Anyone know how much power is lost when using regular fuel vs premium in the 4.0 V6?

[rgilingham1]

My 07 4.0 manual says use 87 or higher and that detergent additives are recommended.

[TacoGuy]

Originally Posted by briq4

I'm new to the forum and looking to purchase a Tacoma 4x4 Access cab with the v-6 and manual 6-speed. The fuel "requirement" is confusing to me, nowhere on Toyota's site does it say what is required, When going to fueleconomy.gov they say that all the tacoma models use regular.

yet on here, several people say it requires premium. Does anyone actually have the manual and can say definitly what it says for the 07 Tacoma with the v-6?

Thanks in advance.

I have the owners manual for my '07 Taco V-6 4X4 in front of me as I speak. On the outside back cover of the manual, it recomends 87 Octane or higher. To me that means use whatever you want.

Some mountain states, Wyoming comes to mind, "regular" may be less than 87 Octane. The fuel available in this case has to do with the prevailing "Altitude" above sea level of the area. TacoGuy

[bob1044]

I have the scan guage II installed in my 07 CC TRD. Reading the ignition advance display is enlightening. At 70 MPH level road with regular 88 octane timing is in the 13-16 degree range. Under identical conditions with premium, which is 91 octane in the area, it is 25-28 degree advance. There also seems to be an accompanying 2-3 mpg improvement using premium. One of the stations here uses E10 as their premium fuel, that tank resulted in ignition advance in the 10-13 degree range with a avg MPG of 12.5, about 3 less than I've normally seen. So it appears to me that the knock sensors do have a significant effect on performance. The 2-3 mpg difference I'm seeing between regular and premium are worth the 5 cents defference in price. Just wish the thing would get better mileage overall. Average 15-16 in small town rural diving and never seen over 19 on highway. Traded off a 5.3 chevy on the Taco that did the same and consistantly over 20 on the highway, on regular fuel.

[ASE_Master-Tech]

Yes, no power is lost (none at all). Using anything above the recommended fuel rating is foolish as no benefit is gained. (see below)
_________________________________________________

"The octane rating is a measure of the autoignition resistance of gasoline (petrol) and other fuels used in spark-ignitioninternal combustion engines. It is a measure of anti-detonation of a gasoline or fuel.
Octane number is the number which gives the percentage, by volume, of iso-octane in a mixture of iso-octane and normal heptane, that would have the same anti-knocking capacity as the fuel which is under consideration.
Octane is measured relative to a mixture of iso-octane (2,2,4-trimethylpentane, an isomer of octane) and n-heptane. An 87-octane gasoline, for example, has the same octane rating as a mixture of 87 vol-% isooctane and 13 vol-% n-heptane. This does not mean, however, that the gasoline actually should contain these chemicals in these proportions. It simply means that it has the same autoignition resistance as the described mixture.
A high tendency to autoignite, or low octane rating, is undesirable in a gasoline engine but desirable in a diesel engine. The standard for the combustion quality of diesel fuel is the cetane number. A diesel fuel with a high cetane number has a high tendency to autoignite, as is preferred.
Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause knocking. (Note that it is the absolute pressure (compression) in the combustion chamber which is important - not the compression ratio. The compression ratio only governs the maximum compression that can be achieved).
Octane rating has no direct impact on the deflagration (burn) of the air/fuel mixture in the combustion chamber. Other properties of gasoline and engine design account for the manner at which deflagration takes place. In other words, the flame speed of a normally iginted mixture is not directly connected to octane rating. Deflagration is the type of combustion that constitues the normal burn. Detonation is a different type of combustion and this is to be avoided in spark ignited gasoline engines. Octane rating is a measure of detonation resistance, not deflagration characteristics.
It might seem odd that fuels with higher octane ratings explode less easily, yet are popularly thought of as more powerful. The misunderstanding is caused by confusing the ability of the fuel to resist compression detonation as opposed to the ability of the fuel to burn (combustion). However, premium grades of petrol often contain more energy per litre due to the composition of the fuel as well as increased octane.
A simple explanation is that carbon-carbon bonds contain more energy than carbon-hydrogen bonds. Hence a fuel with a greater number of carbon bonds will carry more energy regardless of the octane rating. A premium motor fuel will often be formulated to have both higher octane as well as more energy. A counter example to this rule is that ethanol blend fuels have a higher octane rating, but carry a lower energy content on a volume basis (per litre or per gallon). The reason for this is that ethanol is a partially oxidized hydrocarbon which can be seen by noting the presence of oxygen in the chemical formula: C2H5OH. Note the substitution of the OH hydroxyl radical for a H hydrogen which transforms the gas ethane (C2H6) into ethanol. Note that to a certain extent a fuel with a higher carbon ratio will be more dense than a fuel with a lower carbon ratio. Thus it is possible to formulate high octane fuels that carry less energy per liter than lower octane fuels. This is certainly true of ethanol blend fuels (gasohol), however fuels with no ethanol and indeed no oxygen are also possible.
In the case of alcohol fuels, like Methanol and Ethanol, since they are partially oxidized fuels they need to be run at much richer mixtures than gasoline. As a consequence the total amount of fuel burned per cycle counter balances the lower energy per unit volume, and the net energy released per cycle is higher. If gasoline is run at its preferred max power air fuel mixture of 12.5:1, it will release approximately 19,000 BTU (about 20 MJ) of energy, where ethanol run at its preferred max power mixture of 6.5:1 will liberate approximately 24,400 BTU (25.7 MJ), and Methanol at a 4.5:1 AFR liberates about 27,650 BTU To account for these differences, a measure called the fuel's specific energy is sometimes used. It is defined as the energy released per air fuel ratio.

