# Fuel economy and octane, 2005 Frontier



## Reverendbiker (Jan 29, 2005)

I have just completed my test of fuel economy using 87-octane vs. 93-octane. To read about it, click here:
Fuel Economy Test


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## islander (Jan 29, 2005)

Reverendbiker said:


> I have just completed my test of fuel economy using 87-octane vs. 93-octane. To read about it, click here:
> Fuel Economy Test


I agree with your statement that the price difference is not worth the switch for mileage gains; however, (excuse my ignorance) does not premium fuel offer any other benefits in maintaining the overall condition of the engine? Otherwise, does Premium fuel contain any other agents that regular lacks that keeps the engine running cleaner and efficient over time?
Islander

ps. Thanks for posting, I was wondering if there was much of a difference. I usually alternate ie. 91,89,87,91,89,87, etc. etc.


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## Reverendbiker (Jan 29, 2005)

islander said:


> I agree with your statement that the price difference is not worth the switch for mileage gains; however, (excuse my ignorance) does not premium fuel offer any other benefits in maintaining the overall condition of the engine? Otherwise, does Premium fuel contain any other agents that regular lacks that keeps the engine running cleaner and efficient over time? Islander


I was afraid that I would open this can of worms. We'll soon be bombarded with personal opinions, anecdotal evidence, and pure fairy dust about the relative benefits of regular vs. premium fuel. Here are some facts that are pretty well supported by research:
-It is best to use the fuel recommended for your particular engine. "Treating" your baby to a tank of premium is an absolute waste of money if she has been designed to run on regular. As a vehicle ages, carbon deposits in the combustion chamber might require the use of higher-octane fuel.
-U.S. Government regulations require that all gasoline contain detergent additives. Of course, not all additives are the same, but the "good for your engine" claims are mostly marketing hype from the oil companies. There is some evidence that the use of premium fuel in engines not designed for it can actually create harmful deposits on the valves. If you're worried about clogged injectors, run a can of injector cleaner through the tank every 6 months or so.
-My 2005 Frontier owner's manual says that the recommended fuel is minimum 87 octane. The next paragraph states that 91 octane can be used for improved performance; as my tests have shown, there is very little (if any) improvement in fuel economy with premium. Is there actually a horsepower increase? I'll let you know next week--I have a dyno testing session scheduled and I'll file a report.


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## jerryp58 (Jan 6, 2005)

Reverendbiker said:


> I have just completed my test of fuel economy using 87-octane vs. 93-octane. To read about it, click here:
> Fuel Economy Test


I thought 93 octane was the recommended fuel for the 6-cyl, no?

You don't get any pinging under load?


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## Reverendbiker (Jan 29, 2005)

jerryp58 said:


> I thought 93 octane was the recommended fuel for the 6-cyl, no?
> 
> You don't get any pinging under load?


No, and no. As stated in my earlier post, 87 octane is the minimum recommended in the owners manual for the 4.0 V-6. Nissan' s rating of 265 HP was done on 87 octane, probably as a competitive edge to Toyota which uses premium fuel to get 245 HP from the Tacoma. My truck runs perfectly well on 87-octane with no sign of pinging, even under heavy load. If you've checked out my page on dyno testing you'll see that my truck managed 222 REAR WHEEL horsepower on 87-octane (very impressive, and showing that Nissan's 265 crank HP might even be conservative) and we had no pinging during the testing. To see the tests, click here:

dyno tests


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## jerryp58 (Jan 6, 2005)

Reverendbiker said:


> No, and no. As stated in my earlier post, 87 octane is the minimum recommended in the owners manual for the 4.0 V-6. Nissan' s rating of 265 HP was done on 87 octane, probably as a competitive edge to Toyota which uses premium fuel to get 245 HP from the Tacoma. My truck runs perfectly well on 87-octane with no sign of pinging, even under heavy load. If you've checked out my page on dyno testing you'll see that my truck managed 222 REAR WHEEL horsepower on 87-octane (very impressive, and showing that Nissan's 265 crank HP might even be conservative) and we had no pinging during the testing. To see the tests, click here:
> 
> dyno tests


COOL!

I just looked at my '04 Owner's Manual again and it is only the supercharged 6-cyl that requires a higher (91) octane rating -- I thought I had seen all 6-cyls as 91. :crazy: 

BTW, very nice Website.


