2019 Hemi Premium Fuel?

[mtofell]

Just noticed in searching Dennis Dillon for 2019 Rams that the engine is listed as the following:

Premium Unleaded V-8 6.4 L/392

So, does this mean the new gassers will require premium? I'm not sure why since it doesn't seem much with the engine has changed. Up to this point the game with the 6.4 Hemi (all the way back to my 2014) is the manual says 89 octane is recommended but 87 octane is acceptable. "premium" would seen to dictate 92 octane, right?

 

[tidefan1967]

Must be a mistake. I checked the other large dealers in the US and they didn't say anything about octane. Kind of reminds me of my original RAM dealer who made it a point to put "Regular Unleaded" under each and every description when talking about the 5.7 HEMI in the 1500's. I even asked the salesman about that and even he said that he only used Shell 89 in his RAM. I can see pushing the cheaper gas theory but not the opposite. Not too many people are going to buy an HD truck that drinks premium fuel.

 

[MADDOG]

Sounds like a mistake. Was the foun in an FCA document or just in the dealer's website description?

 

[McBroom]

I run 87 in my HD. If I’m planning on towing heavy then I bump it up to 93.
On long road trips (empty) I use 93 because I’ll get about a 20% increase in fuel mileage.
I’m a conservative driver I try to keep the cruise set at 65/67 mph. That’s towing or not.



I love my truck!
Blue Mule 18 Ram 2500 4x4 C/C Off Road.

 

[Fitz-0518]

We run 89 in both our 03 1500 5.7 and 2018 2500 6.4. Towing and drive trips we run 91. Have also found that we get slightly better mileage with 91.

 

[Strange Ram]

Its no mistake.. the engines are factory tuned for premium. Same for the Challengers with the 5.7 and 6.4's.. It will not kill your engine to run a lower octane fuel, but your engine will adjust timing and such to compensate for knock. Our 2015 Power Wagon was the same, 91, right in the manual. But, we got the best performance and mileage with 91.

Octane is very misunderstood.

 

[McBroom]

[QUOTE="Strange Ram, postOur 2015 Power Wagon was the same, 91, right in the manual. But, we got the best performance and mileage with 91.

Octane is very misunderstood.[/QUOTE]


^^^^ That’s a no *******!!^^^^
Octane is VERY misunderstood!!




I love my truck!
Blue Mule 18 Ram 2500 4x4 C/C Off Road.

 

[Jimmy07]

Its no mistake.. the engines are factory tuned for premium. Same for the Challengers with the 5.7 and 6.4's.. It will not kill your engine to run a lower octane fuel, but your engine will adjust timing and such to compensate for knock. Our 2015 Power Wagon was the same, 91, right in the manual. But, we got the best performance and mileage with 91.

Octane is very misunderstood.

Hmmm...here’s the 2015 owner’s manual- https://carmanuals2.com/d/72783
Not seeing the 91 requirement

 

[1500ram12]

2018 6.4L recommend 89 but 87 acceptable




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[bigdodge]

Yup. 89 is what my PW says and I run. Octane does nothing for gas mileage by the way. It also does nothing to make power.

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[Strange Ram]

Hmmm.. could have sworn our 2015 required premium fuel. Went diesel and haven't had to fill up a gas tank in years. Good catch.

If you're following factory and do not add any upgrade tunes, then 89 it is.


And yes.. octane can affect mileage.. if you are getting knock on 87, you will see less performance/economy. Higher octane fuels do serve a purpose, albeit not in the way most understand it.

Hmmm...here’s the 2015 owner’s manual- https://carmanuals2.com/d/72783
Not seeing the 91 requirement

 

[Fitz-0518]

Years ago I did some work for a large truck fleet company. 200+ trucks. They burned premium fuel in their gas engine fleet. I asked why? They claimed that they got better mileage and spent less on fuel by burning higher octane gas. As I remember their explanation went like this. Take 1 gal of 87 oct and 1 gal of 91 oct. If temp, combustion and mass are the same. The 91 oct fuel will propel the mass farther OR faster. But not both. The energy expelled can not do both. They had governors on the trucks and their trips were long drive. I always suspected that if the physics were true, a lot of their savings could be at risk depending on throttle pressure of the driver.

