Anyone switched to 87 octane?

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ramffml

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The thing to remember about pulling timing; the knock occurs first, then the computer detects it (audibly using what is basically specialized microphones) and pulls timing. That can't be good, I'd rather have no knock in the first place.

My lay person understanding of all this is that the computer is setup to run best on 89 and falls back to 87 when it can't (it senses knock). Id rather have a tune that just puts me permanently on the 87 tune so that it doesn't knock (or knocks far less).
 

HEMIMANN

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I have always ran 87 in all my Rams. Current one has 239k always on 87. I believe the manual even suggests 87 so don't know why anyone uses 89 or 91 all the time.

Manual says 89 octane is "preferred" and 87 octane is "acceptable". Without a Ram Fuel System Engineer to tell us, we are educatedly speculating what they mean. Most of us interpret this as meaning the PCM can advance the spark timing when it senses 89 octane via knock sensor, meaning it will yield some improvement in mileage and torque. How much is what we are trying to find out. Doesn't seem like much, but when I pull full loads, I like to have the extra oomph for the hilly regions around here.
 

HEMIMANN

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The thing to remember about pulling timing; the knock occurs first, then the computer detects it (audibly using what is basically specialized microphones) and pulls timing. That can't be good, I'd rather have no knock in the first place.

My lay person understanding of all this is that the computer is setup to run best on 89 and falls back to 87 when it can't (it senses knock). Id rather have a tune that just puts me permanently on the 87 tune so that it doesn't knock (or knocks far less).

Exactly - so the question is really how sensitive the knock sensors are, and how quickly they respond to knock.
 

HEMIMANN

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RAM recommended 89 octane for my 2019 Limited, especially when towing. I have only used 89 octane. If something bad happens to the engine, then they can't blame it on the gas used!

meh, you'd have to prove you fueled with nothing but 89 octane by saving every fuel receipt you ever had. Then they'd argue anyway.
 

HEMIMANN

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I don't tow or race (periodically put the hammer down when getting on the interstate in heavier traffic), so I just run 87 conoco top tier. About 40 years ago read an article in Scientific American about the synergistic effects when you mix low & mid octane fuel you end up with a higher octane fuel...(don't kill me...I'm just the messenger!) And regarding the use of non-ethanol, what would be the benefits anyone has experienced??

Fewer fuel stops. Ethanol has less energy density than gasoline. Supposedly, the fuel system materials can handle up to 15% ethanol, but I'm suspicious since they explicitly state not to use 85% ethanol. Alcohol has much higher solvency than gasoline so it dissolves certain elastomers.
 

MontanaHandyman

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I always use 87 in my 14 semi with no issues and changed plugs and they were clean. my son has to run 91 in his 14 charger rt 100th anniversary with his semi
How many miles were on the hemi when you changed plugs? I've got 70k on mine, and there seems to be some debate about changing early or letting them run to as much as 120k. I'll probly just pull a plug or 2 and take a gander at 'em...
 

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Non ethanol fuel is much more stable, doesn’t eat seals like ethanol. Modern cars designed to handle it. I have very little first hand experience but the chain saw, leaf blower engine crowd won’t run pump gas, only ethanol free. Claim is lots of issues with starting, running, etc on ethanol fuel. All goes away if you run ethanol free fuel.

Absolute truth - we had all sorts of problems on our small engines at work and in storage with alcohol fuel, even with stabilizer. I worked at Cummins (Onan Corporation subsidiary) for 22 years.
 

Adam E

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I have always run 87 since my truck was new.
When I tow my travel trailer I pour in 2 bottle of this.

Rislone Hy-per Fuel Octane Booster​

...because I've been told I should run 89 while towing. I can't say I can tell a difference even when the TT is parked and we're driving around.
2 bottles should bring 20 gallons from 87 to 91.

At about $2.50 a bottle that's $0.25 a gallon. ($2.50x2)/20 = $0.25
Regular near me is $4.499 and mid is $4.899.
$0.40 higher and I can easy raise the octane rating when filling up even if my tank is already 1/2 full.

I've never ran this by anyone so I'm open to any feedback or suggestions.
 

HEMIMANN

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How many miles were on the hemi when you changed plugs? I've got 70k on mine, and there seems to be some debate about changing early or letting them run to as much as 120k. I'll probly just pull a plug or 2 and take a gander at 'em...

Go to the spark plug threads. OEM plugs are dual iridium, guys seem to go app. 100k on these, 50k on platinum. You can go to 150k like the manual says, but they're pretty shot by that point, just like platinum is at 100k.

NGK has been pushing ruthenium for even longer life and stronger spark, but geez - the price and claims are gettin' kinda ridiculous. Waiting for 'unobtainium' coating for infinite life and ignitability.
 

indept

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The thing to remember about pulling timing; the knock occurs first, then the computer detects it (audibly using what is basically specialized microphones) and pulls timing. That can't be good, I'd rather have no knock in the first place.

My lay person understanding of all this is that the computer is setup to run best on 89 and falls back to 87 when it can't (it senses knock). Id rather have a tune that just puts me permanently on the 87 tune so that it doesn't knock (or knocks far less).
There's no difference adjusting for 87 or 89, the pcm adjusts timing for best economy & power for the gas used. It's always tweaking it as you drive. I've run 87 since new. I'll put 89 in if I'm traveling a long ways. Since I regularly use 87, when I want 89 I'll fill it with premium when the tank is half full of 87 so I wind up with 90 octane which saves money since around here they charge 10 cents less for 89 than for premium instead of pricing the 89 halfway between regular & premium.
 

