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Old 12-07-2017, 07:17 PM   #1
Troll Boy
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Default 2015+ STI boost peak level

I would like to know how many people with stock STI's 2015+ that register over 14.7 psi? I was hitting 19 psi with a stock 2015 STI.
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Old 12-07-2017, 07:26 PM   #2
GlarryHoodDIT
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Is it on the stock tune?
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Old 12-07-2017, 08:06 PM   #3
Sarcoughaguy
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Yes it will sometimes creep to 20-21 pounds. Again this is peak and not sustained. It is not good for your car to sustain that boost on the stock tune

Your car should be dialed in at 14.7 though, if stock
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Old 12-07-2017, 08:22 PM   #4
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IDK if I would say it's "normal", buts its very common on 15+. I used to work at a Subaru dealer when they came out and pretty much every single one peaked at 20-21PSI.

As far as sustaining that boost, i don't think its anything to worry about. The stock turbo is a bit small to do any more than peak at anything over 19PSI. You can get rid of the overboosting with a good tune.
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Old 12-08-2017, 12:31 PM   #5
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I have a '17, going by the reading on the dash, mine appears to peak at 17 psi, I'll have to re-check it since the weather is getting colder.
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Old 12-08-2017, 05:41 PM   #6
thatdamnalex
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The highest I've seen mine peak is 18. Usually the peak stays around 17. I believe between 14 and 15 is the target. The people saying in the 20's are probably talking about wrx's
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Old 12-08-2017, 05:57 PM   #7
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Quote:
Originally Posted by atm0706 View Post
IDK if I would say it's "normal", buts its very common on 15+. I used to work at a Subaru dealer when they came out and pretty much every single one peaked at 20-21PSI.

As far as sustaining that boost, i don't think its anything to worry about. The stock turbo is a bit small to do any more than peak at anything over 19PSI. You can get rid of the overboosting with a good tune.
So if you say it's not normal, did you do something to remedy all those cars that had the issue? Sounds like if every single one did that, it's seen as normal.
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Old 12-08-2017, 06:34 PM   #8
Sarcoughaguy
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Quote:
Originally Posted by subarulz! View Post
So if you say it's not normal, did you do something to remedy all those cars that had the issue? Sounds like if every single one did that, it's seen as normal.
I guess you can call it normal but not ideal. There are so many other variables between sea level, temperature, phase of the moon, etc. The stock tune is a generic tune put on all cars, but they obviously won't act the same. Although it isn't ideal, it's accepted because this is what happens. All turbo cars do this. They creep slightly, and it only hits that level for a split second which is why we say it's peak and not sustained. Unless your car is running mods as well as a BCS of some kind, you're going to see fluctuations in your readout.
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Old 12-08-2017, 06:37 PM   #9
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Quote:
Originally Posted by thatdamnalex View Post
The highest I've seen mine peak is 18. Usually the peak stays around 17. I believe between 14 and 15 is the target. The people saying in the 20's are probably talking about wrx's
Gotta say that this is wrong. 14.7 psi is stock on 15-17 STI's. 18 STI has target boost set at 16 psi. My 18 has crept up into the 20's so it does happen and even other 15+ STI's creep into the 20's too.

The new FA setup is a bit different, the map is built entirely different than the EJ's and actually has a higher target built into the stock map mid power band.
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Old 10-26-2018, 06:30 PM   #10
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Default Stock 17 sti peak 9.4???

I just got this car and Iím new to Subaruís but when I got it peak was around 13.5 now the best I saw (one month later) was 9.4 the car has 12888 when I got it. I take it this means I have a vac leak and need to take it in please help!
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Old 10-27-2018, 10:03 AM   #11
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I've seen 21.9 peak a few times in the right weather. It's just a brief period of overboost and nothing to worry about.
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Old 10-31-2018, 07:29 PM   #12
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i have an ewg tuned @16psi and have never went past 16.5 *knocks on wood*
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Old 02-21-2019, 12:10 AM   #13
ImprezaJTR
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Stock 2019 STI here with 19.8 peak boost

Last edited by ImprezaJTR; 02-21-2019 at 12:20 AM.
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Old 02-21-2019, 08:05 AM   #14
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Quote:
Originally Posted by avikm289 View Post
i have an ewg tuned @16psi and have never went past 16.5 *knocks on wood*
That's b/c with EWGs you have more than enough available WG volume to dump all turbo pressure if necessary. So the turbo can never build pressure faster than the wg can dump it, thus eliminating the possibility of boost creep.
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Old 02-21-2019, 08:06 AM   #15
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My 18 STI (stock) never broke a peak of 17.8 PSI, which is fine because it shouldn't be shooting up that high. STIs have had sustained boost levels of 14.5psi, eventually tapering.
Under WOT my psi bounces between 14.3 - 14.7.

If it's very cold out, like right now, I'll only peak 15-16ish and hold 13ish PSI. Cold weather = less psi on a stock tune, to maintain A/F ratios.

When it's warm out, I'll peak high 17s in PSI, and maintain 14.5 psi.

The numbers have been the same before and after a brand new PCM, which was warrantied by Subaru.
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Old 02-21-2019, 10:23 AM   #16
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Quote:
Originally Posted by defaultstivaper View Post
Cold weather = less psi on a stock tune, to maintain A/F ratios.
has nothing to do with maintaining an AF ratio
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Old 02-21-2019, 10:35 AM   #17
2018wrx_newbie
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Quote:
Originally Posted by Redrider0727 View Post
I just got this car and Iím new to Subaruís but when I got it peak was around 13.5 now the best I saw (one month later) was 9.4 the car has 12888 when I got it. I take it this means I have a vac leak and need to take it in please help!

Peak boost will be lower in colder temps, so the info you provided by itself may not necessarily mean you have a leak. Is this the max you hit on WOT? If so, may warrant a deeper look.
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Old 02-21-2019, 12:06 PM   #18
SirBrass
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Quote:
Originally Posted by 2018wrx_newbie View Post
Peak boost will be lower in colder temps, so the info you provided by itself may not necessarily mean you have a leak. Is this the max you hit on WOT? If so, may warrant a deeper look.
Not that low, though. In just below 0 temps (Fahrenheit), my peak boost was always around 13. Around 10psi is wastegate spring pressure, so yes he's got a leak somewhere.
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Old 02-21-2019, 01:52 PM   #19
Llama92
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My 03 wrx I just bought is doing the exact same thing, hitting 20-25psi on gague idk if its correct or not. The only mods on car are intake and exhaust, no ap or tune
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Old 02-26-2019, 12:59 PM   #20
2018wrx_newbie
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Quote:
Originally Posted by SirBrass View Post
Not that low, though. In just below 0 temps (Fahrenheit), my peak boost was always around 13. Around 10psi is wastegate spring pressure, so yes he's got a leak somewhere.
Got it. Learn something new every day on these forums, did not know about the wastegate spring pressure. Thanks.
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