Will it hurt my engine or not?

[Plum Ranger XLT]

My 2008 Ranger 2.3L is recommended to run on 87 octane gas and have been wondering IF using 89 octane or maybe 93 octane gas for one full tank of gas will hurt it in any way? The engine has almost 189,000 miles on it.

 

[scotts90ranger]

No, it only hurts going the other way around, if premium is recommended then regular can hurt sometimes...

 

[lil_Blue_Ford]

Yup. I’ve actually seen some 87 vehicles gain in mpg running 89. Sometimes it was worth it to pay a little more and sometimes it wasn’t, so it wasn’t a huge gain

 

[RonD]

If your engine has compression ratio of 9.4:1 or higher then running 89/91 octane can increase MPG and performance

The 2.3l Duratec looks to be 9.7:1, so it will have a Knock Sensor that allows it to run 87 octane with no issues

Driving around town I doubt you would notice any difference between 87 or 91 octane, on a longer road trip yes, would get better MPG, but higher cost for fuel, lol

Knock sensor allows computer to adjust spark timing to prevent lower octane Knock/Ping as it occurs
And this reduces power, so reduces MPG, but its not alot

 

[gw33gp]

The main thing it will hurt is you wallet. I have heard you can get a little carbon build up using higher octane fuel than needed, but one tank would not be a problem. As RonD indicated, your compression ratio is high enough that you could benefit from it in gas mileage and possibly even a little in performance.

 

[Blmpkn]

The main thing it will hurt is you wallet. I have heard you can get a little carbon build up using higher octane fuel than needed, but one tank would not be a problem. As RonD indicated, your compression ratio is high enough that you could benefit from it in gas mileage and possibly even a little in performance.

Higher octane fuels burn slower and somewhat incomplete in low CR motors, the incompleteness of the burn is where the extra carbon comes from.

 

[RonD]

Octane is a heat rating
A gallon of 87 octane and a gallon of 93 octane have the same energy stored

Its how the energy is released and used that makes the difference, the efficiency of the conversion
Gasoline engines are 25% efficient
If a gallon of gas costs $4 then $1 pushes you down the road, $3 is used to heat up the engine and air around it
SUCKS don't it, lol

Newer gasoline engine designs are pushing close to 30% to 35%

Diesels were 30% to 35% and now pushing 40% to 45%

Electric vehicles are 85-90%




Simple explanation of octane rating, not scientific just an explanation
Oct = 8
Tane = carbon chain

Octane molecule of 8 carbon atoms is very stable hard to break part, ignite
Shorter carbon chains are more volatile, easier to break apart, ignite

87 octane has 87% 8 chain carbons so 13% shorter chains
89 octane has 89% 8 chain carbons so 11% shorter chains
91 octane has 91% 8 chain carbons so 9% shorter chains
93 octane has 93% 8 chain carbons and 7% shorter chains

The 87 octane will be more likely to self ignite during compression stroke, and that causes pinging/knocking noise that you can hear, and this also causes cylinder damage so its a bad thing, lol
Knock sensors detect this(before you can hear it) and computer will advance the spark timing to prevent it, this means "full explosive" ignition will not occur at the optimal time on power stroke for best power

Compression generates heat so the higher the compression ratio the more likely self ignition becomes

89/91/93 octane fuels are less likely to self ignite, but still can if heated up high enough

A gallon of any gasoline has the same number of carbon atoms, so same potential energy, its just the configuration of those carbon atoms that decides Octane rating

Obviously since there are fuels with over 100 octane the percentage thing is just used as a example of "how it works"

 

[scotts90ranger]

Only thing I can throw at what Ron just posted is the knock sensors RETARD the spark advance, not advance, but yeah, didn't have it in me to expand last night

Pre ignition is bad, cast pistons start to wear away until they burn into the ring lands, forged pistons are more forgiving but knock is never a good thing...

 

[RonD]

You can't say that, spark is "differently abled" is the correct term

 

[dvdswan]

You can't say that, spark is "differently abled" is the correct term

I think we need to ban @RonD for making a new gender label...

 

[pjtoledo]

fun for all quest

how do you define cetane?

 

[dvdswan]

cetane, as octane is for gas, cetane is for electric cars. "C" batteries. no?

how about,

cetane fuel for the 7 seas... no?

IIRC, it's something to do with diesel fuel compression.

 

[duffy]

Cetane is the octane equivalant in diesel.......

 

[Bill]

Driving around town I doubt you would notice any difference between 87 or 91 octane, on a longer road trip yes, would get better MPG, but higher cost for fuel, lol

I really don't think it is going to make a difference in fuel economy unless there is a load placed on the engine such as towing or driving uphill, but not for normal freeway cruising where the same speed is maintained.

 

[scotts90ranger]

It all depends on cylinder pressure... in some boat engines at work (GM 6.2L direct injection, high compression ratio... like 11.2) we "recommend" premium, but there's two spark tables that it learns between with the knock sensors so it doesn't hurt the engine in theory, in those the WOT engine speed can change as much as 200rpm which if you look at the impeller curves (jet boats, impeller not propeller...) is above insignificant... On the 4.3L DI and 5.3L DI engines it isn't as big of a difference even though the compression ratio is still like 10.5:1