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Old 05-26-2018, 11:50 AM
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Wojo7
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Default Garrett G25-660 boost control

Just finished up installing a Garrett G25-660 and Iím having some issues controlling the boost level, Iím running a 46mm wastegate and a Gizmo MBC that was working great with my 27/6 but just canít seem to react fast enough for the new Garrett. Iím wondering now if the wastegate discharge pipe should be bigger? I believe itís only 1 1/4Ē now. Iím going to lighten the spring as well, itís 1.1 bar now, thinking of going down to .7?
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Old 05-26-2018, 01:13 PM
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Paulyy
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Im interested in results of your turbo. What A/R rear housing you running?
There is so little info about these turbos at the moment so posting some would be amazing, Dyno figures or even what RPM full boost hits in 3rd gear.

What's it doing? Over boosting? Boost spiking? What is your boost target? 1.1 bar is 16psi. if your target boost is 16+ psi then remove the MBC and let the wastegate do it's job.
I've never heard of your boost controller, Is it electric or manual? assuming manual as you said MBC but i googled it and nothing came up. Is it a bleed type or ball and spring?
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Old 05-26-2018, 02:41 PM
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My bad, Gizzmo is EBC, I started looking at the paperwork and it seems there is a ď spike stop ď setting as wel, Iíll try adjusting that some itís currently at 0 and has a max setting of 100. As far as the turbo goes I got it with the .72 turbine housing, itís very small dimensionally so it fits great, even the stock water pipe works. Iíve only driven the car a few times since I finished it ( complete re seal as well ) but I can say this turbo is a beast, it spools very quickly and I would imagine has very little back pressure compared to the 27/6. I havenít measured back pressure yet but the exhaust note sounds like I added 2 more cylinders. I will continue to post as I drive it more.
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Old 05-26-2018, 04:22 PM
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Sounds like you need to adjust your EBC to a lower duty-cycle to accommodate your faster spinning turbo. Where did you buy your G25-660 from?
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Old 05-26-2018, 08:01 PM
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Im assuming you've got a set of chips installed for your mods ect right?

First i'd set your duty cycles to the lowest. or turn the controller off and make sure it's not the controller. If it's not the controller, there's an actual issue that needs to be resolved. or just disconnect the vacuum lines from the solenoid.
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Old 05-27-2018, 07:22 AM
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An EBC needs room to control properly the wastegate in the boost range between the rating of the wastegate spring and the peak boost target. This is the range where the solenoid should show the advantage of an EBC over an MBC, and I have found that this boost range needs to be relatively "wide" on a 951 engine when smoothness and things like throttle-based boost control have to be enabled.

I had nothing but problems running an excessively stiff wastegate spring with an EBC. Running a peak boost of 1.2 bar, I went down from a 1.0 to 0.4 bar wastegate spring which solved my issue. This means I tripled, from 0.2 to 0.6 bar, the width of the effective working boost range of my EBC.

I imagine your peak boost is not much higher than 1.1 bar, and in this case the solenoid used with your EBC may struggle to actuate the wastegate because its spring is too stiff, and it obviously does not have time enough to react within the excessively narrow 0.1 bar boost range to avoid the boost spikes you may be seeing.

I would therefore suggest that you install a softer wastegate spring.
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Old 05-28-2018, 06:47 PM
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I think I've got this worked out, I canít believe how much lower the duty cycle had to be set to achieve the same boost pressure, I had to lower the gain down to 10 from 35 as well. Holding rock solid at 18 psi now and the car is running great. Iím hoping to get to a dyno in the next few weeks for some numbers but one thing for sure is this turbo is a huge improvement over the 27/6 it replaced, it's a different car. I plan to log some runs to get more accurate numbers as far as boost vs RPM but from what Iíve seen so far the turbo is all in under 3k and thereís a ton more power everywhere, part of this Im sure has to do with the head and intake work I had done by Joshua at Valley Performance. I think Iíll post a separate install thread for the turbo build as well. Thank you everyone for your input.
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Old 05-28-2018, 07:28 PM
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What all did Joshua do to your head and intake? Heís building one for me currently, excited to get it on my 3L build.
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Old 05-28-2018, 10:59 PM
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Originally Posted by Wojo7 View Post
I think I've got this worked out, I canít believe how much lower the duty cycle had to be set to achieve the same boost pressure, I had to lower the gain down to 10 from 35 as well. Holding rock solid at 18 psi now and the car is running great. Iím hoping to get to a dyno in the next few weeks for some numbers but one thing for sure is this turbo is a huge improvement over the 27/6 it replaced, it's a different car. I plan to log some runs to get more accurate numbers as far as boost vs RPM but from what Iíve seen so far the turbo is all in under 3k and thereís a ton more power everywhere, part of this Im sure has to do with the head and intake work I had done by Joshua at Valley Performance. I think Iíll post a separate install thread for the turbo build as well. Thank you everyone for your input.
That would be all turbo. Headwork wont improve your spool that much. 100-200 rpm if you're lucky. Head work is more towards mid and top end.
You're saying you get 18psi before 3k rpm???
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Old 05-29-2018, 08:35 AM
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Any chance you can measure your crossover pipe exhaust pressure to add more data?
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Old 06-01-2018, 11:12 PM
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Originally Posted by NCLA951 View Post
What all did Joshua do to your head and intake? Heís building one for me currently, excited to get it on my 3L build.
He did new SS back cut valves, isky springs, multi angle valve job, seats, seals and full race port. The intake was port matched to the head. He really did a great job.

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Old 06-02-2018, 03:00 AM
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Is this the turbo you chose?
871389-5010S 0.72 V-Band V-Band No N
https://www.turbobygarrett.com/turbo...series-g25-660
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Old 06-02-2018, 08:42 AM
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Originally Posted by gruhsy View Post
Is this the turbo you chose?
871389-5010S 0.72 V-Band V-Band No N
https://www.turbobygarrett.com/turbo...series-g25-660
Yes, I bought it from Turbo Kits the first day they were available with inlet and outlet flanges.
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Old 06-13-2018, 12:04 AM
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Originally Posted by Wojo7 View Post
Yes, I bought it from Turbo Kits the first day they were available with inlet and outlet flanges.
Same amount of effort/fab as GT/GTX to install?
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Old 06-13-2018, 10:11 AM
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Originally Posted by jasonlp View Post
Same amount of effort/fab as GT/GTX to install?
Yes. All Garrett turbos are interchangeable provided they're the same rear housing i.e t3 t4 ect.
it will still require a custom down pipe and modded xover.
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