Not holding boost, need stiffer wastegate spring?

[Chicken Patty]

Hello guys,

I have never had a problem holding boost when I was up to 22-23 psi of boost. I tried turning up to 26-27 and it spikes to it and then it starts dropping off. By 6000RPM's I'm at 21-20psi.

My profile is updated with all my mods, the spring I have currently is a 0.9 bar spring.

I have checked and ZERO boost leaks. I'm using the bottom port on the TiAl wastegate. Some people have suggested to use the top port. Any input on that?

Here is my most recent dyno sheet showing above conditions. I feel as if it is cutting my peak power short, making peak power at about 5500RPM's, usually I've seen peak power at around 6200RPM's with these setups.


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[JusMX141]

Definitely a symptom of too light of a spring.

 

[Chicken Patty]

Figured. Any recommendations on what spring to get?


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[JusMX141]

Pick the lowest boost pressure you'll ever plan on running, and buy your spring(s) to suit.

 

[black_gst]

How do you have you WG vacuum lines set up? You should be able to get 150% of the spring pressure.

Run a line to the top port that sees just boost with no controller and then run your boost controller to the bottom port

edit: actually it looks like you are already maxing it out to that based off your provided numbers

 

[Chicken Patty]

@Justin

Good method.

@black gst
What am I maxing out? The spring?


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[black_gst]

@Justin

Good method.

@black gst
What am I maxing out? The spring?


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Yes but if your WG isnt hooked up the way I described you may be able to get a few more psi out of it without having to change the springs

 

[Chicken Patty]

I get what you mean, I'll try that tonight.


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Well, using both ports on the wastegate fixed my issue, spiking and holding a steady 26psi till redline.

I should've remembered this is how I ran it on my SRT-4 on a 50 trim and a .9 bar spring as well. Just didn't hit me till it was mentioned above.

 

[black_gst]

I get what you mean, I'll try that tonight.


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Well, using both ports on the wastegate fixed my issue, spiking and holding a steady 26psi till redline.

I should've remembered this is how I ran it on my SRT-4 on a 50 trim and a .9 bar spring as well. Just didn't hit me till it was mentioned above.

cool glad I could help

happy boosting!

 

[Chicken Patty]

cool glad I could help

happy boosting!

You sure did!

 

[matt98eclipse]

Im haveing the same issue here. Adam how are u saying to hook up the vac lines? Im also running a MBC.