fuel octane

<font face="Verdana, Arial" size="2">Originally posted by jag:
Stay with the 87. On trips at 65-75 on interstate driving our 2000 LX has logged 27-28 mpg. This has been with any brand of 87. I used 87-89-93 on my other Honda's and got the same mileage with no increase in performance! Are you aware that higher octane burns slower and the reason higher octane reduces an engine-knocking problem. Also using higher-octane fuel when it is not specified for that engine may increase carbon build-up in the engine. Save your money and only use the lowest octane recommended. All my Honda's since 1983 have performed with the 87 and have run well over 200K miles.

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The Odyssey is not like other Hondas. It IS specified to run and get better performance on high octane gasoline. The computer control and VTEC allow it to get a boost of 5HP and 12 ft-lb of torque on high octane, as specified by Honda. Whether it's worth it or not is debatable, but it is not necessarily a waste of money as it is on many other cars, especially if you tow or want shave every fraction of a second off-the-line. One review I read claimed that premium unleaded shaved a nearly a second off the Odyssey 0-60 time compared to regular...


I've used Shell/Mobil/Speedway 87 octane for the first 4000 miles. I might try a few tanks of 93 Octane to see if it affects fuel economy in addition to performance, but I'll wait to do that until my mileage has stabilized now that winter is almost over.

[This message has been edited by caviller (edited 03-29-2001).]

I'll be using premium gasoline with 91-93 octane on my Odyssey from now on after reading this at car.com:

"If your car requires high-octane gasoline and you habitually use regular gas because the engine exhibits no sign of knock, you’re outsmarting yourself. Most modern, computer-controlled engines include a knock sensor that detects knock and retards the ignition timing, causing the spark plugs to fire slightly later in the cycle. This typically prevents abnormal combustion and knock, which allows vehicles specified for premium fuel to run on lower-grade gasoline if it is all that’s available. While this removes the immediate hazard, it’s a bad idea to make a habit of running a vehicle on gasoline of lower-than-recommended octane. Retarding the spark causes a richer fuel/air mixture, which decreases fuel economy, increases emissions, causes the engine to run hotter, and reduces the longevity of both the engine itself and the catalytic converter. The money you save by pumping low-grade fuel into a car that demands higher octane is lost anyway, in decreased fuel economy and possibly gradual damage."

You can read the whole article at:

http://www.cars.com/carsapp/national/?srv=parser&act=display&tf=/featu res/truthabout/gas/todaysgas1.tmpl


[This message has been edited by MarioB (edited 03-29-2001).]

Hi MarioB,

Read the article, and I think the key is "required" octane. Article also mentions owner's manual recommendation. The 2001 Owner's Manual says on page 196, "Your Honda is designed to operate on unleaded gasoline with a pump octane number of 86 or higher." Also, on the last page, "Unleaded gasoline, pump octane number of 86 or higher."

When we ordered ours, we were told by the dealer that they only use 87 octane. When we picked it up, it came with a full tank of 87 octane, the Customer Service Manager said to just use 87 octane, no need to waste money on higher octane. He did say that when towing, we may want to go to premium octane for a slight boost in torque. Which coincides with what the Owner's Manual says on page 231 concerning Towing a Trailer, "You may want to fill the fuel tank with premium fuel. Premium fuel provides improved performance."

So, I don't see premium as being required, I see it as 86 or higher being required and recommended. We also used to run higher octane in our Accord until a few years ago, after watching an expose about what people really are getting at gas stations. The gist of it was you were as likely to get 87 octane no matter what nozzle you used or button you pushed. They showed the same truck filling all the tanks, etc. They only found one or two stations in their under-cover research that actually gave the appropriate higher octane for the higher price. They summized that if your car ran okay on 87, you might as well buy it ... as that's what you probably are getting anyway. So, from then on we started using 87 in the Accord, and have never seen any difference, including mileage. Maybe, as your article suggests, since modern engines have computers that compensate, gas stations can more easily get away with it... who knows?

