How to combat boost spike

[funguy]

yes, now how do we do that?
i'm getting massive spike about 5 psi, hit 20 then backs all the way down to 15. this is on a t28, and its really hard to tune it.

 

[mjarrell20]

There are many different ways to combat boost spike:

1. External waste-gate

2. Internal waste-gate with larger flapper and ported housing

3. O2 dump (helps a little on it's own but add an o2 dump with a larger flapper and ported housing and should pretty much cure the spike)

 

[No_Skillz]

How is your MBC hooked up? Teeing into the BOV line may cause spike. If that's the case, try your compressor housing or j-pipe.

 

[funguy]

mine was hooked up straight to the compressor housing nipple and wastegate actuator nipple.

i got fed up and am now testing out my new turbosmart electronic boost control unit

 

[oldman]

There are many different ways to combat boost spike:

1. External waste-gate

2. Internal waste-gate with larger flapper and ported housing

3. O2 dump (helps a little on it's own but add an o2 dump with a larger flapper and ported housing and should pretty much cure the spike)

That would be boost creep. Though easing of the entrance to the wastegate path in the turbine inlet as if you would when porting for boost creep have also known to help with boost spike. With that said, spiking is what T25s do although 5psi is a little too excessive, which brand/type of mbc?

 

[Jeff822]

Maybe your wastegate is not opening, this happened to me on the t-25, you might want to look into that.

 

[compression]

correct me if im wrong but usually quick spooling turbos spike quite a bit because they cant release the exhaust gases and fast as the they are spooling the turbine wheel. that and the mbc could cause it and make sure you make the vaccum lines to and from the mbc as short as possible so theres less area for the air to travel.

 

[mjarrell20]

That would be boost creep. Though easing of the entrance to the wastegate path in the turbine inlet as if you would when porting for boost creep have also known to help with boost spike. With that said, spiking is what T25s do although 5psi is a little too excessive, which brand/type of mbc?

Sorry for the misleading post, I was under the impression that the 2 were solved the same.

 

[kenamond]

mine was hooked up straight to the compressor housing nipple and wastegate actuator nipple.

i got fed up and am now testing out my new turbosmart electronic boost control unit

If you had really long vac lines to and from your MBC, that can slow down WGA response, too. Shorten them as much as possible, possibly relocating your MBC closer to the compressor if you can.

I searched a few weeks ago about BC reviews on a 2gt with an evo3b16g. They compared several expensive EBCs, and I'm not sure if the turbosmart one was also tested. Some of the EBCs wouldn't help with boost spike any better than a ball-spring unit, but they had creep problems on that car which complicated interpretation of the test results. Might want to search around to see what you might expect.