OK Subie.. All I'm going to say is, my owners manual only mentions 87 octane once. It was a warning to not use gasoline with with an octane rating below 87. There was no mention of a recommended fuel grade. That is all.

 

Choice and preference... That is all.

 

Exactly. I was talking more of the 09 and newer with the eco cam but the GD3 is similar.

No octane debate needed. Its about timing and lack of with knock.

 

I see that knock causes oil consumption but don't have exact numbers. Honda likes Moly in the oil and from other people seen better results with this new Mazda 0w20 GF5 oil with Moly especially after using M1. New 0W-20 Synthetic Motor Oil from Mazda - CleanMPG Forums

 

This is some of what I've been reading.

http://www.ijetae.com/files/Conferen...SD_0213_16.pdf
http://www.ijetae.com/files/Volume3I...AE_0313_42.pdf

Can't post the paper you want to see. Site was moved or closed. It seems someone found it and took it off like others I can't find anymore.

 

Vtec engagement on a GD is between 2500-2800 that has been settled by flashpro installation and spec. So they are not the SAME.

And the ECM adds timing with higher octane fuel ACROSS the board not at specific ranges.

 

I got them open and they are about alternate fuels NOT octane. And further don't apply to either version of the Fit engines as the ECM automatically controls ignition timing.

 

When they talk about alt fuels they are talking octane because ethanol is higher in octane and that is what they use to raise octane now. I was just showing what I am reading now and has seen this and felt this. I know the vtec comes in at 3500 which is the crossover from 3 to 4 valves. On the ivtec it won't go into econ mode under knock conditions and what vtec really is econ or normal mode and is not performance like the K series or dual cam vtec on some B series motors.

Here is what you're waiting for and some of you guys know that there is up to 10 degrees of retard if knock is present from MBT. They are comparing Natural Gas to Gasoline and using timing instead of octane. Make of it as you will because I am sure not everyone understands it.

http://www.buet.ac.bd/me/icme/icme20...ME05-TH-36.pdf

 

Did you actually read that article entirely? They state that one for one, an engine running gasoline versus natural gas, the gasoline motor WINS EXCEPT in the case of finding the PERFECT timing setup for the natural gas.

Once the perfect timing is found, then the advantages take over.

Ill stick to a well known easy to tune gasoline engine. All you need is the proper fuel ratio, and enough timing to make use of the motor without beating your top connecting rod bearing to death.

Honestly, in my opinion, if natural gas was worth it, more people would be using it. Honda offers natural gas vehicles, and has been for several years, but they do not sell very well. All they managed to do was provide a great all motor piston for us oldschool D series NA builders.


FYI, via a quick google search, the 2012 civic NG car only was rated for 38mpg, which roughly translates into maybe a 45-46mpg best (Seeing as honda underrates all their vehicles for marketing purposes and covering their asses if you actually get the rating)

Comparison, my buddy's wifes' 2009 civic R18 automatic 4dr normally gets over 40mpg with the whole family inside (2 kids, plus one on the way)

 

As to point one nope you are misreading the thing. It is not just the octane number it is the TYPE of fuel making the difference. And it still doesn't apply to the stock Fit as the ECM CAN NOT adjust to alternate fuels uless you have something like flashpro.

You haven't been keeping up much on GD Vtec just read up on the threads and the flashpro specs and you will learn that it is 2500-2800. And there are two types of cam profiles on the GD and it ALSO moves to the higher lift cam when in VTEC.

 

I was not comparing Gas to natural gas. They were and using charts to show how higher timing (ie premium) lowers oil temps. Use what you will but I am getting great mpg 25 percent higher than Honda said. Higher than most hybrids and NG engines. They are talking more about NG because its more plentiful and higher in octane.

I know what the Civic R18 gets I own one. My Fit got as good as my 2010 Civic and my 12 is getting close to 50 mpg average and on the highway its over 60 mpg on the ultra gauge.

 

There are people on this forum that has successfully mixed E85 to the point close to E50 with no problems except a CEL light once in awhile and they did that before Flashpro. Maybe you should tell them there ecu did not adjust and that it won't work.

The Vtec comes in at 3500 which it goes it to normal mode that all four valves open. You can adjust vtec with the flash pro to whatever you want so that is what you were reading. The Truly Amazing Honda Fit/Jazz

Honda L15 is the base for a lot of racing and is a great building block. Honda Racing Parts & Engines - Honda Performance Development

 

Heats of combustion for naturak gas (18k bTu /lb) is about 20% higher than gas(19k/lb) and burns cleaner so yes natural gas is a better fuel. finding the best timing to initiate burning is the same process for both and isn't much different.
The reason more cars aren't running on natural gas is the supply is very difficult to do. Transporting and storing and dispensing compressed gas is many times hader than for liquids like gasoline. Now for cars its a lot like the system for using propane for home fuel. Put that in the trunk of your car. And think of the result of even one compressed nat gas ruptured in a wreck.
The trick many of us are working on is finding that system that converts natural gas to a liquid so it will be a suitable fuel for all applicatuons including substituting for gasoline. Sure, fuel injectors and carb jets require a change but thats about it and its not hard..

