Gas Octane

I definitely notice a diff 91 v 87.my08 2.7 auto, in both pep and mileage. Iprefer shell or chev. never valero or unbranded gas.

 

The 1GR-FE is the 4.0 L version. Bore is 94 mm and stroke is 95 mm. 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.

found this on wiki! so i guess it DOES make a small difference

 

See, ASE_MasterTech! I'm not the only one. LOL

The fact is that facts and factoids are both useful to the inquisitive mind, and verification is something we all do individually. We trust Webster and Britannica, because they are well established resources. However, no resource conjured by man is the ultimate keeper of fact, nor do we want it to be. George Orwell had it right. The minute we delegate such authority to think tanks is the minute we quit thinking for ourselves. The right to agree or disagree is one that must be exercised constantly, lest we all become mindless subjects to Big Brother.

 

Right on!!!

 

I agree with this completly...too bad we don't have any in cleveland:-(

I hate ethenol!!!

 

The biggest issue with wikipedia today is not the accuracy of the majority of the articles, (although accuracy is still an issue with every publication) it is the lack of complete information. That is where the biggest issue arises. For example say that the article on the 1GR-FE is correct and 91 octane does yield higher numbers for torque and bhp, **yet doesn't include any additional information about the effect on the engine lifespan or the fuel management system's ability to properly utilize the higher octane in real world applications... And that is where real experience comes into play.

** I have no idea if that is correct as I simply made it up for sake of the argument on the basis of using wikipedia. I should note that I frequently use wikipedia as a tool to learn the broad facts of a subject, I just don't think it should be used to prove anything.**

 

Wiki is NOT a reliable source!!! Anyone can add info on it.

I am NOT a doctor or a nurse, nor have I had any medical training. But yet I can add info on medical issues. And just because I added them, that does NOT mean they are correct. Do not make the mistake and think that wiki is always reliabe.

Octane does not "add" HP or TOUQUE. Octane IS a burn inhibitor. It is added to slow the burn rate...basically it effectively raises the burn/flash temp. so the fuel does not ignight to soon befor the piston is fully at the top of it's stroke.

Think about a desale engine...they do not have spark plugs. The desale ignites because the piston rises up compressing the air-fuel mixture, causing it to heat up. That heat is what causes the desale to ignite instead of a spark plug.

Well, same principle happens to gas. The higher the compression ratio/cylinder pressure, the hotter the air-fuel mix gets. And that heat can cause a premature ignition, befor the piston is at the top of it's stroke. So octane is added to prevent that from happening.

Octane, itself, has no energy. "Energy" in this case, is how big of a boom does it make...some things make a bigger explosion then others.

So if it does not have any energy, it can not add any HP or TORQUE.

What may happen though is this....the added octane allows the engine to ignite the fuel at the right/better time, and therefor the energy released by the gas will be used more efficently.

I do not believe that our engens require the increased octane. We may infact see some impovement as you stated above, however that small amount is not that big of an impovement to justifie the increase cost; nor does any increased mileage. Do the math...divide the price per gallon by how many miles that gas will allow you to drive, for both high and low octanes.

Lets say 2.80/gallon @ 87 octane:
17 miles/gallon = 16.47 cents per mile

Say 3.10/gallon @ 91 octane:
18 miles/gallon = 17.22 cents per mile

Those are just numbers, I took a ruff guess at the 91 octane price here in ohio, and I took a guess about an increase in milage of 1 mile more per gallon. But you get the idea. Run the number for yourself.

My rule of thumb is...unless it saves me money OR it is needed because of ruff running or pre-ignition, I use the cheeper octane. If someone here "needs" to run higher octane, and others don't and we all have the same engine; the person who "needs" the higher octane has something going on that needs to be looked at.

 

Assuming 20 cents difference from 87 to 9X
I think I used
87 $3 a gallon at 19 gallon fill up
87 = 19 mpg = 361 miles per tank = $57 per tank $.1578 cents a mile
9X = 21 mpg = 399 miles per tank = $60.80 per tank $.1523 cents a mile
9X = 22 mpg = 418 per tank miles = $60.80 per tank $ .14545 a mile

@21 mpg thats about $50 savings per 10,000 miles
@22 mpg that is about $125 savings per 10,000 miles

 

??? Sorry just a little lost. 87 octane, I got. 9X= what octane...91 or 93? also what is the price per gallon for those octanes? And did you rally see a 2 or 3 mile per gallon increase?

Other then that, you did exactly what I would love everyone to do...question everything and do the math (literal or figurative) for yourselves.

edit: opps...i just noticed you listed the price differene at 20 cents. Is that accuate where you live...not her in ohio :-(

 

All assumptions based on what people are reporting here.

9X = 91/92/93 (X being a variable as premium availability varies)
Massachusetts generally sticks to the dime per grade; give or take a penny or 2.

 

Thanks all for the support, & the comments also.. it all helps us become better..

One last site to visit though as this one explains far better, most of what I've been trying to convey in this thread regarding 'octane'..

http://www.offroaders.com/tech/octane.htm

 

There are a whole lot of assumptions in your post that totally miss the mark. There is simply no way to correct them all in this venue. However, I should correct you in that I have never put forth the argument that Wikipedia is either reliable or not reliable. My argument is that it is a useful resource. The other error in your assumptions that bears correcting is that I am not, nor have I ever been laughing at anyone on this thread, least of all ASE_MasterTech. When I posted LOL, it was in reference to the situation whereby the very thing I had posted, that he had corrected me for, was then again posted by BrandonTorgerson. It was quoted in my post for his reference.