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## islander (Jan 29, 2005)

Thanks for answering my questions.
This is good to know. Regular fuel right now costs $.93 a litre and Premium costs $1.00 per litre. Or $3.53 a gallon for regular and $3.8 for a gallon of premium. Big difference in price makes a big difference in my wallet. 
Islander


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## Front'in (Jul 1, 2005)

I dont know if anyone knows, but the octane is used primarily to control detonation. Higher the octane, it retards the timing. The lower...etc...etc...


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## Reverendbiker (Jan 29, 2005)

Front'in said:


> I dont know if anyone knows, but the octane is used primarily to control detonation. Higher the octane, it retards the timing. The lower...etc...etc...


Actually it's just the opposite--the higher the octane the more you are able to ADVANCE the timing. The 2005 Frontier owner's manual states that the minimum fuel requirement was 87-octane but higher octane could be used for increased performance. I only ran this test to see whether this engine made significantly more power on 93-octane than it did on 87; my (admittedly unscientific) dyno test indicated that it didn't. Since that time I have used only regular unleaded fuel and my engine runs happily on it.


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## Gerald (May 23, 2005)

*Fuel economy and octane*

Reverendbiker,

You are the greatest. You do a lot of time consuming research for the rest of us and I for one want you to know
that your time and effort is greatly appreciated.

Keep the information coming as it is always interesting.

Gerald






Reverendbiker said:


> I have just completed my test of fuel economy using 87-octane vs. 93-octane. To read about it, click here:
> Fuel Economy Test


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## Reverendbiker (Jan 29, 2005)

Gerald said:


> Reverendbiker,
> 
> You are the greatest. You do a lot of time consuming research for the rest of us and I for one want you to know
> that your time and effort is greatly appreciated.
> ...


Thanks, Gerald. I am still waiting to see if anyone comes up with a well-designed intake kit so that I can test it. AFE is about to sell one that looks promising, and they are claiming an 11HP increase. Can't wait to get one installed and put the truck on the dyno. Stay tuned...


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## DHHawaii (Jul 19, 2005)

Reverendbiker, check out this thread from another board. They may be getting ready for a mass order. And I really appreciate all the time you spent letting all of us know how things are going with your truck and for showing me my trucks potential. At least I can dream...


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## Reverendbiker (Jan 29, 2005)

DHHawaii said:


> Reverendbiker, check out this thread from another board. They may be getting ready for a mass order. And I really appreciate all the time you spent letting all of us know how things are going with your truck and for showing me my trucks potential. At least I can dream...


Thanks, Bro. I have been watching that thread and am ready to jump in on a group buy if they can get one together.


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## Front'in (Jul 1, 2005)

Reverendbiker said:


> Actually it's just the opposite--the higher the octane the more you are able to ADVANCE the timing. The 2005 Frontier owner's manual states that the minimum fuel requirement was 87-octane but higher octane could be used for increased performance. I only ran this test to see whether this engine made significantly more power on 93-octane than it did on 87; my (admittedly unscientific) dyno test indicated that it didn't. Since that time I have used only regular unleaded fuel and my engine runs happily on it.


Octane retards timing.....it help pre-ignition. Yes, it allows you to advance timing to correct the ignition phasing.


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## Reverendbiker (Jan 29, 2005)

Front'in said:


> Octane retards timing.....it help pre-ignition. Yes, it allows you to advance timing to correct the ignition phasing.


Don't know how we got on this discussion, but higher octane does absolutely nothing to retard timing. Knock sensors retard timing.


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## Front'in (Jul 1, 2005)

Reverendbiker said:


> Don't know how we got on this discussion, but higher octane does absolutely nothing to retard timing. Knock sensors retard timing.


Do your reseach....I race motorcycles...it makes a difference on a standard ignition system. You tune according to your octane....especially on 2 strokes.

9:1 engines can use lower octane gas. 11:1 engine will only run on higher octane gas, which is due to the fact that it needs to fire at the right time. Lower octane will "pre-ignite". Octane is meant to keep your pistons from knocking, plain and simple....remember, octane keeps fuel from burning...the hight the octane the longer it takes to ignite.....


