87 octane vs 89 octane, fuel economy differences

[Enve46]

Are we doing off road fuel economy now?

Pretty sure my Wrangler gets 2-3 gallons per mile when I'm rock crawling.

Ok wise a$$ hahaha I’m just updating this thread with my results purely for my own entertainment and talking to myself via the thread hahaha trying to give real world results of running 89 vs 93. Unfortunately my life is not really consistent lately to be an exact comparison as **** happens and this short trail ride was one of them that popped up last minute so felt it was worth mentioning. The trail only takes about 30 mins max to travel as it’s a county road and 5 miles which doesn’t really effect the mileage that much especially when factoring the 30 minute highway trip to get there, kinda offsets but supplying the data.

 

[Ramtop]

Are we doing off road fuel economy now?

Pretty sure my Wrangler gets 2-3 gallons per mile when I'm rock crawling.

Is that Downhill and Uphill or Uphill and Downhill??

 

[Enve46]

Another fill up. 241 miles and filled 24.690 gallons. Evic said 9.8 mpg.

 

[kevin588127]

Highway mpg while towing is the only thing I truly care about with my truck. The only reason I care is for range estimation, which is extremely important when you only have a 33 gallon fuel tank. That is my only gripe with this truck.

Doing this test off and on over the last year and a half, I have found no power or mpg benefit to running 89 or 91.

Doing this test under city driving would be inconclusive, at least in my situation. The city mpg is so erratic with mine. It can range anywhere from 9 to 12 on any given tank, though I've never had a tank that was 100 percent city, meaning no freeway driving at all. The biggest factor seems to be time sitting idle and there is no way to compare this from one tank to the next.

 

[Crusty old shellback]

Here is the video from engine masters that shows the difference between octane doesent really matter. Now if you go E85, then it does.

 

[Firebird]

Here is the video from engine masters that shows the difference between octane doesent really matter. Now if you go E85, then it does.

Great video!

 

[MarkCO1]

Here is the video from engine masters that shows the difference between octane doesent really matter. Now if you go E85, then it does.

I ran my 6.0L, 450HP on 91 Octane LS2 motor on Corn juice for 2 years. Lost 30% in mpg and picked up 90 HP. Fun costs money. I ran the 5.7 Hemi with 85 to 93 Octane, towing and city, with a telemetry logger. Once I normalized everything, there was no difference in mpg.

 

[Enve46]

Not sure who even cares much but figured I’d update this with another fill up
26.538 gallons
252.9 miles
Evic showed 10 even on the trip and 9.9 on the fuel econ screen

This is my third fill up on my “new” commute with the new house. Mileage seems to be increasing slightly weekly but so have the temps. With the new commute I wish I had a diesel to compare to since it’s more country roads at 55ish.

 

[kevin588127]

Not sure who even cares much but figured I’d update this with another fill up
26.538 gallons
252.9 miles
Evic showed 10 even on the trip and 9.9 on the fuel econ screen

This is my third fill up on my “new” commute with the new house. Mileage seems to be increasing slightly weekly but so have the temps. With the new commute I wish I had a diesel to compare to since it’s more country roads at 55ish.

Country driving at 55ish should be getting you much better than 10mpg unless you have a bunch of idle time or city driving mixed in there. My best mileage has been country driving with speeds 50-55 mph.

 

[Enve46]

Country driving at 55ish should be getting you much better than 10mpg unless you have a bunch of idle time or city driving mixed in there. My best mileage has been country driving with speeds 50-55 mph.

It’s still more city than anything else but before my new house was completed it was 99% city. Now it’s probably more 60/40 city/hwy. would be interesting to see what a diesel would yield. Not sure I want to go back down the diesel path though, I simply don’t need it. There is a 2016 AEV diesel by me that’s awfully tempting but I have to remain strong hahaha I love my PW

 

[MarkCO1]

My first tank (2022 2500 Big Horn) was 13.7 mpg with 87 Octane. My 2nd tank is 85 Octane and it's about 2/3 used up and I am up to 14.6 mpg. About 50/50 highway city. I am learning the transmission, and it seems to be that going over 2000 rpm is where it really gets thirsty. Oh, and MDS is always off and I do have a bed cover on it.

