87 octane wha???
 

Hey guys,
Here's the deal. Timing is set to 14 degrees btc. For a while I ran 87 octane and had lotsa fun with the car. Then I've been using 93 octane cuz 14 degrees should take advantage of the extra octane right? Well, it runs more sluggish with the 93... what gives? seriously, it feels faster and lots more fun to drive with 87... any ideas? Motor is totally stock, btw.

Use mid-grade
 

the octane that STOCK mustangs perform the best at is midgrade and if/when you used premium fuel the car can get sluggish a bit... i used to know the reasons, but it might be something how it effects the sensors.... but im 100 percent sure mustangs are recomended to use mid-grade fuel. There was an article on the HP stock mustang produced and the order is...
1. mid-grade... most power
2. regular... a few hp less
3. premium...was way back in the HP
-hope i helped

Unfortunately, many people assume that higher octane fuel is better for all engines, no matter what. This is absolutely false. Ultimately, the best octane for any vehicle is the lowest one you can run without detonation (pinging) occuring. It's not the fuel that increases the performance, it's the fact that the timing has been advanced. The higher octane permits this to happen. In your case 87 should be just fine.

Octane, for all intents and purposes, is used to slow down, or control the burn rate. Modifications that increase performance, such as increased compression, or advanced ignition timing, will cause the mixture to become too unstable, and pre-ignition (aka: detonation, pinging) will occur. This is when the mixture fires on it's own, at the wrong time. Severe damage will occur if left untreated.

People often think of high octane fuel as being more flammable, and easier to explode, whereas that is actually the opposite of the truth. 93 octane will be tougher to ignite than 87 octane. Because of that fact, 87 octane will burn quicker, and 93 octane will burn slower. That's why you feel sluggish with higher octane.

I've run 12.91 @ 105 mph on 87 octane, i get no detonation, but with my old stock e7's i HAD to run 93 with advanced ignition, even in the cold weather.
on 93 i have the same results you do, i tried some VP 104 one day, and it made my car sputter, and slow down.
Good thread here.:)

It has been a while since I have seen a thread like this. It seems like it comes up every so often and facts about octane always get jumbled up. Glad to see that that good info was presented quickly here.

Oh, no wonder good info is out there. It came straight from Chris, kind of :) !

At least give the man some credit and show where you came up with that info, or paraphrase it next time:D !

I thought my ears were burning because it's in the f-ing 80's here today. Now I see why.

LOL

:)

As long as the facts get out, I don't care if I don't get credit. What would really piss me off is if someone wrote something bogus, and then said I said it. lol.

:)

Hey! That was my 8900th post! I need to stop by more than once a month.

:)

i was actually going to post a similar question to this. i have always used super when filling up my stang. when cold it would pop under hard acceleration. i also got like 11-12 mpg. i decided to switch to regular gas and i have no popping at all when cold and get more mpg's!! does this make sense? mym mods are in my sig! thanks,

jim

Every car will be a little different. Like it was said before, you want the lowest octane gas you can run without getting detonation.

It is very possible that you don't need high octane gas with your combo.....look at Coupe5ho running 12.9 on 87 octane.

Awesome guys! thanks for all the info. I guess its 87 from now on.... phew what a relief on my wallet, heh. That premium was killing me. :p

Sorry I didn't give you credit Chris! I have so much info saved as text files on my computer, that I can't remember where half of them came from. Anyway it was good info you gave, that must have been why I saved it. No hard feelings?

-Craig

I still like to run midgrade every now and then, just to be safe, especially when it's 100 degrees outside, and im cruising through traffic ect......toodles:)

That's because you weren't spraying enough nitrous;)

-Josh, aka the tireburner