Hemi395

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Unless you're watching the ST Knock and LT Knock PIDs on a scantool, you wouldn't know if there was minor pinging occurring or not. The pinging you hear is severe knock and the the pcm pulls up to 6⁰ of timing on demand in order to stop it. This is ST Knock. If it continues then the PCM will automatically pull timing up to 12⁰ when it assumes pinging will occur until the key is turned off. This is LT Knock.

Just because you don't hear it pinging doesn't mean it's not happening and you're not losing power/MPG. The Knock sensors in these truck are crazy sensitive.
 

leroys73

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We own a 2008 T&C 4.0, a 2011 Challenger 5.7 R/T, and a 2018 Ram 6.4 2500. Rarely do we run anything but 87. The owners manual states 87 is acceptable. I cannot tell the difference. I have traveled from Dallas to Tampa, checked the mileage with 87 and the same route running 89, no difference. I run 70 and 80 MPH.

Probably if I was pulling a heavy trailer with my Ram I would be able to tell the difference, especially on hills.

The computer adjusts.
 

Docwagon1776

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Lose what? 2hp?

The general rule of thumb is each degree of timing pulled on a naturally aspirated motor equates to roughly 2-3hp. So, it depends on the variables. Could be anywhere from zero to about 40. Is the motor already heat soaked? What's the ambient air temperature? At what altitude? What's the throttle at? What's the load? All are going to impact the actual loss, if any.
 

boblonben

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Hello!

With these great gas prices we are experiencing! Has anyone switched to 87 octane from 89. I haven’t yet. I will next fill up! I never thought I would! But this is getting ridiculous!
Take care,
Matt
Hello!

With these great gas prices we are experiencing! Has anyone switched to 87 octane from 89. I haven’t yet. I will next fill up! I never thought I would! But this is getting ridiculous!
Take care,
Matt
Did a one year study of 87 vs 89 octane using three RAM vehicles- a 2017 RAM 1500 Sport 4X4, a 2021 RAM 1500 Lone Star, and a 2020 RAM 1500 Limited - all 5.7L v8 automatics. One had a 3.23 rear ratio, two had 3.91 ratios. Ran three months of each octane in each truck. Covered approximately the same number of miles - between 7K and 8 k in each. After six months re-ran the same tests for three months each of 87 and. Only one of these truck was used for any kind of towing and that towing was evenly split between the 87 and 89 octane times. At the end of the year here is what I found out. No noticeable difference in driving abilities or power or general driving, he truck used towing did have a noticeable difference with 89 being better, but less mileage than the 87 was - towing. The towing ruck still got between 1 -2 mpg better mileage with 87 than 89 but was less peppy. The other two trucks averaged between 2-3 miles better gas mileage with the 87. Power in every day driving was the same 87 or 89, could tell no difference actually. Never once had any pinging with the 87 on any of the three trucks. Bottom line, if I was towing regularly I probably would still use 87 over 89. So 87 it is for all of them. Now I live in Texas at 684 feet above sea level on average, warmer temps, no big mountains, just Texas Hill country hills and lots of flat land. So, there ya go. Cheers
 

Compu-Doc

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I went to 87 octane myself (from 89 or 91 depending where I gas up). Not noticing any differences except a little more sluggish and a tad higher fuel consumoption VS the higher octane fuel. I can live with that. No pings, noises, ticks etc but it's only 1 year old.
2.339/L in Lower Mainland today....thanks Putin!!
Gas prices in Canada are stupid high, today they are at $2.03 per Litre in my area and keeps going up. (some places it's above 2.10/L)
 

Retiredsailor

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I run 91 I have better acceleration and fuel economy especially on the highway 21 mpg It just feels better driving I also disable the MDS when I think of it
 

HEMIMANN

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Did a one year study of 87 vs 89 octane using three RAM vehicles- a 2017 RAM 1500 Sport 4X4, a 2021 RAM 1500 Lone Star, and a 2020 RAM 1500 Limited - all 5.7L v8 automatics. One had a 3.23 rear ratio, two had 3.91 ratios. Ran three months of each octane in each truck. Covered approximately the same number of miles - between 7K and 8 k in each. After six months re-ran the same tests for three months each of 87 and. Only one of these truck was used for any kind of towing and that towing was evenly split between the 87 and 89 octane times. At the end of the year here is what I found out. No noticeable difference in driving abilities or power or general driving, he truck used towing did have a noticeable difference with 89 being better, but less mileage than the 87 was - towing. The towing ruck still got between 1 -2 mpg better mileage with 87 than 89 but was less peppy. The other two trucks averaged between 2-3 miles better gas mileage with the 87. Power in every day driving was the same 87 or 89, could tell no difference actually. Never once had any pinging with the 87 on any of the three trucks. Bottom line, if I was towing regularly I probably would still use 87 over 89. So 87 it is for all of them. Now I live in Texas at 684 feet above sea level on average, warmer temps, no big mountains, just Texas Hill country hills and lots of flat land. So, there ya go. Cheers

Thanks for the report. It doesn't make intuitive sense - 89 octane is supposed to allow advanced spark timing, which we all know results in more power and / or higher fuel efficiency.

Does Texas change gasoline energy content based on season like the norther tier states do? I think EPA forces all states to do this? In summer, EPA mandates all gasolines have a lower RVP (Reid Vapor Pressure) to limit release of VOC's (Volatile Organic Compounds) when refueling. This fuel has higher energy density = more power, higher mileage. In winter it is the opposite.

Was all your test data within a single gasoline season and outdoor temperature? And truck loads?
 

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