 

[dieselscout80]

My first tank (2022 2500 Big Horn) was 13.7 mpg with 87 Octane. My 2nd tank is 85 Octane and it's about 2/3 used up and I am up to 14.6 mpg. About 50/50 highway city. I am learning the transmission, and it seems to be that going over 2000 rpm is where it really gets thirsty. Oh, and MDS is always off and I do have a bed cover on it.

I seldom get over 2000 RPM unless I am towing. However, it is sweet to have that option when needed.

 

[Enve46]

Shoot, I drive my PW like I drove my 69 camaro hahaha. I also run 37s which doesn't help my results. I don't really care about the number but if I can run a lower octane, save some money and not lose performance...

 

[Crusty old shellback]

Mine see 6K RPM all the time.
Drive it like you stole it.

 

[Enve46]

Im tossing a gallon of gas on the ambers here... I filled up two tanks of 93 running the same route with no variations... Results were 10.3 first tank, 10.4 the second tank, hand calculated. Anyone kind enough to speculate on the reason? Weather, route, everything the same. I am currently about 1/3 through my 89 tank to update with that.

 

[kevin588127]

Im tossing a gallon of gas on the ambers here... I filled up two tanks of 93 running the same route with no variations... Results were 10.3 first tank, 10.4 the second tank, hand calculated. Anyone kind enough to speculate on the reason? Weather, route, everything the same. I am currently about 1/3 through my 89 tank to update with that.

What was the speed and wind conditions? Those seem to be the biggest killer of mpg in these trucks, aside from idle time.

The best mileage I've ever gotten in mine was on the way home from buying it. Through the hills of Arkansas. I got almost 19 mpg on a complete tank. I think it was due to a lower average speed due to the twists and turns and lack of wind due to being in a forrest. Since then, my average tank of hiway/interstate driving is usually 14-17 mpg. Speeds are higher and the wind is always blowing in my area.

 

[Enve46]

What was the speed and wind conditions? Those seem to be the biggest killer of mpg in these trucks, aside from idle time.

The best mileage I've ever gotten in mine was on the way home from buying it. Through the hills of Arkansas. I got almost 19 mpg on a complete tank. I think it was due to a lower average speed due to the twists and turns and lack of wind due to being in a forrest. Since then, my average tank of hiway/interstate driving is usually 14-17 mpg. Speeds are higher and the wind is always blowing in my area.

Speed and wind have no bearing on my travels daily. Mostly hilly, twisting country roads with about 30% city, wind speeds simply aren't going to hurt me much with how/where I drive. If I were on the highway more I would analyze. That said, its really interesting to get back to back better MPG with 93 than 89 with all things being equal.

 

[Crusty old shellback]

Man I envy you guys with the high MPGs.
I'm lucky if I get into 14 MPG.
Usually more like 12.5 to 13.3.
Crusing 75 to 80 with the cruise control.

 

[Enve46]

Man I envy you guys with the high MPGs.
I'm lucky if I get into 14 MPG.
Usually more like 12.5 to 13.3.
Crusing 75 to 80 with the cruise control.

I’m about the same on the highway with the 37s but with my local driving breaking 10 is shocking

 

[Dave01]

Im tossing a gallon of gas on the ambers here... I filled up two tanks of 93 running the same route with no variations... Results were 10.3 first tank, 10.4 the second tank, hand calculated. Anyone kind enough to speculate on the reason? Weather, route, everything the same. I am currently about 1/3 through my 89 tank to update with that.

Maybe just the result of a bad 4th grade math teacher?

Those numbers sound awfully low for mixed driving. I'd have to have a lot of local stops, or idling time, to get down to 10.