Gas Octane

Dick. Nice.

Look, I don't know why you're being so defensive. If you've worked with dynos (which measure torque, not horsepower. HP is a calculated), you know they can be gamed. I'm not saying a test wouldn't work, I'm saying I doubt it would silence the skeptics.

If you can't afford to throw money away, don't. What you're getting for your premium fuel is 13 ft/lbs of torque. Useful in certain situations, but not life changing. Save your money.

Since you are a mechanic, you'll appreciate this bit of interesting reading. Starting on page 40 is a list of sensor inputs for this engine, and a corresponding list of variables managed by the ECU. As a mechanic, I'm sure you'll agree that it's at least possible that some of them affect power output. Note in the specs where it asterisks the horsepower number and qualifies it as being according to the SAE standard.

Dude, relax. First world problems.

 

I owned an old Supra, it's manual stated use 91 for best performance, but that 87 could be used with a drop in performance. I used premium but it wasn't a daily driver. I also owned an Acura TL 3.2, it's manual stated premium was required, but the salesman said I could use mid-grade at high altitude. So I did & it was still the fastest 6 cylinder I ever drove.

 

87 octane is good for most Tacomas. I have used 91 octane for towing with really good results for extra power and gas mileage. I haven't used 91 just to see if I'd get better mpg's for regular driving. My mpg's would probably be better, but since 91 is 20-30 cents more per gallon than 87 you'd have to calculate if it's worth it. With premium costing $4-$6 more per tank you'd need to average 2 mpg's better on average to make buying 91 octane worth it for normal driving. For the best mpg's you need to find a place that sells gas without ethanol. In California that is near impossible.

 

My 84 RX-7 said minimum 91 octane. I remember because I was a student, and it killed me filling the 65 L tank. Damn Wanker engine!

I haven't crunched the numbers yet, but first glance it doesn't appear much difference. There are some fluctuations, and I have a feeling those would be the stations where premium is ethonal free. Unfortunately, I wasn't paying attention at first, so I think I pooched my experiment. When I start getting clients to pay me, I might give it another shot.

 

I get better gas mileage using premium gas. Along with response it just feels much smoother driving around. Also, does premium really help clean injectors along with engine life?

 

Tacomathom, I'm curious as to why you think one should get a horsepower gain by running a higher octane rating fuel. Are you assuming that there are other distinguishing features of the premium fuel vs. regular fuel besides the octane rating?

I believe you that you know what an octane number measures. But if you (or anyone reading this thread) wants a refresher, you can read this post I wrote:

http://www.tacomaworld.com/forum/technical-chat/241043-octane-rating-explained-engineer.html

As an engineer, it makes sense to me that if nothing is changed on an engine designed to run on 87 ON fuel, the identical engine will not see any performance increases with only a higher octane fuel (again, assuming there are not other performance enhancing additives in the premium fuel). Have you modified your engine in any way? Higher compression ratio, Super Charger, etc?

We could make an argument that the Tacoma engine is not designed to run on 87 ON fuel, but it has been my experience that it was. By "designed" I am referring to OEM ignition mapping, compression ratio, etc.

Just curious and trying to assist you with a theoretical answer from an engineering and design perspective.

 

Hunter, I agree with you, our engines are designed to run on regular fuel and all things being equal, premium fuel will not give a horsepower increase. Other members believe otherwise and I just wanted to know if anybody's put it to a test. Apparently the answer is no one has.

 

Modern engines with variable valve timing and a knock sensor can compensate for lower octane fuel. Here's the engine specs I found somewhere awhile ago...

My real world results on pure highway driving (V6 w/ 6spd tranny) is about 19.3mpg on regular vs 19.5mpg on premium.

That said, my results on ethanol free gas were 20.4mpg on regular vs 20.8mpg on premium.

Long story short, try to buy ethanol free if it's available in your area.

 

I can see how those numbers would make sense with a on-board computer that could adjust the engine settings to take advantage of the different fuel.

I completely agree with the bottom line though - buy ethanol free gas if possible.

 

Yeah. Local stations are typically an ethanol blend in the regular and mid grades and ethanol free for the premium grade. In this case I think the extra performance of ethanol free offsets the increased cost of premium.

If you live in an area where every grade has ethanol then I don't think the increased cost is worth it.

 

I'm sorry, but seriously? You need to find something important to worry about. Either you were never a mechanic, or you were a mechanic in the middle of the last century. Once upon a time, yes, an engine comprised a fixed set of mechanical inevitabilities and was "designed" to run on a specific fuel. All you could do without changing parts was manually mess with timing and mixture. Then, you would have been right. Now, you are wrong. And the problem is that you refused to read the SAE definition for rated power, and you refused to read the Toyota document that listed the number of parameters managed by the ECU, or possibly didn't understand it. Nobody said it wasn't designed to run on regular; it is designed to run safely on regular. It is also designed to run optimally on premium. Here in 2012, it is quite common to have both of these be true of one engine.

No, tacomathom, nobody here has enough money lying around to waste it on two dyno runs to find out whether their pickup truck will give them 13 more lb/ft of torque on premium fuel (torque, tacomathom, not horsepower). Imagine that. Thus, we are all fools and victims of a vast octane conspiracy. Or quite possibly no corporation has enough to gain by lying about it in such an elaborate way, so that it might just be true.

You can continue to bleat that you were "just asking a question," but I think you got your answer a long time ago. This is just trolling. Every time you say "prove it," you're tacitly accusing people like me of being stupid or lying. I wish you'd stop.

 

Jesus H Christ Creemore! I just asked a question! Do we need to use premium fuel to get our rated horsepower and has anyone put their Tacoma on a dynamometer to measure the difference? I never did get a yes or no answer from the membership, just your blah, blah blah. Did a dyno operator break your heart in high school? I guess asking a question on T/W makes me a troll, well okay. Your posts show you're a jerk.

 

You're the one calling names, cupcake.

To your first question: No, because the "rated horsepower" assumes regular fuel per the SAE standard. It's just that the rated horsepower isn't the maximum horsepower.

To your second question: For the love of all that is holy, no.

If you're still not getting it, I'll see if I can act it out with puppets and put the video on YouTube for you.

 

Gentlemen, please find a tree outside to continue this pissing contest. just sayin...

 

X2

 

Respectfully, you're welcome to unsubscribe.

It's not my intention to have a contest. I just don't take well to being dismissed without some kind of counter-argument. I think I'm not the only guy on this board with that quirk

 

Wishful thinking. Was that US gallons for 87 and Imperial for 91?

 

What is wishful about that??

 

What's not wishful?

Believing 7.9 mpg or 42% increase in mpg simply switching from 87 to 91.

Impossible.

 

If you say so. I have had similar results. Not quite as dramatic but 16.47 MPG on regular ethanol blend, 3 tanks of premium later I got 22.99 on premium non-ethanol. It took that long to burn through the ethanol in the tank I feel.

It can happen. Do other conditions affect it?? Of course. It is possible though to see these kind of swings in mileage. In my instance it was all on the same trip from central Alberta to Vancouver Island and back with a brand new truck.

Right now I am comparing two stations to see which gives me better mileage as I get 19 some times and 21 others. So I need to determine if there is a connection there.

Just my 2 cents and probably worth both pennies.