As a petroleum chemist I can tell you how it works.
When a car manufacturer designs a new engine, the car company works very closely with a Technology Center (TC) of an oil company. There are 4 TC's in the US: Shell (Houston, TX), Chevron (Richmond, CA), ExxonMobil (Annandale, NJ and Paulsboro, NJ). I visit these TC's frequently and I worked at the Gulf Oil TC.

These Technology Centers have engine labs and dozens of car engines are bench top installed and are running for thousands of hours to test the engines on the following parameters, among many others:
- Fuels and fuel mixes
- Lubricants
- Wear and tear
- Durability
- Exhaust gases
- Fuel economy

All these test results are sent back to the car manufacturer before the new engine is put in the market. So, what is in the car manual that comes with the vehicle is based on extensive research and testing to get to the optimum performance of the car engine.

Besides the engine lab, vehicles are donated to the TC's for long term field testing, meaning that TC employees drive these cars for many, many miles for durability testing to give the car manufacturer data to make any changes to the engine for next generation vehicles with that specific engine.

What I am trying to say is that the recommended fuel type in the manual is there for a reason: optimum performance on all parameters listed and not only fuel economy or HP's.

 

^ wait, what? you mean Ford engineers actually know better than all the self-made experts around here? you gotta be kiddin', right?



never tried premium, don't plan to unless I start towing "heavy"! (did just fine with a ~ 3,000 lb U-haul on regular)

 

had to take a 1200 round trip avg speed 70-85 got avg 19 mpg with my 5.0 with 87 octane...... ran great no problems..... and i see no need to change, of course i wasnt towing nor do much towing at all

 

forced induction DOES increase cylinder pressures that's true, and fairly obvious, ... but we're not talking about bolting turbo's onto old honda engines. in a DIRECT INJECTION engine the fuel is added in a measured quantity at almost the top of the compression stroke, and is therefor HARDLY COMPRESSED AT ALL.

since octane is a measure of how much compression (and by extension heat from friction) is required to ignite the fuel, there is no possible performance gain to be seen in an ecoboost from premium gas. period. full stop.


Please read the other thread.

 

Here's an acronym for you guys to GOOGLE....LSPI or Low Speed Pre Ignition......it's a very common problem in Forced Induction DI engines. The engineers can't figure out what causes it, some say it's the oil, some say it's the fuel....who knows, but I for one will continue to run 93 octane in my Ecoboost for maximum (pre ignition) resistance. It's a very violent & sudden event that literally blows pistons apart. It's a problem across every manufacturer that has forced induction DI engines.

 

Ford has over 500,000 3.5L ecoboost motors in the F150. If this was a problem, we would know about it.

 

I suggest you reasearch before you make comments about stuff you know nothing about. I've personally seen pistons hanging out of blocks because of this (Ford & GM). It seems to be worse on 4 cylinder engines vs V6 engines though. Then there's that little timing chain stretch issue that Ford claimed wasn't a problem & "that noise is normal" until you're out of warranty & have to fix it.....but they never stated they had a problem there either.

 

From the Manual, page 169....

2.7L and 3.5L EcoBoost Engines

To provide improved performance, we
recommend premium fuel for severe duty
usage, such as trailer tow.

3.5L V6 and 5.0L V8 Engines
We recommend regular unleaded gasoline
with a pump (R+M)/2 octane rating of 87.
Some stations offer fuels posted as regular
with an octane rating below 87, particularly
in high altitude areas. We do not
recommend fuels with an octane rating
below 87.

 

Those that play Russian Roulette once can vouch that they played and survived. Now ask them to play six in a row (constant towing, back to back to back to back WOT applications or aftermarket tunes for max performance gains). They want the insurance of premium.

 

People don't even read their manuals anymore, I read this also.....our knock sensors CAN & WILL adjust for different octane fuels, you WILL make more power in an EcoBoost with premium fuel, I doubt you will see any MPG change though. The 4 cylinder EcoBoost even states YOU WILL lose power using 87 octane BUT you can safely run it.

Exactly, at just about $5-$7 more per fill up, I'll take 93 everytime.