higher octane does not equal higher MPG.

 

Hi

I live in Worcestershire England.

Stuart

 

1- MPG- 15 city- 21 hwy
2- Type & Year- GCL 2003
3- Engine size -4.0L
4- Odometer -98,000
5- Type of fuel used- Cheap as I can get 87oct.
6- Any additives?- Seafoam every now and then (gas & oil)
7- Highway or city driving? Mixed
8- Any suggestions to improve the milage- lite right foot(tire press and then normal stuff)
9- Are you satisfied? Hell yes. Just sold a truck that got 9.8mpg hwy

 

1- 10-15
2- 92 5speed 4x4
3- 4.0
4- 260,000
5- good ol' 87 octane
6- whatever is in the gas
7- mostly city
8- buy a honda
9- ofcourse, its a jeep

 

1- MPG - 14 city, 18 hwy
2- Type & Year - 97 Sport (stock)
3- Engine size - 4.0 sixer
4- Odometer - 118K
5- Type of fuel used - mid-grade
6- Any additives? - pint of denatured alcohol every few tanks, Mystery oil in the crankcase every other oil change
7- Highway or city driving? - mostly city
8- Any suggestions to improve the milage - keep it tuned up! I'd have better mileage if I weren't so lazy about maintenance
9- Are you satisfied? - very

 

Your gas probably doesn't have ethanol either. When they used to sell E0 here, on 91 octane I could get 20mpg, now on E10 I am down to 16.

 

1- 20 to 22 hwy
2- Cherokee 2000
3- 4.0 I-6
4- 164XXX
5- 87 octane
6- Lucas one a year
7- Both highway and city driving
8- Mustang fuel injectors
9- Are you satisfied? Never!

 

I was always under the impression that octane didn't reflect the efficiency of the burn, but rather was related to the pressure rating the fuel can take before it combusts?

ie, low octane for older vehicles because the engine compression is not as high as newer high performance engines. if you have a low octane in a high pressure engine, it will combust early and start causing that dreaded "knock" But high octane in older engines is a waste of money. someone please correct me if i'm wrong, but have a good explanation why.

also, did you do your conversions right, cause i know yall work in liters and kilometers over there hehe j/k man.

another input for this should also be tire size and gear ratio as that makes a big difference as well.

1- MPG- 12 city, 15 hwy
2- Type & Year- sport, 1999
3- Engine size -4.0L
4- Odometer -150,000
5- Type of fuel used- 87oct. cause it's cheap
6- Any additives?- depends what's on sale, but every now and then.
7- Highway or city driving? both
8- Any suggestions to improve the milage- good tire pressure, don't burn out from stops, coast behind traffic so you hopefully don't have to fully stop for a red light, or if someone brakes
9- Are you satisfied? better believe it, one of the best decisions i have made in my life was to get my xj, no regret
10- Tire Size - 35"x12.5x15 (added this because larger diameter is harder to turn, plus more width adds more friction, and smaller wheel size means more rubber = heavier tire.
11- Gear Ratio - 3.55 right now, will be moving to 4.10

 

Hi Chex Mex

Firstly we work in MPH and IMP Gallons, EU have forced Litres etc on us.

As for 98 octane over hear in contains special additives to clean injector etc and over time increases the efficiencies of the engine.

Lower octane fuel cause problems with burn not higher as far as I am aware that is why older (20 + years) need to have the ignition timing to be retarded to run on unleaded instead of 100 octane 4 star leaded petrol.

Stuart

 

We should probably also state if we're using imperial gallons or US gallons, since the imperial is 20% larger from what I understand...makes a big difference if you're not thinking the right units.

 

1- MPG-14-16 city, 20-24 hwy
2- Type & Year-96 sport 5 speed
3- Engine size-4.0
4- Odometer-211xxx
5- Type of fuel used-87 octane
6- Any additives?-none
7- Highway or city driving?- little of both
8- Any suggestions to improve the milage-keep the rpms 2500 and lower, get unlocking hubs
9- Are you satisfied?-yes 16 mpg is good enough with 3" lift with 31s

 

under the username it says Worcestershire lol. easy thing to look over, but some ppl will give you major crap over it.

 

What did you do for your injector upgrade?

 

2000 Cherokee
4.0L / L6 w/ 5spd
114k +
no additives run
87-92 octane
60/40 more in city
did injector upgrade, bored throttle body, CAI, Throttle body spacer, changed gear ratio to 3.73:1
Around 15... goes up or down according to the amount I am on the highway.

 

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2. 2001 Cherokee
3. 6 cylinder 4.0
4. 165k
5. Mid grade
6. None
7. A happy mixture of both
8. …
9. wish I could get at least 21mpg out of it