Hemi 6.4, gasoline. 87 or 89.

[Ribtipram]

Are trucks will run a little better or worse not that noticable depending on heat, cold ,type of gas used and things like that. A car that needs high oct say a super charged or turbo really needs it to perform to its highest potential. And it is very noticable when low oct is used in these cars. Hell does anybody remember the days when the grand national guys always wanted to race at night. Why you say? Cold air. All the 5.7 and 6.4 have more hp held up inside. Many guys here have proved that it can be dragged out. But not with gas

 

[dhay13]

Running on 87 octane is not always true across the board. Sure newer computer controlled cars can get away with it but don't try it in your old 12.5:1 compression race engine unless you want holes in your pistons

 

[Hemi395]

The factory tune in the 5.7/6.4 is designed to run "optimally" on 89 but has spark and fuel tables that allow it run fine on 87. If you want the best mpg and performance out of a stock 5.7/6.4, 89 is the way to go.

That said, the performance difference between 87/89 is minimal on the stock tune. Custom tunes set for higher octane are the only true way to gain noticeable power from 89/93 octane fuel. But then you're stuck running the higher octane fuel or it will spark knock like crazy.

 

[SouthTexan]

Generally, the hard parts of the engine like the cam profile are designed for a certain octane. However, modern engines can turn the cam to alter valve timing. This adjustment along with variable ignition timing allow these engines to increase/decrease power depending on knock resistance of the fuel being used.

Dual over cam engines generally have more adjustability since they can alter both intake and exhaust timing separately. Push rod engines generally have less adjustability due to only having a single cam.

These engines can only turn the cam so much so you can only add or pull timing to a certain extent. So if an engine is designed to run on premium like the GM 6.2L, then it can run 87 in optimum conditions, but will start to knock in high heat/high load conditions. Engines like my old 3.5L EcoBoost are design to run on 87, but can adjust for higher octanes. It can only adjust so much and there will be a point where higher octane will be pointless.

 

[RoadRamblerNJ]

The only thing I can find is federal law about minimum Octane being produced/ manufactured. Nothing on a law that state's all vehicles produced have to be able to run on 87 Octane. A manufacturer of a vehicle can say it's recommended that it's vehicles only be run on whatever Octane they want, it's probably a loop hole for engine warranty and performance claims


2018 2500 6.4L Tradesman

I'm finding what you're finding. Haven't been able to reach my guy yet. This dude's not just a trooper. He works with Homeland Security in DC. He explained that it was done so in case of a national emergency, cars would still remain drivable. I never questioned it.

 

[1500ram12]

I'm finding what you're finding. Haven't been able to reach my guy yet. This dude's not just a trooper. He works with Homeland Security in DC. He explained that it was done so in case of a national emergency, cars would still remain drivable. I never questioned it.

That makes sense.




2018 2500 6.4L Tradesman

 

[nwsewell]

What does your owner's manual say?
89 preferred, 87 acceptable?

The book says my truck (5.7) prefers 89, so 89 is what I feed it.

The difference in cost of a full 26gallon tank of 87 vs 89 is less than $10 where I live. I'll pay the extra couple bucks to run the fuel my truck prefers.

Sent from my VS996 using Tapatalk

 

[turnerje]

Doesn’t anyone read the manual anymore?

As the others have stated, 87 ok 89 recommended. I have run both in the 2013 5.7 1500 I had and now the 2017 6.4 in my power wagon. I’ve seen a slight increase .5mpg in fuel economy using 89 on road trips. In town I use 87. Now, if you can get ethanol free 89 that’s something different. I don’t have numbers to back my claim, but the truck felt awesome. It was so responsive and just felt like it had a lot more power. I only found this in Oklahoma on a road trip . I live in New Mexico. I can only get regular or premium in non ethanol.

 

[Hootbro]

I ram 87 octane fuel almost exclusively in my 6.4 with no issues using Tier 1 branded fuel. Few times I put in 89 octane, never noticed a difference and MPG's were never any measurable amount better from the Lie-O-Meter variance or hand calculation.

 

[22hemi13]

Doesn’t anyone read the manual anymore?

As the others have stated, 87 ok 89 recommended. I have run both in the 2013 5.7 1500 I had and now the 2017 6.4 in my power wagon. I’ve seen a slight increase .5mpg in fuel economy using 89 on road trips. In town I use 87. Now, if you can get ethanol free 89 that’s something different. I don’t have numbers to back my claim, but the truck felt awesome. It was so responsive and just felt like it had a lot more power. I only found this in Oklahoma on a road trip . I live in New Mexico. I can only get regular or premium in non ethanol.

