waste gate Flutter help

[slow1gentsi]

so I have unclipped 20g in an evo3 turbine housing and I think I am getting waste gate flutter not bov flutter or turbo flutter I know what they sound like and its not that. what would cause this to happen? And as of right now I am not running any boost controller or line to the waste gate actuator so it is solely controlled by the spring pressure only.

And this only happens at high boost like 25psi is when it happens

What causes it?

is it harmful to my motor?

what is the cure for this problem?

any input would be appreciated thanks.

 

[GRAVEDIGGER]

And as of right now I am not running any boost controller or line to the waste gate actuator so it is solely controlled by the spring pressure only.

If you're NOT running a line to the wastegate actuator you're NOT controlling boost pressure at all. Instead you're just giving the turbo the freedom to boost as high as it can. I'm surprised it hasn't overboosted and blown itself or your engine.

You need to hook up the wastegate actuator to a boost source like the compressor housing or the j-pipe right off the turbo. If you don't hook it up, the wastegate will never open.

 

[evo1rice]

Wouldn't the wg open according to spring strenght?

 

[GRAVEDIGGER]

Wouldn't the wg open according to spring strenght?

Sure it would... If it's hooked to a boost source like the compressor housing or j-pipe like I previously stated.

Without a boost source it will not open up at spring pressure.

 

[evo1rice]

I c, good to know!

 

[slow1gentsi]

But the thing is I would not go full throttle because of this. And I would let off at about 25psi when I saw the boost gauge needle starting to dance. But dose this sound like waste gate flutter and would not having a boost source attached cause this? Oh and is waste gate flutter hard on the engine?

 

[GRAVEDIGGER]

Hook up the damn boost source!

 

[FromFordtoDSM]

I've seen a good amount of cars blow because of that. Mostly hondas

 

[slow1gentsi]

OK I did hook up the boost source. And the reason I ever unhooked it was because every time the wast gate would open it would get stuck open and not close and that is why I unhooked it in the first place I know now it was a dumb mistake but it wont happen again.

 

[GRAVEDIGGER]

OK I did hook up the boost source. And the reason I ever unhooked it was because every time the wast gate would open it would get stuck open and not close and that is why I unhooked it in the first place I know now it was a dumb mistake but it wont happen again.

You need to find out why it's getting stuck then. The flapper door should move freely with the wastegate actuator rod pulled off. If it doesn't, that's a problem.

 

[brian9397gsx]

Is this an ebay 20g? I know they have an issue with the wastegates either not opening or sticking open. What your describing almost sounds like your experiencing compressor surge.

 

[VETTE_50_TH]

No boost source is needed on an external BTW.

 

[slow1gentsi]

the turbine housing its self is a ebay one but the rest of the turbo is a HRC 20g. so trying to make the actuator work right isn't going so well it gets past a certin point and the wastgate actuator holds the wastgate open. its like it gets past a certain point and the it pulls it over the top and wont go back un less i hit it down with a hammer. I am begining to think its the angle of the actuator arm its self that is causing this.

 

[evo1rice]

No boost source is needed on an external BTW.

Knew I was right to some extent, hehe.

 

[GRAVEDIGGER]

You'll just have to play with it until you get it right. You can just apply air pressure to the wastegate actuator nipple and get it to move back and forth so you can it watch move and adjust as necessary.

 

[slow1gentsi]

it would probably be best if I just get an external wast gate. But one thing about the external ones is i know they will bolt on to an evo3 turbine housing but is the o2 pipe the same size as an evo3 turbine exit their like 2.5" right were as the standard 7cm housings are 2" right? that would cause major turbulence then. Because I was looking at the map external waste gate not shour of the o2 pipe size.

 

[GRAVEDIGGER]

No boost source is needed on an external BTW.

Really?? Would you like to explain why? I know they don't need anything hooked up to the top port, but they still need some sort of boost reference at the bottom/side port or they would never open.... right? My external gate and every other one I have ever seen has had a boost source line going to the wastegate.

 

[TSITurbo95]

That is correct, you SHOULD have a boost source hooked up. However, with an external wastegate, the boost will hit the proper boost level to whatever size spring is in it, and open it once it reaches it limit. The point of the boost source is to help keep the wastegate shut to maintain proper boost level.

 

[slow1gentsi]

then if that is true how dose a MBC work because I was under the impression that the spring inside mine was to keep boost away from the diaphragm of the waste gate actuator until the pressure in the line was enough to over come the spring pressure allowing the air to enter the diaphragm and push it open, Am I right?

 

[JusMX141]

You need a boost reference for proper wastegate actuator function- you really cannot rely only on the spring pressure.

For our cars the wastegate must open fully at the initial peak boost setting then close slowly as the RPMs begin to rise in order to keep the boost stable at that RPM....otherwise you have spikes, drops, and other issues.

 

[slow1gentsi]

would going to an electronic boost controller be better for controlling larger turbos than my MBC? do EBC prevent boost spikes?

 

[Absit]

EBCs, when tuned properly, are more stable than MBCs.

 

[evo1rice]

I have seen some drag cars without a boost controller running solely on wastegate pressure, I have a hard time understanding why it could cause spikes/drops/etc.

Could you explain further?

 

[slow1gentsi]

so it isn't necessary for a 20g like mine then.