I realize on the Ody, you'll get about 205 hp on regular versus 210 on premium... but is 5 hp worth an extra 20 cents a gallon? Not to me, unless I'm towing. Now, if someone can demonstrate to me actual mpg improvement specifically on the Ody using premium over regular, ...enough so to more than compensate the higher price per gallon for premium, then you might have something. The article eluded to that for vehicles that "required" and recommended higher octane in their Owner's Manual... I'm not reading that as the situation of the Ody.

At this point, I plan to continue to use 87 octane.

Although, it's nice to know that no matter what car you siphon gas from... you'll have the right octane for your Ody! LOL, only kidding!!!

Best Regards,
Skybolt








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2001 Starlight Silver LX
Splash Guards
Cargo Tray
Cargo Mat
Keyless Remote Entry & Alarm
Trans. Oil Cooler
Tow Package
Fog Lights

<font face="Verdana, Arial" size="2">Originally posted by fordsdad:
the magazine articles i have read and kept on file (road and track, consumer report and motor trend) since the introduction of the new odyssey have shown premium as the recommended fuel. only in the last few months have i read that anything above 86 octane is ok. i understand that the engine will run on the lower octane fuel but, what did the engine designers really want the vtec to run on?

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I've noticed a couple of posts that implied that VTEC is a factor in the engines octane requirements. I don't think this is the case with the Odyssey. In modern cars, the octane requirements of the engine are geared more toward compression ratios and how aggressive the fuel and ignition timing curves are. While the Odyssey does have VTEC technology, it's engine is still in a relatively mild state of tune when compared to other Honda VTEC engines. The VTEC on the Odyssey is gear more toward improving low and mid range power than top end power as it is in something like an Integra. All a higher octane fuel does for the Odyssey is allow the computer to run the ignition timing a bit more advanced which accounts for a few more horsepower but otherwise, I doubt the engine cares.

FWIW,
Steve

Holy smokes batman!! I don't know who writes all these "analysis" that have been referenced in this thread but it is really very simple: using 87 minimum pump octane gas will NOT harm the Odyssey engine in any way, shape, or form. It simply removes some spark advance based on feedback from the knock sensor as many have already said in this thread. This simply reduces rated hp from 210 to 205 and torque is likely affected also.

It will not make the engine run richer. The engine always runs at stoichiometry, unless, of course it is in power enrichment mode under whater acceleration conditions Honda has chosen. Stoichiometric engine out constituents are essential to the catalysts to operate properly and Honda would not pass emissions unless that worked very well.

It will not make the engine run hotter or any other undesireable type of condition. It just doesn't have as much spark advance available and therefore calculates the appropriate fuel schedule based on the conditions at that moment in time. Carbon build up with 87 octane? What?? If true, that would happen with any car using 87 octane gas.

Premium gas, as someone said already, literally does burn "slower" but a better description is that it burns at a more controlled rate with less propensity to autoignite or "knock". This allows use in higher compression engines and/or takes advantage of engines with knock sensors, VTEC, turbos, etc...

So there!



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Jim

Here is a link to an article on Gasoline. MOre info than you ever want to know about gasoline. Enjoy

ftp://rtfm.mit.edu/pub/usenet-by-hierarchy/rec/autos/tech/Gasoline_FAQ_-_Part_1_of_4/

ftp://rtfm.mit.edu/pub/usenet-by-hierarchy/rec/autos/tech/Gasoline_FAQ_-_Part_2_of_4/

ftp://rtfm.mit.edu/pub/usenet-by-hierarchy/rec/autos/tech/Gasoline_FAQ_-_Part_3_of_4/

ftp://rtfm.mit.edu/pub/usenet-by-hierarchy/rec/autos/tech/Gasoline_FAQ_-_Part_4_of_4/

woops, that didn't work. Have to go the long route.

http://rtfm.mit.edu/

Go this site which than lets you go to
Usenet FAQ archive
from there select the "rec" directory, then "autos" then "tech". Enjoy

[This message has been edited by exindenver (edited 04-01-2001).]