PS so far I've bet lunch to about a dozen people who stated they got 40+ mpg on their Civic (not hybrid) and haven't lost once; most just don't know how to calculate mpg.

 

The Dallas Morning News had a fleet of natural gas powered delivery trucks from the mid 1950s until 1982.. The engines needed very little maintenance and wouldn't wear out.. We had a few cold winters and got late deliveries to the districts because they could barely go the speed limit or make it up hills when the weather was below freezing... They were replaced by Mercedes Benz Diesels..

 

The bottom line is that if you think putting higher octane fuel reduces your oil temps or what ever then enjoy yourself spending money on octane that doesn't do anything to your car. If Honda thought that your Fit needed higher octane gasoline they would have recommended that in your owner's manual. Using higher octane fuel is just like burning your money in the engine and letting it go up in smoke out the tailpipe.

 

If that is what you want to believe that's fine... I have seen the results gained by monitoring a scangauge and stopwatch readouts from using fuel with higher octane rating.. The ECU would not advance the ignition timing with higher octane fuel if not to increase the power output of the engine.. There is a limit on how low of an octane rating you can use in a Fit but no limit on how high of an octane rated fuel you can use.. There have been quite a few guys over the years that thought the same as you until using a scangauge and other tools that gave computer readouts on graphs and saw for themselves.. Some of them said they couldn't go back to using low octane stuff after experiencing the improvement in performance.. Until you have a scangauge type gauge and can see what's going on when you are driving you are only speculating about things that you have minimal knowledge of.

 

You surprise me saying that. You should know how important good oil and fuel is being a pilot and all.

Honda has had adaptive ecu for years before everyone else. The owners manual says 87 or higher and it also says it adjusts timing constantly and if work(tune up) is done to remove the battery cable to erase the RAM that it uses to run properly to retune from the work done. If knock happens it detunes the whole rpm band. The engine is tuned for 91 octane for MBT timing and as it hits MBT timing in different rpm range it fine tunes the motor and the engine become more efficient over all rpm ranges including the high load range.

 

Frankly jet engines run on aviation grade kerosine which is basically number 2 diesel or fuel oil. They can burn any thing you can squirt into the burner assembly under high pressure. There is no timing because we only use the igniter plugs to start the engine. Once it's running it's self igniting. For safety we turn the ignition on for takeoff and landing in the event there is an interruption in the intake air the engine might relight Jet engines use synthetic oil such as Mobil Jet II or Exxon 2380. The oil never gets dirty because it never comes in contact with the combustion process. The oil is forced through the bearings under high pressure and recovered to a separate oil tank. The oil cooler uses the fuel to cool and melt any moisture in suspension in the fuel. The rotating parts turn at RPMs in the 30,000 RPM range. The fuel and oil systems have to operate at ambient temperatures from +50C degrees to -50C.

Piston engine cars and jet airplanes are totally different things. BTW my 2000 Accord Coupe V6 uses no oil between changes running on regular motor oil and regular 87 octane gasoline for 158,000 miles and still going strong.

The higher cost of higher octane fuel offsets any increase savings in milage or performance.

 

(The higher cost of higher octane fuel offsets any increase savings in milage or performance.)
That depends on where you drive, how you drive and how much you value performance.. In stop and go city driving where you spend a great deal of time sitting and waiting for traffic lights to change, you are losing quite a bit of money. In hilly back roads the exhilaration I experience is worth the difference in price as is having enough power to pass slow moving trucks on 2 lane highways...Driving at high speeds, which is common in the fast lane on interstate highways in Texas, I usually broke even in the cost difference between doing that with 87 octane and 93 octane fuel.. I can't say the same for my sidecar rig though.. It overheats in stop and go traffic and lacks power running on 87. It does fine in all types of riding on 89 octane.. The ECU on it lacks the ability to adjust the timing to run on 87 or benefit from 93 octane like the Fit and other more recently built cars do.. If I hadn't been able to feel a difference in performance in my Fit I would have used the one of the two more affordable grades of fuel...You must drive fast and hard for at least a few seconds a few times every time you drive in order for the ECU to recognize the need to maximize the amount of ignition advance to optimize fuel mileage and performance for load and speed.. I was consistently getting 37 to 39 MPG driving at 85 and 90 when my car was still in it's stock form.. That's the same as I got feather footing the accelerator pedal at 65 and 70..

 

This has been a very informative thread. I've learned about jet engines and octane and all kinds of neat stuff.
Personally, I'd still top up the half litre of oil. But that's just me.