Octane

[HEMIMANN]

Yeah, the difference in combustion would be between 87 and the other two, hardly anything between 89 and 91.

Again, this is about engine longevity and lack of deposits. Those that beat their trucks and don't keep long, this discussion is completely irrelevant.

 

[HEMIMANN]

2021 2500 Owners Manual, Canadian Specification Pickup. No mention of 89 Octane. 2020 GrandeCherookee with 5.7 does talk about 89 and 87 as the option.

View attachment 537636

"a light knocking is not cause for concern" It's GOOD for the engine to knock! omg

Anyway, they drop the octane rating for sales at the expense of engine durability, and then add a top tier fuel recommendation for engine durability?

Is anybody in charge at this company? wtaf?

 

[Docwagon1776]

There's no law forcing them to be accurate with the power numbers anyways.

Well, other than false advertising and fraud laws. Ask Ford.

 

[Riccochet]

Well, other than false advertising and fraud laws. Ask Ford.

That's a little different. No matter what those 7.3 engines were down on power from what Ford stated. In the case of the 6.4 they could point to their little statement about knocking and say that reduced power is by design due to the engine preserving itself in the event of knock. Go buy better gas.

The adverse is true. No one complains when the advertised horsepower is significantly lower than what was delivered. Just look at every Japanese sports car from the 90's in to early 2000's. They were all rated for 276 HP at the crank. While the Supra, 300ZX and 3000GT VR4 were all putting down over 300 HP to the wheels.

 

[HEMIMANN]

I went from 89 octane to Exxon 93 octane for 1 tank, both "top tier" by pump label and the web site. MPG seemed to drop a couple tenths.
Now I'm using Sunoco 89, official butt dyno results are good, and MPG is back up a couple tenths. That said there are more important concerns for me than, say, 0.3 MPG.

As with the 6.4L has the documentation for the 5.7L seen such changes over the years? My Sunoco has a good variety of octanes and I haven't tried the 91. I'm on my 3rd fill of 89 octane from the same station.

My tank is 95% full right now so it will be a bit before I can fill with 91, but all I get from my butt dyno is that there is no difference in anything from 87 to 93 so I don't know what to look for. Maybe another 0.3 MPG variance?

We're not looking necessarily for mpg or power because the gains aren't huge.
We're looking for the longevity of the engine. Knocking prematurely wears out engines.

 

[HEMIMANN]

Well, other than false advertising and fraud laws. Ask Ford.

Remember the class action lawsuit against small engine makers a decade or so ago?
Now they won't label engine power at all, because they can't keep themselves from being dishonest.

If you don't know about this, you can google about it, or just look at any newer small engine and you won't find any horsepower numbers. Only engine displacement.
Hilarious, if it wasn't so ridiculous. I got something dumb like $50 for all small engines I own.
Lawyers got hundreds of millions of dollars for word twisting, of course.

 

[Docwagon1776]

That's a little different. No matter what those 7.3 engines were down on power from what Ford stated. In the case of the 6.4 they could point to their little statement about knocking and say that reduced power is by design due to the engine preserving itself in the event of knock. Go buy better gas.

The adverse is true. No one complains when the advertised horsepower is significantly lower than what was delivered. Just look at every Japanese sports car from the 90's in to early 2000's. They were all rated for 276 HP at the crank. While the Supra, 300ZX and 3000GT VR4 were all putting down over 300 HP to the wheels.

Not sure what you mean by the adverse.

I was thinking of the various Mustang lawsuits, including when Florida's AG announced they were looking in to the overrated Cobras.

And of course nobody complains when they get *more* than they asked for. Always have to read the fine print. A car that makes 300hp also makes 276hp...just at a different point on the curve...

 

[HEMIMANN]

Meant reverse.

 

[rzr6-4]

Just look at every Japanese sports car from the 90's in to early 2000's. They were all rated for 276 HP at the crank. While the Supra, 300ZX and 3000GT VR4 were all putting down over 300 HP to the wheels.

That 276 rating was because of the gentlemen's agreement to tame down cars so people wouldn't get hurt. But of course every company wanted to have the fastest car, so that is why they broke the agreement and actual HP was greater than the rating. And to Doc's point, no one complains about free HP.

