not at cruise it doesnt

 

A friend has a 3.7 ecoboost and it sucks the gas when he tows anything

 

a 3.7? what engine is that? do you mean a 3.5? or a 2.7?

Everything this forum owns sucks fuel when towing. That no surprise to us, imo

 

It takes very little power to cruise down the highway. For a small car anywhere 20-30hp, and trucks might be up to 60hp. You would not be in boost under these conditions. Of course, these values are on a relatively flat grade with light wind resistance. Going up a large grade or high headwind, or accelerating to pass can be a different story.

 

My 3.5 gets better mpg then my 14’ 5.3, runs WAY better also. Highway mileage is similar but it’s better in the city.

 

Do the ecoboost models require 91+ fuel?

 

Correct, that is where you would see improvement for two reasons. Under part throttle acceleration, the engine can use the energy from the exhaust (via the turbo) therefore requiring not having to work quite as hard (this changes though when you go heavy throttle and transition into high fuel enrichment to protect the catalyst and cylinders from excessive heat) - basically light boost. And secondly from the fact that you can get away with less displacement and few cylinders (less friction).

Although comparing a 6 speed all steel body to a 10 speed aluminum body might not be fair comparison as to how much the engine size and turbo effect performance. :-)

 

Is the turbo spinning at cruise? Yes
Is that air going somewhere? Yes
Is that air reducing the pumping losses in the engine? Yes
Does that lead to better econ? Yes

If it doesnt help, explain to me how a 2.7 ecoboost F150 4x4 gets better highway economy than my 1997 Buick Regal GS? One is a slippery sedan and one is a brick of a truck. But one spins a blower 24/7 and the other one gets to breathe easy on its waste energy. This isnt the only example I have in my pocket, so lets not harp on the differences of this 1 example. The truck in question also hauls tools around day in and out. Probably 500lbs of tools. So its a brick, its heavy, its 4wd and gets 27mpg on the highway. Its got turbos. Turbos help at cruise because they increase the VE of any internal combustion engine

 

According to the owners manual, it will run on 87, but they recommend 91+ for best performance. Which means they probably pull back timing and reduce boost when it detects enough knock to know your running low octane fuel. If all things are equal, direct injection is usually more knock tolerant because the it helps cool the combustion chamber mixture due to the latent heat evaporation effect.

 

Well I guess if you want me to explain it while disregarding the facts that:

• The 2.7L is still smaller than a 3.8L
• The compression ratio of 10.3 vs. 8.5 improves efficiency
• The supercharger on the 3.8L increases parasitic losses
• The 2.7L has improved ring technology and coatings to reduce internal friction
• The 2.7L has variable valve timing to increase efficiency at low speed
• The F150 has same coefficient in drag compared to a 23 year old Buick (albeit higher effective area), so not as much as a brick as one would think
• The F150 has 2 overdrives which are lower than a Regal GS
• The newer Ford has a must more sophisticated control systems than a 23 year old Buick

...if we should ignore all that, then it must be the magic of turbo.

Sorry but the effect of the turbo on pumping losses is almost insignificant compared to other factors, and we will have to agree to disagree. Peace out.