Stock MK7 GTI Boost PSI
The other day I decided to log some boost data with my computer on my stock 2016 GTI. A few things had changed since doing so on my 2006 GLI like the block that was needed to measured and that the value is now in bar and not mbar.
One important note, if your car came with the Performance Monitor built into the entertainment system (mine did not) this is reading pressure with atmospheric pressure. To get the real boost reading you will need to subtract your atmospheric pressure first, which is typically 14.7PSI at sea level. If you are in a higher elevation region this might be less.
After logging with my VCDS I threw the data into an excel sheet and was really confused by the results. It said I was holding boost at 20PSI. That surely could not of been right since 2006 GLI was only 10PSI from the factory and the 99 Audi A4 was 8PSI. 20 PSI was what used to get after my modifications on both cars and the GTI is still stock. The curves though did look correct as well as the timing. So I must of just had the formula wrong. Here is the formula I was using =sum((Value – atmosphere pressure in bar) / conversion value from bar to PSI )
=sum(value-1.01)/0.0689475728
Taking one of the higher values that was about constant (holding boost) that would of been 2.403 which would make it 20.2037569…
So I made a forum post asking what I was doing wrong and an employee of the company that makes the software (VCDS) I use for data recording replied. He said that the values looked correct to him and showed me his plot chart of boost pressure from his 2015 GTI. I am shocked that from the factory these engines hold nearly double the PSI from my previous engine.
The other thing I noticed is that the time it takes to build that pressure up to 20PSI in the turbo is also significantly shorter, this does explain a lot as to why the stock 2016 GTI feels similar to my 2006 GLI modified performance wise. They both are running about the same PSI just the GTI is being less aggressive on the timing and fueling due to the stock software.
I really cant wait to get software on the GTI, its going to be such a beast. From what others who already have the software say, I should be holding around 1.8bar or 26PSI once I do get it.
Here is a chart of the Specified and Actual boost over an RPM range. Specified is what the computer is requesting and actual is what the pressure actual is.
In VCDS the data I logged for this is are: Group 564 (RPM), Group 84(Specified Boost), Group 85 (Actual Boost). For how to log data use this guide here: http://www.ross-tech.com/vcds/tour/adv-meas-blocks.php