Chip on 87 octane

[DEFYANT]

Can this be done. I have a relative who wants the power, but not the expencive gas.

[RF Overlord]

Part of the reason the MM requires 91 octane is that the compression ratio is upped to 10.1, vs. the 2V's 9.37. While Dennis, Wes, or Lidio could most likely make a program to ALLOW the car to run on 87 octane, I doubt you'd get a performance increase; most likely you'd get a decrease...you WOULD however, get the improved shifting...but that's about all. IMHO.

[TripleTransAm]

Can a 10.1:1 engine even support 87 octane regardless of ignition timing?

[cyclone03]

Can a 10.1:1 engine even support 87 octane regardless of ignition timing?


I've run mine on 86 for about 3 tanks.
But I DID NOT run it WOT.
BTW it gets better mileage on mid (89) than 93 but again very limited WOT.

[gdmjoe]

Defyant - Can this be done. I have a relative who wants the power, but not the expencive gas.
2cents .....

You don't mention the vehicle / engine combination, but yes it can be done ( provided it doesn't require premium from the factory ).

Recent Team Ford, SCT tune ( with the addition of a Marauder airbox + MAF ) gained 15HP / 20FtLb; specified an 87 octane tune ( which usually means not mucking with the timing ); additional tune items were - harder shifts, raised shift points, speed-limiter removed, idle RPM bump ( to compensate for the underdrive pulley ). *These are performance related too, eh?

Several bolt-on mod's respond well to a performance tune @ 87 octane ( especially if you improve air / exhaust flow ).

[SergntMac]

For some elusive reason I can't put my finger on, none of this is adding up for me. Our Intech 4V is roughly a 10:1 compression engine, and 87 octane...Well I suppose you could tune for it, just in case the low octane was short term necessary drink when traveling OTR, but it wouldn't be much fun to drive. I'm guessing that the consequence would cause the driver to push the car harder just to keep the fun exciting, and that won't be good. Detonation is a very serious threat to our engines, and long term use of less than optimal octane fuels will damage the engine...IMHO.

[Mad4Macs]

For some elisive reason I can't put my finger on, none of this is adding up for me... (snipped) IMHO.

I cannot agree with you more, sir! If you go out and buy a car that is ADVERTISED as a performance sedan, and if you're spending more than you'd pay to buy a Ford Focus, then WTF is the problem with paying PENNIES more for a gallon of gas? If it's for the "looks" of the MM, just buy a Grand Marquis and black out the trim or something. Thermodynamics "is what it is", and performance doesn't come free.
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[CRUZTAKER]

I have an emergency program set for 89 octane. I had better be in the middle of nowhere in bum-fark sahara desert before I'd run with 89.

87...your'e kidding right? :shake:

[BlackHole]

My way of thinking on this is IF YOU CAN'T AFFORD THE GAS THEN YOU CAN'T AFFORD THE CAR! Sorry but thats the truth. When Prem was inching up to the $2.50 mark there in early May I was driving my Mystique about 80% of the time.

[CBT]

When I'm behind the wheel MPG stands for Miles Per Gas station, muhahahahaa....

[FordNut]

As I've said every time one of these octane threads comes up, I run 93 in mine due to the performance mods. The wife's is stock and she has used 87 in all 40,000 of the trouble-free miles on it. And my 93 is from the "good" stations while her 87 is rot-gut grade. Lucky? Maybe.

[TripleTransAm]

My MM pings occasionally on 91 octane. But it does get slightly better mileage from that fuel than from 94 octane.

[Bradley G]

Hey FordNut,

If your real easy on the pedal it won't hurt IMHO.Unless it Pings, I feel it is little risk.My wife filled with mid grade with out me knowing .
It only took once to learn me not to use anything but 93.I could tell right away as soon as it hit the 3500 powerband.She promised me never to do it again:rolleyes:
Bradley G


As I've said every time one of these octane threads comes up, I run 93 in mine due to the performance mods. The wife's is stock and she has used 87 in all 40,000 of the trouble-free miles on it. And my 93 is from the "good" stations while her 87 is rot-gut grade. Lucky? Maybe.

[purelux]

my 98 tc also has 10:1 and recommends prem even factory. however it has knock sensors which the mm probably has too. I used to use 94 ultra and noticed that on sunoco 93 it seemed to get better mpg and performance. Now I have the meziere e-water pump the 180 t-stat and water wetter. With probably 40 extended prestone anti vs about 60 distilled water. And i had about 1/4 tank of 94 then filled up with 89 and it seemed fine. I did just about the same the next couple of tanks and it seemed to run very well. Now that it has gotton cold though the mpg has dropped off from an avg of about 15 or so to about 12-13. However i also went from 225-50-16 to 225 60 16 for the winter. And the ecm tuned by ford chips for 93 and the 225 50 series shifts 180 t-stat etc.. But on my dads 97 conti the lower octane doesn't get as good of performance or mpg though with the 270 hp 32 valve 4.6 intech. And his is completely stock and has new plugs, wires and has had seafoam run thru the intake.

[TechHeavy]

I cannot agree with you more, sir! If you go out and buy a car that is ADVERTISED as a performance sedan, and if you're spending more than you'd pay to buy a Ford Focus, then WTF is the problem with paying PENNIES more for a gallon of gas? If it's for the "looks" of the MM, just buy a Grand Marquis and black out the trim or something. Thermodynamics "is what it is", and performance doesn't come free.
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Well said!! :awe: