Gas Octane

I think the debate here stems from the fact that Toyotas manual used recommend minimum of 87 octane, or 91 for increased performance. In this case, it has nothing to do with compression ratio, but ignition timing. Its possible the software was programed with more ignition advance to take advantage of 91 octane, with a "backup 87 octane" ignition map which it used when/if pinging or knock was detected. The new ford EcoBoost engines do the same. As a manufacture, it allows you to advertise great power/torque numbers, but still allow for the use of regular fuel. I have no idea if Toyota changed just the wording in the manual, or if they changed the tune as well. FWIW, the difference in mileage when using premium vs. regular could be attributed only to the fact that most regular (87) fuel is blended with ethanol and most top tier brands premium (91) is not. Being the ethanol blended fuel is less energy dense, you'll naturally get more mileage out of the premium.

 

You need to either go back to school or go back to the school you just graduated from with that 4.0 and get your money back because you obviously don't know the difference between Detonation and Pre-Ignition.

Detonation always happens AFTER normal combustion. Pre-Ignition, just like its name, happens BEFORE the spark plug fires.

Also, a Dynamometer uses a "Correction Factor" to adjust to a standard temperature.

 

Here is an article on Detonation verses Pre-Ignition;
http://www.contactmagazine.com/Issue54/EngineBasics.html

 

87 when not towing/ around town...93 for towing and highways runs

 

yes I know the difference. pre ignition melts parts detonation blows parts into pieces I know detonation happens after combustion I was trying to bring it down to lamence terms for the less mechanically inclined. I prolly used the wrong terms then I should have but no matter what terms you use the result is the same a higher compression engine can ignite with out a spark because it seperates the H from C in HC (hydrocarbon-also know as gas) with the compression. higher octane gas prevents this by making the H and C chemical bond stronger to where it requires a spark to combust. there it is in non lamence terms

 

and what you are talking about is calculated horsepower. it is what the horsepower could be in perfect conditions but no one usually even looks at this numbe unless you are trying to sell an engine to someone across the country where there weather conditions are wrong.
I do know we can dyno a nascar engine at 60 degrees F and get 900 hp (round numbers) and come back the next day at 50 degrees F and have 910 hp
moral of the story no correction factor

 

layman's terms

 

Lamence

NASCAR tech don't English.

 

all has ethanol in town. When you get out of town you can find 87 without but higher has ethanol. Ethanol is used to increase the octane. It sucks because I like to run non-ethanol in boat but it takes 93. Some of the diffs that people see in MPGs could be dur to ethanol content

 

you trying go blow that thing up? As far as the ethanol sticker placement on the pump it just happens to be near the 87 nozzle because that is where they put it. Since I own an older outboard running high compression I have done a lot of reading on ethanol and the impact on outboard motors. A lot of people around here who are serious about their boats use ethanol test kits. I can tell you most all premium has ethanol even at stations that sell ethanol free regular. Mid grade is a blend of the 2 at the pump.

 

Lol so I can't spell "laymans"
And yes NASCAR don't "teach" English

 

NASCAR == Redneck

 

LMAO!!! That has to be one of the best excuses yet.

Yeah, I always give incorrect information and contradict myself when I'm trying to make it easier for others to understand and I ALWAYS tell everyone how smart I am while I'm doing it. Mmhmm, sure you really knew the difference. Still LMAO!!!

 

Agree with Brunes, I'll through a tank of the 91/93 for road trips or what not.

 

Minimum 91 octane is what's recommended by Toyota in my manual... I trust Toyota over a bunch of yahoo's and I own mine so I want it to last

 

I'm willing to bet money your manual does NOT say that, go back a page and look at my post. Research octane rating and octane rating aren't the same, yours has a recommended octane rating of 87. Nobody yet has answered my question about why the recommended octane changed after 06, but since 07 it looks like toyota has been saying you only need 87.

 

Maybe Toyota stopped getting money under the table from the big oil companies.

 

Mine says 87 and up

Not 87

 

In my area 93 octane costs roughly 10% more than 87 octane. I can't precisely replicate driving conditions for each tank full, but I am relatively sure that I get 10% more miles per gallon out of the 93 (only 1.6 - 2.3 more mpg=10%) therefore I am convinced that fuel cost is at worst the same, but there may be some benefit in fuel detergents, additives, etc. So for me I can rationalize buying the higher octane stuff.

 

An engine that was designed to run on a lower octane fuel can actually suffer with higher octane. The higher octane RETARDS the ignition to keep auto combustion from happening in high compression engines. 91 octane burns SLOWER than 87 octane.