The power output of an engine depends on many different aspects, only one of which is the energy content of its fuel, and this bears no simple relationship to the octane rating. A common myth is that adding a higher octane fuel to a vehicle's engine will increase its performance and/or lessen its fuel consumption; this is false—engines perform best when using fuel with the octane rating they were designed for and any increase in performance by using a fuel with a different octane rating is minimal or even imaginary."

See also;
Howstuffworks "How Gasoline Works"

Hope all this helps clear things up......

[Splicer]

Originally Posted by bob1044

The 2-3 mpg difference I'm seeing between regular and premium are worth the 5 cents defference in price.

I ran 87 for several thousand miles, then switched to 91 for about 4 thousand or so. I saw absolutely no difference in mpg, average was about 18 (I don't have the numbers in front of me right now). And 91 runs from 20 cents to 30 cents per gallon more than 87 around here, so I went back to 87.

If I got 2-3 mpg better for a difference of 5 cents per gallon, you bet your life I would do it.

[walters]

I used premium exclusively until one time I mistakenly put in mid-grade. I decided to continue to use mid-grade for while to see if I noticed any difference. My mileage dropped about 2 MPG and this was over several tankfuls compared with many previous tanks. I had been averaging 22MPG and dropped to about 20 (2005 V6 PreRunner Access Cab -- auto). When I went back to premium my MPG did not rebound. I later disconnected my battery to "reset" the control unit and noticed an immediate increase in MPG -- back to at least 22 hiway, got 23.5 on last tank -- which still continues today, about a year later. I was meticulous about my numbers and don't think this was a mirage. I'm sticking with premium.

[J4RR]

My first tank of the lot I got 17.80mpg second tank with premium I got 16.25mpg and 3rd tank 15.97 w premium again, 3rd I went with 89 octane and got 16.69mpg. I've stuck with 89 octane rather than 91 becuase I did not see any diff if anything a saw an increase in mpg. From seeing other posts I think that I wil go back to 91 oct. for a couple of tanks and see if it goes up.
I'll have to try the battery disconnect to see if that was the problem.

[steve762us]

Originally Posted by ASE_Master-Tech

Yes, no power is lost (none at all). Using anything above the recommended fuel rating is foolish as no benefit is gained.
......

<snipped: a bunch of irrelevant info on octane, but nothing on timing advance>

The concept that "No engines benefit from use of premium" is old thinking.

Some modern ecu controlled, knock-sensing engines do utilize the characteristics of premium to advance timing and generate more power, and will correspondingly retard timing when fed lower octane fuel, and will generate less power.

Bob1044 found an average of 12* timing advance, when running premium, over 87. That IS a difference in operation, due to higher octane fuel...how much of a difference in mileage and horsepower, is now the question.

