Help with BHP calculation.

[A19quattro]

Hi, I had a calculation written down from a while back of how to calculate BHP from VCDS. With the engine off I had to record atmospheric Pressure which was 999.6 when I did it earlier. Then log (Engine, Block 115) Actual boost pressure; peak was 2601. Then deduct one from the other (1601.4) and multiply by .0145 to give PSI. Now the last bit I am not sure about and the answer I get is 23.2203, so that doesn't make sense. there is a file on the VCDS website about this calculation but apparently I don't have the correct software to read it so that was no help. Anyone shed any light on this.
Should have said the car is an B7, A4 Quattro TDI 170 with emptied DPF and a panel filter. It's going to get chipped on Friday so I was hoping to do a before and after kind of thing.

 

[-Ju-]

The usual way from vcds is to log maf airflow g/s and then divide by 0.8

 

[-Ju-]

Actually I see your tdi so maybe that only applies to the petrol ones, ignore me lol!

 

[A19quattro]

There seems to be a few ways to do it and I think that does work for TDIs as well but I would need to do another log run.

 

[vivalacoulter]

I would imagine that the formula would apply across fuel types? Only way to be sure is have someone try it and get a rolling road to compare.

 

[desertstorm]

You haven't calculated HP, by doing what you did you have converted the peak boost pressure reading from hPa to PSI. Basically 1.6 bar is 23.2 PSI . So if you had a boost gauge you would be seeing 23 PSI peak boost.
To calculate power you really need to look at the injected fuel and compare with the standard car. If a standard 170bhp car say injects 60 mg/str to make it's 170 bhp if the mapping is altered and the maximum injected is now 80mg/str the car is roughly making 80/60 = 1.33 times more power. 170 * 1.33 = 227bhp . This is all finger in the air stuff as there needs to be the air to burn the fuel, so if there is masses of black smoke that's no good. Also sometimes when mapping the injector calibration tables are altered so the injected fuel quantities are no longer accurate.
If you are able to log stuff with VCDS, You could have tried using Virtual dyno to get a before and after idea of a power increase.
http://www.virtualdyno.net/

Karl.