08-07-2004, 03:52 AM
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#16
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Junior Member
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Join Date: Aug 2004
Location: Tampa/Sarasota, FL
Age: 38
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Junior Member
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Location: Tampa/Sarasota, FL
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Okay.. i'm a pretty much broke college student with an SUV.. *sighs* I've used all grades on my 4runner. Sometimes 87 works the best.. and other times it works sluggish. That goes with the rest of the grades. Now, I believe that its the brand that you use. I've found that Amocco is the best fuel for my truck. whichever grade. I usually get around the same gas mileage.. 15/16 in the city and around 23-24 on the highway. I do'nt see a "big" difference in power. It may feel a little anemic.. but then again I don't need the speed.
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2003 Toyota 4Runner SR5 V6 2wd
Color: Galactic Grey
Lower Front Grille Guard
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Previous vehicle: 1992 GEO Prizm
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11-27-2004, 02:09 PM
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#17
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Join Date: Jun 2004
Location: Texas
Age: 42
Posts: 47
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Join Date: Jun 2004
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My mom has a 2004 V6 Limited and she only puts 87 in her truck. I have always put 93 in mine, so the other day I was driving her truck when I was in town and noticed a big difference in power. I thought I was nuts so my mother and I switched cars for a week and at then end of the week she also agreed that there was a difference in power but it did not make sense to her why gas would do that. I hate putting 93 in my truck but for some reason it just seems to work better.
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2004 V6 Sport Edition - Natural White
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11-28-2004, 04:25 AM
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#18
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Join Date: Sep 2003
Location: Vista
Age: 78
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I make a 400 mile comute about once a month, traffic is not a problem and I leave at the same time each trip, very early. I've now done the trip with 87 and 91 octane. I'm not able to 'feel' any difference, but after a half dozen trips, each grade it looks like 19 mpg regular and 18 mpg high octane, driving pretty much the same, every trip. So for me it's regular gas.
It's hard to tell what makes for better mileage, but I drive carefully, use synthetic everything and keep the tires pumped up to about the max on the sidewall. And now I can add regular gas to the mix.
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12-12-2004, 09:48 PM
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#19
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Senior Member
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Join Date: Dec 2004
Location: calgary.alberta.canada
Age: 42
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I believe the manual says "Premium Fuel Only"... so.. I follow that....
I've always put premium fuel in any vehicle and the extra costs don't really bother me.. (its not that much)
Make sure your tires are properly inflated too.
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Black 2003 4Runner Limited V8 4WD
(Canadian Edition)
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12-12-2004, 10:41 PM
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#20
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My tires are checked frequently and held at 35 pis mileage.
iForce, show me anywhere in any Toyota publication of any kind where Premium is required. There are half a dozen threads on the subject.
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12-13-2004, 12:09 AM
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#21
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Join Date: Dec 2004
Location: calgary.alberta.canada
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Quote:
Originally posted by Larry
My tires are checked frequently and held at 35 pis mileage.
iForce, show me anywhere in any Toyota publication of any kind where Premium is required. There are half a dozen threads on the subject.
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I believe I read it in my owners manual. Let me check when I head out to the car... in like.... 2 hours or so.
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Black 2003 4Runner Limited V8 4WD
(Canadian Edition)
- TRD High Performace Air Filter
- TRD Cat-Back Exhaust
- 25% Front Tint / 15% Rear Tint
- Bridgestone Dueler Revo A/T
- Projector Foglights w/ 4300K HID
- Black JDM style Taillights
- 2006 Projector Headlights w/ 4300k HID LINK
- Custom Rear Fog Lights w/ Switch - LINK
Pictures on My Website
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12-13-2004, 04:21 PM
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#22
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OK. I'm wrong.. I read it this time without my chinese eyes. It says for "Better Performance"..... how much better? dun dun dunnnnn...