Gasoline:

In case anyone didn't realize it, every state has different requirements for their gasoline that is sold in that state. In many states, they allow excess amounts of alcohol in their gasoline, which to be brutally honest negates any "octane rating" whatsoever- with the amounts of alcohol that they are allowed to put in the gas, 81-93 octane all ends up burning the same. Secondly, most states give an octane "allowance", an allowed variance if you will, for instance +-2 points. This means that a gas company can concentrate on highly regulating one single batch of gasoline at 89 octane, and it can be fed into 87 octane tanks and 91 octane tanks. Some states allow up to a +-4 octane rating! So even in states that allow +-3, you can still have the 87 octane pump pumping the same gas as the 93 octane pump, but you're really only getting 90.

As well, as is obvious with these exorborant (sp?) prices, the gas companies are allowed to lie, cheat, and take advantage of us, with no one to answer to. Do you think any state that's getting 46 cents on the gallon for every gallon sold is going to complain?

Additionally, with all these other additives that they put in gasoline these days, like gasline antifreeze and fuel injector cleaners, the octane rating just doesn't matter much anymore.

Lastly, I think you'll find that while the VTEC is working in the engine, the knock sensor is probably overridden by the VTEC timing settings. The reason the VTEC gets better performance from the premium gas is assumed to be from more complete and efficient burning, because the whole idea behind VTEC is precision timing. But there's no reason why the VTEC "needs" the premium gas.

PS- All the mags and reviews may say that the Odyssey "requires" premium, but that's most likely because they misread Honda's "recommendation"- most car companies either say "required" or nothing at all- and it's probably assumed that "recommended" means "required", when it does not.

<font face="Verdana, Arial" size="2">As well, as is obvious with these exorborant (sp?) prices, the gas companies are allowed to lie, cheat, and take advantage of us, with no one to answer to. Do you think any state that's getting 46 cents on the gallon for every gallon sold is going to complain?</font>

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I work for an oil and gas exploration and production company; I can't speak for the refining end of the business but to my knowledge my company doesn't lie, cheat, or take advantage of anyone, nor would we be permitted to by the government or the states if we were to try. The oil and gas (and refining) industry is one of the most highly-regulated industries in America. The problem the previous poster is referring to is not one of dishonesty by any particular industry but one of simple supply and demand - the more gasoline Americans want and the less supply of it there is to go around the higher the price will be to purchase it. (Sound familiar to anyone who has recently purchased an Odyssey minivan???) Have you bought a gallon of milk lately? Chances are you paid more than the gasoline you're currently buying. If the price for a gallon of gas had gone up over the last 20 years at the same rate as a gallon of milk, we'd be paying around $6.00 per gallon. Are the dairy farmers lying, cheating and stealing? We consumers control our own choices - such as to not buy Odyssey minivans at MSRP or above, and to curtail our driving when gasoline goes higher.

--------
David

[This message has been edited by groupset (edited 05-14-2001).]

2002 different octane requirements

The salesman that helped us when we bought our van said something very puzzling about the octane requirements. I believe (don't have my manual in front of me) that the requirement for the 2002 is the same as before, "use 86 octane or better". Here in Salt Lake City, the regular unleaded octane is 85, medium grade is 87 and premium is 90 or 91, I think. The sales man told me that they asked Honda if it was okay to use 85 instead of 86 and that Honday said that was fine. In fact, he was told that you should NOT use the premium gasoline because it burns hotter and is not good for this particular engine.

This puzzled me. I am not octane scientist but I had never heard anything like that before. Does this make sense? Does the new engine in the 2002 have these peculiar requirements? I really haven't asked anybody else about it but I saw the thread and figured I'd post this question.

Thanks,
Jeff
'02 EX