Premium Gas

[fu_im_from_texas]

Originally Posted by jdium

... I think the Toyota engineers are smarter than us.

...toyota has spent 100s of 1000s of dollars looking at these issues. toyota says use 87 ... end of argument...

[WRBlue]

Originally Posted by forpinks

Also the 106HP (not high performance? I know.) is achieved using high grade high octane gasoline for testing (Since Japan don't have anything lower than 93 octane they even have 120-125 octane) the engine power will drop to 100flywheel HP when you use 87 gas and it will make more gunk to the engine because of the slight combustion difference even with the knock sensors, remember the 1NZ-FE is japan made and tested so It should run 90+octane and will get 51MPG elsewhere except US (may be possible with acetone) which don't have anything higher than 93 basic fuel 100 octane cost like 4.30 vs 3.30 91...

The rest of the world measures octane different than us in North America. In the EU and Australia, they advertise RON. Here we use an average of RON and MON. MON is a lower number than RON. YOU CAN'T COMPARE OCTANE RATINGS BETWEEN NORTH AMERICA AND THE REST OF THE WORLD.

The ignorance in this thread makes my head hurt.

Octane only measures the autoignition characteristics of gasoline. How easily it will explode without a spark.

THE ONLY THING THAT WILL CAUSE MPG TO INCREASE ARE O2 READINGS.

If the O2 sensor reads the car running rich, it'll lean it out within safe parameters. Lean = less fuel used = higher MPG.

HIGHER OCTANE DOES NOT CHANGE THE AIR-FUEL MIXTURE.

Higher octane gasoline can only prevent detonation. If your detonating with 87 octane, something is wrong with your engine/ECU.

A car runs a base timing and advances or retards it only within set parameters. And those parameters are ones set by Toyota Engineers as to be safe with low octane gasoline. The computer will not exceed those if you put high octane gas in and magically the computer knows.

Besides, there is no sensor that can tell what octane is used. To measure octane, you have to find out the percentage of volume is iso-octane and the percentage of volume is heptane. NO production car has the ability to do that...

And anyway, advancing timing does not cause less fuel to be used. It cause more power to be made from the fuel.

Everything else in this thread is anecdotal evidence. There are many, many, many variables. Elevation, wind, drag, tires, air pressure, surface type, load, weight, etc. The most important thing is repeatability. If you REALLY want to prove higher mileage, rent a couple weeks of dyno time in a lab. Control all the environmental variables to be constant for the whole week (temp, humidity, air flow, tire pressures). Empty the car 100% of all gasoline. put a predetermined mass of fuel in the car of a certain octane. Run about 40 tests and take the mean. IIRC 40 is the number where statistically each incremental test after that does not statistically significantly change the mean. Now change the octane and repeat all 40 tests.

Then and only then you can make assumptions if octane can change MPG.

[fu_im_from_texas]

Originally Posted by WRBlue

The ignorance in this thread makes my head hurt.

...a keyboard and a strong opinion make me an expert on this topic ;)

Originally Posted by WRBlue

Everything else in this thread is anecdotal evidence. There are many, many, many variables. Elevation, wind, drag, tires, air pressure, surface type, load, weight, etc. The most important thing is repeatability. If you REALLY want to prove higher mileage, rent a couple weeks of dyno time in a lab. Control all the environmental variables to be constant for the whole week (temp, humidity, air flow, tire pressures). Empty the car 100% of all gasoline. put a predetermined mass of fuel in the car of a certain octane. Run about 40 tests and take the mean. IIRC 40 is the number where statistically each incremental test after that does not statistically significantly change the mean. Now change the octane and repeat all 40 tests.

Then and only then you can make assumptions if octane can change MPG.

great idea for a test...but even if someone does perform a scientific experiment i, for one, am not willing to let the statistical facts get in the way of my own strong opinion (sarcasm intended!)

Originally Posted by fu_im_from_texas

...toyota has spent 100s of 1000s of dollars looking at these issues. toyota says use 87 ... end of argument...

toyota has already performed these experiments....toyota recomends 87...

[Black Yaris]

Originally Posted by WRBlue

The rest of the world measures octane different than us in North America. In the EU and Australia, they advertise RON. Here we use an average of RON and MON. MON is a lower number than RON. YOU CAN'T COMPARE OCTANE RATINGS BETWEEN NORTH AMERICA AND THE REST OF THE WORLD.

The ignorance in this thread makes my head hurt.

Octane only measures the autoignition characteristics of gasoline. How easily it will explode without a spark.

THE ONLY THING THAT WILL CAUSE MPG TO INCREASE ARE O2 READINGS.

If the O2 sensor reads the car running rich, it'll lean it out within safe parameters. Lean = less fuel used = higher MPG.

HIGHER OCTANE DOES NOT CHANGE THE AIR-FUEL MIXTURE.

Higher octane gasoline can only prevent detonation. If your detonating with 87 octane, something is wrong with your engine/ECU.

A car runs a base timing and advances or retards it only within set parameters. And those parameters are ones set by Toyota Engineers as to be safe with low octane gasoline. The computer will not exceed those if you put high octane gas in and magically the computer knows.

Besides, there is no sensor that can tell what octane is used. To measure octane, you have to find out the percentage of volume is iso-octane and the percentage of volume is heptane. NO production car has the ability to do that...

And anyway, advancing timing does not cause less fuel to be used. It cause more power to be made from the fuel.

