![]() ![]() Well the answer is yes absolutely it matters.Ī lot of people say that when you have a NA engine it matters a ton but on a turbo engine it isn't as big of a deal. But the real question is how much does it really matter? I mean the turbo compresses air anyways so does a little less atmospheric pressure really matter? Now as we all know there is less air the higher in altitude you go. When gauge pressure is referenced to something other than ambient atmospheric pressure, then the units would be pounds per square inch differential (psid). For example a bicycle tire pumped up to 65 psi above local atmospheric pressure (say, 14.7 psia locally), will have a pressure of 65 + 14.7 = 79.7 psia or 65 psig. The converse is pounds per square inch gauge or pounds per square inch gage (psig), indicating that the pressure is relative to atmospheric pressure. Since atmospheric pressure at sea level is around 14.7 psi, this will be added to any pressure reading made in air at sea level. Pounds per square inch absolute (psia) is used to make it clear that the pressure is relative to a vacuum rather than the ambient atmospheric pressure. Therefore, 1 atmosphere is approximately 14.696 pounds per square inch. Now converting the psi to standard atmospheres: Therefore, one pound per square inch is approximately 6894.757 Pa. It is the pressure resulting from a force of one pound-force applied to an area of one square inch: The pound per square inch or, more accurately, pound-force per square inch (abbreviations: psi, lbf/in 2, lb f/in 2,lbf/sq in, lb f/sq in) is a unit of pressure or of stress based on avoirdupois units. I am gonna quote some wiki info from to show how PSIA is caluclated You can figure out this number by doing some basic math seen below. We need to remember that at sea level there is about 14.7 psi of pressure in the air you breath. The princples work the same on a Cummins 24v vs common rail and powerstroke or duramax.įirst thing we need to look at why altitude plays a role. But what the high idle does is add a little load to the engine to help warm it up without requiring it to carry the weight of the truck.This Article covers the effect of being at higher altitude in a Turbo Diesel powered vehicle. Just my preference, like I said each to their own. I've known several trucks that weren't warmed up and they are weak as can be. ![]() But I'm no engineer, just a guy with several cars with 250-350K miles on them, all with great compression and oil pressure. I'm always a little leery of information from someone that has everything to gain from selling more of something. I think it helps the rings seal and gets the combustion temps up. If I am going to idle with the EB on I will let the truck run for a few minutes at a fast idle, then turn the EB on. I also don't like using the exhaust brake on a cold motor, I am pretty sure it puts tons of soot into the oil (based on UOA). But I prefer to let it get warm with 90 minutes of block heater and drive off. Now thats generally what I do, but depending on what I am doing (taking the kids out, up and down the road at elk camp, etc) I will let it warm up first for some comfort. Let it get good oil pressure, run for 30 or so seconds if really cold and drive away is the best thing you can do for your motor. Cummins released a brochure that stated the engines should be driven sooner rather than later when cold. ![]()
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