Boost Pressure - Specified v Actual & MAF readings

[TopBear]

When looking at a output of others log data, its common to see there is some difference in the Boost pressure specified & actual figures.

Is it quite normal not to have the same numbers for both, and to see a small numerical difference?
If so, what in terms of deviation between these numbers, is acceptable, and at what point does it start to indicate a leak?

Also I presume the numbers will be different depending on state of tune, i.e. Std\remapped.

So are there any working examples of what is normal or good for these figures, for the following examples

1. Std map
2. Stage 1
3. Stage 2

Similarly what kind of readings should for a normal\healthy MAF as well?

Cheers

[soapy_g]

Hi Top Bear, i am actually orginally from greenock, but living for the past few years in hong kong !

I agree with you on the issue of it being interesting to have a better feel for RS4 stats for boost ( both requested and actual), since all my recent searches come up with S4's etc !

I have some worries on the state of my own turbos and logged boost peaks of 2,100 mbar and 1,400 mbar ( requested , actual) at 6,500 rpm on my stock RS4.

Obviously i am concerned about the gap between requested and actual, but having just read another thread on peak boosts that are around 1,000 mbar i am now concerned that the engine has been mapped for high boost and the actual levels aren't reaching that - suggesting it is even more knackered than i thought !

[TopBear]

Hi Soapyg,

I'm a bit dissapointed we havent seen more replies here, as we have a wealth of knowledge on the subject from some members on here, but that seems predominantly in the S4 model.

Anyone perhaps from MRC (or other tuning companies) able to comment or give us some guidance on the metrics ?

[TopBear]

When looking at a output of others log data, its common to see there is some difference in the Boost pressure specified & actual figures.

Is it quite normal not to have the same numbers for both, and to see a small numerical difference?
If so, what in terms of deviation between these numbers, is acceptable, and at what point does it start to indicate a leak?

According to the Audi workshop manual provided via another thread. The measured deviation between Specified pressure and Actual pressure must not exceed ± 20 mbar.