1GR-FE Reg Unleaded vs Super Unleaded HP Gain???

From the Wiki...

The 1GR-FE is the 4.0 L...

"Output is 236 hp (176 kW) at 5200 rpm with 266 lb·ft (361 N·m) of torque at 4000 rpm on 87 octane, and 239 hp (178 kW) at 5200 rpm with 278 lb·ft (377 N·m) at 3700 rpm on 91 octane."

So the question is... is this true? Has anyone done a comparison?

 

I see better mileage with 91 on the freeway as I drive to Salt Lake City every weekend which is about 220 mi. I have not seen dyno results on this though.

 

I haven't noticed a difference from Reg to High grade. I have made notes of small gains running Mid-Grade though. All East Coast NC-PA driving.
When I offroad I tend to put High grade in because it's mostly idling and 4Hi-Lo, figure if it's true more torque would be good.

 

I bought my '12 Taco in Nov and have been running 87 in it but I think I'm going to try a tank of 91 as a test, both for milage and perceived hp gain. My driving is pretty consistent so I'll set my trip meter for both fuel types as a control then post my non-scientific results.

 

I wouldn't argue with you if you were to say it was my imagination but I swear when I use 91 octane, the pedal seems a little bit more responsive, I do generally drive alone and I don't carry around a bunch of tools or extra weight in the truck either so weight wise it's pretty much exactly as it came from the dealer.

 

Octane rating is simply the amount of energy needed to ignite the fuel, or resist pre ingiting under heat and compression. There is no more energy in higher octane gasoline.

From wiki

A common misconception is that power output or fuel efficiency can be improved by burning fuel of higher octane than that specified by the engine manufacturer. The power output of an engine depends in part on the energy density of the fuel being burnt. Fuels of different octane ratings may have similar densities, but because switching to a higher octane fuel does not add more hydrocarbon content or oxygen, the engine cannot develop more power.

 

I think it is a very minor increase in mpg's but I do notice the higher the octane the smoother my truck runs. And I also feel that the truck is also more responsive with the high octane and this is why I will not use anything less then 89 octane.

 

I just filled my DCSB with a full tank of ethanol-free 91

Butt dyno says there's a bit moar power!

 

Ethanol free is probably where that's coming from. I hate the fact that we have to use ethanol and pay full price for it. As for 87 and 91 I have noticed no difference with them, but that could be a lack of know-how on my part. I wish I could say I felt a difference but I don't.

 

Higher Octanes can deal with more aggressive timings that would cause pinging with lower octane fuels. If your ECU can tell the difference and adjust the timing (VVT) then you can make some extra power with 91. Most ECU's don't or can't tell the difference and therefore make no more power with 91 over 87 octane rated fuels. I know it's right in the old FJ manual that 91 makes more power in the 1GF-RE before the new twin VVT engine came out and I think that's where that wiki number comes from. I don't know if our Tacoma was programmed to advance the timing with 91 octane.

This is also is why some engines require 91. Either the boost or the timing is high enough that 87 would ignite to fast/unevenly for the stock tune which would producing pinging and rob power from the engine.

 

Anyone who understands octane will tell you that octane in itself does not have more horsepower locked up in it or increase the horsepower (available energy) of a particular fuel. Octane is an anti-knock compound and does not change the amount of horsepower, (energy within a particular fuel) a fuel can produce. However Octane can help an engine capture more of the horsepower in the fuel depending on the engine electronics. Different kinds of fuel can make different amounts of Horsepower but octane does not make horsepower.

For instance gasoline makes a different amount of horsepower than diesel fuel, and diesel makes a different amount of horsepower than propane, and so on, and even different gasoline's make different horsepower depending on its make up, but adding octane to any of these will not increase a fuels horsepower rating. One reason winter blends get less MPG is that they have a different blend, but the octane is the same as summer gas. Winter gas has more butane in it which has a lower horsepower (energy) rating. More octane cannot overcome the lower energy (horsepower) rating. If it could you would get the same MPG in the winter as the summer since the octane rating is the same.

It is the job of the engine to get all the possible horsepower from any given fuel. Depending on the engine, if it is not getting all the horsepower possible from a particular fuel because of engine timing, a higher octane can allow the engine to change timing and get more of the available horsepower.

So when using a higher octane it is possible for a particular engine to produce more horsepower because of advanced timing. In other words a particular engine may not be able to get all the horsepower from a particular fuel because of timing issues as well as other factors.

