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Discussion Starter #1
Hi all,

Not trying to beat a dead-horse here or bring up an old thread from the grave. I got one of th 2.5L 4-cyl RWD engines. So far I'm on my second tank in the brand new truck. Drove it home from Ohio to Virginia and averaged about 22.5 mpg crusing at 65-70ish.

After reading a lot of blogs it seems like the only way to save efficiency is to drive cautiously and not mash the pedal, which I'm fine with.

Has anyone tried to fill mid or premium grade fuel? Does it have any effects on power or fuel economy? I'm thinking about giving it a try on my next fill up, which may be awhile since we're all in quarantine right now and I have nowhere to go haha! Thanks guys.
 

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Hi all,

Not trying to beat a dead-horse here or bring up an old thread from the grave. I got one of th 2.5L 4-cyl RWD engines. So far I'm on my second tank in the brand new truck. Drove it home from Ohio to Virginia and averaged about 22.5 mpg crusing at 65-70ish.

After reading a lot of blogs it seems like the only way to save efficiency is to drive cautiously and not mash the pedal, which I'm fine with.

Has anyone tried to fill mid or premium grade fuel? Does it have any effects on power or fuel economy? I'm thinking about giving it a try on my next fill up, which may be awhile since we're all in quarantine right now and I have nowhere to go haha! Thanks guys.
There is no more energy in mid-grade or premium fuel. The only way that it would work is if your truck was tuned for higher octane and therefore ran poorly on regular.
 

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Discussion Starter #3
I see. Yeah that's probably not worth the hassle. I don't use the truck too often anyways. Thanks for the speedy response!
 

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the only thing the increased octane does is to SLOW the speed of the flame travel while your gas is being burned in higher compression ratio motors.If you don't have 12:1 compression or greater it wont do anything but burn a hole in your wallet.
 

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the only thing the increased octane does is to SLOW the speed of the flame travel while your gas is being burned in higher compression ratio motors.If you don't have 12:1 compression or greater it wont do anything but burn a hole in your wallet.
What you described is more of how an alcohol (methanol/ethanol) fuel burns compared to how petrol fuels burn...slower burn rate for alcohols. All petrol grades burn at the same rate once spark ignited.

Octane is simply a fuel's resistance to ignition by heat/pressure. The higher the octane the more heat/pressure it can stand before igniting. All grades of petrol will immediately ignite when the spark plug pops and burn equally as fast. The reason why high compression motors need high octane petrol is to avoid accidental pre-ignition from the high cylinder pressures/heat they generate from high compression ratios. Advancing the timing will also create higher cylinder pressures and more heat.
 

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You will get better mileage with premium, but it cost 15-20% more, so your savings are nil.
Your engine management computer will advance ignition timing up to 45 degrees and will pull it back when it detects knocking. Premium fuel is more resistant to knocking, so timing will stay further advanced than with regular, giving better mileage.
 

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You will get better mileage with premium, but it cost 15-20% more, so your savings are nil.
Your engine management computer will advance ignition timing up to 45 degrees and will pull it back when it detects knocking. Premium fuel is more resistant to knocking, so timing will stay further advanced than with regular, giving better mileage.
Where did you hear that?




 

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You will get better mileage with premium, but it cost 15-20% more, so your savings are nil.
Your engine management computer will advance ignition timing up to 45 degrees and will pull it back when it detects knocking. Premium fuel is more resistant to knocking, so timing will stay further advanced than with regular, giving better mileage.
Only in a scenario where your engine would constantly ping due to running low octane fuel would the above would be true. But our engines are built and tuned to run on the lowest octane fuel's...so this is not true for our trucks. All grades of fuel will return equal fuel efficiency in our trucks.

Now if you are referring to a Corvette or a Viper that is built and tuned to run on higher octane fuels and you dumped some regular unleaded in it...then your theory would be correct. But you'd have to be on a professional level of stupid to do that.
 

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In all my trials, I've never seen higher MPGs from higher octane fuel.
 

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Discussion Starter #11
Hahaha

Looks like i'll just pump regular and be easy on the throttle. With all this quarantine stuff I only ran a quarter tank with just doing regular grocery shopping and errand runs that totaled a little over 100 miles. So far so good!

At the end of the day, it is a truck. So it's going to suck on bad mileage. I've heard people say you will save fuel by buying a tonneu cover. But I think that's false too. Although I will probably end up getting on eventually just because I like to have my grocery dry when it gets home if it rains haha.
 

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Yeah gas is finally at a decent price and I'm not driving much so don't need any of it...FML.
 

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Only in a scenario where your engine would constantly ping due to running low octane fuel would the above would be true. But our engines are built and tuned to run on the lowest octane fuel's...so this is not true for our trucks. All grades of fuel will return equal fuel efficiency in our trucks.
.
"For improved vehicle performance, NISSAN rec-
ommends the use of unleaded premium gasoline
with an octane rating of at least 91 AKI number

(Research octane number 96)."
-- 2005-2008 Frontier Owner Manuals.
 

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What you described is more of how an alcohol (methanol/ethanol) fuel burns compared to how petrol fuels burn...slower burn rate for alcohols. All petrol grades burn at the same rate once spark ignited.