Seems it changes by what year you have lol. My owners manual for my 14’ says 87 on 6.4. My manual for 1700 says 89 recommended 87 acceptable. But I have. 2500 with the 5.7 I run 87. But I don’t put cheap gas. Only chevron or shell. That’s only time I feel any difference with my truck. Top tier fuel vs circle k or sams.

 

[Cham]

I only use 89 since it's the only fuel I can get bulk without ethenol. Some of the older engines I have on the farm won't run on 10% ethenol, or run very badly. My '19 Ram 2500 with the 6.4 runs fine on the 89 but would use 87 ifm I had to buy at the pumps.

 

[HammerHead]

Here is my little gas MPG’s experience, all hand calculated.

EF 87= 334/25.5=13.5

89= 371/26.7= 13.8

89= 370/27.4= 13.5

89=312/22= 14.1 Highway

93= 371/27= 13.7

 

[boblonben]

I filled up using both gasoline from Shell fuel. I ran 87 and 89. I dont know if it's me but truck seem to like 89 better. What is recommended gasoline for these 6.4? Mines a 2018, by the way.

87. runs better, and small difference in performance you would actually even be able to tell, better mileage by a small percentage.

 

[Lucy Girl]

Oh God..... not this again. Last time I think this went about 20 pages.

Cliff notes:

-Read the manual.
-89 octane "may" give a slight improvement in performance and MPG gain but usually not enough to offset cost
-Some swear there is an increase in towing power but those same folks also believe in ghosts.

Honestly, I have run a few tanks of 92 octane non-ethanol and gotten pretty good MPGs and power but I think it's more to do with the absence of ethanol rather than the octane. I only run that fuel due to camping deep in the woods and having only one type of fuel available. Otherwise, it's 87 octane regular.

I run 93 in my V6 and in my weed eater and mower. Just me LOL. I like the extra expense. Keep the gas company in business.

 

[mrduelly]

I have had a 2015 Power Wagon with a 6.4L and now have a 2107 Power Wagong with a 6.4L. There is a significant increase in performance but a minimal increase in Mileage due to the better performance as it is more fun with a bit more performance. If you were to drive mildly the fuel milage increase would be better though. With this being said you can not have such capability and fuel economy all in one package. I use 89 octain .

 

[scott lass 18]

I filled up using both gasoline from Shell fuel. I ran 87 and 89. I dont know if it's me but truck seem to like 89 better. What is recommended gasoline for these 6.4? Mines a 2018, by the way.

 

[Ron Green]

I filled up using both gasoline from Shell fuel. I ran 87 and 89. I dont know if it's me but truck seem to like 89 better. What is recommended gasoline for these 6.4? Mines a 2018, by the way.

89 is recommended that’s all I use in my 2018 2500

 

[scott lass 18]

when new mine ran so bad had to go to 89 and ran smother and alot better ! later i went with a turner and 91 dumb in California dont have 93 ! but mine is better air intake set up bigger air horn that seems to help a lot with power up hill and for years now my truck runs really well ! as for mileage started at 9 in town now about 12 mpg and on freeway 70mph have gotten 18 to 21 depends on if my foot is on the gas ! loaded all up moving on freeway ran around 19mpg so happy with that ! the one thing a feel is Shell runs the best for me and with two plugs furring you well burn most all the gas and I feel I get alot better power with my truck ruining this way ! I know my horsepower is higher and my tiers burn up fast cuz lead foot hahaha ! so check if you can do a turner cuz i got my train mission ruining better and truck seem great for me ! oh its set up for 91 so engine can run better from my turner ! thats the key for best output I feel ok !

 

[2bikemike]

I have the 5.7 and my manual recommend 91 but said 87 was acceptable. I added 5 gal of 89 into the 87 and didn't notice any difference. I then added 4 gal of 93 and again no noticable difference in engine running. I don't drive it enough to know if milage improves. I did clock it last week for a 90 mile run, refilled again to 4.2 gal. So that's about 21 mi/gal. Seems reasonable. No load except my 165lbs, a few hand tools and not towing.

 

[Lucy Girl]

Oh God..... not this again. Last time I think this went about 20 pages.

Cliff notes:

-Read the manual.
-89 octane "may" give a slight improvement in performance and MPG gain but usually not enough to offset cost
-Some swear there is an increase in towing power but those same folks also believe in ghosts.

Honestly, I have run a few tanks of 92 octane non-ethanol and gotten pretty good MPGs and power but I think it's more to do with the absence of ethanol rather than the octane. I only run that fuel due to camping deep in the woods and having only one type of fuel available. Otherwise, it's 87 octane regular.

I am still with you on this. How many times do I have to say I use 93 in my weed eater?? Wake up folks. lol