Using 89 octane for first time.

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JKP3885

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Since I bought my truck about 14 months ago, I've been running 87 octane. Truck ran ok but after reading my owners manual and some things on here, I learned that 89 octane is recommended. I ran the tank down til the light came on and filled with 89 today. It might just be in my head but it seems like the truck is running a lot better and smoother now. Anxious to see if my gas mileage improves even a little. But the performance seems much much better so far.


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blackbeautyhemi

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I believe it cause I could tell a difference as well, and when I got my hemifever tune and did a data log for hemifever he could tell I was running ****** Exxon gas. Ran my tank down low, got the Sunoco gas he recommended and my data log looked better and I could feel a difference as well.
 

MR.Z06

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Yeah but that's on a tune.
Running higher oct will reduce the chance of the ECM pulling timing because of knock. It's not going to magically deliver tons more power.
You have to do what you did. Which is get a tune to take advantage of a higher oct fuel.

For example the OP.
Runs 87 the ECM detects knock and pulls timing and he's been running around with 15% less power than normal.
Puts higher oct in and the ECM restores stock timing and he gains that 15% back.
Comes online and brags how putting in 89 gave him "much much better" performance. When in reality he just gained back what he should have had all along. NOT a performance gain, more a performance restoration.
 
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bassheadhemi

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gas quality can be for something too, with my 91 hf tune if I use anything other than Shell v-power 91 the truck doesn't feel as strong
 
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JKP3885

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Yeah but that's on a tune.
Running higher oct will reduce the chance of the ECM pulling timing because of knock. It's not going to magically deliver tons more power.
You have to do what you did. Which is get a tune to take advantage of a higher oct fuel.

For example the OP. Runs 87 the ECM detects knock and pulls timing and he's been running around with 15% less power than normal. Puts higher oct in and the ECM restores stock timing and he gains that 15% back.
Comes online and brags how putting in 89 gave him "much much better" performance. When in reality he just gained back what he should have had all along. NOT a performance gain, more a performance restoration.



No bragging. Just being informative to others about using 89 and it running better than 87 because it's recommended.


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MANual_puller

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I have been running the DSP canned towing tune out of my Trinity since I got my truck about a year ago. I didn't like what the computer was having to do with 89 octane, always pulling timing. It sounded fine, the computer was doing a great job of avoiding detonation. When I switched to 91 octane on the same tune the knock retard all but went away. Very seldom do I see timing being pulled now. I could barely feel a difference when I switched to 91 but my 4x4 crew cab 2500 weighs quite a bit over 6000#, probably closer to 7000#. The selling point to me was not making the computer work so hard and having to rely on sensors working properly to keep it from grenading.
 

ernbrdn

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I have to agree with the OP. I ran 87 for a few months. Probably because I'm a cheap ass and I seemed to get better mpg with it. Well for the last two weeks I've been running 89 and my truck feels new again.
My RT would roast the tires new, on 87 it would spin a but. I boned traction control in reality it was fuel.


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noupf

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funny stuff here.......i've began to see better mpg's with 87 octane. I only buy brand name gas as well.

anyhow, here goes.......Stock 2015 Ram CC Sport, 6'4 bed, 4x4 with 3.92 gears and a flowmaster 50 series bolt on.

I've been working on a little experiment for the last month and half. I take two trips a week ( one is about 80 miles round trip, 90% highway ) and another ( about 65 miles round trip ( almost 95% highway ).

I ran 89 octane for the last 6-8 months, so the truck was used to having the 89 octane in there. With cruise control on 70 mph for almost 95% of the time ( mainly on the highway ) and me driving somewhat gingerly when i had to get off the highway to get to my destination ( about 2-3 miles ) i would average about 19 mpg. Some times the trips total mpg would be as low as 18.6 and others i've have it up to about 19.3. Obviously head winds, outside temps and other factors played their parts, so there are going to be various

Now, for the last month or so I have switched back to 87 octane. While I do think the truck seems to be slightly less responsive ( possibly placebo, but i cant really measure, so i will just stick with my butt dyno ), I see that my mpg may have actually gone up with 87. I have made 2 trips on each of my variations ( so 4 total ). Not once have i dipped below 19.2 mpg and my most recent one actually had me at 20.0 mpg and one at 19.7.

For this experiment, I got my truck up to 70 mph and hit cruise control at the exact same starting point on the highway and reset my trip meter ( which also calculates mpg for that trip ) and then I checked my overall trips mpg at the same point as i came near the end of my trip ( same point that i turned the cruise control on ) on the highway.

For my miles off the highway, i made sure to drive the same way ( as best i could ) each and every time to keep the test as accurate as possible.

Next test will be to add my oil catch can and see if the elimination of the misty oil vapors ( which lower octane ratings ) makes a difference either way. My theory, i can run 87 octane and have something closer to 89, without paying 25-30 cents a gallon more for it. If the mpg's go down, so be it, if its more responsive, than great.
 

MANual_puller

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funny stuff here.......i've began to see better mpg's with 87 octane. I only buy brand name gas as well.

anyhow, here goes.......Stock 2015 Ram CC Sport, 6'4 bed, 4x4 with 3.92 gears and a flowmaster 50 series bolt on.

I've been working on a little experiment for the last month and half. I take two trips a week ( one is about 80 miles round trip, 90% highway ) and another ( about 65 miles round trip ( almost 95% highway ).

