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Max Boost Pressure

demon342

Ready to race!
Just installed a P3 gauge on my APR stage 2 R and when testing it out the gauge read at max 32 PSI for boost. Is that ok/normal? I know boost pressures should be higher if you're tuned but 32 seems a little high on stock internals
 

GolNat

Autocross Champion
I think you have to subtract 14.7? Boost will also be lower if it's cooler out.
 

demon342

Ready to race!
Stage 2 on a GTI peaks around 22-24psi. 32 does seem pretty high.

Moderate throttle was putting me around 23-28 PSI but peaked a couple times at 30-32
 

demon342

Ready to race!

GolNat

Autocross Champion
14.7 is atmospheric pressure so subtract that from what the gauge says.

You are getting this reading from the OBD2 port right? Most accurate way is from the intake manifold
 

jtmu6982

Passed Driver's Ed
Careful to not blow out your DV...(n)
 

demon342

Ready to race!
14.7 is atmospheric pressure so subtract that from what the gauge says.

You are getting this reading from the OBD2 port right? Most accurate way is from the intake manifold

Ah I see, yes it's through OBD. But that would mean I'm peaking boost at 18 PSI, is that right for a stage 2 golf R? Stage 2 GTI's push 22-24 according to a previous poster
 

GolNat

Autocross Champion
Unitronic Stage 2 GTI is 20psi. Not sure what a APR Stage 2 R is suppose to be.

Is it cold outside? The ecu is set for torque target not boost target. When it’s cold out you will boost less because the air is denser so you need less of it make the same amount of power.

To check if it’s correct you can data log requested boosts vs actual and see if the numbers are close. If the ECU is requesting 24 and you are only getting 18 then you could have a leak somewhere. If the ECU is requesting 18 and your actual is 18 then all should be good.
 

GolNat

Autocross Champion
Also 14.7 is at sea level. If your elevation is higher then that number is smaller. If it is lower then it will be higher. There are charts online to give you ideas.
 

demon342

Ready to race!
Unitronic Stage 2 GTI is 20psi. Not sure what a APR Stage 2 R is suppose to be.

Is it cold outside? The ecu is set for torque target not boost target. When it’s cold out you will boost less because the air is denser so you need less of it make the same amount of power.

To check if it’s correct you can data log requested boosts vs actual and see if the numbers are close. If the ECU is requesting 24 and you are only getting 18 then you could have a leak somewhere. If the ECU is requesting 18 and your actual is 18 then all should be good.

I mean the car doesn't feel slow so I don't believe there would be a boost leak. With boost leaks you would feel a decrease of power right?

I'll look into this however with my local tuner, there's an APR dealer that has good reviews
 

GolNat

Autocross Champion
Generally depending on how bad the leak is but if it was a progressive leak you may not notice it. You can hear them sometimes too. I have seen 3-4 psi lower then what I should on my GTI when it is cold out. If you do a lot of pulls it will start to go up as IAT's go up.

This is a little log I did just to play around with things but as you can see my specified and actual are pretty close to each other. I should peak at 18 but it was a cool night so it only requested 16.5.

3rd Gear Boost Log.JPG
 

demon342

Ready to race!
Generally depending on how bad the leak is but if it was a progressive leak you may not notice it. You can hear them sometimes too. I have seen 3-4 psi lower then what I should on my GTI when it is cold out. If you do a lot of pulls it will start to go up as IAT's go up.

This is a little log I did just to play around with things but as you can see my specified and actual are pretty close to each other. I should peak at 18 but it was a cool night so it only requested 16.5.

View attachment 161134

How'd you get this chart? VCDS? I'm not new to the VW group but I'm new to really understanding tunes and interpreting gauge/log information
 
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