Boost Pressure

[Dug1]

Hi Guys, just wondering what max boost pressure is standard. I am seeing about 18psi at full throttle. It will peak momentarily at about 20psi then drops to 18psi.

I am reading off the Ultragauge manifold pressure which I have not set up as boost pressure but absolute pressure.

Reason for this is that if set up for boost pressure it subtracts an arbitrary value of about 14. (something) psi to compensate for normal atmospheric pressure whereas my atmo pressure typically varies between about 12.5 psi at work (1,760m) and 13.1 at home (900m). Much easier for you guys living at sea level.

Look forward to seeing if my 18-20 psi is normal. Thanks.

[erad]

Those readings are the same as my NW Pajero, so hopefully they are normal. I live at 880 m elevation, but these readings apply pretty well anywhere I travel, regardless of altitude. You are measuring gauge pressure, not absolute pressure. The actual absolute pressure (and hence the amount of oxygen available to burn) will vary according to the altitude, but the boost pressure will remain the same. This means that at higher altitudes, you will get less oxygen and hence less power. Hopefully the ECU takes this into account and reduces the amount of fuel it squirts into the engine the higher you go.

I don't know how the actual boost levels would compare with an ASX diesel - I thought that the ASX may have had a higher boost pressure, being a smaller and newer engine than the Pajero. For example, I imagine that the Pajero Sport has a higher boost than the old Pajero because it puts out the same amount of power, yet is a considerably smaller engine.

[Dug1]

Thanks erad- yes I was referring to the NX Pajero. Our ASX does boost a tad higher around 22psi.

One thing the ASX has all over the Pajero is intercooler efficiency but that is a different story given the Pajero's one appears to be an afterthought.