87 vs 91 Octane?

[Osco]

That is a very good observation lol. Well according to the poll it looks like 87 has the slight advantage. Reading the posts, it seems to be split in the middle....which still leaves me undecided hahaha

Easy as pie.
Run five tanks on 87 and five on 93, then five tanks on 91 non ethanol and report your findings.
But I think it should be done in summer weather where Ford says it's most noticable.
If you do I'll do it.

Advertisement

 

[Kperry62]

Using 91 in my Outer Banks. I feel it's worth the slight price difference.

 

[Jaythor74]

I’ve trie both in my Big Bend. I’ve noticed a little better performance climbing hills on 93 but identical mileage on both. Definitely not worth the 55 cents more per gallon we pay in Screw York. IMO

 

[tRex]

All you're trying to do with 91+ octane is stop knock, and allow the engine computer to advance the timing further (and possibly adjust other inputs) for higher output. The timing is continually adjusted due to RPMs, load, and fuel (propensity to knock under different conditions). The computer will automatically adjust things for 87 octane, but then you will not get the maximum "as-tested" performance. My bet is, we can save a bunch of money driving in Eco mode with a light foot and on 87 octane. The 2.0L maxes out at 125mph and goes 0-60 in anywhere from 5.7 to 6.7 sec. (according to various reports) -- presumably on that 91+ octane, do I really need that? If you do, go ahead and spend the money, it's a free country!

 

[tRex]

What I WILL do is use Top Tier gas, and I think install a good oil catch can ("separator") setup. DI engines are terrible for carbon and sludge deposits on the valves and pistons, because a.) they are not constantly washed by a port injector, and b.) because of all the recirculated oil and unburnt fuel being pumped back into the intake by the PCV system. (PCV relieves pressure buildup in the crankcase, but for emissions reasons also recirculates all that gunk to be burnt by the engine instead of just released into the atmosphere). An even bigger problem on DI-only engines with higher compression ratios and turbo (more blowby in the cylinder). So blow it all into a catch can instead, and empty that once in while, better than burning it. Top Tier gas -- it's a program to assure that the gas has the correct detergent additives in the correct proportions to burn the cleanest.

 

[tRex]

But...I'd say to anyone and do so myself -- if you're getting more than the occasional pinging, switch to 91+ octane. The engine/computer have their limits and, it's really dependent upon your driving habits in the end.

 

[wiyeti]

Given 91 octane premium is about 75 cents on average more in WI, I'll stick with the 87 top tier. The mild benefits are not worth the added cost.