Premium fuel in non S/C Tacoma

Yeah i have found a noticable gain in how many kms i can go on a tank, and the 91 where live on the west part of canada i have found that they all are ethanol free, and TBH the price diffrence when you filling your tank full is not very much diffrence IMO, having a 15$ diffrence is nothing it keeps me from eating junk fast food haha.

 

Your fuel prices aren't an option for us

 

^^ This.

 

What about the whole "you'll burn out your valves" issue? Personally, I've always theorized that if the vehicle can be adjusted for high octane, whether automatically or manually, then it can negate the danger. I'm just a desk jockey, however, and not an engineer, so I don't know. I know with the Mustang guys who've used the same programmer I have for years, and haven't had a problem.

The other thing that has always bothered me is when I get a knocking in one of my vehicles, and people say, "Just put a higher octane in." To me, if you're getting knocking on the grade it's built for, then either you need to buy from a different station, or there's something wrong with the car. While a higher grade may eliminate the knocking, the underlying issue is still there.

 

About $6 more to fill up with premium. If you can't put just $6 more into your truck and know it'll run better with little to no ethanol.....




of tacomaworld.com. Bob doesn't like you.

 

I think its not the overal cost that scares people but the .14$ more per litre. I always fill with 89-91 the vehicle runs smoother.

 

Thanks Chris good info! I ran 5-7 tanks of 91 in a row and didn't see any noticeable difference in mileage or performance. This was in October/November. I'll be trying it again this summer. also, around Seattle 91 is more like 30-40 cents more per gallon than 87.

 

I know. Which had been answered. And his poll was asking what people run. I don't run it for that reason.

 

I think it's more appropriate to say that the truck compensates for lower octane.

All higher octane does is make the fuel more resistant to detonation (knocking). When the truck senses no knocking it runs normally. Should the truck start to detect knocking it retards the ignition timing to compensate, reducing power in the process.

When fuel detonates is variable and depends a lot on ambient air conditions, so it's quite possible that during the winter the truck will be able to run on 87 octane with no knocking, which means that under those conditions there would be no performance difference between 87 and 91 octane fuel.

I believe the S/C is designed to use the stock air intake and doesn't run correctly with the TRD intake.

 

And your ethanol content is not an option for us

 

I get 1mpg better on premium, pays for itself.

 

I always run 91. It's a matter of $73 vs $78 dollars for a fill up to keep the engine from knocking when I trounce on it.

 

There are a lot of myths about octane.
One is that premium has more power. It does not.
One is that premium burns slower. It does not.

Higher octane is more resistant to preignition/spontaneous ignition through compression. The simplest (but not the most accurate) way to put it is that it has a higher flash point. The spark from the plug had a heat that exceeds the flashpoint of any octane fuel. The burning fuel has a heat that exceeds the flashpoint of any octane fuel.

So higher octane is technically harder to ignite... but it is not harder for the spark plug to ignite, and once ignited, the speed of the flame front is nearly identical.

I saw one post from a guy who claimed that "pinging" was caused by the flame front breaking the sound barrier! Derp.


Burned valves? Here's where we get to "shadetree mechanics".
Higher octane is harder to spontaneously ignite. It will run "properly" with higher cylinder temperatures and pressures.
Before computers took over control of our ignition systems, shadetree mechanics would advance the timing to the ragged edge of "pinging"... then back it off a degree or two. This produced more power and improved MPG... at the cost of higher cylinder temperatures that did indeed lead to burned exhaust valves.

+10,000
The owner's manual will often state that SOME momentary light pinging under high load conditions in some weather conditions is normal (I haven't had a properly tuned engine that pinged under load since my '94 SR5), but for the most part, yes, you are 100% correct.
Pinging could be caused by a problem with the knock sensor, ECU, or carbon buildup in the cylinders from "grandma" driving or oil consumption issues. If the plugs are carbon-fouled, the chambers are also likely carbon covered and that will lead to hot spots.
Seafoam and any other magic product is not going to repair an engine that is that far gone.

 

For the most part, true, however, on the 4.0, the engine will apparently adjust to the higher octane fuel. While it is spec'd for 87 and runs perfectly on 87, many members have reported improvements on 91. Enough to make even a skeptic like me believe that there is something to the claims. Reportedly, yes, the 4.0 was designed for 91+, but the ECU's mapping is written to accommodate 85-91. Running ONE tank of 91 will not immediately reactivate the timing and mixture maps for 91, but over the course of several tanks, the computer will re-learn that more advance can be safely run. Example (pulling numbers out of my ass): Normal operation on 87 At Cruise = 10^ Light Load = 7^ Heavy load = 2^ Decel = 20^ The computer is "used to this" and expects to see it. Remember, the computer is looking for knock, but it's not going to constantly advance timing to actively seek knock and then back off. No... it is the absence of knock over time that allows it to advance the map So first tank of 91.... At Cruise = 10^ Light Load (no knock detected) = 10^ Heavy load (light knock detected) = 2^ Decel = 20^ Computer realizes that something changed. Next few load cycles.... At Cruise = 10^ Light Load (no knock detected) = 10^ Heavy load (light knock detected) = 4^ Decel = 20^ At Cruise = 10^ Light Load (no knock detected) = 10^ Heavy load (light knock detected) = 6^ Decel = 20^ At this point, the computer is seeing a trend that doesn't match it's history. It can only assume that there has been a major change in driving habits, or a change in octane... so it may then begin to advance the cruise and light load timing figures. Those who have made these claims indicate that it takes several tanks to see any change. Perhaps those who are towing, live in hill country, or drive in heavy traffic might see improvements more quickly as the computer would be cycled through more frequent load variations. So yes... the 4.0 is compensating for lower octane... but we are told to run lower octane from the factory so it is an odd case where it apparently does adjust for higher octane.

 

My 2.7 RC gets anywhere from 24.5 to 26.5... and this is a weekly variation. It's always somewhere in that range, but it's never dead on for more than 2 tanks in a row. There are simply too many variables in driving and weather to be able to make a claim that something has made an improvement that is within statistical variation.

The only way to be able to make such a claim with any level of certainty is if you are religiously logging fuel in a spreadsheet and tracking averages.

http://personal.linkline.com/rlockyer/TundraGas.xls
http://personal.linkline.com/rlockyer/2500Gas.xls

But even accepting a 1mpg improvement as truth, how much does it actually save?

Assume regular is $4.30
Assume premium is $4.50
Drive 300 miles

300 miles at 26mpg = 11.54 gallons = $49.62 regular or $51.93 premium
300 miles at 25mpg = 12 gallons = $51.60 regular or $54 premium
Premium costs $0.33 more to get 26mpg

300 miles at 18mpg = 16.67 gallons = $71.68 regular or $75.02 premium
300 miles at 17mpg = 17.65 gallons = $75.90 regular or $79.43 premium
Premium saves you $0.88 to get 18mpg


So IF premium is actually resulting in a 1mpg improvement, you might be saving some small amount if your normal MPG is around 20. Of course, if the engine actually is making more power and running better, then that can't be quantified using $$... it's a positive tradeoff that makes an extra few bucks a tank worth it.

 

See my post above regarding the SAE standard for rating horsepower. It turns out that every car is "an odd case." A couple of years back, Car & Driver did a test to see if premium fuel affected power output. The answers were all over the map. In some cars they saw increases, in many they saw no difference at all, and in the case of one car actually saw horsepower decline.

Nobody can credibly make a blanket statement about the effect of higher octane fuel. It totally varies by vehicle.

 

The 2.7 does not have a map for 91.

 

Touche