 

[ramffml]

Was that you that ran the datalogger showing how the ECM did short and long term knock sensing to r*e*t*a*r*d ignition timing?

That was hemi395 but I do hear pinging in my truck, which occurs less on higher octane and colder temps.

 

[HEMIMANN]

That 276 rating was because of the gentlemen's agreement to tame down cars so people wouldn't get hurt. But of course every company wanted to have the fastest car, so that is why they broke the agreement and actual HP was greater than the rating. And to Doc's point, no one complains about free HP.

Hell, nobody even knows unless you pay for dyno yourself.
That's how small engine makers got away with lying for years - until they didn't when some entity did dyno them and launched the massive class action law suit.

Like I said, damage award was so big they quit publishing ANY power numbers.
Morons.

P.S. - @ Onan, we did do small engine competitive benchmarking, including dyno testing, and knew other engine makers were lying sacks of $hit.
But in that market it doesnt matter because owners don't give a $hit.

 

[Curmudgeon]

We're not looking necessarily for mpg or power because the gains aren't huge.
We're looking for the longevity of the engine. Knocking prematurely wears out engines.

We agree, hence the part about having concerns beyond the 0.3 MPG.

I don't tow, carry, or race. The truck is 10, I am 67. We're both in good health. I want the truck to outlive me because I really like it. And I don't want loan payments.

 

[HEMIMANN]

We agree, hence the part about having concerns beyond the 0.3 MPG.

I don't tow, carry, or race. The truck is 10, I am 67. We're both in good health. I want the truck to outlive me because I really like it. And I don't want loan payments.

Or a new truck to have to fix all the design problems with!!! We've got our trucks fixed up to the point where they might last. Like you, I'm getting too on in years for another do-over project. Let the damn kids have them.

I added a travel trailer for towing this last year, previously had an RV, and my current tires are due for replacement. So I will only use 89 or higher octane. Hopefully Top Tier, but here on the edge of flyover country, major gas suppliers are no longer interested in locations that aren't max profit margin (distance from pipe terminal = bad), so we got all sortsa cut rate gas here over the past decades.

Now I'm carrying a bottle of Red Line Pl-1 PEA additive with me at all times due to this. Modern society sucks.

 

[CanuckRam1313]

To be honest, the owners manual seems to be ridiculously unreliable, changing it's mind more than an angsty teen.

Between the changing octane and oil requirements from year to year, its safest to just follow common sense and put the best stuff in we can find at all times. So minimum of 89 for octane, and 5w-30 for oil.

I agree on all points!

Common sense; well, it's unfortunately going the wayside as each generation comes on board, but that's a topic for another day, and should probably go in the synthetic oil thread as we all like to caveat there to add some useful content to our incredible database...lol, but yes, common sense

Then higher quality oil/filters, and fuel; these all lend to a greater ownership experience for the long-term reliability and dependability of ones engine, in my opinion.

My only comment regarding 89 is that it's a blend of regular and premium at the pumps themselves and not a singularly produced fuel from the refinery.

For the few pennies difference between 89 and 91, I personally always go 91 as it is a refinery produced fuel with no blending at the pumps.

These are just my opinions though, and subject to my glass of vodka or whiskey's volume, or lack there of, in my glass

 

[HEMIMANN]

I agree on all points!

Common sense; well, it's unfortunately going the wayside as each generation comes on board, but that's a topic for another day, and should probably go in the synthetic oil thread as we all like to caveat there to add some useful content to our incredible database...lol, but yes, common sense

Then higher quality oil/filters, and fuel; these all lend to a greater ownership experience for the long-term reliability and dependability of ones engine, in my opinion.

My only comment regarding 89 is that it's a blend of regular and premium at the pumps themselves and not a singularly produced fuel from the refinery.

For the few pennies difference between 89 and 91, I personally always go 91 as it is a refinery produced fuel with no blending at the pumps.

These are just my opinions though, and subject to my glass of vodka or whiskey's volume, or lack there of, in my glass

Don't get me re-started!