I ran 89 octane for the last 6-8 months, so the truck was used to having the 89 octane in there. With cruise control on 70 mph for almost 95% of the time ( mainly on the highway ) and me driving somewhat gingerly when i had to get off the highway to get to my destination ( about 2-3 miles ) i would average about 19 mpg. Some times the trips total mpg would be as low as 18.6 and others i've have it up to about 19.3. Obviously head winds, outside temps and other factors played their parts, so there are going to be various

Now, for the last month or so I have switched back to 87 octane. While I do think the truck seems to be slightly less responsive ( possibly placebo, but i cant really measure, so i will just stick with my butt dyno ), I see that my mpg may have actually gone up with 87. I have made 2 trips on each of my variations ( so 4 total ). Not once have i dipped below 19.2 mpg and my most recent one actually had me at 20.0 mpg and one at 19.7.

For this experiment, I got my truck up to 70 mph and hit cruise control at the exact same starting point on the highway and reset my trip meter ( which also calculates mpg for that trip ) and then I checked my overall trips mpg at the same point as i came near the end of my trip ( same point that i turned the cruise control on ) on the highway.

For my miles off the highway, i made sure to drive the same way ( as best i could ) each and every time to keep the test as accurate as possible.

Next test will be to add my oil catch can and see if the elimination of the misty oil vapors ( which lower octane ratings ) makes a difference either way. My theory, i can run 87 octane and have something closer to 89, without paying 25-30 cents a gallon more for it. If the mpg's go down, so be it, if its more responsive, than great.

doood.....mpgs normally go up in the summer......switching to 87 right as summer starts and concluding the 87 octane gets you better fuel mileage is kind of silly, maybe it's just me.
 

blackbeautyhemi

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Yeah but that's on a tune.
Running higher oct will reduce the chance of the ECM pulling timing because of knock. It's not going to magically deliver tons more power.
You have to do what you did. Which is get a tune to take advantage of a higher oct fuel.

For example the OP.
Runs 87 the ECM detects knock and pulls timing and he's been running around with 15% less power than normal.
Puts higher oct in and the ECM restores stock timing and he gains that 15% back.
Comes online and brags how putting in 89 gave him "much much better" performance. When in reality he just gained back what he should have had all along. NOT a performance gain, more a performance restoration.

Yea you over thought my statement, I was just making a point the different octanes do make a difference and so do the brands. I know many people that just think the different octanes are a gimmick and don't mean ****.. Wrong.
 

noupf

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doood.....mpgs normally go up in the summer......switching to 87 right as summer starts and concluding the 87 octane gets you better fuel mileage is kind of silly, maybe it's just me.

good point, i forgot about that. I'll run the 89 for a few more tests just to see.
 

MR.Z06

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doood.....mpgs normally go up in the summer......switching to 87 right as summer starts and concluding the 87 octane gets you better fuel mileage is kind of silly, maybe it's just me.

It's still interesting. It means he's at least not getting worse MPG. If he can get parity in MPG with either then why not opt for the cheaper gas.
 

Pull Ya

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Just wait until you install that catch can----you'll be amazed at the results. I bet you'll see a significant increase in mileage and for a bonus I think that you will see about 25 more hp. This has to be true cause I read it on the internet on this site----and these guys wouldn't ******** anyone would they???????
:naughty::naughty:
Jay






Sorry sometimes I just can't help myself----
 

MANual_puller

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It's still interesting. It means he's at least not getting worse MPG. If he can get parity in MPG with either then why not opt for the cheaper gas.

Depends on how you look at it. He's likely getting worse MPG with the 87 right now than he would be getting with the 89. I normally pick up 1.5ish average for the summer months and that seems to be fairly constant no matter what octane rating people run. Idk if giving up that gain is worth it. I run 91 octane because I didn't like what I was seeing watching knock retard numbers with 89 octane. It wasn't bad, it would pull about 4 degrees in the mid RPMs at WOT and up to 7 in the high RPM ranges. The better fuel made it all but go away. DSP recommends running 89 or higher with all their tunes. I would set it back to stock and see what the factory tune does with the 91 octane but then I'll have to write down my shift schedule....yada yada yada, I'm not really that curious since my truck is much happier than it was. :happy107:
 

MANual_puller

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Just wait until you install that catch can----you'll be amazed at the results. I bet you'll see a significant increase in mileage and for a bonus I think that you will see about 25 more hp. This has to be true cause I read it on the internet on this site----and these guys wouldn't ******** anyone would they???????
:naughty::naughty:
Jay






Sorry sometimes I just can't help myself----

No, that never happens! :roflsquared:
 

03MopaRamman

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A lot of Mopar engines recommend the use of 89. Just Got my 14 Ram and 89 it is but arournd here not all stations carry it and I can usually get 91 cheaper at Cosco so I half and half it leaning heavier on the 91. I also have no probs doing 87 if that's all there is at our local station 30 miles from Town.Fuel cost are what they are and I know what being married to 91 is also (Thanks Johan!). Danny
 

big_red06

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i don't have a tune and was running 87 for a while the truck seemed a bit sluggish to me i decided to go with the 89 that the owners manual recommends while i didn't see much increase in mpgs the truck does seem much more responsive with the 89 so thats what i will be sticking with I also primarily use either Shell or BP which have given me the best results
 

schul788

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Yeah but that's on a tune.
Running higher oct will reduce the chance of the ECM pulling timing because of knock. It's not going to magically deliver tons more power.
You have to do what you did. Which is get a tune to take advantage of a higher oct fuel.

For example the OP.
Runs 87 the ECM detects knock and pulls timing and he's been running around with 15% less power than normal.
Puts higher oct in and the ECM restores stock timing and he gains that 15% back.
Comes online and brags how putting in 89 gave him "much much better" performance. When in reality he just gained back what he should have had all along. NOT a performance gain, more a performance restoration.

This is exactly what I saw. Switched to 87, got sluggish, switched back to 89 and it's a lot better. I don't think anyone thought it was going to magically give more power just that 89 performs better in the Hemi engine for the reasons you describe.
 
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