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Old 11-18-2020, 11:16 PM   #1
John1218360
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Default 2015 stock boost 13?

I just got a 2015 wrx with 44k miles and ive heard people making more than 13psi of boost is it normal to be making 13 on stock tune
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Old 11-19-2020, 09:08 AM   #2
alapilusa
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I'm gonna have to go with no. I know the boost will vary by temperature, and with your location being in the northeast where it is currently quite cold (with dense air), it will take less boost to get the same amount of airflow through the engine. But even still, 13 sounds low. Typically, stock boost will peak to about 19-20 and then taper down to about 15 by redline.
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Old 11-19-2020, 10:37 AM   #3
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Quote:
Originally Posted by alapilusa View Post
I'm gonna have to go with no. I know the boost will vary by temperature, and with your location being in the northeast where it is currently quite cold (with dense air), it will take less boost to get the same amount of airflow through the engine. But even still, 13 sounds low. Typically, stock boost will peak to about 19-20 and then taper down to about 15 by redline.


Do you think it might be a boost leak?
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Old 11-19-2020, 11:35 AM   #4
crazy_irishman
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Originally Posted by John1218360 View Post
Do you think it might be a boost leak?
I think you should have someone look at your car.
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Old 11-19-2020, 12:38 PM   #5
killadawg
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As mentioned above, if it is cold out, you are just fine! with super cold weather you might just see 12 or 13 as the air is much more dense and you cap on your fuel delivery.. a datalog would show more info than just OMG it only hit 13psi or whatever. You should be fine if its super cold out.
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Old 11-19-2020, 01:13 PM   #6
rtv900
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does the wrx have the S and S# modes that affect boost peak?
my STI is down about 5 psi in S mode compared to S#
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Old 11-19-2020, 01:27 PM   #7
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Quote:
Originally Posted by rtv900 View Post
does the wrx have the S and S# modes that affect boost peak?
my STI is down about 5 psi in S mode compared to S#
I was thinking the same thing but I'm pretty sure SI modes for the WRX are only available in auto and it just changes the way it shifts.
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Old 11-19-2020, 01:49 PM   #8
SnoBrrru
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Quote:
Originally Posted by rtv900 View Post
does the wrx have the S and S# modes that affect boost peak?
my STI is down about 5 psi in S mode compared to S#
My 2015 doesn't have those settings. I think they're only on the STI.
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Old 11-19-2020, 02:24 PM   #9
John1218360
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Originally Posted by SnoBrrru View Post
My 2015 doesn't have those settings. I think they're only on the STI.


Yeah mine doesnít have those settings either maybe for auto wrx?
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Old 11-19-2020, 05:56 PM   #10
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Originally Posted by rtv900 View Post
does the wrx have the S and S# modes that affect boost peak?
my STI is down about 5 psi in S mode compared to S#
nope none of that coolness for us wrx kiddos.. that is only for them grown up STI's.. I don't even get this via MapDCCD with an STI Trans..
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Old 11-28-2020, 11:54 AM   #11
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Quote:
Originally Posted by killadawg View Post
As mentioned above, if it is cold out, you are just fine! with super cold weather you might just see 12 or 13 as the air is much more dense and you cap on your fuel delivery.. a datalog would show more info than just OMG it only hit 13psi or whatever. You should be fine if its super cold out.
This. Iíve seen boost peak at 11 psi when it was below zero F.
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Old 11-29-2020, 06:40 PM   #12
tegxsi
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On a stock tune, the base boost targets is about 15 psi. It will subtract from base boost target based on intake temps.
It will take away:
-8.6psi @ 32F
-4.7psi @ 50F
-1.6psi @ 68F

It will also add boost at warmer intake temps. In extreme heat it will take boost away again.
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Old 11-30-2020, 03:10 PM   #13
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Originally Posted by tegxsi View Post
On a stock tune, the base boost targets is about 15 psi. It will subtract from base boost target based on intake temps.
It will take away:
-8.6psi @ 32F
-4.7psi @ 50F
-1.6psi @ 68F

It will also add boost at warmer intake temps. In extreme heat it will take boost away again.
Whatís your source on those numbers? Iím curious cuz Iím seeing higher boost on a stock engine than what you say I should.
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Old 11-30-2020, 06:37 PM   #14
240se
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Don't confuse intake air temp with ambient air temp. Intake air temp is usually a little higher. You can use a OBD2 scan tool to see intake air temp.
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Old 12-01-2020, 08:17 AM   #15
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Originally Posted by killadawg View Post
nope none of that coolness for us wrx kiddos.. that is only for them grown up STI's.. I don't even get this via MapDCCD with an STI Trans..
honestly I wish the STI didn't have it either
It is a total nonsense feature. Every time I start the car I have to flick that knob to get full boost, and it's not like you have to be driving hard just because full boost is available
But the dumb thing will not stay in S# after shut down, always reverts back to S
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Old 12-01-2020, 03:55 PM   #16
tegxsi
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Quote:
Originally Posted by vladd View Post
Whatís your source on those numbers? Iím curious cuz Iím seeing higher boost on a stock engine than what you say I should.
I have AccessTuner software.

You will see spikes and overshoot on the stock map because of the aggressive wastegate duty cycle tables.
Intake temperature compensations also apply to wastegate similar to boost targets.
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Old 12-01-2020, 06:39 PM   #17
saaiello21
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Peak boost on 2015 WRX is 15.9 PSI and will taper down to 13 towards redline so if that is what you see this is normal. Stage 2 tune would peak at about 19psi and taper off at redline. Lower then expected boost can be so many things. I would check all intake hose and fittings first if nothing is obvious, smoke test it under pressure.
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Old 12-13-2020, 04:48 PM   #18
vladd
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Quote:
Originally Posted by tegxsi View Post
I have AccessTuner software.

You will see spikes and overshoot on the stock map because of the aggressive wastegate duty cycle tables.
Intake temperature compensations also apply to wastegate similar to boost targets.
I'm guessing there's more that goes into the boost target, such as elevation, cuz I was seeing around 11 PSI at -17F. This would be around 5K elevation.
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Old 12-14-2020, 06:09 PM   #19
killadawg
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Quote:
Originally Posted by rtv900 View Post
honestly I wish the STI didn't have it either
It is a total nonsense feature. Every time I start the car I have to flick that knob to get full boost, and it's not like you have to be driving hard just because full boost is available
But the dumb thing will not stay in S# after shut down, always reverts back to S
Gross.. I guess not knowing what you don't have you might want it.. but thanks for that info!! I will take my full boost without extra knob fiddling anyday!! OH yeah we still need to switch off the damned traction thingy (not real traction control, but "slippage >> cut power" bs these cars have).. This is where the MapDCCD really shines
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Old 12-27-2020, 06:40 PM   #20
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When I was living in CT, my boost would peak around 18psi then taper down to 15psi so maybe a boost leak? I would check the stock BOV as I've heard that some will leak at peak boost.
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