Power loss pulling hills in Arizona

[RADAR]

Last week I was pulling about a 6,000 lb travel trailer from the Phoenix area to Show Low. On some of the 6%+ hills, I couldn't get much over 55mph...and my truck ran just a tad hotter than it used to on the same hills. I used to be able to pull these hills any speed I wanted. I did change the fuel filter about 200 miles ago. The new filter was tapered at the bottom where the one I replaced was not. I also replace the air filter before the trip, so it was new.
-- Any ideas why the loss in power..? Thanks in advance for replies.

[More Power]

Higher outside air temperatures, an engaged fan-clutch and running the A/C can reduce total power, when compared to driving in cooler temps.

It's also possible to get crap fuel at any fuel stop. This actually happened to me several years ago. I changed the fuel filter right before a 200 mile trip, filled up in town and headed out. Upon arriving at our destination, the truck began running poorly, but well enough to return home the next day. It took another fuel filter change to get back to normal.

A fuel pressure/restriction gauge (http://www.thedieselpage.com/reviews/jkfuelpressure.htm) lets you test the fuel filter without swapping it out.

Jim

[RADAR]

Thanks More Power. I'm still confused on the replacement fuel filter I installed as the new filter was tapered at the bottom where the one I replaced was not. Did I get an older type or newer type filter..?

[16gaSxS]

Higher outside air temperatures, an engaged fan-clutch and running the A/C can reduce total power, when compared to driving in cooler temps.


Jim

Jim;

Many people don't understand the effects of high outside air temperatures on engine performance. Those of us with an Aviation back ground understand this it's called "density Altitude".
This how it works. An engine has a rated horse power of say 300 hp that is at SEALEVEL on a standard day which is 59F or 15C. Rule is to add 1,000 foot for each 3 1/2 degree above Standard Temp. Also subtract 3 1/2 degree's for 1,000 above SL to find standard Temp for your Elevation.

For example Phoenix is at 1800 foot above Sea Level so let's just call it 2,000 foot. So 2 X 3.5 =7 degrees less than 59 or Phonenix Standrd Temp is 52F if the outsid Temp is 100F then we are 48 degree's above Stardard. 48/3.5=13.7 so add 13,700 foot to the 1800 foot elevation for a total of 15,500 DENSITY ALTITUDE. In other words your engine thinks it operating at 15,500 foot above Sea Level...........
Any wonder your Power Level's are down???
What it all boils down too is hot air is less dense (less Oxygen) per Cubic foot than cool air.
I hope this helps.

[letsgo]

Having driven and towed 10,000# through AZ. CA. and British Columbia up as high as 4000' to 9000' I have never lost power , BUT I have never driven in temperatures close to 100f so your explanation for power loss is quite interesting.

[BurnsK]

Whether it is interesting or not, I don't know, but it is true. Simplistic answer for why normally apirated piston engines don't do high altitude research. My old F350 PS had, as I remember an 11,000 critical altitude, above which it would no longer develop sea level horse power (again that is density altitude). I have never seen a figure for our Duramax turbos.

[JeepSJ]

I can attest to the drop in power when in Phoenix. I was monitoring my IAT (yeah, it was in my gasser, but same theory applies) and they were running just above ambient. Ambient just happened to be 113*. I can really feel the power drop when the IAT goes over 100*. I know my gasser is pulling timing out to combat detonation with the high temps. I would assume that the DMAZ computer is also making some fueling adjustments to try to control the temps. In stop and go traffic I saw some IATs as high as 135.

[RADAR]

JeepSJ,

113 ? - Don't you love the coooool summers we have here :) Thanks for the reply