would no longer be the case? I'm not sure if I could overboost with a VF-52 and a catless DP?

 

 

 

Oh boy.

 

Wastegate wide open, still above target boost = boost CREEP.

 

Boost above target = overboost

 

Yes, a catted DP makes tuning boost control easier because you're reducing the pressure drop across the turbo which gives it less incentive to spin and make boost. Some combinations of engine and turbo result in very hard and fast spool that's hard to limit. Some tuners will suggest more restrictions in the exhaust to slow it down and some will suggest hybrid boost control.

 

Some turbos are notorious for a tendency to boost creep because the wastegate isn't big enough. The VF-52 is okay in this regard. Even with a catless downpipe and open exhaust you usually need quite high WGDC to push boost past 1bar at redline.

Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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Oh boy.

 

Wastegate wide open, still above target boost = boost CREEP.

 

Boost above target = overboost

 

Yes, a catted DP makes tuning boost control easier because you're reducing the pressure drop across the turbo which gives it less incentive to spin and make boost. Some combinations of engine and turbo result in very hard and fast spool that's hard to limit. Some tuners will suggest more restrictions in the exhaust to slow it down and some will suggest hybrid boost control.

 

Some turbos are notorious for a tendency to boost creep because the wastegate isn't big enough. The VF-52 is okay in this regard. Even with a catless downpipe and open exhaust you usually need quite high WGDC to push boost past 1bar at redline.

 

 

 

The last reading I remember seeing was around 24-25 psi before fuel cut kicked in.. assuming that it was larger than a VF52?

 

 

Sent from my iPhone using Tapatalk

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The last reading I remember seeing was around 24-25 psi before fuel cut kicked in.. assuming that it was larger than a VF52?

 

 

Sent from my iPhone using Tapatalk

 

 

 

24-25psi is spiking in the midrange. A VF-52 barely wants to do 1bar at redline, so no way is it doing that at high revs. Bigger turbos have less problems with spiking as they spool slower.

Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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24-25psi is spiking in the midrange. A VF-52 barely wants to do 1bar at redline, so no way is it doing that at high revs. Bigger turbos have less problems with spiking as they spool slower.

 

 

 

Here is the link when I posted it when it happened it was always WOT in high gears.

 

 

 

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I'm sorry. If there's a question in there I haven't answered yet then I'm not getting it.
Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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I'm sorry. If there's a question in there I haven't answered yet then I'm not getting it.

 

 

 

You said it does not happen at high revs then how did it happen to me?

 

 

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You are not going to 24 or 25psi anywhere near redline. What does your tuner have to say about this?
Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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:lol:

 

You started this :lol:

 

wait I thought overboost happens when the wastegate is fully open but still can't bypass the turbo so the turbo is still building pressure? for me when my car was running I had a catless.. everyone said that if I got a catted DP the issue would no longer be the case? I'm not sure if I could overboost with a VF-52 and a catless DP?

 

Quick question, are you on the stock catback?

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What size piping is the catback? Any other details?

 

 

 

3" and for the psi numbers maybe I can find it I was logging in torque I do remember the max being around 23-25 which causes the cel I don't remember the code but I remember it was something range/performance wastegate.

 

 

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3" and for the psi numbers maybe I can find it I was logging in torque I do remember the max being around 23-25 which causes the cel I don't remember the code but I remember it was something range/performance wastegate.

 

 

Sent from my iPhone using Tapatalk

 

Torque? The phone app with the wireless obd2? Not accurate enough.

You'll want to talk to the tuner

 

 

Even with a catless downpipe and open exhaust you usually need quite high WGDC to push boost past 1bar at redline.
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  • 2 weeks later...

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