[MBC not working on new Evo 3 16g]Whats My Problem?

[mwracing]

ok MONTHS ago i bought a MBC for my stock 14b and it boosted perfectly straight to 15-16lbs or whatever i set it to...


then i upgraded the turbo to evo3 16g.

my mbc now wouldnt go past 10psi or just spike to 20+ and hit fuel cut. so i just kept it at 10 psi cause i couldnt hold anything past 10psi...

now after my full 3" exhaust was installed when i floor it, it goes to 10-11... then returns to 10psi( within a second) and after around 4K rpm it slowly creeps to 18-20 psi.



what im trying to get at is, with my stock turbo i can go WOT and my boost goes straight to 16lbs and holds it from 2500-7000 rpm.

but now i hit 10psi and creeeeeeep up slowly (like watching your speedo climb) to 18-20psi.

where is my problem.... shitty MBC? bad but brand new turbo wastegate? any suggestions would be a big help

 

[playitlouddsm]

Boost creep is when the wastegate opening is not large enough to bypass the turbine on the turbo. To control boost creep try porting out the o2 housing, turbine housing, and the manifold. Or if you have the cash step up to an external wastegate setup. Best of luck.
-Nick

 

[vr4play]

Porting is always a good thing. I don't think your problem is the internal gate setup. Try a new boost controller first. It maybe that your boost controller was letting your 14b open up just enough to contol boost, but can't do the same for the increased flow of the 16g. Also, pull the turbo and check to see if the gate is free to open all the way.

 

[shortydtp]

16g's are and been known to boost creep and solutions to those problems as stated above.. porting you internal 02 housing, or go external wastegate.

 

[mwracing]

ok i forgot to mention that i have an SS o2 housing, SS tubular headers, and 3" O2 back exhaust. pretty free flowing... any more suggestions?

 

[hottboost]

Correct porting will eliminate most creep. Make sure to smooth the divider!

 

[donmagicjuan]

If you have a SS O2 housing, I doubt you will need to port anything other than the turbine housing, specifically the path to the wastegate opening. There are quite a few threads covering this. Here is just one: http://www.dsmtuners.com/forums/showthread.php?t=207016&highlight=port+16g

 

[kenamond]

You can also test for creep by disconnecting the WGA arm, verifying that the WG lever on the turbine housing turns freely by hand, then do a couple full throttle pulls to near-redline. If your boost is more than a few psi, you have a creep problem.

If you have a creep problem (that's my bet), there is a third option besides porting or external gate: get supporting mods to run 20psi. If you have higher hp goals than your current setup, it'll be cheaper in the end to just mod and run 20psi safely, but you won't be able to run below 20psi without addressing the creep.

 

[bushy]

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You need to port the metal around wastegate flapper so it looks like that. By doing this, you allow the flapper to open a full 90 degrees and open all the way.

Just follow this helpful guide found in the technical section

http://dsmtuners.com/forums/showthread.php?t=186525


This will solve your creeping issue.

 

[kenamond]

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You need to port the metal around wastegate flapper so it looks like that. By doing this, you allow the flapper to open a full 90 degrees and open all the way.

Just follow this helpful guide found in the technical section

http://dsmtuners.com/forums/showthread.php?t=186525


This will solve your creeping issue.

Some have said that the throw on the evo3 actuator is small, and the WG won't open 90 degrees even if you port it like the picture. If you hook a vaccuum tester to the WGA, you could tell if 15psi or whatever boost he's running opens it and how much. That would give a definitive answer rather than rumors.

 

[ShapeGSX]

Some have said that the throw on the evo3 actuator is small, and the WG won't open 90 degrees even if you port it like the picture. If you hook a vaccuum tester to the WGA, you could tell if 15psi or whatever boost he's running opens it and how much. That would give a definitive answer rather than rumors.

It isn't a rumor. It is true. I hooked up a mity-vac to the wastegate actuator and pressurized it. It opens maybe 1/2" at most. It will always be in the way of the exhaust, which is why bigger flappers are a bad idea. It is just a larger obstruction in the path of the exhaust.

I've stated this in multiple threads. And Tom Stangl even posted it on the VFAQ web page in freaking 1997!

http://vfaq.com/mods/porting-O2.html

"See that light tan line? The wastegate opens very little and that is the line where the hot exhaust gases hit the side of the wastegate chamber. Grinding the wastegate chamber on the turbine housing and the gasket to match the O2 housing meant in my case that the exhaust gasses would hit a CURVED wall, instead of head on, and be aimed towards the exit in the process. The red lines are an exaggeration of the grinding involved, to give you a better idea of what is going on. The dotted lines are roughly how far down it was taken - into the "blast line"."

 

[kenamond]

It isn't a rumor. It is true. I hooked up a mity-vac to the wastegate actuator and pressurized it. It opens maybe 1/2" at most. It will always be in the way of the exhaust, which is why bigger flappers are a bad idea. It is just a larger obstruction in the path of the exhaust.

I've stated this in multiple threads. And Tom Stangl even posted it on the VFAQ web page in freaking 1997!

http://vfaq.com/mods/porting-O2.html

"See that light tan line? The wastegate opens very little and that is the line where the hot exhaust gases hit the side of the wastegate chamber. Grinding the wastegate chamber on the turbine housing and the gasket to match the O2 housing meant in my case that the exhaust gasses would hit a CURVED wall, instead of head on, and be aimed towards the exit in the process. The red lines are an exaggeration of the grinding involved, to give you a better idea of what is going on. The dotted lines are roughly how far down it was taken - into the "blast line"."

Simmer down Josh. You'll live longer .