Gas Octane

Yep! I guess that greater torque at a lower RPM is the "you can feel it" difference. As for differences in gas mileage, variations in quality at the pump can account for such a small gain or loss.

I wonder. ... That updated version with the Dual VVT-i has significantly improved torque and HP. Is it available on the Tacoma?

 

With all due respect to the 'experts' on this, I think there is sometimes a difference between what you can run and what you should run. It's true that the ECU can cope with lower octane, but it does this by retarding timing and enriching the mixture. On many, many cars, this is moot. The engines are understressed so much that they aren't that sensitive. But high compression engines can be a different story. Only a fool would run regular octane in my 911, for example, where even a bus driver could feel the difference (and if you didn't, the sooty tailpipe and eventual cat damage would get your attention).

High octane is not 'necessary' on most cars. But to generalize that it's a total waste of money on any car is silly conspiracy theory nonsense. Anyway, heaven knows that gasoline isn't the only thing we spend more money on than we need to in order to get a 'theoretical' advantage. I'd say most of us do that all the time.

 

i ran 93 in mine once (4 cyl) and i didn't really notice any difference than when i ran 87....so i just run 87

 

Well, I can't say that i'm an expert on this, but I don't think the mixture is enriched and it's not a simple case of retarding the timing. In the case of the 4 banger, I couldn't find any information on 87 vs 91 octane. The 6 banger, however, is well documented on the net.

Here's a 4 page pdf on the 1GR-FE engine. It is very informative and graphs the timing cycle with the capable range of adjustment.

I suspect that running 87 octane calls for later intake closure during the upstroke to effectively reduce compression. The mixture stays relatively the same. Even though an engine's maximum compression ratio is fixed, closing the intake later than BDC will reduce the effective compression from its maximum. As long as the fuel/air mixture is correct and ignition is controlled by the spark and not pre-ignition, the gas mileage should remain about the same. The HP and torque improve with higher octane due to maximum utilization of the piston stroke up to a full 10:1 compression ratio which must happen with 91 octane.

 

I put in some 89 for shits and giggles. I don't really drive no more than 10 to 15 miles daily. I got 17 mpg. The truck is just a little past 500 on the odo.

 

Wikipedia is a website with information that can be edited by anyone!! although it is informative in some aspects, it is very often factually incorrect..

Rare do you find a standard production vehicle with a constant 'compression ratio' over 8.5/1 today..
& compression ratios as a basic measurement for performance, are misleading & not what a good mechanic/technician would use as a performance indicator as they are 'averages'..
'Cylinder pressure' is a much more precise (& definitive) measure of performance potential, & therefor 'octane' requirements.
'Octane' is a term that has come to be confused with overall performance, when really it simply defines the probability of a 'refined/combined mixture' to exhibit pre-ignition under certain combustion conditions in a controlled environment (ie-no humidy, 14.7/1 atmospheres, etc..)
It has nothing to do with how much heat energy potential per quantity (gallon) a particular combination of 'fuel' possess.. as a matter of fact, regular (ie-higher in heptane quantity) fuel contains slightly more potential heat energy per unit..

Hope this helps explain things...

 

No. Not really. It was a nice try though.

I'm not sure what you're beating the tom tom about. I agree completely about energy being the same per a give volume of 87 or 93 octane gas.

I realize that Wikipedia must be taken with a grain of salt, but then so should any source of information these days. Wikipedia has proven to be a great resource and, though second source verification is recommended in critical applications, has been found to be quite reliable by me. So, I respectfully disagree with your assertion that "it is very often factually incorrect.."

The pdf I posted a link to independently verifies the compression ratio in the 1GR-FE to be 10:1.

Wikipedia has an article on Compression Ratio as well and gives a treatise on the use of gauge pressure on diagnostics.

The compression ratio in all standard automotive gas engines (Saab VCR engines excluded) is fixed by the physical structure and mechanics and is the product of a calculation.

From Wikipedia

The subject here was not to look for a definitive measure of performance. It was to find if using higher octane gas in the Tacoma engine yielded any tangible results. Apparently it does.

 

The only thing I would add is that the different output numbers with the different octane ratings is also stated clearly in 05 to 08 Tacoma manuals.

For some reason, 09+ they simply switched to "use 87 octane or higher", apparently to reduce confusion for stupids. However, since the 1GR-FE is identical regardless of model year, the higher output on higher octane stands.

Dual VVT-i 1GR-FE is not available in the Tacoma as of yet. It was debuted this year for the FJ/4Runner. The smart money says it'll be dropped in the Taco for the third gen.

 

THANKS!

