If you put to much of a load on it at low RPM you will pull timing even with premium but low RPM on a Honda engine is still pretty high when compared to most engines.

 

MBT is the secret of better running car and mpg that premium allows. http://www.users.on.net/~fivebob/documents/mbt.pdf

 

I do belive Chris that you and Dee could be related some how
Don't beat round the bush just tell it like it is

 

HAHA... gotta love this thread.

I don't know how to describe Steve... but if you've got DSM, TC, KC and a few others going against you... you might want to reconsider your position. If nothing else, be SURE about it.

Don't come online and quote this or that paper or supposed study. Your best proof is... (long) term PERSONAL experience. Those "studies" tend to be biased... even that first post you put, has alterior (or even ulterior) motives. To "earn" your trust in their brand. The thing about Selden... did he use cruise control? And yes, there are LOTS of little variables that can change mpg, but he refuses to acknowledge that (he thinks the test is "controlled"). A slight tail wind or even no wind going up vs a slight headwind coming down... can do quite a bit.

As for myself... I went about 6 months on regular, then I switch to premium. Not because I suddenly "changed" my mine... but because I wondered if the Fit, was like my Mirage. And they are similar... they feel much better with premium.

Give it a try, for the next, say three tanks... pump premium and then observe any differences (in quantifiable and subject terms, ie mpg and "butt dyno"). If nothing else, see how it feels to take off from a light!

 

You're a courier, you should have pretty good records of fuel consumption and you're not saying you get better MPG, just that it feels better. Which is it?

 

I can't say I get better MPG for one reason and one reason alone... I don't drive consistently. My MPG data... is ALL OVER the place. One tank in the dead of winter can be just as good as one tank in the summer. One tank in Spring can be super depressing, while the very next tank is super awesome... with the weather seemingly the same. On one tank I can take 4 hour cruise in the "back roads" (which will raise the mpg quite a bit) and on the next tank, do nothing but deliveries. Heck, just taking a hop into Chicago once in a while kills my mpg!!! I randomly become more "energetic" on some drives and more "drone" on others.

It "feels" better because it's a near instantaneous action when I take off from a stand still. When I ZOOOMMMM down the ramp to 70 mph before the ramp even ends.

As for "which is it?" What is it in my post that conflicts?

The reason my mpg data from deliveries (courier? I'm just a delivery guy, no hoopla) isn't presented here... is because I'm to lazy to tally up my receipts. I don't use it for tax purposes, cause I simply don't make enough to itemize it (the standard deduction is greater!).

 

The world isn't black or white and neither is engine efficiency.... The ECU is going to adjust to make the engine run in the most efficient manner that is possible to based on the octane rating of the gasoline being used.... You get both better fuel mileage and a wider power band using higher octane fuel, there is no trade off of one thing for the other as you would get with an exhaust modification or a change of seasonal tires.

 

Cool. Your impression running a normally aspirated GE is meaningful.

DSM: GD, turbocharged, aftermarket ECU
TC: GD, supercharged, dunno if he's running the factory tune or what.
KC: GE, stock (I think), but before he drank the kool aid he weighed in on the side of "premium is no better." Everyone is entitled to change their minds though.

None have published any kind of log showing improved MPG when normally aspirated using premium instead of regular. All we have are shout outs: today I got such and such.

The only careful comparison was done by Selden. DSM was so sure of himself he got Selden's results backwards, failing to note Selden got worse MPG using premium, and then attributed the results to lack of controls. Selden controlled as carefully as he could in a casual experiment. No one acknowledged this.

We have no published articles stating any car whose manufacturer doesn't require/recommend premium might benefit from its use. There must be lots of these if there was a perceivable improvement. Instead there are lots of articles stating that premium fuel in a car that doesn't recommend/require it is a waste of money.

 

Show me a published article that states this, please.

 

Steve you were so close to getting it right. All those people ran premium in a stock car. Unless selden had a ultra gauge or scan gauge and ran to empty and filled up with premium and did a reset of the ecu his numbers are bias. You just dont want to agree totally, but engineering sites is the closest your going to get to the truth.

 

Please find one, link it, and quote it for the truth. (Please don't post links to unrelated papers.)

Selden ran 1,500 miles, half on premium, half on regular. If there was an advantage this would have been apparent. Instead you guys are falling over yourselves to make excuses why there wasn't.

 

The two papers I posted today is enough for now. You are not asking questions that make sense. My wife gets lower mpg with premium because she cant adjust to the driving style. When your use to a certain driving style because of regular you wont get better mpg with premium because your driving the same. Premium allows you drive more efficiently. Dont twist my words steve look it up and find engineering sites and post it if dont make sense.

