3.6 engine and 87 octane a no-no

dgoodhue

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So, is there any pinging with this engine? sounds the same as it did day 1

You're not going to hear pinging at idle. If it was to occur, you will most likely hear it going up at hill.

Does anyone have any data logs to show what the engine is reacting to high load driving? (My Jeep has not been delivered yet)
 
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Petey

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So, is there any pinging with this engine? sounds the same as it did day 1

Here is the only video I could find on engine knock/pinging, still cant tell what it should sound like
So, is there any pinging with this engine? sounds the same as it did day 1

Here is the only video I could find on engine knock/pinging, still cant tell what it should sound like
don't hear any knocking on the first vid ..knocking sounds are usually heard under load ..not @ idle.
The second vid might have knock but I wouldn't recognize it as such because it sounds so artificial..at least to me.
 

aeonixx1001

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I feed our dogs top shelf foods, luckily our Jeep runs fine on top-tier 87 octane. Like I mentioned earlier, if I can find crapanol-free gas I'm all over it, but unfortunately it's only available on our road trips, not locally :(
Yeah the fricking ethanol thing really drags the spunk out of lift-off. That's why I run +91, I think the +87 is just crap here in Az, Hell I'm thinking the +91 is crap.. Ha Ha
 

dgoodhue

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Yeah the fricking ethanol thing really drags the spunk out of lift-off. That's why I run +91, I think the +87 is just crap here in Az, Hell I'm thinking the +91 is crap.. Ha Ha
You have that 'special' ACN gas. I bought a used turbo car from CA, that I had 91 in the tank and had it shipped to me. It was noticeably faster when I filled it up with local 93 gas.
 

J.Ralston

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I'll just put this here.
20201125_210749.jpg
Stupid question of me to ask, but I’ll go ahead and ask it anyway.

I was born and raised in San Diego, California and always lived at the very most, only a few hundred feet above sea level, if not exactly at sea level. The unleaded gasoline out there was always rated at 87 Octane, 89 Octane and 93 Octane for Super Unleaded.

In August of 2003, my Dad, wife, kids and I all moved to a very small, rural, Northeast town that was predominantly an agricultural and cattle area. The altitude out here is right around 3,875 feet above sea level to 3,950 feet above sea level. But no matter where you go in Colorado, the fuel is either 85 Octane, 87 Octane or 91 Octane. But the moment you cross into Utah, Nebraska, Wyoming, New Mexico or Arizona, all of those States use the same octane as Commiefornia does even though in parts of them, they are at the same altitude as Colorado is.

I know with Colorado, I have been told that the entire State runs lower octane fuel because of the higher altitude and thinner air and so for everyone out here, we are told to treat the 85 Octane how other States treat 87 Octane in there’s. So for my Rubicon, I have still been running 87 Octane in it but was wondering if I should run the 85 Octane in it instead, since we live in a higher altitude.
 

tk1700

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I live at 7000 ft in NM. I routinely drive between 5500 ft and 10000ft. I run 86 octane, the lowest grade we have, year round in a 3.6 JLU and 2.0 JLUR. My daily commute is from 7000 ft to 5500 ft in the morning and from 5500 ft to 7000ft going home. I don't have any issues with it. Right now I'm visiting CO with the 2.0 and have been driving it west of Denver between 6000 and 10000 ft. I've been using 85 octane and haven't had any issues.
 

timn1984

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Americans spend a few billion a year on premium gas that is not needed. In a car not designed for it, any difference is imagined.

However, I have notice over the years my vehicles drive much better when I give them a good wash, wax, and interior cleaning.
I beg to differ, but there is definitely a difference. If you run with a couple of tanks of premium gas in your Jeep then go back to regular gas, you will notice a difference. It is not imagined. But I do agree, a clean car does drive better.
 

TheRaven

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I beg to differ, but there is definitely a difference. If you run with a couple of tanks of premium gas in your Jeep then go back to regular gas, you will notice a difference. It is not imagined. But I do agree, a clean car does drive better.
There is no difference in power, fuel mileage, or engine manners, whatsoever in my 2021 3.6l. This has been my experience with every single vehicle i've owned over the past 12 years. I'm not going to speak for anyone else because who knows what different locations and whether can do to results. But here, in eastern PA, with my Wrangler, NO difference.
 

AnnDee4444

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Notice the test subject being an economy chevy four that is lightweight and has lower CR ratio. Theres no denying that lower octane can actually make better power but there is limit for every engine . Look @ this



LS Family = Gen. 3, 5.7L, Aluminum Block, Car Engines
10.2 CR

2013 Chevrolet Cruze/Compression ratio
9.5 to 10.5
...............and then compare this to our Jeeps

11.3 CR
Pentastar V6 Specs

Guess who in this group would likely need higher octane ?...
It's worth mentioning that camshaft overlap and VVT play a pretty big part in the effective compression ratio.

Also timing advance can be the cause of pinging.
 

Jeepsmashin

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I've only used 87 octane in my 18 JLUR 3.6 with now 45k miles and no problems 🤷‍♂️
 

AnnDee4444

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It's worth mentioning that camshaft overlap and VVT play a pretty big part in the effective compression ratio.

Also timing advance can be the cause of pinging.
From https://www.comeanddriveit.com/engine/detonation-and-knock



https://www.comeanddriveit.com/engine/detonation-and-knock said:
Most people express compression ratios using the static compression ratio generated by the reduction in total cylinder volume (head volume + deck height volume + swept volume) from BDC to TDC. However, the dynamic compression ratio is more complex, but is a better representation of the actual compression ratio.

Dynamic compression ratio uses the rod length, stroke, and rod angle, known as the rod to stroke ratio, or rod ratio for short, to determine the physical location of the piston when the intake valve closes. This begins the real measure of the compression ratio.

As an example, a stock engine with a 10.5:1 static compression ratio may have a dynamic compression ratio of 8.0:1, but adding a higher duration camshaft can lower this dynamic compression ratio to around 7.7:1. This is why big camshafts necessitate higher static compression ratios, to help offset the original loss.

Anything that alters the intake valve timing will also change the dynamic compression ratio. This includes secondary cam lobe profiles like those used on Honda’s VTEC as well as cam phasing technologies like BMW’s VANOS and Subaru’s AVCS. It’s important to adjust ignition timing to meet the needs of advancing or retarding the intake valve’s timing.
 

Johnbuz

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The pinging occurs when the engine is fully warmed up and the ambient air temp is at least 60 degress, under load at rpm's in the 1500-2000 range. In the MT its easy to reproduce. I use 87 in winter and 93 in summer. The 93 helps but does not fully stop the pinging. I doubt 93 helps with power or mpg to any large degree and I don't care. But engines that ping are not happy engines. And since there are hundreds of others that report the same issue and mitigation, it's not our imagination.
 

AnnDee4444

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The pinging occurs when the engine is fully warmed up and the ambient air temp is at least 60 degress, under load at rpm's in the 1500-2000 range.
Sounds like a lugging issue, or the OEM tune is too advanced at that spot.

Anyone with a tune have this issue?
 

JeepU4IA

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Sounds like a lugging issue, or the OEM tune is too advanced at that spot.

Anyone with a tune have this issue?
Lugging is when you're in a higher gear than you should be. The pinging occurs even in first gear. The tune is obviously the culprit, part of an effort to maximize fuel economy. Aftermarket tunes are usually designed for 91 octane minimum.
 

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