[Wataru]

I just wonder what everyone here thinks of the octane ratio for their Mustangs?

I checked MSN for the MPG on my car and it was 16MPG. When I purchased the car, I was getting about 12-14. So I put in some STP Octane Boost (yknow, the junk that claims it has jetfuel in it, which is just kerosene) and it helped, I was going from 12-14 to 16. It was $4 a bottle and I wondered one weekend, why not skip it in and see. Maybe I just had some older gasoline.

I noticed after 2 fill ups on 87 octane, there was some black corrusion starting on the end of the tailpipe. I read on another Mustang board, that a higher octane would only matter if you were tuned for it. The next week, I went from 87 to 93 and since then, the corrusion hasnt come back (I cleaned it off with a metal pad) and Im geting 16-17 MPG in the city.

Opinions, stories of the like?

[mattf0509]

I've never tested all that out but I've always heard that premium is more efficient in cars and burns cleaner, but I've also heard it burns faster. So that's cool you get better gas mileage I would have thought it would make the corrosion stop but bring your mileage down

[ReverendDexter]

Originally Posted by mattf0509 I've never tested all that out but I've always heard that premium is more efficient in cars and burns cleaner

That's true if the car has the capability to take advantage of it, which comes from either high compression, timing advance, boost, or some combination thereof.

Most modern cars will advance the timing until they detect knock, which means that if you run higher octane fuel they'll run more advanced. That's where you get the increases in efficiency.

[mustanginky]

unless your car has knock sensors (only shelby's have them as far as mustangs go) then there really is no advancing timing in our mustangs based on detonation. it will advance under cooler weather, and retard under warmer weather.

[itschristorres8]

Originally Posted by ReverendDexter That's true if the car has the capability to take advantage of it, which comes from either high compression, timing advance, boost, or some combination thereof. Most modern cars will advance the timing until they detect knock, which means that if you run higher octane fuel they'll run more advanced. That's where you get the increases in efficiency.

Originally Posted by mustanginky unless your car has knock sensors (only shelby's have them as far as mustangs go) then there really is no advancing timing in our mustangs based on detonation. it will advance under cooler weather, and retard under warmer weather.

The car and computer are electronically controled and programed. They dont have a mind of their own and say hey lets advance the timing under this load even though it was never programed for that.
Why do you think hand held tuners such as Diablo, SCT and other actually increase power? because they increase timing and other super safe features the factory programs the car too.
lol basically what was being said is the car tunes itself....lol soooo why do I need a tune for my turbo? shouldnt the computer know the timing and the MAF know to add fuel for pressure?

[6ER THEN I 8ER!]

^
i dunno about anything they said...but i did notice a better MPG from upgrading to 89 from 87...just a few though nothing major...i haven't gone back to 87 since...

[v606er]

Damn watru that's some shitty mpg. Do you have forced induction, or are you gunning it everywhere you go? I get between 18 and 20 in the city, and that's having fun with it.

[Wataru]

Originally Posted by v606er Damn watru that's some shitty mpg. Do you have forced induction, or are you gunning it everywhere you go? I get between 18 and 20 in the city, and that's having fun with it.

Eh its the EPA rating 16MPG per city. Nope, I dont gun it. I just do alot of city driving. I do have the stock CAI, which Im going to change soon. And I didnt just do a fuel system cleaning.

[JRicky]

wow...put a good exhaust or something on there....I average 24 mpg with bolt ons..

only the latest 05+ GT's with those spanish oak computers actually react to octane in fuel, its documented that jumping from regular to premium actually can up output...but only by maybe 2 hp...

your car will have no idea there's any different fuel in there, however, you may be getting crappy gas, I usedto run mid-grade 89 octane because the car would ping a little on regular from sunoco gas, I switched to the local citgo station and dropped back to 87...and not a sound

[mustang227]

i have a predator in mine so i run 93. slight increase in mileage. barely noticable.

[ReverendDexter]

Originally Posted by itschristorres8 The car and computer are electronically controled and programed. They dont have a mind of their own and say hey lets advance the timing under this load even though it was never programed for that.

If it was never programmed for that, you're absolutely correct.

The algorithm for cars with a knock sensor is that every firing cycle they incrementally advance the timing some set amount until knock is detected, then they retard it some larger amount. The timing is never constant while the engine is running, it's always being advanced or retarded based on what happened the previous firing cycle.

If Mustangs aren't equipped with a knock sensor, then obviously they wouldn't be capable of this sort of adaptive timing. I'm guessing that at least 3Vs are, though, as dyno pulls with high octane show a hp increase over pulls with 87.

[Wataru]

Originally Posted by JRicky wow...put a good exhaust or something on there....I average 24 mpg with bolt ons.. only the latest 05+ GT's with those spanish oak computers actually react to octane in fuel, its documented that jumping from regular to premium actually can up output...but only by maybe 2 hp... your car will have no idea there's any different fuel in there, however, you may be getting crappy gas, I usedto run mid-grade 89 octane because the car would ping a little on regular from sunoco gas, I switched to the local citgo station and dropped back to 87...and not a sound

Just did a complete fuel system cleaning. Jumped to 19MPG. Woooo!

[ewells2420]

Originally Posted by Wataru Just did a complete fuel system cleaning. Jumped to 19MPG. Woooo!

please define complete fuel system cleaning?

[Trick Tuners]

You will not see an increase in mpg with higher octane unless the vehicle has knock sensors. What you are seeing is just chance. You need to drive the exact same roads, and fill up at the same PUMP at the same station to get any accurate mpg data. Go for at least 2-3 tanks and then change something.

[Wataru]

Originally Posted by ewells2420 please define complete fuel system cleaning?

As I was told, guy at work does car repair..

Flushed rails, checked seals, clean injectors, decarbonized, clean throttle body by handle w/kerosene, replaced 9 year old stock fuel pump, dropped fuel tank, resealed it, drained tank, cleaned all sediment out, repressurized the lines.