What octane gas do you guys run

[yoda13]

I have only put one tank in so far, but 87 octane for me. I got 16.0 even, hand calculated.

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[mazeppa]

I run mine on the worse swamp piss 87 Octane fuel I can find, If it can't handle it, I have the wrong machine.

Actually for my 3.6 I purchase 100% Ethanol free 87 Octane fuel most of the time that is available in my area, it's actually about equal price as the Ethanol based 91 Octane fuels. Historically in my area as fuel prices increase, the 100% Ethanol free fuels become proportionally more difficult to find to nonexistent.

But NEVER do I purchase higher than 87 Octane for my 3.6 Jeep unless it was unavailable.

 

[MrZappo]

You just don’t know what you’re taking about. Pretty common.

Spoken like a garden variety troll.

I'm right, everyone else is wrong, I offer no facts, no data, just the claim that "i'm a mechanic", and that others don't know what to listen for.

Very convincing and detailed analysis. Well said.

 

[Overloaded]

91 no ethanol

 

[j.o.y.ride]

Patently false. It’s 10.2:1. Up from 9.6:1.

General rule of thumb is 9.3:1 and below for 87. Jeep got this one wrong. Which is why the new 3.6s ping so much.

This PDF spec sheet says 11.3:1

file:///C:/Users/markley1/Downloads/2020_JP_Gladiator_SPamknhgr3g718bnft6e2lii6rla%20(6).pdf

I believe I get pings but like has been said, not entirely sure what to listen for. For me I hear it when I first apply throttle it will often give a little noise that I can't really describe, but is noticeable and consistent.

 

[AustinL911]

Wouldn't the obvious solution be to hook up a data logger and see what the knock sensors are hearing? I'm sure someone has done this (probably the engineers...). What were the results?

 

[BLK HOLE]

Spoken like a garden variety troll.

I'm right, everyone else is wrong, I offer no facts, no data, just the claim that "i'm a mechanic", and that others don't know what to listen for.

Very convincing and detailed analysis. Well said.

I stated the facts in my original comments. Reading is hard.

 

[BLK HOLE]

This PDF spec sheet says 11.3:1

file:///C:/Users/markley1/Downloads/2020_JP_Gladiator_SPamknhgr3g718bnft6e2lii6rla%20(6).pdf

I believe I get pings but like has been said, not entirely sure what to listen for. For me I hear it when I first apply throttle it will often give a little noise that I can't really describe, but is noticeable and consistent.

Yeah I misspoke. Google reference failed me. But yeah that’s the ping I’m referring to.

I’ve heard the ping on many JTs and even JLs. I’ve had 2 JTs and both do/did it. On my first one even 93 wouldn’t help. On my current one it takes about 95% of the pinging away.

 

[XJADDICTION]

87 all the time with no ping.

I do use 93 octane if towing a heavier load, no tune yet (like 6500lbs). I do this probably because I am used to ping with tuners on the gas 5.4L Fords I’ve had with load.

I’ve never had any pre-detonation with the 3.6s even in my previous JKUHR loaded down.

 

[BLK HOLE]

HAHAHAHA - copy and paste. Right. I wrote papers and articles on this topic. The only thing I copied and pasted was what I pasted from MIT - the post you quoted from me is my knowledge on the topic from years of research, and training others. No copy/paste, I typed it from what I know.

What a hoot.

Bro -

The pinging issue is real (I've experienced it many times on many new 3.6s and its easily Googled for similar complaints)

The rule of thumb on compression VS octane is also real. Yes environmental conditions and driving style (along with knowing what to listen for) all matter too.

All of the dissertation level typing and MIT pasting won't change that.

 

[ShadowsPapa]

Compression ratio isn't the only thing that impacts detonation (which is different from PREIGNITION)
Newer design combustion chambers can reduce ping, more swirl, fast burn chambers, etc. all work to reduce or eliminate ping.
Ping by detonation takes time - so a faster burn reduces the chances of ping. It's why the fellow driving his high-performance street car gets ping with 10:1 while the guy using basically the same engine on the track does not - he keeps it revved and there's no time for ping. I know guys running 11:1 and running 87 street gas in their muscle cars. Happens all the time.
The old bit about certain compression ratios requiring certain fuel went out the door with the 1990s. Combustion chamber design has thrown that out the window. That's so 1960s......

A fellow in MN who has developed a head modification for the 1970 AMC 390 - which was prone to detonation from the factory) and his head mod allows you to keep the small chamber high compression engine - and have no ping. They are running close to 11:1 and 87 octane - no ping.
TIMING also impacts ping - keep timing so the peak combustion pressures happen 14-16 degrees ATDC and you can reduce ping - and max out HP.

It's not all about compression ratio, engine builders for racing know that.

I upped the compression on my 4.0 significantly when I had the head shaved a fair amount and went with a different cam - and I run 87 with no ping.

The compression vs. ping is old-school thinking and google is not your friend on that because any fool will post what uncle Bubba told them.
Ask the guys running 10:1 and 11:1 with no ping on street gas, often 87 octane.
My wife has owned 3 WK2 now, 2015, 2018, 2021, no ping at all. Mine has no ping and I do know what to listen for (and I've worked it hard with heave loads and hauling a trailer on our 4 and 5% grades here)

It may be fair to say a lot of 3.6 ping, or a fair number may ping, but not all, not even most. Remember, the internet is where people gather to complain, it's not a fair reading of the whole story. When you visit a hospital, you find sick people. When you google for engine troubles, you find all of the reports of trouble, but you don't find the 90% who have NO trouble because people don't enter forums or post on the web "hey, my truck has NO trouble! Yeah!" So telling people to search for it is like telling people go visit a jail and tell me how many people there have broken some law.

The internet sucks for finding percentages. It only shows the troubles, not the no-troubles.

 

[ShadowsPapa]

87 all the time with no ping.

I do use 93 octane if towing a heavier load, no tune yet (like 6500lbs). I do this probably because I am used to ping with tuners on the gas 5.4L Fords I’ve had with load.

I’ve never had any pre-detonation with the 3.6s even in my previous JKUHR loaded down.

We've owned at least 5 Jeeps with the 3.6 and I KNOW what to listen for, decades of experience, and zero ping issues. None have ever had any engine troubles at all except for the 2021 - and that was spark plug related as per the TSB issues for ignition misfires. It's resolved.

 

[Thomasjbrothersjr]

I buy 87 octane but only from The major companies that have fuel cleaner additives. I have had fuel related issues in a vehicle that only ran the cheapest I could find it independent stations. Mechanic suggested a better grade, with additives.

 

[ScottBeach]

So no one else is running 85% corn?

 

[Jason Oliver]

OMG - Has this debate truly not be flogged to death before?...

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