 

[Strange Ram]

Years ago I did some work for a large truck fleet company. 200+ trucks. They burned premium fuel in their gas engine fleet. I asked why? They claimed that they got better mileage and spent less on fuel by burning higher octane gas. As I remember their explanation went like this. Take 1 gal of 87 oct and 1 gal of 91 oct. If temp, combustion and mass are the same. The 91 oct fuel will propel the mass farther OR faster. But not both. The energy expelled can not do both. They had governors on the trucks and their trips were long drive. I always suspected that if the physics were true, a lot of their savings could be at risk depending on throttle pressure of the driver.

From my understanding.. Less octane, easier to ignite. More octane, harder to ignite. 91 octane fuel is not more powerful.. it is harder to ignite, meaning you can build an engine with higher compression, more advance, with turbo or supercharged forced air.. and the spark ignites the fuel when the computer wants it to, instead of pre igniting (which would destroy your engine.. or at the very least cause it to run with ******** timing).

The piston is on its upward stroke when pre ignition occurs.. thus much less efficient (if not blowing holes in your piston).

An engine which is running well, tuned for premium fuel, will be a more powerful, more efficient engine due to this.. not the inherent power in the fuel.

A ******** engine, due to knock, will not be as efficient.. thus not as good fuel mileage.

 

[bigdodge]

This guys got it.

Harder to ignite by heat and pressure.

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[boxofrokx]

.....

Premium Unleaded V-8 6.4 L/392

.....

It's quite simple actually. The 5.7l is considered the 'standard' engine. The 6.4l is considered a 'premium' engine. It's dino numbers come when using 89 octane. 87 will work fine.

 

[reigninslayer]

In Colorado we only have 85, 87 and 91 octane fuel. So I’m good if I only put in 87 in my 2019 1500 5.7? Haven’t even filled up yet. Truck is only 3 days old.


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[Elkman]

Octane rating is a measure of knock resistance or pre-ignition of the fuel when it first hits the hot walls of the engine cylinders. It is not a measure of the btu power in the fuel. The higher the compression ratio of the engine the more prone it is to pre-ignition of the fuel and that is why a higher octane gas is recommended.

My Mercedes coupe had a high compression engine and a 93 octane recommendation for fuel. I could use a lower octane gas and the engine computer would retard the spark to prevent knocking and my mpg would decrease so no real dollar savings.

But octane is not a fuel power number and so mixing 5 gallons of 87 octane gas with 5 gallons of 93 octane gas does not result in a 90 octane blend. It actually is going to be around 92 octane in terms of knock resistance. Auto racers who have to pay for their own cars' fuel have known about this for decades.

 

[lharrell79]

Octane rating is a measure of knock resistance or pre-ignition of the fuel when it first hits the hot walls of the engine cylinders. It is not a measure of the btu power in the fuel. The higher the compression ratio of the engine the more prone it is to pre-ignition of the fuel and that is why a higher octane gas is recommended.

My Mercedes coupe had a high compression engine and a 93 octane recommendation for fuel. I could use a lower octane gas and the engine computer would retard the spark to prevent knocking and my mpg would decrease so no real dollar savings.

But octane is not a fuel power number and so mixing 5 gallons of 87 octane gas with 5 gallons of 93 octane gas does not result in a 90 octane blend. It actually is going to be around 92 octane in terms of knock resistance. Auto racers who have to pay for their own cars' fuel have known about this for decades.

With your example of 5 gallons 87 octane and 5 gallons 93 octane, equaling 92 octane. How did you get this result. Sunaco race fuels states it would be exactly 90. My math leads me to believe it would be 90 as well. I don't know much about octanes though, so I could be wrong.

https://www.sunocoracefuels.com/tech-article/mixing-fuels-calculating-octane

 

[BarbinLA]

I’ve e been looking at the 2020 and 2021 2500’s, and every one specifically states “Premium fuel.” After having had three 1500’s that ran well on 89 octane, now I’m wondering if the 2500 will need 91? Or could I get by with 89 unless I’m hauling?

 

[392DevilDog]

I’ve e been looking at the 2020 and 2021 2500’s, and every one specifically states “Premium fuel.” After having had three 1500’s that ran well on 89 octane, now I’m wondering if the 2500 will need 91? Or could I get by with 89 unless I’m hauling?

Actually there are pics showing the manual for 2020 says 87. No mention of 89.

All of the years say premium 93 is not recommended and offers no benefit.

https://hdrams.com/forum/index.php?threads/octane-level-for-2020-ram-2500.3471