Today's engines are computer controlled and the computer is always searching for the best timing depending on knock. While they cannot evaluate what octane we are running they can find a knock range and change the timing accordingly within certain manufacturer parameters. Not only can they change spark timing but injection timing depending on the engine.

In regards to the Tacoma 6 cylinder it has a high compression which creates a problem with lower octane ratings. They have overcome this with a number of sensors, one being an anti-knock sensor, so that the vehicle can use lower octane gas. The problem is however it is not perfect and the engines usually still do not get all the benefit of the gas because the timing is not perfect so we do not get all the possible horsepower from the gas.

When someone uses a higher octane the vehicle can adjust the timing to get more of the power locked up in the gas, but the octane itself is not making any more horsepower than the lower octane. It is simply the vehicle that is better utilizing more of what is already there waiting to be released.

So it is possible to get more Horsepower from an engine by using a higher octane and also get better MPG but it is because of the computer changing the timing, not because higher octane has a higher horsepower rating.
Here is a technical video explaining it.

Keep in mind that each manufacturer is different in how they program their vehicles so depending on the manufacturer there may or may not be a change with different octanes. Also each vehicle is different even from the same manufacturer. So two Tacoma's with the same exact engine may not respond exactly the same to an octane change. MPG is the best way to determine if there is a change short of a dyno test. So bottom line octane can allow an engine to better utilize the horsepower of a particular fuel, but octane does not make horsepower itself.
https://www.youtube.com/watch?v=gqvhaPLuTPI

Here is a simple explanation on winter blends.
http://jalopnik.com/what-you-should-know-about-the-fuel-youll-be-putting-i-1450089585

Also here is a more technical explanation on horsepower and octane.
http://www.enginelogics.com/confirm-your-dyno-results/

 

Did my own little experiment... drove a full year on 87 octane followed by a full year of 91+ octane. I only used ethanol-blended fuels. No noticeable gains in fuel economy, but I can feel the difference in throttle response when running higher octane (probably due to the ECU taking advantage of the VVT-i as the higher octane can withstand more compression before knocking).

Thread in case you want to read: http://www.tacomaworld.com/forum/2nd-gen-tacomas/310636-regular-v-premium-experiment.html

 

These are both good explanations, but I'll try to explain in simple (different) terms:

High octane fuel burns slower than low octane fuel. Ping occurs when the ignited fuel burns quicker, creating pressure before the piston reaches TDC, and completes the burn too soon after TDC. Engine design and tuning determine the need for high octane, and will be specified as required.

If the driver has a lead foot, he may "feel" a slightly higher output, but normal driving will not show a difference, other than a small gain in MPG. Given the additional cost of high octane fuel, there would actually be negative value in using high octane if not specified by the manufacturer.

A note on Wiki: NOT the last word in any discussion, just like this Forum. Edited and re-edited by normal mortal (we hope) human beings.

 

That is simpler way but not totally correct. In my case using the higher octane does benefit me monetarily. As long as there is no more than a .15 cent increase between each octane level increase, in my area it is usually .10, I actually save money by purchasing the higher octane because of enough increase in MPG to pay for the higher price in gas. I find this true on both of my Toyotas. It will not work for everyone as every engine is different, but it does work for some.

 

Actually less heat energy in 91

 

Depends on the 91 and what additives were used to make it 91. If I remember correctly that's one of Shell V-Powers selling points. It makes equivalent or better energy than Shell 87.

A lot of 91 uses it's Ethanol content to boost the octane rating (ethanol has an octane rating over 100), which leads to a lower energy yield.

 

This can be argued to death, perception is not a science “my truck feels better” does not cut it. My mileage has improved by XX% with figures that are not plausible. A small gain in mileage could have more to do with the way it was driven trying to get better mileage to substantiate the extra cost than other factors. Personally I have tried twice with 1,000 mile trips one with 87 the other with 91 just for my own curiosity the figures were too close to be conclusive. Once the 91 was slightly better (less than 2%) the next time the 87 was better. My truck will not ping no matter what I burn in it, it is a 6 spd and if you can make something ping it will be a stick shift so no gain there either. The huge jumps sited by some with no ethanol don’t cut it either it is conceivable to gain 3% but that is about it. Of course others may get different results but saying it has more power “I can tell by the way it feels” or “I got 27 more miles out of a tank full” is not science. In my case I’ll stick to 87 I don’t like to waste money for no gain.

 

Too bad this forum doesn't have a LIKE button.

 

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