Getting an extra 2-3 miles per gallon would justify the extra 20 cents for premium, IMHO.

[ASE_Master-Tech]

Originally Posted by steve762us

<snipped: a bunch of irrelevant info on octane, but nothing on timing advance>

The concept that "No engines benefit from use of premium" is old thinking.

Some modern ecu controlled, knock-sensing engines do utilize the characteristics of premium to advance timing and generate more power, and will correspondingly retard timing when fed lower octane fuel, and will generate less power.

Bob1044 found an average of 12* timing advance, when running premium, over 87. That IS a difference in operation, due to higher octane fuel...how much of a difference in mileage and horsepower, is now the question.

Getting an extra 2-3 miles per gallon would justify the extra 20 cents for premium, IMHO.

Please read my entire post & understand what "octane ratings" refer to. Higher "octane ratings" do not indicate that more energy (ie-BTU's/calories) is/are available for work in a particular fuel.
How can you get an increase in power (ie-work) if a given fuel (premium or otherwise) contains less energy?
What you imply in your post is not only mis-leading (as it lacks complete info), but by failing to consider the ramifications of advancing ignition timing excessively it defies the known laws of physics/thermodynamics - namely -The conservation of matter/energy (ie-you can't get something for nothing).

[Mike-in-WV]

Originally Posted by qk94dawg

The power difference has nothing to do with why I run premium. Its the thousands of miles I'm earning on the other end of the engines life - you CANNOT hear/feel all detonation, is that simple. They didn't reccommend it to be funny, they did it for a reason.

Have fun destroying valves and pistons you guys running 87.

Tell that to the guys who have over 300,000 miles on there engine and still running and have never run anything but 87.
They test Toyota's gas mileage with high end gas, they do not say that you have to run it in your Toyota at all. It may be different with a Lexus and so on. Mike

[Strop]

None at all. Don't use Premium unless your engine is knocking.

[elfiero]

The V6 Taco engine has a 10:1 compression ratio. This is why high grade premium fuel is required for optimal preformance and fuel mileage. When you use 87 octane fuel(like I do most of the time), the ECU will back the timing down until the anti-knock sensor is satisfied. This all happens in milliseconds and the timing can/will change more than 200 times per second depending on load and throttle position. Anyone who claims to be able to here their truck "pinging" better get it in for service 'cause there is a problem with the ECU! The whole debate about which fuel to use really doesn't make much sense because we can all run what we feel like paying for and our trucks will happily make the necessary "adjustments"

[Splicer]

Very well said, elfiero... you've nailed it. I couldn't agree more.

[flyman767]

I've experimented with both 87/89/91 octane. My experience has been that running 89 over 87 the mileage has improved 1-2 mpg(that in itself pays for the 10 cents higher cost over 87) there's also less downshifting and slightly lower cruise rpm's. I've ran different brands of gas, drove the same routes to and from and consistently found this to be the case. However, I have found absolutely no improvement between running 91+ over 89. Therefore, based on the 10 to 1 compression ratio it appears logical that a 89 octane would outperform an 87.

[Snakeii]

Originally Posted by flyman767

I've experimented with both 87/89/91 octane. My experience has been that running 89 over 87 the mileage has improved 1-2 mpg(that in itself pays for the 10 cents higher cost over 87) there's also less downshifting and slightly lower cruise rpm's. I've ran different brands of gas, drove the same routes to and from and consistently found this to be the case. However, I have found absolutely no improvement between running 91+ over 89. Therefore, based on the 10 to 1 compression ratio it appears logical that a 89 octane would outperform an 87.

I've found 89 to be a good fit for everyday driving, but for towing or heavy work Id bump it up to 91+.

Id definitely be careful running anything lower then 89 in a 10:1 engine. I dont like the idea of the engine having to detune itself in order to run 87 octane.

The supercharged 89 MR2 had a manual switch in case you had to run anything but 91+. It basically does what our engines do automatically (if/when it detects pinging/knocking) and adjusts the timing. Personally, I dont like the idea of an engine having to automatically adjust when it detects pinging, if it reaches that point you are losing power and risking damage to your engine. I used the switch in the MR2 a couple of times because the stations I had to stop at didnt have premium, and noticed a loss in power and mpg.