HP vs altitude & gas vs diesel

[noteven]

Thinking on a new truck... thinking on gas vs diesel...etc.

At the moment we need tow capacities in the 13,000 - 15,000lbs trailer weight range with 13ft high frontal area...

We live just above 2000ft elevation (lots of windy days too) and most of our TC hauling and 5th wheel towing happens from 2000ft - 7000ft and we haven't travelled Colorado yet...

Watching the manifold pressure (sorry "Turbo Boost" sounds more powerful doesn't it?) on the diesel engine I see it "normalizes" at various altitudes (stays the same) which means the engine maintains it's power output.

Plugging in some advertised numbers and altitudes to this calculator I see the 6.4 Hemi I like (410HP at 5600rpm) would be 50HP down at 2200ft and over 100HP down above 8000ft...

HP at altitude calculator clicky

Prolly have to wait for F150's turbocharged, direct injected, Vsomething MegaEcoBoost bigger brother to enjoy spark plugs...

[Targa]

I would go diesel in your situation.

[Denny___Jami]

Dave H M wrote:

Denny & Jami wrote:
The trailer we are pulling last time I weighed it was 15901lbs and yes I pulling it with a gasser and just like all motors it has power lose at altitude. Newer gas motors adjust to the higher elevations on the fly unlike older models. But you can't run diesel gears in them, you have to gear them so they run in their power band when pulling grades, but when we are running down the interstate I can still run in 6th gear at 2K rpm at 65 mph. My not sure about the other brands but Fords 6.2 with the 6 speed and 4.30 gears is a very capable pulling platform.

If you want to give your truck a test take hwy 191 south of 80 in Wyoming to Flaming Gorge Lake in Utah. On our last trip we were from sea level to 10K feet and it was a pleasure to drive.

Denny

You are preaching to the choir Denny - in my opinion.

I am running the 6.2 with 4.30's in an F 250 towing 11.5K fifth wheel. I switched to gas.

You just have to relax when you see another diesel thread spooling up. :W

I'm just letting others know that there's other options out there :B

Denny

[Dave_H_M]

Denny & Jami wrote:
The trailer we are pulling last time I weighed it was 15901lbs and yes I pulling it with a gasser and just like all motors it has power lose at altitude. Newer gas motors adjust to the higher elevations on the fly unlike older models. But you can't run diesel gears in them, you have to gear them so they run in their power band when pulling grades, but when we are running down the interstate I can still run in 6th gear at 2K rpm at 65 mph. My not sure about the other brands but Fords 6.2 with the 6 speed and 4.30 gears is a very capable pulling platform.

If you want to give your truck a test take hwy 191 south of 80 in Wyoming to Flaming Gorge Lake in Utah. On our last trip we were from sea level to 10K feet and it was a pleasure to drive.

Denny

You are preaching to the choir Denny - in my opinion.

I am running the 6.2 with 4.30's in an F 250 towing 11.5K fifth wheel. I switched to gas.

You just have to relax when you see another diesel thread spooling up. :W

[Denny___Jami]

rhagfo wrote:

Denny & Jami wrote:
The trailer we are pulling last time I weighed it was 15901lbs and yes I pulling it with a gasser and just like all motors it has power lose at altitude. Newer gas motors adjust to the higher elevations on the fly unlike older models. But you can't run diesel gears in them, you have to gear them so they run in their power band when pulling grades, but when we are running down the interstate I can still run in 6th gear at 2K rpm at 65 mph. My not sure about the other brands but Fords 6.2 with the 6 speed and 4.30 gears is a very capable pulling platform.

If you want to give your truck a test take hwy 191 south of 80 in Wyoming to Flaming Gorge Lake in Utah. On our last trip we were from sea level to 10K feet and it was a pleasure to drive.
The onlyh
Denny

So what gear and what speed are you running at say 5,000" pulling a hill with that rig.
Just wondering what the mileage is at, with those pulls.

Some just don't like the engine revving to 4,500 rpm, time to start pulling the feet back from the bell-housing.

I normally run it between 3200 and 4500 rpm on grades that need it, it will do 55 mph in 3rd no problem (and higher) on heavy grades. When we left our home base in Nebraska and headed west to Nevada by way of Utah to meet up with some rving friends before heading to Yuma by way of the North Rim of the Grand Canyon the truck averaged 8 but it was also still breaking in. After we came out of Mexico and headed to Texas and out of the big grades but still in the wind and rolling hills it averaged 9 by the time we got to the hill country. It took a while to figure out the power band and the manual shift mode on the transmission but after that it was fun to drive.

