91 Octane - ECT Test

I tried ethanol free gas and higher octane gas. At first there is a difference. But after time 4-6 weeks the computer figures it out and goes back to what you had before ie same mph and performance. so it don't matter. In the long run the truck will overall be with 87 oct reg gas.

 

Engineering Explained guy does a fairly thorough test on dyno with a bunch of different vehicles with premium and regular. Really there isn't much of a case for premium unless you're towing or your engine knocks while driving on regular.

 

So I'm not batshit crazy? On the way into work this morning I left the ECT off, so just rode in on 91 octane. Still felt better, smoother. Maybe my 4 previous fill-ups were just shitty 87, as I went to a different station for the ethanol-free 91. In any event, I appreciate the feedback everyone!

 

I run 91 non ethanol in my F150 along with a 91 performance 5* tune. It does make a difference power wise compared to the 87 performance tune.

I thought I read in the manual that you are not supposed to run 87 or higher and nothing over E15 in these trucks?

 

Octane is just a rating to tell you how much "pre-bang" resistance gas has. A lower compression engine (like the one in our trucks) will run just fine on 87 octane. If you have a high compression engine (or are running boost) then you NEED to run higher octane to combat pre-ignition. Pre-ignition is when the gas/air mix in the cylinder detonates before it should (i.e. before the piston has finished it's stroke during the compression stage). This causes a lot of problems.

If you mess with timing and create more compression (atkins cycle actually lets some "intake" fuel/air mix out of the cylinder during compression to make the engine compress less volume, is more efficient) you will need more octane. I'm not sure what the tuning these guys do (if they change valve timing) but it would be worth it for me just to have peace of mind to have higher octane.

Can't comment on ethanol content. I know ethanol/alcohol burns cooler than gasoline so you can use more of it along with more air (turbo/supercharger) and get more bang-per-volume while not melting stuff in your engine as quickly.

 

Great post, enjoyed watching the video.

 

stewart's gas is better IMO. I think my truck does run better on 91 non-ethanol from them. I tried 1 tank of 87 after never running anything less than 91 and the truck felt sluggish, my mpg readout was lower for that tank to (25 on 91, 20 on 87)

 

Save your money and get 87/89

 

This

 

I'm a fan of his videos as well.

What I'd like to see, is a comparison involving:
-various octanes of E0 vs E10 fuels
-summer vs winter blends
-delivered through a high-pressure delivery system
-under cold and hot conditions

I'm curious about vaporization and cavitation characteristics under those conditions.

 

Good to know my fellow Upstate New Yorker.

 

Or, just run multiple regression afterwards. Or...could run a principle components analysis followed by an independent component analysis to identify the unique variable.

Just saying. Then, the results are so muddled, you can tell the reader whatever the hell you want because they are so confused.

 

I vaguely recall someone logging ignition timing on the stock tune with 93 vs 87 and there was actually a modest, but consistent, difference in peak advance at some throttle openings and rev ranges. I don't remember the details ... makes me want to run some data-centric experiments of my own, since I've also noticed a (subjective) difference between the two.

 

Wide. Open. Throttle. If you continually run the higher octane, you will see a few more HP at WOT. True statement.

 

Engineering Explained is a bit of a twat and can we for the LOVE OF GOD screw off with all the octane 'rumor' nonsense , if you don't know what octane ratings are / mean at this point in life you probably never will

 

Octane is Latin for partial horse power.

So if you have 87 Octaines that = 1 Horse Power per gallon.

Tacoma 21 gallons x 87 octanes= 1827 total Octanes.
So 1827 / 6 cylinders = 304 hp.

Tacoma 21 gallons X 91 octanes =1911 total Octanes.
So 1911 / 6 cylinders = 318 hp.

Thus. 91 octanes = 14 more hp than 87 octane.


Basic GED math.

 

Higher octane fuels burn slower than lower octane fuels. They cost more because they are refined more...a claim of increased horsepower and fuel mileage is more mental than factual on a computer controlled vehicle. Octane is a measurement of the efficiency of fuel blend expressed as a ratio relative to the efficiency of pure hydrocarbon.