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    Cobb Ap Needed for Octane Change or E85?

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    Do I need the Ap to change octane? I run 89 octane now, have been for 7K miles so far. Manual states you can run 87 although 93 is recommended. I bought the car more for economy reasons although if I run 93 how much more performance will I get and will there be mileage improvement? I drive it light footed and get over 39 MPG now. The car is my long distance commuter for work and my budget is tight, I'm close to retirement.

    And how about E85- can the car run on it, is it good or bad? I assume the Ap is needed and what else is needed for the E85 tune? I already have MBRP exhaust. Will it provide increased performance and what about gas mileage? I am looking at it as a cost savings- if I invest $500, will I get the pay back over 100K miles since E85 is cheaper than even regular and much cheaper than 93. (I have a gas station 1 mile from my house that has E85.)
    2017 Fiesta ST Base, 2018 Mustang GT Base, 1966 Bronco Project

  2. #2
    Senior Member 396 Rep Points danbfree's Avatar
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    Stock tune can handle 87-93 automatically. The higher the better to not only get the posted power but with that added power is cleaner burn from more intense combustion at higher timing, so less carbon buildup, especially if you are light footed, but you'll also get a little better mileage to make up for it... One trick is to do ONE gallon of e85 per full tank with the rest 89: So 3/4 gallon if refilling at 1/4 tank once you have done your first full gallon. This will give you a bit more octane for cheap on a stock tune and you are at the safe limit for a stock tune of around e15 total. This is a cheaper way to get to about 91 octane for less than just filling with 91 octane, hehe. :)

    As far as the AP, you can find used ones for ~$350 but from there will need ~$75 for an e30 tune, that's all you need to go in ethanol to max out the stock turbo, and you shouldn't go above ~e40 anyway, e50 is the very upper limit of safety with our fuel pump system... But with an e30 tune you'll get CRAZY good power but about 10% less MPG's depending on your driving habits... I'd stick to my example above in your case to keep the engine cleaner and get a bit more octane on a budget.
    '17 Magnetic - black wheels/red calipers - New Feb, '18.
    Tunes: Dizzy V2 e30/93 with Cobb TC at 3.
    Performance: Drop-in filter w/shroud cut, upgraded crossover and turbo inlet, symposer delete and hotside J pipe, TurboSmart VR2 electric recirc DV, 18" glasspack muffler swap with 9" resonated DC Sports black tip, step colder plugs.
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    Senior Member 1306 Rep Points M-Sport fan's Avatar
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    Some on here have gotten away with an E20 blend (mixed using 93 E10) on the factory tune (raises hand, done back when E85 was still sold around here :( ), but that is probably right at the borderline of being 'safe'.
    Magnetic 2016 Fiesta ST base model

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    Senior Member 396 Rep Points danbfree's Avatar
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    Quote Originally Posted by M-Sport fan View Post
    Some on here have gotten away with an E20 blend (mixed using 93 E10) on the factory tune (raises hand, done back when E85 was still sold around here :( ), but that is probably right at the borderline of being 'safe'.
    Good point! I was going off the fact that even 1 gallon of e85 (if actually 85% ethanol) puts us at e16.3 overall so people need to be careful running non-ethanol tunes. I'd say 1.25 gallons per full tank would be the safe limits unless the exact percentage in the e85 available to them is known and can be factored in.
    '17 Magnetic - black wheels/red calipers - New Feb, '18.
    Tunes: Dizzy V2 e30/93 with Cobb TC at 3.
    Performance: Drop-in filter w/shroud cut, upgraded crossover and turbo inlet, symposer delete and hotside J pipe, TurboSmart VR2 electric recirc DV, 18" glasspack muffler swap with 9" resonated DC Sports black tip, step colder plugs.
    Mounts/bracing: Torque Solutions 75a RMM, Powerflex Street engine upper side mount inserts, TB Performance Traction Bar
    Interior: Mojo Mfg short shift plate, Savanini ball shift knob, upholstered leather padded arm rest.
    Lighting: Techmax proper reflector LED low beams, DeAutoLED bright white reverse and trunk LED's
    Next Steps: Intercooler, induction hose, tint, Eibach springs, hybrid, seats

 

 

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