Gee, now I don't know if I should wait another year and make do with what I have. (Worry worry. Think. Worry.)

 

It was sort of a concern for me, but I figure if I get jealous of the new engine when gen 3 comes out, I'll just slap a blower on and be happy.

 

Please, please, please, stop quoting Wikipedia.. it is an unsubstantiated & unreliable source..
In today's world of direct injection, positive pressure intake sytems &/or 'variable everything' powertrains, engine compression ratio stats - which are virtually meaningless to anyone involved in true performance, beyond the 'fast & furious' movie crowd - are redundant..
'Cylinder pressure' is a more meaningful measuring device of performance.. & gasoline/combustion efficiency..

 

Please, please, please, stop quoting Wikipedia.. it is an unsubstantiated & unreliable source..
In today's world of direct injection, positive pressure intake sytems &/or 'variable everything' powertrains, engine compression ratio stats - which are virtually meaningless to anyone involved in true performance, beyond the 'fast & furious' movie crowd - are redundant..
'Cylinder pressure' is a more meaningful measuring device of performance.. & gasoline/combustion efficiency..

Please see the article in this link;

http://www.kb-silvolite.com/article.php?action=read&A_id=36

 

I don't believe that there was anything in what I quoted from Wikipedia that was untrue. You're welcome to point it out if I did.

The compression ratio of the 1GR-FE was germane to the discussion in that it substantiated reader's assumptions of greater torque and HP with higher than 87 octane gas usage.

Thanks for the link. That's good information to have. I bookmarked it in my Library: Automotive subheading.

Can I still quote Wikipedia if I'm careful about what is correct?

If you find anything that you'd like corrected and can back it up, I'll change it for you.

 

I've encountered school teachers that are wrong in what they teach their students just as often as wikipedia is wrong in it's information. IMO, you should be open minded and question ALL sources of information and never assume that what you have is 100% reliable and correct. Read it, and make an informed decision. As the previous poster said, most of what he posted is factually correct. Who cares if it came from Wikipedia. I could go to an ASE Master Tech class and learn wrong information tomorrow if I wanted to. I guarantee you it's happened in the past and will happen in the future. We learn, correct, and move on. Use all the resources you have at hand and make informed decisions. To close yourself off to a resource is negligent.

You guys want a definitive answer, go get a scan tool and scan the knock retard/timing of your engine running different fuels. I can tell you right now that on 87 mine pulls timing WAY faster then on 91. Doesn't mean it's wrong to run 87 vs 92, but as everyone else has stated, it makes a difference on this motor, compression values be damned.

 

I consistently get 1-2 more MPG by using "pure" gasoline with no ethenol. I guess I am lucky that I have two stations near me that offer it.

 

87 octane Sunoco with a touch of Lucas oil every now and again to keep the fuel system clean and lubed and eliminate carbon deposits in the combustion chambers.

 

This is a ridiculous generalization, and no more true of Wikipedia than of all books. It doesn't take much literacy or effort to recognize and qualify a good entry in Wikipedia. The best ones include citations (just scroll down), just like academic papers, and you'll find that the quality of entries on most subjects are vigorously policed by other users.

If only internet forums worked the same way.

 

The above quoted statement is the 'ridiculous generalization'..
As an example, Motor Manuals, Chilton Manuals, Factory Repair Manuals, etc, are all written & edited by people directly involved in the field being covered by the material (as are all legitimate 'technical manuals' produced for any industry that i know of).
Information contributed to Wikipedia may be from any source, legitmate or not, & will only be edited out when disproved by another 'legitmate' source..
I am not saying that Wikipedia isn't a good source of 'general' information, it certainly is that.. But on technical info, it lacks merit..
I certainly wouldn't rely on any information from it to repair a vehicle I am working on..
Would you authorize a $1000 repair from a Mechanic who said he diagnosed your vehicle problems using Wikipedia??

 

I'm sorry, but you're just being obtuse. This is not a repair shop, it is a discussion forum. If you toss out all of Wikipedia for it's potential inaccuracies, then you'll have to toss out all the posts from opinionated guessers as well. Wouldn't be much left to read here then, would there.

Let's not quibble over one source of information, when all we're trying to do in a discussion forum is to exercise the dialectic to the greater knowledge of all.

 

Agreed, we shouldn't quibble..
The point I was trying to make was that questions involving technical issues deserve to be answered with information from sources that are reliably/technically correct..
I realize this is a forum & not a "repair shop", however, the majority of questions (not statements) that I see posted on this site are asking for 'technical' advise/help of one sort or another, & most are related to mechanical repair &/or modifications.
Please excuse the mechanic in me, there was never any malice intended, I was just trying to be helpful..