Premium Gas

[forpinks]

Go buy a "Maximum Boost" book and it will tell you that a higher octane gas will give you more power compared to lower octane gas.

there is a comparison on the N/A and Turbo there really is a big difference especially if your running RPMs higher than 4500 on N/A... The turbo with high octane gas is damn more powerful than low octane.

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...

(It's new here in the USA and Toyota USA wouldn't put the 91 reccomended fuel since it will hurt sales...)

Hope this helps!!!

[jdium]

Originally Posted by forpinks

Go buy a "Maximum Boost" book and it will tell you that a higher octane gas will give you more power compared to lower octane gas.

there is a comparison on the N/A and Turbo there really is a big difference especially if your running RPMs higher than 4500 on N/A... The turbo with high octane gas is damn more powerful than low octane.

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...

(It's new here in the USA and Toyota USA wouldn't put the 91 reccomended fuel since it will hurt sales...)

Hope this helps!!!

Ignorance is bliss eh? Higher octane will NOT give you more power in a Yaris. Go buy some dyno time if you can't believe me. It will NOT give you higher mpg either. Put the car on jack stands, and idle a tank away of each if you can't believe me either.

On a turbo car, higher octane allows more boost, thus higher hp.

Knock sensors have nothing to do with engine "gunk" buildup.

If it was possible for the Yaris to get 51 mpg in the U.S., it would. Why would Toyota not want a car that destroys every other car in its class? Try 51 kpg maybe.

The Yaris is sold in America. I think the Toyota engineers are smarter than us.

[churp]

Originally Posted by jdium

Ignorance is bliss eh? ......
On a turbo car, higher octane allows more boost, thus higher hp.

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

I'm sure the Toyota engineers aren't any dumber than us. That is why they say the Yaris run's with 87 octane, and that is why cars have had ECU's installed for the last few decades....don't you believe there is a reason...it's not because they cost a lot. They allow the timing to be retarded in a load situation to prevent knocking with the high compression engines (above 9 to 1 compression) in a load situation like maintaining 60-70 mph up a steep hill while using 87 octane.....this is not the optimum timing for power or gas milage but it keeps the engine from self destructing.

My 53 Buick I used to have, had no timing marks. The shop manual said to said to set timing by turning the distributer until it ran good, then test drive by accelerating or going up a hill. If there was a knock go back and retard the timing,then repeat until only a very faint knock was heard. This is fine and dandy until you got a batch of poor gas, then it would knock like crazy. You could increase milage by advancing timing (set according to the gas you used) and driving consertively. ECU's have changed this to the better, but 'good' gas does work.

During slow acceleration or maintaining speed on flat land the ECU allows the optimum timing because knock isn't present (even with 87 octane).....most hypers drive in this condition 99.9% of the time while the common everyday driver is in this condition 95% (guesstimate at maximum). So theoreticaly, scientifically, or any other way you think about it....the very concientious driver sees no gain from higher octane, the common driver may see better milage on a small fraction of their driving, and the leadfoot would see the best gains. Granted this is a small percentage gain over a very small percentage of a persons driving....but it is a gain.

[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?

[Yarii]

Engine's don't detect the octane of fuel... They just retard the timing if they detect knocking. Without doing some ECU tuning, the timing will always be set to or below (if knocking is present) whatever toyota engineers pre-programmed it to be based on engine and air conditions.

Premium might help keep the timing from retarding under high engine load like heavy acceleration or towing/hill climbing when knocking might occur, but for most daily driving, the engine will use the same timing settings it uses on regular gas.

Originally Posted by cleong

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?