3.6 engine and 87 octane a no-no

[Petey]

The pinging is also a strong function of ambient air temp. In winter here in the North, 87 is fine. But once tbe weather warms up, I switch to 93 to avoid the pinging.

I wanted to chime in here. My Jeep seems much more picky about gasoline than every vehicle I've had since my Chevy S-10. I remember when I bought my S-10 in 1995 they sent out a supplement saying to use 89+ octane fuel for a N/A 4.3L V-6. It ran amazing on Amoco Ultimate (remember the gimmick with the see through gas nozzle with the little ball in it). Ever since I got rid that truck I've always used 87 from any pump available.

On my Jeep, I've been noticing pinging at low RPMs so I've started only using Top Tier gasoline (i.e. Shell) at 87 octane. The pinging at low RPMs seems to have gone away. Unfortunately there are no top tier gasoline stations near me, so I have to make sure to get gas when I'm out running errands. I figure when I do trail rides that I may try 89 octane fuel.

same here

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[Petey]

Here is an investigation/test on if higher octane really performs better for an engine optimized for 87;



Long story short, don't waste your money on 91 octane if you have 3.6

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 ?...

 

[zgrw]

Guess who in this group would likely need higher octane ?...

Unfortunately, FCA disagrees with you

Please check this post as well
https://www.jlwranglerforums.com/fo...-87-octane-a-no-no.61889/page-14#post-1458022

 

[Petey]

Unfortunately, FCA disagrees with you

Please check this post as well
https://www.jlwranglerforums.com/fo...-87-octane-a-no-no.61889/page-14#post-1458022

FCA has many recalls on our rides ..it seems to disagree with itself at times it seems...

 

[NBB]

Unfortunately, FCA disagrees with you

You would need to sit in on a design meeting to state that, otherwise you have no clue.

Fact - EPA requires an emission target to be met on regular octane gas and higher compression helps meet the target. Love to see these RTFM citations to the owner’s manual, but a little applied brain is also sometimes helpful in addition.

It seems obvious from this thread including second hand word that there is a couple horsepower gain plus pretty much unaminous agreement that pinging occurs tells you the engine was designed right on the edge of preignition in order to meet all other design goals.

Kind of follows in a no brainer way that higher octane buys some operating margin on this motor - at least - to allow for all variations in operating conditions and fuel quality - things impossible to perfectly quantify at design time - and often impractical to account for even if such numbers could be found - ie margin here breaks a hard rule on emissions elsewhere.

87 likely fine, but I would not call higher a waste of money here.

It’s also well known the EPA is exploring octane regulation in the interest of lower emissions through higher compression motors.

 

[zgrw]

You would need to sit in on a design meeting to state that, otherwise you have no clue.

Fact - EPA requires an emission target to be met on regular octane gas and higher compression helps meet the target. Love to see these RTFM citations to the owner’s manual, but a little applied brain is also sometimes helpful in addition.

It seems obvious from this thread including second hand word that there is a couple horsepower gain plus pretty much unaminous agreement that pinging occurs tells you the engine was designed right on the edge of preignition in order to meet all other design goals.

Kind of follows in a no brainer way that higher octane buys some operating margin on this motor - at least - to allow for all variations in operating conditions and fuel quality - things impossible to perfectly quantify at design time - and often impractical to account for even if such numbers could be found - ie margin here breaks a hard rule on emissions elsewhere.

87 likely fine, but I would not call higher a waste of money here.

It’s also well known the EPA is exploring octane regulation in the interest of lower emissions through higher compression motors.

I don't need to be a design meeting to know this. Their manual clearly says (which I referenced), "there is no additional benefit for 3.6L engine with higher octane". That's an official document.
Same document also says that, if you have 2.0L engine, 91 Octane provides the optimal performance. It is all about how the factory calibrated engine. If it was about EPA and low emissions, they also wouldn't write this for 2.0L (hence contradicts with your argument).

Unless anyone in this forum is from Jeep, or put their vehicle into a test like the one in the video, everything written here about performance gain is pure speculation. There is no scientific evidence to prove otherwise. Up until then, manufacturer spec clearly says that it is pointless to put 91.

 

[NBB]

Their manual clearly says...

Everyone here knows what the manual says. The law allows it to say nothing else. The discussion beyond that sounds a little over your head, really.

 

[zgrw]

Everyone here knows what the manual says. The law allows it to say nothing else. The discussion beyond that sounds a little over your head, really.

Please re-read my post (and the manual), especially about the 2.0L part. Considering manual says 91 is better for 2.0L, I think you are mistaken about the law.

 

[Petey]

I don't need to be a design meeting to know this. Their manual clearly says (which I referenced), "there is no additional benefit for 3.6L engine with higher octane". That's an official document.
Same document also says that, if you have 2.0L engine, 91 Octane provides the optimal performance. It is all about how the factory calibrated engine. If it was about EPA and low emissions, they also wouldn't write this for 2.0L (hence contradicts with your argument).

Unless anyone in this forum is from Jeep, or put their vehicle into a test like the one in the video, everything written here about performance gain is pure speculation. There is no scientific evidence to prove otherwise. Up until then, manufacturer spec clearly says that it is pointless to put 91.

Please re-read my post (and the manual), especially about the 2.0L part. Considering manual says 91 is better for 2.0L, I think you are mistaken about the law.

Kind of undermining their claim. It kind of admits that 87 is iffy at best for the turbo. (read into this)They want to cover their butts .. when damage occurs they'll tell u should have used the more expensive stuff. The 3.6 is not that much of a coin toss because the lack of turbocharging.... damage occurs at a slower pace in NA engines. . Pinging is no good for any engine no matter how little of it occurs or don't want to hear it. So yes ,u can use 87 or maybe 85 but ...the warranty on our jeeps isn't exactly the longest in the industry. Long term owners will know better

 

[PyrPatriot]

Kind of undermining their claim. It kind of admits that 87 is iffy at best for the turbo. (read into this)They want to cover their butts .. when damage occurs they'll tell u should have used the more expensive stuff. The 3.6 is not that much of a coin toss because the lack of turbocharging.... damage occurs at a slower pace in NA engines. . Pinging is no good for any engine no matter how little of it occurs or don't want to hear it. So yes ,u can use 87 or maybe 85 but ...the warranty on our jeeps isn't exactly the longest in the industry. Long term owners will know better

There have been plenty of the 3.6 engines with hundreds of thousands of miles on them. I doubt the van that got something like 400k miles used anything but 87 octane

 

[PyrPatriot]

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

 

[Cappy]

The placebo effect is very powerful.

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