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

[Threxx]

Like maybe actual dynograph numbers? Or maybe tech specs from Toyota that shows how much the spark timing is typically retarded by the knock sensor when using regular (if it does at all?)

Acceleration number comparisons would only be useful if it was the same vehicle on the same day, same temperature and humiduty, on the same track with roughly the same amount of fuel in the tank. But it's probably more likely that somebody has dyno numbers or spark timing specs than that....

[j4x4ar3]

The only "loss" would be if your engine was knocking with regular fuel as the knock sensor would limit throttle to decrease knocking. In terms of "power" there is no diffence in fuel between regular and premium. Premium burns a little cleaner as it's refined more but really the only difference is in the additives which increase the octane. Additives are put in to inhibit knock by changing the burn characteristics of the fuel to prevent premature ignition. Premature ignition = knock.

Toyota recomend Premium fuel for "optimum performance" because under heavy acceleration, heavy towing, heavy payload, hard core offroading regular fuel will tend to knock a lot (I've experienced this with my trailer) and will decrease performance and acceleration. Premium fuel as stated will prevent the knock and keep acceleration at it's peak.

[Splicer]

Yes, but.... in simplest terms, the increased octane of premium fuel allows the timing to advance further before detonation (spark knock) occurs. Increased ignition timing = more power.

Sorry, Threxx, I am not aware of any dyno readings.

[lelandstanford]

A reasonable estimate on 4.0L (1GR-FE) can be made by comparing 2GR-FE in car applications.

ES350: 272/254 (premium)
Avalon: 268/248 (regular)

Tacoma: 236/266 (premium)

[Darnefnet]

9 HP at 5200 rpm

[point45]

Originally Posted by j4x4ar3

The only "loss" would be if your engine was knocking with regular fuel as the knock sensor would limit throttle to decrease knocking. In terms of "power" there is no diffence in fuel between regular and premium. Premium burns a little cleaner as it's refined more but really the only difference is in the additives which increase the octane. Additives are put in to inhibit knock by changing the burn characteristics of the fuel to prevent premature ignition. Premature ignition = knock.

The ecu in the tacoma limits det by pulling the timing, and higher octane does have additives to increase octane but most of the octane rating comes from the ratios of isooctane and heptane, I think up to about 90 before they add stuff. Higher octane rated gasoline does not burn cleaner or better and is not distilled or refined longer or to a higher standard.

Actally using a higher rated octane than you need can mess with your emsissions system as as it will burn slower and the unburnt fuel will go into the cats.

[j4x4ar3]

Originally Posted by point45

The ecu in the tacoma limits det by pulling the timing, and higher octane does have additives to increase octane but most of the octane rating comes from the ratios of isooctane and heptane, I think up to about 90 before they add stuff. Higher octane rated gasoline does not burn cleaner or better and is not distilled or refined longer or to a higher standard.

Actally using a higher rated octane than you need can mess with your emsissions system as as it will burn slower and the unburnt fuel will go into the cats.

The point about burning cleaner can be debated as different manufactures do different things to their fuel when it comes to premium. Some manufactures add additional detergents to their fuel only in their premium lines while other manufactures will add the detergents in all lines of fuel.

As well Premium does not burn "slower".. in premium fuels the flash point of the fuel is changed to prevent premature ignition. Once ignited though it burns at the same rate and burns completely if your engine is running correctly. It has nothing to do with emissions.

Quoted from online articles about Premium Fuel:

The main advantage of premium-grade gas is that it allows automakers to advertise a few more horsepower by designing and tuning engines to take advantage of premium's anti-knock properties. But auto engineers generally agree that if you use regular in a premium engine, the power loss is so slight, most drivers can't tell.

- USA Today

Import brands, especially, use premium fuel to distinguish their upmarket models. Most Toyotas, for instance, are designed to run on regular or midgrade, while the automaker's Lexus luxury brand prefers premium. Same with Honda and its Acura luxury line.

- USA Today

Automakers say they don't test premium engines on regular to check the difference, but some auto engineers estimate that power declines roughly 5%.
"We can't guarantee the vehicle will perform as specified if other than premium fuel is used," says Mercedes-Benz spokeswoman Michelle Murad. All U.S. Mercedes engines specify premium.

- USA Today

Premium, in fact, sometimes is worse fuel than regular. It resists knock because it's harder to ignite than lower-octane fuels. As a result, some engines won't start as quickly or run as smoothly on premium, notes Gibbs, the SAE fuel expert.
High-test does have a potential fuel economy benefit. It is slightly denser than lower-octane gas, meaning there's a little more energy in a gallon. But the small difference is hard to measure in real-world use, and that same density can contribute to undesirable buildup of waste products inside the engine.
No data show that engines designed strictly for regular run better or longer on premium.

- USA Today -- FYI this is the reason why additional detergents are normally placed in premium fuels. The detergents keep the deposits from forming. Some refiners and noted the benefits of the detergents and now offer them in all lines of their fuels. (Chevron is one with Techron and now Shell with V-Power)

[justinh]

I live at a low elevation (N. Metro Atlanta) and have always run Regular gas and have never experienced detonation even when traveling to higher elevations or towing my large boat. Your engine is most efficient when you are running the lowest octane you can without detonation.

[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.

[point45]

Originally Posted by j4x4ar3

The point about burning cleaner can be debated as different manufactures do different things to their fuel when it comes to premium. Some manufactures add additional detergents to their fuel only in their premium lines while other manufactures will add the detergents in all lines of fuel.

As well Premium does not burn "slower".. in premium fuels the flash point of the fuel is changed to prevent premature ignition. Once ignited though it burns at the same rate and burns completely if your engine is running correctly. It has nothing to do with emissions.

Ill have to look through the text books again but im pretty sure that higher octane fuels do burn slower, hence the increased deposits for engines not designed to take advantage of them and when engines not tuned for the higher octane can loose power. But it may not be directly related to the flash point.

Also federal law regulates the additvies in gasoline so they should all burn pretty clean and anything extra is just that. The extra detergents added to premium are to off set the extra carbon build up that can occur. Though your right and this differs from every supplier but theres only a handfull of sources in the US.

I do know in CA its pretty much the same in all fuels but thats due to this states regulations.

In the tacoma I would not worry about using any grade of gasoline except for the power variation. If the timing is adjusted correctly (im trusting the engineers at toyota here) then build up inside the chamber should be minimal.

[point45]

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.

I will.

[justinh]

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.

Admittedly it has been a long time since I looked at my owner's manual, but I don't remember it saying anywhere that you had to run 89 or 93.

[dickinsonj]

Originally Posted by justinh

Admittedly it has been a long time since I looked at my owner's manual, but I don't remember it saying anywhere that you had to run 89 or 93.

It only says that "for best performance" us 93 - if an engine is going to be damaged by using regular the manufactuor always says that it is required and that nothing else should ever be used. I seriously doubt that I am destroying my engine running on regular, but it should be a good test case since I have never pur anything else in it.

[lelandstanford]

Originally Posted by dickinsonj

It only says that "for best performance" us 93 - if an engine is going to be damaged by using regular the manufactuor always says that it is required and that nothing else should ever be used. I seriously doubt that I am destroying my engine running on regular...

Agree.

No manufacturer will expose itself legally or mechanically by saying "for best performance" which implied 87 is "acceptable"..

[armyoffoo]

The Tacoma specifications acrobat file I downloaded from Toyota's website says the 2.7L recommended fuel is 87, and the 4.0L recommended fuel is 91 octane.