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-   -   2012 WK2 Grade of gas (http://www.jeepgarage.org/f73/2012-wk2-grade-of-gas-36791.html)

Jimbo 02-05-2012 07:20 PM

2012 WK2 Grade of gas
 
Could the 2012 3.6l V6 WK2 run on 91 octane fuel to increase mpg? Or would 91 octane gas create performance loss and is harmful to the engine?

xJoshxx 02-05-2012 07:27 PM

Re: 2012 WK2 Grade of gas
 
the 3.6 was designed to take 87 and has no gains from using a higher octane.

77Cherokee 02-05-2012 07:54 PM

Re: 2012 WK2 Grade of gas
 
+1. You would be throwing away good money for nothing.

UNCjeepWK2 02-05-2012 10:55 PM

Re: 2012 WK2 Grade of gas
 
one of the biggest fuel myths ever... using a higher octane NEVER achieves higher MPG. If it calls for 87, then use 87. If it calls for something else, use the something else. Just go by the manual...

Breitling65 02-06-2012 06:47 AM

Re: 2012 WK2 Grade of gas
 
It is safe to drive regular based on book and no power loss based on driving of WK2. Normally higher octane protects against of very harmful detonation, V6 ignition and compression ratio adjusted to run on regular without.

peckmv 02-06-2012 08:51 AM

Re: 2012 WK2 Grade of gas
 
Quote:

Originally Posted by Jimbo (Post 568100)
Could the 2012 3.6l V6 WK2 run on 91 octane fuel to increase mpg? Or would 91 octane gas create performance loss and is harmful to the engine?

Octane does nothing for mileage. It is an anti-knock additive. ;)

JTS97Z28 02-07-2012 12:10 PM

Re: 2012 WK2 Grade of gas
 
Wow are people still seriously stuck on thinking that just because the fuel is a higher octane that it could deliver better performance and fuel economy.

Like others have said above if your engine is designed to burn regular grade 87 octane, there will be NO benefits of burning premium 91 octane or greater.

Use what the manual says to use and nothing else!!!

Jeep_addicted 02-07-2012 02:50 PM

Re: 2012 WK2 Grade of gas
 
I have used both 87 and 93 and for me think the sweet spot would be 89 for the 3.6

But me personally I get better mileage when I use the 93 because the engine feels like it produces more torque in the lower rpm. If you can run the tank down to practically empty and do your own seat of the pants calculations you will know which one is right for you.

The 3.6 does not require high octane fuel, as the VVT and knock sensors quickly compensates for the lower octane but advancing the timing a bit.

For my Hilly(mountainous) driving conditions the torque at lower rpm also helps with my stop and go moring traffic...

BManz 02-07-2012 07:24 PM

Re: 2012 WK2 Grade of gas
 
I could never tell a difference running 87 or 89 in the Hemi. The Hemi is tuned for 89 but mine's been filled with 87 a few times, full tank too, and I honestly couldn't tell a difference. Still run 89 anyway for most all of my fill ups. But -- about 2 weeks ago I had to fill mine up with 91 at my regular station when they ran out of 87. Since 89 is just a blend of 87 and 91 or 93 as you fill, I just took the premium rather than drive out of my way.

Immediately after that fill up, when I got on my usual I-294 on ramp, I noticed a significant amount more of butt-dyno power. Sure, I would've said to anyone else it was just in their head, but I wasn't expecting any difference at all so I was surprised. There was no fuel economy difference that tank full, mostly highway and got 22+ winter fuel & all.

So, I think my station and some others are cheating on the 89 because after that 91 octane tank got used up that weekend I went back to 89 on the next fill -23gal- at another station and the butt-dyno immediately said "less power" when I got back on the road. I'm about done with that 89 tank now and EVIC says 22.1mpg so again no change in economy. But, actually "butt", I sure felt a difference in power 91 vs the, ahem, 87 er 89, like an engine would do when pulling timing back. Anyone else think some stations might be a little slim in the 91/87 blend to give us "89"? That may be why I could never tell a difference before.

It's possible it was a weather anomaly giving some high pressure but I'm still suspicious.:confused:

JGCCAYENNE 02-09-2012 06:21 AM

Re: 2012 WK2 Grade of gas
 
The difference between 87 and 91 on a Hemi is at most 10 HP. If your butt can measure that, you have a very sensitive butt.

BManz 02-09-2012 11:34 AM

Re: 2012 WK2 Grade of gas
 
Quote:

Originally Posted by JGCCAYENNE (Post 570404)
The difference between 87 and 91 on a Hemi is at most 10 HP. If your butt can measure that, you have a very sensitive butt.

You mean 20+hp. It's more like a 6%-8% reduction in power if the engine has a tune to take advantage of a higher octane and you run a lower one. If the change is more than 10-15hp, oh yeah, a car guy like me will feel that on full honk acceleration. While I'm not an engineer, I built, dyno'd and raced a few engine/chassis combos over the years which involved working alongside some powertrain engineers from various manufacturers who were also racers on the weekends and it's what we saw. One of those guys introduced me to this forum as a matter of fact.

This very octane discussion, and torque/horsepower debating, was had many times over beer and brats. The -8% power reduction number matched what we typically saw on dyno testing changing nothing but the fuel and timing to reduce detonation -- I liked trying to build street-gas friendly race engines when money was tight. Modern engines retard timing quickly at the hint of detonation even running the designated octane fuel. So on a hot day while running your engine hard you'll feel a power loss too even running the optimal gas, 87, 89, 91, whatever, as the computer retards timing. It would be a pain to do a controlled test for this on the Grand without disconnecting the fuel tanks, but it'd be interesting.

SW03ES 02-09-2012 11:39 AM

Re: 2012 WK2 Grade of gas
 
Quote:

Originally Posted by Jeep_addicted (Post 569406)
I have used both 87 and 93 and for me think the sweet spot would be 89 for the 3.6

But me personally I get better mileage when I use the 93 because the engine feels like it produces more torque in the lower rpm. If you can run the tank down to practically empty and do your own seat of the pants calculations you will know which one is right for you..

Thats totally in your head. Seriously, they have done study after study, using a higher octane gas than what is recommended does nothing for performance.


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