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## Reverendbiker (Jan 29, 2005)

Front'in said:


> Do your reseach....I race motorcycles...it makes a difference on a standard ignition system. You tune according to your octane....especially on 2 strokes.
> 
> 9:1 engines can use lower octane gas. 11:1 engine will only run on higher octane gas, which is due to the fact that it needs to fire at the right time. Lower octane will "pre-ignite". Octane is meant to keep your pistons from knocking, plain and simple....remember, octane keeps fuel from burning...the hight the octane the longer it takes to ignite.....


I have done my research. I have worked on performance cars and bikes for over 40 years and am an ASE-certified mechanic. The statements you made here are absolutely correct. What I disagreed with was your statement that high-octane fuel retards timing, which is absolutely incorrect. And we're talking about ecu-controlled engines, not 2-stroke motorcycle engines--you can't "tune" these engines to a certain octane because you can't adjust the timing without re-programming the ecu.
Ths VQ40 engine in the frontier is tuned to run on 87-octane fuel, and apparently produces the advertised 265 crank HP on it. The owners manual says that use of premium fuel can produce increased performance; that would mean that the ecu will actually advance the timing somewhat when the knock sensors indicate that it is safe. Most OBD-II engine management systems do not have this feature, and can only retard timing when they detect detonation. I ran the dyno tests to determine whether the use of 93-octane fuel would produce significantly more power in the VQ engine than did the use of 87-octane; it appears that if there is any additional performance to be gained from the use of premium in this truck it is minimal and not worth the higher cost.


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## Front'in (Jul 1, 2005)

Yes....the ECU factor. I'm so use to a static system and working around types of fuel...forgot about ECU's. As you can tell, I'm a motorcyclist. Technology in our parts are not yet up to snuff. Still leaning how to use programmable ECU unit for bike...nothing like 128-bit units in cars. 

FUZZY LOGIC.....


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## Reverendbiker (Jan 29, 2005)

Front'in said:


> Yes....the ECU factor. I'm so use to a static system and working around types of fuel...forgot about ECU's. As you can tell, I'm a motorcyclist. Technology in our parts are not yet up to snuff. Still leaning how to use programmable ECU unit for bike...nothing like 128-bit units in cars.
> 
> FUZZY LOGIC.....


When cars and light trucks went to OBD-II, it completely changed the rules for us old school hot-rodders; I had to become less of a mechanic and more of a programmer. Better get used to the same thing on motorcycles, too. My last couple of street bikes had digital fuel injection controlled by the ecu. Instead of changing the carb, timing, and/or cams to hop up my Suzuki DL1000 I put it on a dyno and use a PowerCommander III to modify the fuel injection pulses at several different throttle positions. I just wish that someone made an ecu programmer like the Super Chips tuner for our Frontiers...


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## Front'in (Jul 1, 2005)

Reverendbiker said:


> When cars and light trucks went to OBD-II, it completely changed the rules for us old school hot-rodders; I had to become less of a mechanic and more of a programmer. Better get used to the same thing on motorcycles, too. My last couple of street bikes had digital fuel injection controlled by the ecu. Instead of changing the carb, timing, and/or cams to hop up my Suzuki DL1000 I put it on a dyno and use a PowerCommander III to modify the fuel injection pulses at several different throttle positions. I just wish that someone made an ecu programmer like the Super Chips tuner for our Frontiers...


I've messed with a DJ PCIII on an 2001 F4i years ago. It was just a fuel unit, no ignition module. Seemed to be the safest bike to learn (family bike). All I did was upgrade parts and dropped in downloaded maps. Static unit....which does a very good job for the $$. I just wish I had a wide band to see what it is doing. It's good to see another member into riding. My street bike is a DukeII, have an SX125 for dirt, and modded YSR's for my track aggression. The big bikes are WAY too costly to race....plus they are to squidy for the street...(can of worms).

In regards to the Frontiers, we can add a module. Just need to get ride of the OBD thing. Too bad it is a no..no. If everyone is interested, they should make a call to SuperChips...you never know. If you guys dont call..they will never know.


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## eggman (Nov 30, 2004)

[. Just need to get ride of the OBD thing. Too bad it is a no..no. If everyone is interested, they should make a call to SuperChips...you never know. If you guys dont call..they will never know.[/QUOTE]


I live 45 mins from the superchips main office in FL...Hmmmm :banana: 

Maybe they can use my truck as a guinea pig...lol
Jay


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