Denny

[Colorado71]

I live at 10,000ft. Even though I'm only towing around 5,000lb I went with a turbo diesel. I hate driving NA engines up here, unless they are way, way over powered to begin with.

[Blackcell]

Based on the weight & altitude you're in diesel country.

[rhagfo]

Denny & Jami wrote:
The trailer we are pulling last time I weighed it was 15901lbs and yes I pulling it with a gasser and just like all motors it has power lose at altitude. Newer gas motors adjust to the higher elevations on the fly unlike older models. But you can't run diesel gears in them, you have to gear them so they run in their power band when pulling grades, but when we are running down the interstate I can still run in 6th gear at 2K rpm at 65 mph. My not sure about the other brands but Fords 6.2 with the 6 speed and 4.30 gears is a very capable pulling platform.

If you want to give your truck a test take hwy 191 south of 80 in Wyoming to Flaming Gorge Lake in Utah. On our last trip we were from sea level to 10K feet and it was a pleasure to drive.

Denny

So what gear and what speed are you running at say 5,000" pulling a hill with that rig.
Just wondering what the mileage is at, with those pulls.

Some just don't like the engine revving to 4,500 rpm, time to start pulling the feet back from the bell-housing.

[Denny___Jami]

The trailer we are pulling last time I weighed it was 15901lbs and yes I pulling it with a gasser and just like all motors it has power lose at altitude. Newer gas motors adjust to the higher elevations on the fly unlike older models. But you can't run diesel gears in them, you have to gear them so they run in their power band when pulling grades, but when we are running down the interstate I can still run in 6th gear at 2K rpm at 65 mph. My not sure about the other brands but Fords 6.2 with the 6 speed and 4.30 gears is a very capable pulling platform.

If you want to give your truck a test take hwy 191 south of 80 in Wyoming to Flaming Gorge Lake in Utah. On our last trip we were from sea level to 10K feet and it was a pleasure to drive.

Denny

[Wiley75]

Agreed. It's all about air density. Turbocharging with aftercooling reverses some of the air density issues caused by altitude and high ambient temperatures. Problem is I'm not familiar with a 1 ton truck that features a turbocharged gasoline engine (yet). So for now I think a diesel would be the best choice for the OP.

[wcjeep]

Look for a diesel with an exhaust brake and/or transmission brake assist. This keeps the vehicle service brakes cold for an emergency.

[docj]

APT wrote:
It's not gas vs. diesel that is the difference. A turbocharged gasser will maintain higher % of power at higher altitudes too. There just have not been many turbocharged gas engines in thee history of pickups. F-150 Ecoboost does very well at altitude.

Very few people understand this point; it's not a gas vs diesel issue at all.

A "normally aspirated" engine will lose ~3% of its power for every 1,000 foot increase in elevation. Therefore, at ~6,000 feet a normal gas engine will have lost ~18% of its power.

A turbo-charged engine (and all modern diesels in MH's are turbos) will lose ~1% per 1,000 feet. Therefore, at 6,000 ft it will have lost only ~6% of its power.

We lived in Albuquerque for a number of years and our house was at 6,200 feet. All our vehicles were gas but were turbo-charged!

[rhagfo]

mpfireman wrote:
It always puts a smile in my face when approaching some campers pulling those long grades in the western states, smoke billowing out of the tail pipe, limping along at 20 MPH, and i can safely pass them without even breaking a sweat. Diesel power will do that. My 98 Cummins still runs strong with 125,000 miles on it.

Piker!! Our 01 has 270,000 miles and still loves hills pulling an 11,000# 5er.

[noteven]

jus2shy wrote:
OP, you're right in your statement on needing to wait for some OEM to produce a turbo gasser for an HD truck, if they ever decide to in order to avoid power loss in the higher altitudes in the mountains...

Ya I am just throwing the idea out for discussion - imagine a gasohol burner with turbocharging and direct injection giving 600 - 700 lbs ft of torques at 1800 rpm, governed at 3500 rpm so it will run 300,000 miles...

[jus2shy]

OP, you're right in your statement on needing to wait for some OEM to produce a turbo gasser for an HD truck, if they ever decide to in order to avoid power loss in the higher altitudes in the mountains. Otherwise you are stuck with a turbo diesel. If there was a turbocharged HD gas motor out there, I would be weighing harder on whether to have bought a diesel or not. I know I don't want naturally aspirated, it's painfully obvious when a diesel passes you towing their favorite large toy hauler up at altitude and you're struggling with your gas rig with just a payload and no trailer. Hence why I no-longer own a 2010 F-150 (along with payload limitations)