Gas vs PSD
Posting Guru
Joined: Aug 2008
Posts: 2,313
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From: Sunny, Snowy, CO
I don't think you're getting the point. I don't drive through Yellowstone, so what's the point of comparing my engine to yours?
Come on down to my level, find a 3-valve V10 and THEN compare.
Oh wait, that would be comparing from MY perspective. Which would be cheating ... or lying
Come on down to my level, find a 3-valve V10 and THEN compare.
Oh wait, that would be comparing from MY perspective. Which would be cheating ... or lying
Postmaster
Joined: Apr 2006
Posts: 3,524
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From: CA Bay Area
It's different in the vehicles above 5000' and even the dyno's for the AGT-1500 (Tank Turbine Engine) have different ECU settings for altitudes above 500'. Before a deployment the mechanics are running around tuning the engines for where they're going, or they do it when they get there and the tanks start wheezing or blowing smoke. The PCM's in our vehicles adjust for any elevation automatically, but in an NA engine they start to suffer noticeably around 6000' and above. Colorado Springs (Fort Carson) is 6300'. I live at 7200' and when I go on a vacation to California I feel it when I return for a few days. My NA vehicles feel it up here, and haul *** down in Cali.
When I took my Cabin Cruiser to Lake Tahoe above 6000' the local mechanic said there is nothing you can do to adjust the carburetor.
The 4000 lb boat would not go into planning with 205 HP till I switched the propeller to smaller pitch. The engine did not have enough torque to speed up. Just like V10 going uphill on overdrive
Posting Guru
Joined: Aug 2008
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From: Sunny, Snowy, CO
I wonder what they do?
When I took my Cabin Cruiser to Lake Tahoe above 6000' the local mechanic said there is nothing you can do to adjust the carburetor.
The 4000 lb boat would not go into planning with 205 HP till I switched the propeller to smaller pitch. The engine did not have enough torque to speed up. Just like V10 going uphill on overdrive
When I took my Cabin Cruiser to Lake Tahoe above 6000' the local mechanic said there is nothing you can do to adjust the carburetor.
The 4000 lb boat would not go into planning with 205 HP till I switched the propeller to smaller pitch. The engine did not have enough torque to speed up. Just like V10 going uphill on overdrive
Thread Starter
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Modular motor junkie
Joined: May 2009
Posts: 6,190
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From: Texas
Thats not how it works. Your boost should not be any higher at sea level than it is at 6,000' if you truck is running right.
Posting Guru
Joined: Aug 2008
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From: Sunny, Snowy, CO
The boost and the amount of oxygen molecules are 2 different animals. My boost up here at 30psi and in Cali at 30psi are completely different. My truck runs great up here, but ran even better when I was in Cali back in July. Boost is the amount of PRESSURE, not the amount of oxygen getting stuffed into the cylinders.
Postmaster
Joined: Apr 2006
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From: CA Bay Area
The issue might be that re-jetting is not an easy job and part might not be easy available, what makes the job for 5 days use making no sense.
I did hear that one of the generator manufacturers supply jets for high elevation for his equipment. Than the owners take the generator to lower elevation forgetting about high altitude jets and burn hole in the piston.
Than Colorado is selling lower octane gasoline because of high altitudes. Lower octane =lower performance.
Posting Guru
Joined: Aug 2008
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From: Sunny, Snowy, CO
That was a mechanic from most reputable Marina at Lake Tahoe. You have to go there to see how many millions of dollars float there
The issue might be that re-jetting is not an easy job and part might not be easy available, what makes the job for 5 days use making no sense.
I did hear that one of the generator manufacturers supply jets for high elevation for his equipment. Than the owners take the generator to lower elevation forgetting about high altitude jets and burn hole in the piston.
The issue might be that re-jetting is not an easy job and part might not be easy available, what makes the job for 5 days use making no sense.
I did hear that one of the generator manufacturers supply jets for high elevation for his equipment. Than the owners take the generator to lower elevation forgetting about high altitude jets and burn hole in the piston.
Posting Guru
Joined: Aug 2008
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From: Sunny, Snowy, CO
They sell the lower octane GASOLINE because there are less oxygen molecules in the air. Not really less oxygen, just more dispersed because of the lower atmospheric PRESSURE. Because of that, they use a lower octane so it ignites properly. Our highest octane (gas) around here is 87.
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From: Long Island USA
The boost and the amount of oxygen molecules are 2 different animals. My boost up here at 30psi and in Cali at 30psi are completely different. My truck runs great up here, but ran even better when I was in Cali back in July. Boost is the amount of PRESSURE, not the amount of oxygen getting stuffed into the cylinders.
