Has anyone run regular octane gas in their 392?

Left Field

Well-Known Member
First Name
Tim
Joined
Aug 5, 2020
Threads
8
Messages
176
Reaction score
477
Location
Western WA
Vehicle(s)
'67 RS-SS Camaro, 2021 JLUR392
Heading out on an extended trip to the boondocks with the 392 in a couple weeks and in one area there is no premium gasoline available. Near as I can tell the 392 does not have a detonation sensor and hence does not adjust the ignition mapping based on octane (please correct me if that is wrong).
Some options that come to mind are:

1) Run regular gas & keep my foot out of the throttle.

2) Bring extra fuel, probably 10-15g required.

3) Octane booster
Not very excited about this. Most seem like snake oil, providing no quantifiable octane numbers. The legit ones such as Torco and Boostane appear to use MMT (Methylcyclopentadienyl Manganese Tricarbonyl) which is "not for highway use" and by at least some reports can damage O2 sensors and the cats.

My order of preference would be 1,2,3 but if someone has some experience I'd like to learn from it.
Thanks,
LF

 

GATORB8

Well-Known Member
First Name
Matt
Joined
May 30, 2021
Threads
13
Messages
4,242
Reaction score
4,992
Location
CLT NC
Vehicle(s)
21 JLURe
Just a thought that may be worth looking into. IIRC, blending octanes results in a modified octane per the ratio.

What about bringing a smaller amount of something high octane (race gas) to raise the octane.
 

jludave

Well-Known Member
First Name
David
Joined
Feb 13, 2020
Threads
12
Messages
2,599
Reaction score
2,344
Location
The Isle of Long
Vehicle(s)
2020 Wrangler Unlimited Sport Altitude
Vehicle Showcase
1
Best bet is option 2 if you can swing it.
 

Old Dogger

Well-Known Member
First Name
Bill
Joined
Nov 15, 2021
Threads
8
Messages
1,411
Reaction score
1,490
Location
Cave Creek Arizona
Vehicle(s)
2013 JKR, 2018 JLR
Occupation
Retired High level Management.
What part of our Country, doesn’t carry premium fuel? I didn’t know that this existed.
 
OP
OP
Left Field

Left Field

Well-Known Member
First Name
Tim
Joined
Aug 5, 2020
Threads
8
Messages
176
Reaction score
477
Location
Western WA
Vehicle(s)
'67 RS-SS Camaro, 2021 JLUR392
What about bringing a smaller amount of something high octane (race gas) to raise the octane.
Best bet is option 2 if you can swing it.
I think I'll do exactly this combination - bring fuel - but make it race fuel. Allows me to carry less fuel and still satisfy the octane requirements - Thanks!
LF
 


OP
OP
Left Field

Left Field

Well-Known Member
First Name
Tim
Joined
Aug 5, 2020
Threads
8
Messages
176
Reaction score
477
Location
Western WA
Vehicle(s)
'67 RS-SS Camaro, 2021 JLUR392
What part of our Country, doesn’t carry premium fuel? I didn’t know that this existed.
Burgdorf Idaho.

I can drive off-route some distance to get premium, but traveling with a group makes that side trip a logistical problem.
 

6.2Blazer

Well-Known Member
First Name
Brad
Joined
Jul 11, 2022
Threads
1
Messages
117
Reaction score
141
Location
Ohio
Vehicle(s)
2019 JL Sport
I would pretty much guarantee that this engine has knock sensors and the ECM will retard the timing to compensate for lower octane fuel. Would be amazed if it didn't. Out of curiosity, what makes you think it does not have that capability?
And just before somebody jumps my case, I'm not saying the engine will run perfectly fine and have the same power if you run lower octane gas. But I would expect it to be able to run decent at reasonable throttle inputs and loads.
 