I will say this specifically about Wikipedia and, since everyone's opinion has already been expressed and no one is likely to change their mind anytime soon, the off topic subject of Wikipedia is then closed to me on this thread. I like Wikipedia. It is an enormously valuable resource that has been compiled by some extremely knowledgeable people. Nearly all of the facts in this huge body of work are cited from other publications. It is mostly correct. It is a living document that is constantly under revision and occasionally mucked with by the same sort of ne'er do wells that spray paint the sides of buildings. For that reason, I think they should do more to protect it, such as requiring editors to register with loop back verification. But, that's a subject for another thread.

I have nothing but respect for ASE_MasterTech and his argued position. My own experience of 62 years seems to run with a slightly different philosophy. I filter everything, including tech manuals.

You? You leap to too many unfounded conclusions too soon based on too little facts. I don't know how to fix that.

 

My whole beef on this is that there was a lot of grief given for using FACTUALLY CORRECT information from wikipedia. Who cares where the information was quoted from? It was CORRECT. Again.... let me repeat this, IT WAS CORRECT. So why don't we stop arguing this. CORRECT information was posted, wait, did I mention, IT WAS CORRECT!

Christ people. Who cares where it came from, whether it was me, ASE Certified, Wikipedia, the information was CORRECT. Stop arguing over it.

My whole issue with this octane argument is this. Yes, higher octane on this motor lends to lower timing being pulled (this is fact, observed with a scanner). Lower timing being pulled leads to more power under acceleration. However, from my personal experiences with this motor, low power timing tables (ie: idle and cruise) are not dynamic, but static. This means there is no adjustment to the timing based on octane while at cruise speed. This means that overall mileage, unless continuously climbing hills, should never change significantly from octane to octane. This is what puzzles me about this discussion. It doesn't matter if I run 80 octane or 100, on the same stretch of road, at the same CRUISE speed, the computer commands the SAME timing. Only timing under acceleration changes.

 

There is nothing for you to fix, because there is nothing wrong with me. You say I have unfounded conclusions. My conclusions come from YOUR OWN WORDS! If your feelings or oppinions are different from my conclusions, then you need to do a better job at wording your posts so they reflect your opinions better. After all, no-one else in this world is in your mind, and can know what your opinion is exactly. That is why when you or anyone writes anything, explains anything, expresses anything, it is the responsiblity of the person expressing their thoughts to be clear and not mis-understood. It is not the responsiblity of the listener. After all, the listener is passive in the transaction of information.

 

Well, some further observations from my drive into work today. I tried to pay closer attention to when timing was being pulled. Once I hit about 65-70mph it didn't take much additional throttle to get the computer to start pulling timing and using the knock correction values. Even a small hill and it would start doing so. So perhaps based on that I can see where octane would affect mileage. Again however, most of my driving I was sitting at around 25 degrees of advance on 87 octane fuel. That's the same I get out of 92 octane. So I'm a little skeptical of the mileage differences.

Under acceleration though I always see a difference. So there's definitely a small power difference.

 

I agree with you on this one. Given the controls this engine is capable of, 'under load' with 87 would be the only time that it would make a difference. To put in a totally different context, It's like the difference between having a powerfully fast computer and a lesser computer yet only doing text on both. They will perform the same.

The energy in the 87 is ever so slightly higher than that in the 91, but the 91 is more controlled and is therefore utilized more efficiently.

The process is controlled by modulating the fuel supply to a limited adjustment, mechanical combustion cycle. Hence, loaded conditions, sustaining higher revs at greater torque output, produce higher cylinder compressions which push cylinder head pressure and temperature into the autoignition zone for 87 octane fuel.

What that means is that if you have a lead foot, you'll probably see better gas mileage with 91. Grandma probably wont.

 

I think most dyno experts would contend 3 HP is well within the margin of error of a wheel dyno.

The article doesn't state how the measurements were made: I suppose if done in a 'laboratory' type setting, on an engine dyno, things could be better controlled. But the article doesn't make that clear and 3 HP is still pretty tight.

 

Hi: I'm new to both TW and Tacomas... wanted to thanks all for the interesting info, especially this thread which has made for an interesting read!

It sounds like there is some potential to squeeze out performance with more agressive maps then? If so, that raises some interesting questions: does someone make a flash or chip for the ECU? Is the Toyota ECU even flashable? chip-able?

I've seen terrific results on other cars with ECU flashes: almost 15 hp dyno verified on VW 2.5L engines (which I owned before my Tacoma), with gains all across the power band. No hardware changes, just software that uses more agressive timing at all RPM's. You are left with an engine that you MUST use premium (91) at all times though.

 

Those are Toyota's own specs, from the 08 and earlier user manuals.

Aside from that, who cares about HP? It's a pointless number in trucks. No one drives their vehicle above interstate speeds anyway. Look at the torque! That's where the meaningful change is. Why do you think everyone wants a diesel/turbo-diesel Taco? 150hp is plenty if we get 300+ tq along with it.