I don't understand how using premium fuel will reduce the engine temp enough to prevent overheating in this situation. The EGT will be the same or higher with higher octane and the integral turbos are contributing a huge amount of heat into the block. Help me understand this. Thanks.

 

It also could be overloaded. He said that he was 10,000 feet above sea level when he had the warning.

The towing guide it says to reduce GCWR by 2% per 1,000 feet.

"Gasoline engines lose power by 3-4% per 1,000 ft. elevation. To maintain performance, reduce GVWs and GCWs by 2% per 1,000 ft. elevation."

GCWR is this configuration is 17,100 lbs. 17,100 - 20% = 13,680 GCWR. How much does this truck weigh? Around 6000 lbs? Therefore the load include cargo should be a max of about 7,680 lbs when you are up that high. So he was about 400-1000 lbs overweight. This is is pushing the max tow limit and like you said and Ford recommend premium fuel for trailer tow.

From the towing guide:

High Altitude Operation
Gasoline engines lose power by 3-4% per 1,000 ft.
elevation. To maintain performance, reduce GVWs and
GCWs by 2% per 1,000 ft. elevation.

http://www.ford.com/towingguides

http://www.ford.com/resources/ford/g..._F150nov18.pdf

 

Just curious and I'm not trying to offend anyone but how many people overheating while towing are NOT using Premium? I am curious because when i go to buy a new truck next year im debating between the Eco and the 5.0L.

 

The turbos are bolted onto the exhaust manifolds and hang off the side of the engine. You can see them if you look through your wheel well. The heat on they produce is mostly independent of the motor's internal temp, only a small bit of radiant heat will warm up the side of the block.

The issue is that under a load the ECM will let the turbos hold the boost pressures higher for longer periods of time. The higher cylinder pressures generate more heat and lower octane fuel will start to burn too early and detonate. The knock sensor will detect this and pull timing back to stop the detonation which will reduce engine power. This makes it harder for the truck to pull and increases the overall work the engine must do. Work creates heat and the motor starts to get hotter than normal. If you back off the throttle the work load is reduced and not as much heat is made. The higher octane fuel allows the timing to be increased more since it is actually harder to burn. Because it is harder to burn it produces less heat inside the cylinder. Add to this the thinner air does not cool as well so the radiator and intercooler are not as efficient.

A forced induction motor is a different animal than a naturally aspirated one. Because they can compensate for the thinner air a new set of problems is present while the N/A one is panting and wheezing away making considerable less power. Just a few years ago all turbo motors had much lower compression ratios and required premium fuel all the time. The EB runs a 10:1 and a max of 15PSI and only needs premium when it's really loaded up. To me that's doing it right.

 

^ great post

 

Very simple - just refer to your owner's manual. That's what Ford says to do. There has to be a good reason for that recommendation.

 

Thanks for that info. Your calculations for my truck are correct. The owner's manual does not have this towing info in it. The owner's manual mentions using premium fuel, but it says nothing about reducing loads due to altitude.

Interestingly, if we use the %'s they give, I should have lost about 30-40% power up there - but I didn't. I guess that's due to the turbos??

 

Great info - thanks for your reply. The next time I tow heavy at altitude I'll definitely run premium fuel.

 

Correct. Turbos essentially negate the power loss associated with higher altitude since it increases the pressure in the engine, compensating for the lower air pressure at high altitudes.

 

Turbos in a nutshell are nothing more than an air compressor. They use the really hot air coming out of the motor that is still expanding to spin a turbine wheel on a shaft. The other end of the shaft is connected to a compressor wheel that is open to the outside air. The air is drawn in and compressed to supply the motor with more air. This allows the intake to be pressurized which in turn pushes more air into the cylinders. We all know it takes air and fuel to power a motor so as the pressure (boost) increases so does the amount of fuel being added. This is why a small turbo motor can use so much more fuel when it’s being pushed. At 15 PSI of boost twice as much air is being pumped into the motor as it would be if the motor was N/A. In effect the 3.5L engine is now using as much air and fuel as a 7.0L engine, but it also makes that much power too. On the EB the boost is electronically controlled via a waste gate built into the turbo itself. So at altitude the turbos are taking the thinner air and pumping it up to a specified pressure. Therefore the loss at altitude is minimal. The N/A motor is only able to suck in the ambient air and use whatever oxygen is present. As a result it loses power as the air gets thinner.

This is all just general theory and of course there are quite a few more details and finer points to be argued. But it should help clear up some of the questions.

 

The GVW reduction may not exactly apply to a forced induction gas engine.

 

Hey there, new to forums tho been browsing them for a long time now. i did not read all 13 pages. Anyways i have a '12 ecoboost and this weekend we took a trip to the mountains. I too live in arizona where its hot and while going up a 6% grade about 3/4 way up truck did exact same as OP, i didn't notice it until truck said engine power reduced. so i got to the top of the hill and pulled over, popped the hood and hose wasn't hard, coolant wasn't boiling in res.

As soon as i got to the top of the hill the gauge went back to normal pretty much instantly. My assumption is maybe the gauge is tided in with turbo's temp also. At the rate the temp gauge went back to normal there is no way the coolant got that hot and cooled down that quick. It was a matter of 2 maybe 3 seconds tops it went back to normal. Only thing i know in the truck that would heat up and cool of quite quickly would be the turbos.

 

The turbos are big chunks of stainless steel with exhaust gas blowing through them at high pressure on one side and compressing air (making it hotter too) on the other side. The engine coolant is actually circulated through the housing to cool them off. They are not going to cool off quickly even with the engine off. Look up turbo coking and learn more about it.

The "temp gauge" is not really a gauge at all. It is heavily damped so that it slowly moves to operating temp and then stays there until the engine gets to an overtemp condition then it moves to the high point. It's just a fancy light, that's it. Also the aluminum block and heads on the EB will heat up a lot quicker than the cast iron on the older motors. On the other hand they will also cool off much faster too.

 

Spud, being that you didn't read the whole thread, I'll sum it up for you.

Ford recommends premium gas when towing, especially in hot weather. If you weren't using premium, that could explain it.

 

I do run premium fuel only. Problem with taking to dealer is they have no way of replicating it unless they plan on towing my camper through the mountains. There were no signs of overheating aside from the gauge (no ping, loss of power, fluid, boiling res, rock hard hose's, etc). As soon as I got on top of the hill, pulled over, by the time i got the hood up the fans even kicked off. I've owned many of turbo gasoline vehicles and never seen one cool down practically instantly. Maybe that's fords new technology for you?

I suppose I could take it in, they'll throw t-stat, temp sensor, etc at it. Who knows, new doesn't mean it works.