Re: Best fuel for 87 Tune? 87 pure or 89 w/ ethanol - Jeep Hemi
Generally, the ethanol blends will get you up to ~20% less fuel economy than the "straight gasoline". Also, I have found, with the SC 91 tune (running 91 straight gasoline), that I get some knock retard at WOT. Don't know if that would be true with the 87 tune or not, since I have never tried it.
IMO, the best thing to do is try them all, making sure to run several tanks of each through the system (and hand calculate results) before you make your final decision. Remember, all fuels are not created equal. Different brands of the same octane may deliver better or worse fuel economy. If your ride is basically stock, running 91 won't do a thing for you with the 87 tune. It might actually deliver less FE than the 87/89 would. Again, give it a try though Also, if you're at altitude (above ~2000 ft.) you may be able to get away with using lower octane....i.e. with my mods., if I am at altitudes above ~4000 I can run 87 without issue. Where I live (~3000 ft.) I can
"get away with" running alternate tanks of 87/91 (non-ethanol) in the winter, but I must run all 91 in the summer. No matter what, with any of the fuels, at any time of the year, I still get a little KR with the SC tuner. With the Diablosport tuner, running the 93 tune (using the same fuels) I don't get any KR. The DS tuner also delivers slightly better FE, but doesn't allow for complete adjustment of the transmission which is, IMO, essential.
05 LX/RT and 06 WK/GCO, (modded similarly) with MDS "ON" Light, Vortex Gens, Debadged, DashHawk, BT Catch Can, SRT CAI W/Add Air Inlet, K&N Filter, Sonnax Trans Line Press Booster, SC Tuner W/Adv Trans Tuning App, DS Tuner, Cust tubular headers w/3 in. catback, Bilsteins, SRT frt/rear bumpers, Eibach SRT Lwr Sprgs & Sways, FRI Sidewinder Cam Adv 2*, 6.1 valvetrain, SLP 25% UD Pulley, BBK 85mm TB, SOS Coils/.060 spark plug gap.