However, without knowing what the sensor for your boost gauge looks like, I'm going to assume it has no external air pressure reference, so the amount of pressure after the turbo IS directly proportional to the number of oxygen molecules entering the engine.
In other words, there is a direct correlation between PSI (on the boost gauge) and how much oxygen your engine is ingesting. When you are at a higher altitude, there is less pressure pushing BACK on the tubing, but assuming it doesn't expand, and assuming the PSI inside the tube is being read by the boost gauge correctly, 30psi is 30psi. There is 30 pounds per square inch of pressure pushing against the inside of the tubing. To do that, there has to be a certain amount of air inside. That doesn't change.
Ambient temperature has a lot to do with that, and might have a lot to do with the difference you are seeing.
Oh wait, you mean altitude DOES affect your forced-induction diesel?
Postmaster
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From: Rogersville, TN
Postmaster
Joined: Apr 2006
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From: CA Bay Area
For several years I travel with GPS that also shows elevation. From what I remember driving motorhome, once I climbed over 4000 in Utah, going via Yellowstone, Mt Rushmore towards Toronto, I was above 4000 for about 5 days.
Posting Guru
Joined: Aug 2008
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From: Sunny, Snowy, CO
It most certainly does; just not as bad as on an NA engine. I never said it didn't. That was Phillips who said that...Now I'm outta' here...lol
Elder User
Joined: May 2010
Posts: 650
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From: WV
Boost is the amount of pressure, relative to outside atmospheric pressure.
However, without knowing what the sensor for your boost gauge looks like, I'm going to assume it has no external air pressure reference, so the amount of pressure after the turbo IS directly proportional to the number of oxygen molecules entering the engine.
In other words, there is a direct correlation between PSI (on the boost gauge) and how much oxygen your engine is ingesting. When you are at a higher altitude, there is less pressure pushing BACK on the tubing, but assuming it doesn't expand, and assuming the PSI inside the tube is being read by the boost gauge correctly, 30psi is 30psi. There is 30 pounds per square inch of pressure pushing against the inside of the tubing. To do that, there has to be a certain amount of air inside. That doesn't change.
Ambient temperature has a lot to do with that, and might have a lot to do with the difference you are seeing.
Oh wait, you mean altitude DOES affect your forced-induction diesel?
However, without knowing what the sensor for your boost gauge looks like, I'm going to assume it has no external air pressure reference, so the amount of pressure after the turbo IS directly proportional to the number of oxygen molecules entering the engine.
In other words, there is a direct correlation between PSI (on the boost gauge) and how much oxygen your engine is ingesting. When you are at a higher altitude, there is less pressure pushing BACK on the tubing, but assuming it doesn't expand, and assuming the PSI inside the tube is being read by the boost gauge correctly, 30psi is 30psi. There is 30 pounds per square inch of pressure pushing against the inside of the tubing. To do that, there has to be a certain amount of air inside. That doesn't change.
Ambient temperature has a lot to do with that, and might have a lot to do with the difference you are seeing.
Oh wait, you mean altitude DOES affect your forced-induction diesel?
I think the bigger issue is that the turbo will have to work hard to create that 30 psi. You will also see increased turbo lag because of the turbo working harder. And since the turbo is working harder, it will probably heat the charge gas up more, which could result in a lower density of air (and hence less oxygen). However, atmospheric temperature are lower (I think) than normal at elevation, so that might be a wash.
But if your truck is at 30 psi at X RPM's in Y gear at Z speed, it will produce the same hp and torque regardless of elevation.
Of course at some point your turbo will be maxed out and your max boost will drop, but I don't think that's an issue.
Also another side note, Ford claims the new twin turbo Ecoboosted F150 will greatly help those living in high climates. When I read that I thought right away of the PSD owners in CO will at least have a smaller option now with boost.
Postmaster
Joined: Apr 2006
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From: CA Bay Area
The boost gauge is a pressure gauge that shows DIFFERENCE in pressure.
At sea level the atmospheric pressure is 15 psi, so 30 psi boost delivers the air at 45 absolute pressure.
If you go to elevation having atmospheric pressure 10 psi, the 30 psi boost will give 40 psi absolute pressure.
Not as big change like 15 vs 10 psi for NA engine, but still.
At sea level the atmospheric pressure is 15 psi, so 30 psi boost delivers the air at 45 absolute pressure.
If you go to elevation having atmospheric pressure 10 psi, the 30 psi boost will give 40 psi absolute pressure.
Not as big change like 15 vs 10 psi for NA engine, but still.