I am having a little trouble. I have a mechanical Defi Boost gauge. On my factory pulley the boost gauge read about .5 bar and maybe a little more on cool nights. I dyno'd at church on that setup and his dyno said 7.2 psi. Now I have the 3.9" pulley and my defi says about .95 bar which is about 13.7 psi. Well at church it said 12.5psi. On my AEM EMS when I log I am seeing about 11-12 psi under the engine load readout.

Can anyone give me any input?

I am using the 3.9 pulley revving to 9300rpms.

 

Remember, the boost gauge reads gauge pressure while MAP sensors read absolute pressure. Mechanical and electronic sensors are often different. I've never had good luck with dyno sensors matching any other EMS or boost gauge readings either. Altitude, temperature, and even weather tend to exaggerate the differences.

Tim

 

^^ Once again correct, no need to add anything else

 

So what should I be going by? Basically I wont to know that my boost is what it supposed to be. 3.9 should be making around 14psi at 9300. It is according to the defi.

 

Engine load is more for tuning as it takes a lot of factors into play, for simple "what am I boosting" a boost gauge should suffice.