Octane ?

[Yarice]

Ive always been dumping 91 octane in my tank, can the yaris just use regular gas?

[Appalachian Trail 2007]

its rated for 87 octane so 91 won't give you any advantages (other than in some places it has less ethanol)

[Bob_VT]

In the cooler weather you will not see any changes except higher cost.

The yaris is designed to run fine on 87 and the on-board ECU makes sure of it.

87 is regular then 89 91 and 93 or 94...... the higher the octane rating.... the slower the gas burn. Higher octanes work in hotter weather...... during the cooler months (like now) 87 octane will be burning with cooler and more dense air.

Run 2 tanks of 87 through the car and by the 2nd tank you will not be able to tell the differance.

[Yarice]

Thanx guys, just put 9 gallons and it only cost me $21 instead $30-35 putting 91 octane.

[albee213]

I know this is a dead post but your saying reg costs $2.33 per gallon and premium costs $3.50 per gallon, thats a huge difference.

I run mid grade, car seems to run best with that.

Costs to fill up reg 10 gal @ $3.90 = $39.00

Costs to fill up mid 10 gal @ $4.00 = $40.00

Costs to fill up Prem 10 gal @ $4.10 = $41.00

Fill up once a week costs me $52 more per year to use mid or $105 for prem.

Over all savings using regular fuel. Not worth mentioning.

If it costs be $1 per gallon more I would use the reg too.

[albee213]

I read some information about the Yaris engine and I found out some interesting stuff.

The engine specs show 10.5 to 1 compression ratio which would mean it should use premium fuel to prevent early detonation.

This engine can use regular fuel do to improved technology in how the fuel is injected and the shape of the combustion chamber prevents pre-ignition of the fuel while squeezing a little bit more power out of the fuel.

After saying that I still use mid or prem due to the high compression ratio of the engine, to each their own.

[Ben_]

I experimented with this recent at the auto x. Used premium fuel as opposed to regular I usually run. I noticed quicker throttle response and the engine ran a bit smoother. Maybe it's all in my head. The more experienced users will know if premium fuel will change the timing the ecm gives

[why?]

Originally Posted by albee213

I read some information about the Yaris engine and I found out some interesting stuff.

The engine specs show 10.5 to 1 compression ratio which would mean it should use premium fuel to prevent early detonation.

This engine can use regular fuel do to improved technology in how the fuel is injected and the shape of the combustion chamber prevents pre-ignition of the fuel while squeezing a little bit more power out of the fuel.

After saying that I still use mid or prem due to the high compression ratio of the engine, to each their own.

Originally Posted by Ben_

I experimented with this recent at the auto x. Used premium fuel as opposed to regular I usually run. I noticed quicker throttle response and the engine ran a bit smoother. Maybe it's all in my head. The more experienced users will know if premium fuel will change the timing the ecm gives

Except that is bogus. The computers control the system so much more than 30 years ago. Everything is different and your ideas are just wrong. Toyota recommends 87 and it is a waste of money to run anything else on a near stock engine.

10.5 to 1 is not high compression anymore. There are gas engines that run more easily. Toyota has used this engine in this configuration for at least 20 years, probably longer. It is rock solid with the crappiest gas you can find to put into it.

Higher octane could make the engine run 'smoother' although that in no way equates to making more power or getting better throttle response, especially since the throttle is controlled by a computer.