Octane is simply a fuel's resistance to ignition by heat/pressure. The higher the octane the more heat/pressure it can stand before igniting. All grades of petrol will immediately ignite when the spark plug pops and burn equally as fast. The reason why high compression motors need high octane petrol is to avoid accidental pre-ignition from the high cylinder pressures/heat they generate from high compression ratios. Advancing the timing will also create higher cylinder pressures and more heat.
Incorrect. Higher octane fuels burn slower and given the longer dwell time under pressure ( before the fuel's completely consumed ) more power is produced. They are indeed also more resistant to predetonation, but these are two different stories wrapped in one handy package.
My 1992 Grand Prix 4 cam with 9.5:1 CR ( and yes, I know, these days that is borderline on what's considered the low side ) absolutely detests 87 Octane and runs like crap. It runs well on 93 but with Sunoco Racing 100 / 102 or BoosThane in the tank added to 93 as a base, is an absolute beast. Cylinder head and piston shape and design play a massive part in how these factors play out, an engine engineered in the late 1980s ( which this one was ) before fast computer dynamics could be used to model combustion chamber shapes and fluid dynamics, responds quite differently to fuel quality, than more modern engines do. It also carries a fairly high redline at 7400RPM.

 

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.
"For improved vehicle performance, NISSAN rec-
ommends the use of unleaded premium gasoline
with an octane rating of at least 91 AKI number

(Research octane number 96)."
-- 2005-2008 Frontier Owner Manuals.
What exactly do you think is meant by "improved vehicle performance"?
 

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Incorrect. Higher octane fuels burn slower and given the longer dwell time under pressure ( before the fuel's completely consumed ) more power is produced. They are indeed also more resistant to predetonation, but these are two different stories wrapped in one handy package.
My 1992 Grand Prix 4 cam with 9.5:1 CR ( and yes, I know, these days that is borderline on what's considered the low side ) absolutely detests 87 Octane and runs like crap. It runs well on 93 but with Sunoco Racing 100 / 102 or BoosThane in the tank added to 93 as a base, is an absolute beast. Cylinder head and piston shape and design play a massive part in how these factors play out, an engine engineered in the late 1980s ( which this one was ) before fast computer dynamics could be used to model combustion chamber shapes and fluid dynamics, responds quite differently to fuel quality, than more modern engines do. It also carries a fairly high redline at 7400RPM.

I agree with you on everything except for the burn rate. 9.5:1 compression ratio used to be considered high before the age of knock sensors. My '99 Viper is 9.6:1 and also calls for super unleaded. I have also run 102 mix with super through it at the track and didn't notice any difference. Of course it was already beastly to begin with. Track time didn't notice either.
 

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Hi all,

Not trying to beat a dead-horse here or bring up an old thread from the grave. I got one of th 2.5L 4-cyl RWD engines. So far I'm on my second tank in the brand new truck. Drove it home from Ohio to Virginia and averaged about 22.5 mpg crusing at 65-70ish.

After reading a lot of blogs it seems like the only way to save efficiency is to drive cautiously and not mash the pedal, which I'm fine with.

Has anyone tried to fill mid or premium grade fuel? Does it have any effects on power or fuel economy? I'm thinking about giving it a try on my next fill up, which may be awhile since we're all in quarantine right now and I have nowhere to go haha! Thanks guys.
My 2017 2.5L never had anything in it except for Shell premium fuel, I liked that little bit of extra highway HP the octane gave the engine.
 

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My 2017 2.5L never had anything in it except for Shell premium fuel, I liked that little bit of extra highway HP the octane gave the engine.
The only thing is doing is wasting money. Unless you had the truck tuned for it.
 
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I have a 2017, 4cyl, stick and tried 93 as I felt the mid-range was lacking due to timing retard. After all, this engine has a 4 inch stroke. I thought the ECU would use the knock sensor to relearn the timing more advanced and give a bit of torque. Not that I noticed, so 87 is in the tank.

There is no 'predetonation'. It is a recently made up word from the internet. There is preignition and detonation, two different things.

High and low octane burn at the same speed. A slower burn will make fuel more likely to detonate.

One old bike is bored max oversized and has 1.5 points of compression increase. My autocross car is roots supercharged and uses a homemade water injection system. I have studied detonation as a hobby since the mid 70's but really started to understand it much later.

Tt
 

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I have a 2017, 4cyl, stick and tried 93 as I felt the mid-range was lacking due to timing retard. After all, this engine has a 4 inch stroke. I thought the ECU would use the knock sensor to relearn the timing more advanced and give a bit of torque. Not that I noticed, so 87 is in the tank.

There is no 'predetonation'. It is a recently made up word from the internet. There is preignition and detonation, two different things.

High and low octane burn at the same speed. A slower burn will make fuel more likely to detonate.

One old bike is bored max oversized and has 1.5 points of compression increase. My autocross car is roots supercharged and uses a homemade water injection system. I have studied detonation as a hobby since the mid 70's but really started to understand it much later.

Tt
The only the the ECM does with the knock sensor is retard the ignition timing when it gets a signal from the knock sensor indicated engine knock.
 
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