Everything else in this thread is anecdotal evidence. There are many, many, many variables. Elevation, wind, drag, tires, air pressure, surface type, load, weight, etc. The most important thing is repeatability. If you REALLY want to prove higher mileage, rent a couple weeks of dyno time in a lab. Control all the environmental variables to be constant for the whole week (temp, humidity, air flow, tire pressures). Empty the car 100% of all gasoline. put a predetermined mass of fuel in the car of a certain octane. Run about 40 tests and take the mean. IIRC 40 is the number where statistically each incremental test after that does not statistically significantly change the mean. Now change the octane and repeat all 40 tests.

Then and only then you can make assumptions if octane can change MPG.

so the higher octane combined with vvt-i will not change fuel econ?
I ALWAYS get better mpg with premium fuel than 87... the only peple that deny the fact are the ones that have not tried it

[WRBlue]

Originally Posted by Black Yaris

so the higher octane combined with vvt-i will not change fuel econ?

Yes. Why would it?

[cleong]

Originally Posted by WRBlue

Yes. Why would it?

Wouldn't a higher octane allow the engine to increase its timing and make more power, which means that less fuel is needed to maintain a given speed?

[forpinks]

I used 87 on a 3.8 Chrysler rental van (1000miles ODO) with 6 passengers and an icebox and I have to absolutely floor it to go 75MPH uphill at I-15... when we went back (got mad with the slow climbing speed) and bought damn 91 eventhough it's a rental and I did'nt regret it since I can climb a hill at 85-100MPH (still floored) running with an IS with a radar detector.

All I can say is I am definitely satisfied of the 91octane gas even if I pay the high price!

[forpinks]

^^^ Go to Toyota Canada.... it clearly states that it gets 41MPG city and 51MPG highway they measure fuel economy in metric using L/100KM and they don't use KPG, also they have high octane gas to give you better fuel economy...

Don't be a cheapo and face the truth that higher octane gasoline performs better!

(Why does the US form 87 octane anyway? are they the only ones and want to be unique?) I even tried octane 125 at the airport for my AE92 and it definitely cleansed the engine and gave better power and response I drove it like I stole the damn thing.... (one thing I noticed is that the cold engine start white smoke disapeared when I used a tank of 125octane)

I'm gonna try half a tank of octane 100 for the tC and see if it does something nice.

[njyaris]

87 is for lawnmowers .. you decide!

[churp]

You must have a different owners manual, mine states:

SELECT OCTANE RATING 87 (RESEARCH OCTANE NUMBER 91) OR HIGHER.

This is page 178 in my owners manual. Obviously they know what a few of us are trying to pass on here!!!!!!!!!!!!!!!

The tests have been done before higher octane was ever put on the market (probably the 30's). The ECU has taken the "must have" higher octane in your car away....but it hasn't removed the fact that performance and milage will improve in most engines with it. Note that I am not saying it is cheaper to put the higher octane in....but where I live it's very feasable (Iowa and South Dakota 89 octane is the same price or cheaper than 87, and in Minnesota I get 89 for 2 cents more than 87) and I use 89 octane.

[jdium]

Originally Posted by churp

The tests have been done before higher octane was ever put on the market (probably the 30's).

lol. Ya. Back when everything ran on leaded gas...

my head hurts...

[churp]

Originally Posted by jdium

lol. Ya. Back when everything ran on leaded gas...

my head hurts...

Don't quite understand Cars ran on unleaded in the US until 1970. I'm pretty sure sex was even invented by then!

No, I'm actually positive first hand, sex was invented before 1970.

[jdium]

Originally Posted by churp

Don't quite understand Cars ran on unleaded in the US until 1970. I'm pretty sure sex was even invented by then!

No, I'm actually positive first hand, sex was invented before 1970.

Which brings me to my other point, don't smoke crack...

Most every gas was LEADED (no UN) before 1970. Leaded gas has a realative octane rating of todays "race' gas, like 110 or something...

[churp]

Originally Posted by jdium

Which brings me to my other point, don't smoke crack...

Most every gas was LEADED (no UN) before 1970. Leaded gas has a realative octane rating of todays "race' gas, like 110 or something...

Wrong, read WRBlues post.

Thanks WRBlue for correcting me....1970 was when the compression ratio dropped in the US....along with performance.

[Yarii]

They're not telling you to run higher octane... They're just putting the RON in brackets because the entire world except north america uses RON to measure octane. In NA our pumps are labled with the average of the RON and MON measurements, which is generally 4 or 5 points lower. 87 octane gasoline in north american is 91 RON.

Originally Posted by churp

You must have a different owners manual, mine states:

SELECT OCTANE RATING 87 (RESEARCH OCTANE NUMBER 91) OR HIGHER.

This is page 178 in my owners manual. Obviously they know what a few of us are trying to pass on here!!!!!!!!!!!!!!!

The tests have been done before higher octane was ever put on the market (probably the 30's). The ECU has taken the "must have" higher octane in your car away....but it hasn't removed the fact that performance and milage will improve in most engines with it. Note that I am not saying it is cheaper to put the higher octane in....but where I live it's very feasable (Iowa and South Dakota 89 octane is the same price or cheaper than 87, and in Minnesota I get 89 for 2 cents more than 87) and I use 89 octane.

[blacksan]

Ok, I got it now.

[WRBlue]

Unleaded gas didn't become common till the mid 80s. I remember when you had to hunt for the unleaded.

Leaded gas of the 70s was still 87 octane. Its just Lead is a knock detterant and so its a whole lot cheaper to make 87 octane with lead in it ;) . I'm not sure if the reason all the good race gas is leaded is cause its too expensive to make 110-120 octane without lead or if its actually impossible. You can get unleaded race gas up to about 100 or 102 octane...

[cali yaris]

{ OFF TOPIC }
As far as I know, sex was invented in 1976.

Uh... what was the topic about again?

(scrolling back to page one)