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89 Octane Tune for HEMI Jeep?

Predator support for Dodge gas vehicles

Moderators: mikel, JonDiablosport, johan, Vas@Diablosport

Post Tue Jun 29, 2010 1:18 am

Posts: 21
I'm thinking about purchasing a Diablosport Predator tuner for my 2010 Jeep Grand Cherokee 5.7L HEMI but there is one thing that concerns me. The jeep is recommended to run on 89 octane but Diablosport only has a 87 octane tune. Wont i actually lose power by running 87 octane? My dealer recommend 89 because it will provide more power and better fuel mileage because the HEMI retards the timing on 87. If i don't want to spend the money on premium i'd like to stick to mid grade but get the most power out of it and not use 87. Is there a 89 octane tune available?

Post Tue Jun 29, 2010 1:37 pm

Posts: 242
with the 87 tune and 87 octane mine feels better than the stock tuning with 89 octane. if you are really worried about it you can just use the 87 tune and 89 gas to help fight off knock but mine runs really well with the 87 and 87 combo. i think if you want to run 89 with the 87 tune you can add 2 degrees of wot spark in each of the ranges too, i never have added spark though.
2003 RCSB Hemi Ram - Stock 20s, U7137, AIRAID CAI, 180* Jet T-Stat, Black Magic E-Fan, 3 Inch Cutout, Hooker Aero Chamber Muffler, TMR Mod, NGK 5306 plugs, Taylor 8.2 thundervolt wires, Pacesetter Longtube Headers, Pacesetter ORY, magnaflow cat, Innovate LC-1,

Post Tue Jun 29, 2010 2:27 pm

Posts: 875
sanitarium16 wrote:
I'm thinking about purchasing a Diablosport Predator tuner for my 2010 Jeep Grand Cherokee 5.7L HEMI but there is one thing that concerns me. The jeep is recommended to run on 89 octane but Diablosport only has a 87 octane tune. Wont i actually lose power by running 87 octane? My dealer recommend 89 because it will provide more power and better fuel mileage because the HEMI retards the timing on 87. If i don't want to spend the money on premium i'd like to stick to mid grade but get the most power out of it and not use 87. Is there a 89 octane tune available?


Mileage at part throttle will not see much difference regardless of which tune you use. Most of DS lower octane tunes(91,89,87) are just the 93octane tune with a bit less timing.

The great thing about DS tool over pos handhelds is that you can easily customize the tune to your liking. And your not locked in to any specific tune.

Do this:
Datalog ST Knock retard with the 87tune +89 fuel. If its 0 and LT knock retad is also 0, then just add 2 degrees of WOT timing. Check for ST and LT knock again. If LT = 0 and ST is less than 2.0, you're good to go.

A little higher timing with the 87tune will capture some benefits of using a higher octane fuel.

Post Tue Jun 29, 2010 4:08 pm

Posts: 42202
Location: DiabloSport World Headquarters

sanitarium16 wrote:
I'm thinking about purchasing a Diablosport Predator tuner for my 2010 Jeep Grand Cherokee 5.7L HEMI but there is one thing that concerns me. The jeep is recommended to run on 89 octane but Diablosport only has a 87 octane tune. Wont i actually lose power by running 87 octane? My dealer recommend 89 because it will provide more power and better fuel mileage because the HEMI retards the timing on 87. If i don't want to spend the money on premium i'd like to stick to mid grade but get the most power out of it and not use 87. Is there a 89 octane tune available?
By optimizing timing and knock sensor calibration, we are able to make better power on 87 octane than the stock cal makes on 89...
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Post Tue Jun 29, 2010 8:55 pm

Posts: 21
mikel wrote:
sanitarium16 wrote:
I'm thinking about purchasing a Diablosport Predator tuner for my 2010 Jeep Grand Cherokee 5.7L HEMI but there is one thing that concerns me. The jeep is recommended to run on 89 octane but Diablosport only has a 87 octane tune. Wont i actually lose power by running 87 octane? My dealer recommend 89 because it will provide more power and better fuel mileage because the HEMI retards the timing on 87. If i don't want to spend the money on premium i'd like to stick to mid grade but get the most power out of it and not use 87. Is there a 89 octane tune available?
By optimizing timing and knock sensor calibration, we are able to make better power on 87 octane than the stock cal makes on 89...



Can you make/offer a 89 octane tune? Are there special tunes for cold air intakes? I have the mopar cold air intake and gibson 3inch catback. I also read about knocking at WOT, some of the dodge ram guys on here are mentioning that.

Post Tue Jun 29, 2010 9:03 pm

Posts: 42202
Location: DiabloSport World Headquarters

No need for an 89 tune, as at best it may want .5* more timing? Wont see any power like that, so save the .10 a gallon....

The trucks do not lean out with a CAI, so they dont need any CAI tunes.
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