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Black 2003 4Runner Limited V8 4WD
(Canadian Edition)
- TRD High Performace Air Filter
- TRD Cat-Back Exhaust
- 25% Front Tint / 15% Rear Tint
- Bridgestone Dueler Revo A/T
- Projector Foglights w/ 4300K HID
- Black JDM style Taillights
- 2006 Projector Headlights w/ 4300k HID LINK
- Custom Rear Fog Lights w/ Switch - LINK
Pictures on My Website
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12-13-2004, 08:13 PM
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#23
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Join Date: Aug 2004
Location: Bay Area, CA
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Quote:
Originally posted by iFORCE
OK. I'm wrong.. I read it this time without my chinese eyes. It says for "Better Performance"..... how much better? dun dun dunnnnn...
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"better performance" for the gas station's wallets!
how many kind of eyes do you have?
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12-13-2004, 09:16 PM
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#24
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Join Date: Sep 2003
Location: Vista
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He has dealer's eyes.
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12-13-2004, 11:41 PM
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#25
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Join Date: Dec 2004
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dealer eyes? oh man.. quick.. i need new eyes for christmas.
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Black 2003 4Runner Limited V8 4WD
(Canadian Edition)
- TRD High Performace Air Filter
- TRD Cat-Back Exhaust
- 25% Front Tint / 15% Rear Tint
- Bridgestone Dueler Revo A/T
- Projector Foglights w/ 4300K HID
- Black JDM style Taillights
- 2006 Projector Headlights w/ 4300k HID LINK
- Custom Rear Fog Lights w/ Switch - LINK
Pictures on My Website
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12-16-2004, 01:44 PM
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#26
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Elite Member
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Join Date: Nov 2004
Location: New Jersey
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A little info on compression and octane.
The piston, quickly squeezing the fuel/air mixture into a small space, can generate enough heat of compression to ignite the fuel well before the spark plug fires, with unpleasant results. If the fuel prematurely ignites while the piston is on its’ way up, the burning of the fuel, in conjunction with the rising piston, creates even more pressure, resulting in a violent explosion. This explosion is equivalent to hitting the top of the piston with a very large hammer, usually called: "pre-ignition", "ping" or "engine knock". NOT GOOD!
What you really want is a very rapid burn of the fuel, not an explosion. And you want the burning of the fuel to take place while the piston is in a better position to convert this pressure into productive work, like on its’ way down. Think of this burning as a very fast "push" on the top of the piston. Despite the violent noises you hear from some exhaust systems, it really is a rapid push on the top of the piston making the crankshaft go around, not explosions.
So that you can ignite the fuel at exactly the right time with the spark plug, instead of from the heat of compression, they put stuff into gasoline to keep it from igniting prematurely. The more resistant the fuel is to ignition from the heat of compression, the higher its’ octane rating. This is why higher octane fuel burns slower.
At higher temperatures the fuel is burned more efficiently. So, while it’s true that the higher-octane fuel does not posses any more energy than low octane fuel, the increased octane allows the extraction of more of the potential energy that has always been there. Conversely, lower compression engines utilize a little less of the fuel energy potential (2-4% reduction) but there is also less heat generated in the combustion process. To release all the potential power of 91 octane gasoline, it is necessary for an engine to have a compression ratio higher than 9.3 : 1.
Manufacturers really do want you to get the maximum efficiency out of your engine. They do their best to give a good balance between horsepower and engine life. It’s in their best interests to do so.
Moral of the story is; Follow the manufactures octane recommendations.
Koz
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12-16-2004, 02:39 PM
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#27
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Join Date: Sep 2003
Location: Vista
Age: 78
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Quote...
At higher temperatures the fuel is burned more efficiently. So, while it’s true that the higher-octane fuel does not posses any more energy than low octane fuel, the increased octane allows the extraction of more of the potential energy that has always been there. Conversely, lower compression engines utilize a little less of the fuel energy potential (2-4% reduction) but there is also less heat generated in the combustion process. To release all the potential power of 91 octane gasoline, it is necessary for an engine to have a compression ratio higher than 9.3 : 1.
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Who's book did you copy? Higher octane gasoline has less energy (btu's) then low octane gasoline. 9.3:1 is just a number. Design plays a big part, too. That 9.3:1 could move up or down depending on lots of other factors. My Turbo Volvo engine has a compression ration way below 9.3:1 and requires 91 octane. My 84 Honda Civic 3 valve motor follows your ration limit at 9.2:1 but develops 210 psi cranking pressure, way above the usual 175 psi or so of other small engines. It has a pre-combustion chamber that completely changes octane requirements. If you think you should use 91 octane in your 4Runner then use it. You don't need a book to convince yourself, just do it. At least it won't hurt anything.
