V6 (1994-2004) Mustangs Technical discussions on the 3.8L and 3.9L V6 torque monsters

87 vs 89 vs 91 octane tune

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Old 02-07-2010, 12:54 PM
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Matt's 95 Stang
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Default 87 vs 89 vs 91 octane tune

So now that I have the money for a real good tune I was wondering what octane to use? I know everyone says the higher the octane the more power you get but is it really worth spending an extra $2-3 dollars per fill up x 52 weeks ( I have to fill up everyweek as this is my DD) for an extra 5 HP? Not to me. So I am looking for a realistic idea of what I could get between the 3 diffrent octanes...

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Matthew
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Old 02-07-2010, 01:14 PM
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brent4
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Are you using a hand held tuner? If so go with the 87 for DD and when you wana play upload the 91 tune.
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Old 02-07-2010, 01:14 PM
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Shaunmac9128
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If its not worth it to you, don't do it. I doubt you would get 5 hp by switching from 87-89, maybe from 87-91 with a good tune. I don't know though. If it is a dd, to me I would do 87 or 89, I remember awhile ago there was a thread about fuel mileage and a few guys said they get better mileage on average with 89 over 87. Maybe see if there is a difference in mileage for you over the course of a few fill ups and average it out, if there is I would pick that octane. Just my .02
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Old 02-07-2010, 02:09 PM
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JKs95stang
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So true Shaun, I see a big difference in running cheap 87 to good 87, let alone 89 or 91 from Chevron, Shell, etc... OP, you will probably get the same mileage or better with 91 octane, your car will run smoother and better acceleration which means less pedal to move the car. You should go with 89 from the "sound" of your text, not that much more than 87 and will run cleaner.
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Old 02-07-2010, 02:12 PM
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Shaunmac9128
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Agreed. And yeah thats another point, avoid cheap gas.
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Old 02-07-2010, 03:09 PM
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rfcsoulja
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$3 a week is worth the gain you'll see.
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Old 02-07-2010, 03:15 PM
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Richbrad08
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after the tune you will get lead foot syndrome.
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Old 02-08-2010, 11:21 PM
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v6stang07
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91 is the only way to go. you dont want to sometimes fill up with premium then sometimes with regular. its not that much more but so much worth the gain
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Old 02-09-2010, 12:06 AM
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NeoTokyo
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Welp the new Coyote makes 402hp on 87 and 412 on 91.

So if an all out performance production engine only makes another 10hp for the octane points then you should expect less.

According to 5.0 magazine; The Coyote tune is already very agressive as it is to extract as much possible power be it 87 or 91 or 93.



Just keep both tunes handy, when you want to play just upload the 91 tune.
SCT is so fast you can have the original tune back, out and the new tune on in less than 3 minutes.

Diablo is of course much slower.
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Old 02-09-2010, 08:26 AM
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Shaunmac9128
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Hey! Don't hate on diablo.
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