 

No, actually most of those articles are NOT about which is "better".

Most of those are simply about being ABLE to run regular gas in any engine that doesn't "require" premium. Because people are terrified of using "regular" gas in an engine that only "recommends" premium.

Now, go through ALL of those articles... link to any of them, that takes two identical cars, or even just one car that is in an absolutely controlled environment. Or at the least, on a "treadmill" in a room with a piece of wood holding the pedal down. Come on, HOW SIMPLE IS THAT?!? No.. notta one does that.

"We took two identical trips." Oh, except how the temperature changed through the passage of time during the day. Oh, forget about the changing in wind speeds and direction... "it's not THAT important." Yeah, and forget about the fact that before we used the premium, our driver took a nice lunch and is feeling like he needs to work off the calories through the pedal! (as if!).

Not likely. Those articles are just as suspect. A different day, different time, wind can change, slight pressure on the pedals can change. Traffic can DEFINITELY change. A driver's mood can impact it too, let alone TWO separate drivers.

I've yet to see a single article that has any meaningful control. They are about as trustworthy as Fox channels "fair and balanced" bs.

Want to save a few cents per gallon? Regular will do that. Whether it translates into actual MPG, or more specifically, $ per mile... is another story.

Again... the only way to see its effects... is to do the "experiment" yourself.

Or provide data from someone doing exactly this...

edit: Selden looks like the "victim of attacks" for a simple reason... he (and you) are trying to "justify" his claims. Did he at least mention that he put cruise control? Which, I'm sure even you will admit... is a better control than his legs on pedals.

One more thing... a 60-75 mph range is HUGE on mpg. I get MUCH better mpg at 60 than 75... MUCH.

Now, if he had ran multiple FULL trips on regular then, more multiple trips on premium with all being on the same time of year... maybe, I would give him more credit. But alas... half vs half of a single trip... not going to cut it.

 

I just spent the last 6 hours doing this... tallying up all of my gas receipts (76 of them in a little over 1 year).

https://spreadsheets.google.com/spre...mc&output=html

Everything after the first 5 columns is calculated data (formulas).

In 6 of the last 8 columns... the data is pulled from the NEXT receipt. Because if you just pumped gas, you can't get the mpg for the gas you just put in, until the next time you pump.

 

WOW - that's an interestingly complete account. Looking at your lifetime mpg numbers, premium really hasn't shown any increase in them. The interesting thing is your Fit costs you $0.15/ mile to fuel... good info, thanks for all that work!

 

The thing is... ever since I started pumping premium, I have been driving a little more "spiritedly." Along with the springs and tires...



(and it doesn't help that I idle a lot for deliveries).

 

How does the ecu work on the Fit? Does it advance the timing until it detects knock and then retards the timing slightly to obtain the most efficient burn? If so how does this relate to low and premium grades of octane?

 

Here's what Honda Owners Link say's about Fueling The Honda Fit...this is from HONDA...

Does it help to use a fuel with a higher octane rating than required in my Owner's Manual?

Refer to your Owner's Manual for the pump octane number recommended for your Honda. Use of a lower-octane gasoline than recommended can cause a persistent, heavy metallic rapping noise in the engine that can lead to mechanical damage.

There is no advantage in using a fuel with a pump octane greater than that recommended in your Owner's Manual.


So? They admit a "lower" octane can result in "rapping" but admit to no advantage to a higher octane.

To Me? It's NOT a big deal either way. I don't know if I'd necessarily call them "advantages" but I do notice some differences running higher octane. Mostly in the acceleration sound department...The engine seems quieter.

 

Car and Driver did it.

They conclude:
Here's the link to the November 2001 article.

They were using dyno tests and quarter mile results to gauge performance. Interestingly the Honda they used lost power and and gained seconds on premium fuel.

Their results are here.

Here are some of the setup details:

 

Very cool. Thanks for posting and +rep. (your "experience" level should be pegged). I'm not being sarcastic, really, thanks for the time you spent.

At first blush your data shows 0.55MPG gain using premium over regular. You have 42 premium data points and 34 regular data points. I think this is a large enough sample to draw conclusions. The only thing that may be an issue is the periods where the different fuels were used. Regular was used in the summer/fall (June through January) and premium was used in the winter/spring (January through June). Anecdotally, people report worse mileage over the winter, so this may skew results against premium.

I'll do some analysis and report back.