4-Bangers and octane

I go by real world results and if you read every word of what I initially wrote you will see that I stated in bold that if the engine is tuned to run high octane it will undoubtably run better and make better trial run times using high octane. You are also mistaken High octane grades most definately do contain cleaning agents that are not added in 87 grade gas.
Oh and I am not impressed with all the scientific theory BS.

 

I guess you never had a vehicle dyno tuned and different maps programed into ecu. Never the less since you know beyond any reasonable doubt that High Octane Gas is nothing more than a conspiracy by the folks at OPEC to bewilder everyone into spending more money I will send out an urgent notification to nascar and all the affiliate racing organizations to use only 87 grade octane fuel. Thanks for all the knowlege you have imparted on us.

 

Im illiterate. Very funny. Go spread the word that 93 octane is inferior to 87 octane. They have special institutions for people like you.

 

i put 91 in when i leaving town. I live in colorado and in town is a 6700 feet. When i go over the pass to leave town i do use higher octane since i go over 10,000+ feet. The truck seams to climb better, but she still struggles

 

The whole point is, an engine's octane requirement depends on the compression ratio. For engines with standard compression ratios, or what can be considered a "normal" compression ratio (such as the 2.7 4-cyl in our trucks), 87 octane works best because higher octane fuel will provide no additional power and you are not wasting money on excess and unnecessary octane. Yes high-octane grades may have more cleaning additives and detergents which can be considered a benefit, but these additives are not fuel, so the energy content is ultimately *slightly* lower for high-octane fuels. Using high octane in a normal compression ratio engine is a waste of money and in this sense, YES 93 octane is inferior to 87 octane, but only in this context. High-performance and forced induction engines have higher compression ratios so higher octane fuel is required to avoid detonation and engine damage. These engines are highly tuned and are designed to run specifically on high-octane gasoline, and will produce considerably more power per liter than our standard mills. Nobody ever suggested -- even once -- that NASCAR should run 87 octane. Those are racing engines, right? Right!

If you need to clean your fuel system or combustion chambers, there are products and other ways to do that besides buying excess octane, but people do what they want... so I'm not sure why I even wasted my breath but hopefully this will help someone.

 

compression ratio dictates the minimum octane rating For those that are not familiar. octane rating directly related to the point at which the gas that is compressed in the cylinder detonates before spark- which in turn will cause a knock. If you have a compression ratio that can handle 87 octane thats fine although using a higher octane will give you a little better gas milage (1-1.5) and will give you a little better performance. Your engine will also develop fewer deposits. this is real life facts. The toyota 2.7ltr engine on 2005+ is 9.6:1
Here is a simple chart:
Compression Octane Number Brake Thermal Efficiency
Ratio Requirement ( Full Throttle )
5:1 72 -
6:1 81 25 %
7:1 87 28 %
8:1 92 30 %
9:1 96 32 %
10:1 100 33 %
11:1 104 34 %
12:1 108 35 %
Even the manual states 87 octane or higher.

Bottom line 93 or 91 octane will always be better than 87

 

Not for the 2.7

 

really, ok then what is the compression ratio for 2011 2.7ltr engine

 

lets split the diff. and use 89

 

so the 159 hp is from 87 or 93?

 

not a clue call toyota and ask them.

 

OMG blah blah blah. I wonder my scagg lawn mower will make more horsepower if I use goat piss instead of 87 octaine. Go ahead and keep using 87 octaine if you're happy with its performance.

 

The 2.7L does not have a fuel map for 93 octane, only for the 87. So unless you retune the ECU your not gaining any benefits from 93 because it does nothing for timing or anything because your stuck sitting in a fuel map for 87 octane.

 

exactly for significantly more power you have to get your vehicle propery tuned as I mentioned in my earlier post. Although If you run 93 octaine your engine over time will run a lot cleaner with less deposits, this is because there are a lot more cleaners added to 93 octane compared to 87 octaine. I also stated this in an earlier post. My truck which I always run 93 in performs great. At this point if I attempt to run 87 octaine I feel the difference.

 

Lets not forget that the owners manual recomends 87 octaine or higher which would indicate to me that possibly there is a map for this or a learning curve with the ecu although I am not sure about this.

 

High octane is for turbo VWs. Glad my truck runs fine on 87

 

very last page (548) of my 2011 manual
"Unleaded gasoline, Octaine Rating 87 (Reasearch Octane Number 91) or higher"

 

I guess its an individual thing from owner to owner and truck to truck. Possibly my truck runs better on it because I have headers and aftermarket exhaust along with the afe pro dry.

 

trying to find someone close that can tune it. Had my 350z tuned in NJ - huge difference.

 

87 and 93 have the same cleaners....dude its alllllll
placebo

You only need 93 if your engine is knocking or pining. IF that is the case you need a tune up.....