Quadjeeper

Well-Known Member
First Name
Scott
Joined
Apr 22, 2020
Threads
0
Messages
289
Reaction score
619
Location
Winter Springs, FL
Vehicle(s)
2022 392XR
Occupation
retired
I would pretty much guarantee that this engine has knock sensors and the ECM will retard the timing to compensate for lower octane fuel. Would be amazed if it didn't. Out of curiosity, what makes you think it does not have that capability?
And just before somebody jumps my case, I'm not saying the engine will run perfectly fine and have the same power if you run lower octane gas. But I would expect it to be able to run decent at reasonable throttle inputs and loads.
It does not retard timing. According to an engineer who developed the JL 392 package, it will damage the engine if less than 91 is used.
 

stumblinhorse

Well-Known Member
Joined
Dec 17, 2021
Threads
18
Messages
462
Reaction score
466
Location
Colorado
Vehicle(s)
2021 392
It does not retard timing. According to an engineer who developed the JL 392 package, it will damage the engine if less than 91 is used.
Hmm…. Hold on there. You are saying that this sensor doesn’t do anything…. Just detects knock, and nothing happens….

https://www.oem-mopar.com/oem-parts/mopar-knock-sensor-5033316ab?c=Zz1lbGVjdHJpY2FsJnM9c2Vuc29ycyZsPTQmbj1TZWFyY2ggUmVzdWx0cyZhPWplZXAmbz13cmFuZ2xlciZ5PTIwMjEmdD11bmxpbWl0ZWQtcnViaWNvbi0zOTImZT02LTRsLXY4LWdhcw==
 
OP
OP
Left Field

Left Field

Well-Known Member
First Name
Tim
Joined
Aug 5, 2020
Threads
8
Messages
176
Reaction score
477
Location
Western WA
Vehicle(s)
'67 RS-SS Camaro, 2021 JLUR392
Hmm…. Hold on there. You are saying that this sensor doesn’t do anything…. Just detects knock, and nothing happens….
Some vehicles I've had say "Premium fuel recommended; lower octane fuel may reduce engine performance". This sounds like changing the ignition mapping if it detects detonation.

The 392 manual says "Use of gasoline with an octane number lower than recommended octane can cause engine failure and may void the New Vehicle Limited Warranty." ... "The use of 91 or higher octane “Premium” gasoline is required in these engines."

It would be pathetic, but perhaps the knock sensor just throws a 'bad fuel' code? Which unfortunately would then put your engine warranty in jeopardy...

LF
 


Quadjeeper

Well-Known Member
First Name
Scott
Joined
Apr 22, 2020
Threads
0
Messages
289
Reaction score
619
Location
Winter Springs, FL
Vehicle(s)
2022 392XR
Occupation
retired
I'm not the engineer. Nor did I write the owners manual. Do what you want, but I'm not going to risk it.
 

JJMalone

Well-Known Member
First Name
John
Joined
Mar 4, 2020
Threads
8
Messages
156
Reaction score
312
Location
Eugene, Oregon
Vehicle(s)
392, '20 JLR, '00 TRD Tacoma
Detonation is not prevented by retarding ignition timing. Get a clue.
 

guarnibl

Well-Known Member
Joined
Apr 3, 2017
Threads
3
Messages
2,346
Reaction score
2,037
Location
Scottsdale / Sarasota
Vehicle(s)
'21 JLUR 392 XR, '21 JTR, '21 JLR, '09 JK
Well that’s surprising given dealers around here just put 87 in the first full tank 392’s included.

I’d probably carry extra fuel though if I was OP. 2x or 3x cans and split them among guests if they’re cool with it and you don’t have the space.
 

hazards280

Well-Known Member
Joined
May 17, 2017
Threads
2
Messages
48
Reaction score
82
Location
Midland MI
Vehicle(s)
22' JLUR 392 - Sarge Green
No.

The piece of mind when I put the skinny down is worth the extra $20 at fill-up.
 

RoasterBoy

Member
First Name
Todd
Joined
Jun 21, 2022
Threads
1
Messages
6
Reaction score
3
Location
Hudson, WI
Vehicle(s)
2022 Ram TRX, 2019 Dodge Challenger Scat Pack
Make sure if you mix the race gas in that it is unleaded. Some high octane race fuel uses lead to boost octane numbers. Just a tip.

 

Exact Center
 
Top