Engine/Transmission (1998.5 - 2002) Diesel engines and high altitude????

[Nickaru]

I've heard from this forum that Diesel engines don't choke at high altitudes like a gasoline engine would. How is this true if a diesel consumes 3 to 4 times the air a gasoline engine needs? I know someone that was driving their truck up a grade to Big Bear and right at 7500 foot level it chugs. It has the Edge Juice, 4 inch exhaust and an AFE filter that is clean. It doesn't matter if the box is on or off and he can't go above 2000 rpm. Lots of smoke too. I haven't been in that direction with my truck to see if it does the same. Any ideas? Thanks.

 

[fkovalski]

I am sure others will chime in on the technical side of your question, but at 9,100 feet where I live, there is a lot of smoke out of my pipe as compared to the 'flatlanders' ( :-laf ) down in Denver... But I am not at a loss for power... the MPG is less. I get about 16-17.

 

[Crazygoat]

Your mileage is great, I run up and down Magnolia Rd (by Boulder Canyon) which is a 3000 foot climb and get about 14 mi/g. Smoke... maybe more, but again I am having a failing fuel system.



DaGoat

 

[DPelletier]

I've heard from this forum that Diesel engines don't choke at high altitudes like a gasoline engine would. How is this true if a diesel consumes 3 to 4 times the air a gasoline engine needs?

because a normally aspirated gasoline engine ingests ambient air at 14. 7 psi at sea level (depending on atmospheric conditions, which we'll ignore for the sake of this discussion). The same engine at 5000ft only has an atmospheric pressure of 12. 5 psi which represents a 15% reduction in the amount of air the engine can use. Compare this to a turbocharged diesel engine running 30psi of boost; at sea level it's ingesting 14. 7psi plus 30psi boost for a total of 44. 7 psi. At 5000ft the same engine is using 12. 5psi plus 30psi of boost for a total of 42. 5 psi or a reduction of 5%. This is overly simplified but should illustrate the rationale.



Dave

 

[NoSeeUm]

As stated above it is the turbo (supercharger) that makes the difference.



With a supercharged engine, you are able to up the effective air pressure. The supercharger can adjust for the atmospheric air pressure decrease at higher altitudes. So as you go up in altitude the supercharger has to compress more air in order to maintain the same engine intake air pressure.



PR ----> Pressure Ratio = (atmos pressure + boost) / atmos pressure



Specifically, as an example, at see level (14. 7 psia) with 29. 4 psi of boost the PR would be 3 to 1. At 4000 feet (12. 6 psia) with 29. 4 psi of boost the PR would be 3. 3 to 1.



However, you do lose some Hp because the turbo is likely not as efficient at a PR of 3. 3 compared to a PR of 3. 0. This lost of Hp is because the manifold air temperature will be hotter. The turbo compressor churns the air more to raise the same pressure. Hotter (less dense) air at the same pressure makes less Hp.



Jim

 

[SHobbs]

I do know one thing and that is the egt's will go higher in the upper elevations. When I was at Wolf Creek Co ( 8300ft up to 10. 500ft )in Mar. My egt's were as high as if I had the 5er behind me. Seemed that everything ran a little higher as well and since I had #2 in the tank instead of B100 there was alot more smoke.

 

[Supermod56]

I was blowing by Corvette's on Donner Pass in Cal, (7500ft) running close to 40 psi and 850-900F on the EGT's, I was unloaded of course. My Honda will barely go over the mountain!!! So the turbo makes a ton of difference!



Tom

 

[wcjp]

Sometimes I'll tow with a group of gasser's and diesel trucks. The harder and taller the climb the faster the diesel's walk away from the gasser's. All this while towing a heavier load. Plus the technical stuff already mentioned.

 

[PRout]

The turbocharger has been used on piston aircraft motors for years to achieve higher altitudes.

 

[PRush]

I am sure others will chime in on the technical side of your question, but at 9,100 feet where I live, there is a lot of smoke out of my pipe as compared to the 'flatlanders' ( :-laf ) down in Denver... But I am not at a loss for power... the MPG is less. I get about 16-17.

I am moving from the Florida Panhandle to Lake County Co. The altitude at the new home is 9600 feet. What kind of changes should I prepare for at this altitude?

Any info would be much appreciated. 2003 3500 SRW HO Quad 4x4 48RE, 75,000 mi.

 

[fkovalski]

I am moving from the Florida Panhandle to Lake County Co. The altitude at the new home is 9600 feet. What kind of changes should I prepare for at this altitude?... .

I did not do any kind of "high altitude" adjustment on the truck. If you did not get the cord for the engine block heater, I would recommend it. I use a fuel additive especially in the winter as an anti- gel. Get some good winter tires. Other than that, the only thing I can think of is to maybe learn Spanish. :-laf

 

[Joe Mc]

We drove out west a few times with my truck (back when fuel was $1. 30 - $1. 55/gal) and went up the mountains (forget which one) but the elevations was 11,000'. I didn't notice anyhting and this was pre any bombs. The odometer turned 100k on Devils Backbone during that trip. My $0. 02

 

[keimmmo]

I took the old '92 up Pikes Peak a few years ago... 14,000 feet! The turbo lag was NOTICEABLY longer, but it ran fine and had good power. I live at 6000 ft and frequently get up to over 10,000 ft. Both trucks run fine... just takes longer for the turbo to spool up. I also frequently get down to sea level. There are no adjustments needed for the elevation changes on our trucks.



Steve Keim