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12-17-2004, 10:54 AM
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#28
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Elite Member
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Join Date: Nov 2004
Location: New Jersey
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Larry,
The purpose of my post was to share information that I felt was important in understanding the differences between regular and premium fuel. This information was a combination of many sources and knowledge acquired from what I can remember from vocational learning and personal experience, not copied from a book. Everyone has an opinion based on knowledge they have acquired. Just because my opinion is different then yours doesn’t mean I need to insinuate you copied from a book. The fact is, I agree with a lot of what you have posted, regardless of where you got that information.
The energy difference between regular and premium fuel is so minimal it doesn’t matter and has nothing to do with deciding which to use. Octane rating is in no way correlated with engine power or efficiency. We can argue all day about it, the fact is that higher octane fuel is NOT a measure of power but of the fuels’ resistance to ignition from heat. A higher-octane fuel also, under identical combustion chamber conditions, will burn slower.
You can look at the 9.3 : 1 compression as just a number is you want to nit-pick. Since you need to do this I should have said; In the average stock, normally aspirated engine without power (turbo/supercharged, nitrous) added it is necessary for an engine to have an approx. compression ratio higher than 9.3 : 1. to release all the potential power of some 91 octane gasolines.
Yes, an engine’s octane requirements are mainly determined by its basic design and many other variables, such as;
Temperature - Generally, the hotter the ambient air and engine coolant, the greater the octane requirement.
Altitude - The higher the altitude above sea level, the lower the octane requirement. Modern computer-controlled engines adjust spark timing and air-fuel ratio to compensate for changes in barometric pressure, and thus the effect of altitude on octane requirement is less. Altitude extremes and super/turbo charging affect octane requirements. Increased induction pressures (in a turbo/supercharged engine) cause more rapid flame-front propagation. Likewise, decreased exhaust pressure (as would occur at altitude or using a less restricted exhaust) also tends to increase flame-front propagation speed. Both of these effects can combine to raise octane requirements, especially at altitude.
Humidity - The drier the air, the greater the octane requirement. The recommendations that vehicle manufacturers give are for normal, to low, humidity levels.
Your engine's spark timing - The octane requirement increases as the spark timing is advanced. Both the basic setting of the spark timing and the operation of the automatic spark advance mechanisms are important in controlling knock. If equipped with knock sensors, the computer controlled engines have the ability to retard the ignition temporarily when a sensor detects knock. This temporarily reduces the octane requirement and may also temporarily reduce vehicle performance.
Driving style - Rapid acceleration and heavy loading, such as pulling a trailer or climbing a hill, may result in a greater octane requirement. Stop-and-go driving and excessive idling can increase octane requirements by causing the buildup of combustion chamber deposits.
Nowhere in my post did recommend using Premium fuel or that I use it, or that I even have a 4Runner (I’m waiting on a 05 V8), so please don’t put words in my mouth. I suggested using what the manufacture recommended. If you are going to criticize what people write, at least read it carefully. I personally believe that the engineers at Toyota know a little bit more about what octane fuel is needed in their engines, then you or me. Well, maybe more then I, since you have a turbo Volvo and an 84 Honda Civic 3 valve motor.
Peace
Koz
Last edited by Koz; 12-17-2004 at 10:58 AM.
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12-17-2004, 01:13 PM
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#29
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Koz, sorry, I had just come home from a service manager that claimed the 4Runner would only run on Premium and it is required for my warranty. This is the dealer that did not know the 4wd has zerks on the driveshaft. I wonder how many zerks have been missed. You're right, your latest post has a lot of information. And I'm jealous, you get the variable cam timing and a lot more power.....
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12-17-2004, 01:28 PM
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#30
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Location: Los Angeles
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Premium fuel?
What defines "Premium Fuel" ? Does it have a particular Octane rating, been cold filtered ... ?
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