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Ive been filling up my bronco with 92 octane... Some people say that the bronco would run better on lower octane. What octane do you guys use in ur bronco?
 

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I use super in my 88 but only because the 302 is sooo tired we advanced the timing a bit to try to get some power out of it and on reg it chatters a bit.
 

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damn u most be loaded or own part of the oil company...

jk i used to use 88.5 when gas was still a buck something but now 87 oct. with the old motor i had to run 88.5 or it will ping.

i dont really feel much a difference but broncos dont really need 91 oct or greater. the motor isnt set up to run the higher oct, most likely ur just wasting the oct.

sometime ago i remember there was a recall/warning or something to people who run 91 oct or greater in their 4 banger toyota pickups. the unburned oct becomes build up in the motor.
 

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Rest in Peace Friend...
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Ford motors are all designed to run on 87. I have never run anything on mine except 87 octane and have never had a problem. Octane is a rating of resistance to predetonation so if you have boosted the compression rating of the engine you need to move up in ocatane. If it is stock and you haven't done anything to change the compression ratio and it is tuned properly, 87 should be just fine.
 

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unless it was a propane motor converted to gas, like which i have, and i need to run min the mid grade, for it to run good you need to run the super in it.
 

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Gangsta_Bob119 said:
Ive been filling up my bronco with 92 octane... Some people say that the bronco would run better on lower octane. What octane do you guys use in ur bronco?
89 octane. this is a truck motor, not some high performance/highly tuned sports car motor.
 

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You will actually get more power and milage by running the lowest octane fuel you can. If it runs on 87 without pinging, than use that. I have even seen 85 in some places, so if it will run on that without pinging, then thats even better yet. Running the 91/92 is only costing you more money and a few HP if its not needed.
 

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MikE2 said:
You will actually get more power and milage by running the lowest octane fuel you can. If it runs on 87 without pinging, than use that. I have even seen 85 in some places, so if it will run on that without pinging, then thats even better yet. Running the 91/92 is only costing you more money and a few HP if its not needed.
Couldn't agree more

and I run my base timing advanced to 13.5 instead of the stock 10, no rattles on 87 and the mileage and pickup are great.

I actually use 89 ethanol, only because it's the same price as 87 unleaded here, but I've often run several tanks of 87 through it with no ping or detonation at all.

I've got a theory that guys with huge, heavy wheels and tires and tired ignitions on their 302s are the only ones who need premium.

Sixlitre

p.s./
Gunner I've never even seen 85 octane, I don't think it's sold up here. How much cheaper is it than 87 ?
 

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I run 95 in mine most of the time. It helps, but mine has some things here and there done to it.
 

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Satyr of the Midwest
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I can't run my baseline ignition timing any more than 12 degrees BTDC using 87 octane, otherwise she starts knocking up around 4500rpm. Must mean I have great compression, eh? :toothless Plus the low end torque is better with the timing not up so high.
 

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Sixlitre...it is the same price as 87 pretty much. Colorado uses 85 for regular, 87 for premium etc... There is really no difference in price that I have seen. With the altitude though, it is okay to run 85, and some say better.
 

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SigEpBlue said:
I can't run my baseline ignition timing any more than 12 degrees BTDC using 87 octane, otherwise she starts knocking up around 4500rpm. Must mean I have great compression, eh? :toothless Plus the low end torque is better with the timing not up so high.
Either your chambers have major carbon deposit, which is raising the compression ratio or your wheels and tires are too heavy (can't see that being a problem with a 351 though).

There's yet another possibility that is the harmonic balancer has slipped on the rubber, making your 12 acuallu 16 or more.

Most everyone else, with your combo, who has done the ignition mods is getting away with 87.

Gunner

Thanks. Is that because of your alttitude ?

Sixlitre
 

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Satyr of the Midwest
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[HIJACK!!!]

Sixlitre said:
Either your chambers have major carbon deposit, which is raising the compression ratio or your wheels and tires are too heavy (can't see that being a problem with a 351 though).
I've thought about that, but I've peered into the cylinders. There's nothing besides the usual blackishness on the valves and piston crowns, and surprisingly little at that for an engine with 116k on it. I have yet to do a compression test, but I have no reason to doubt the engine's tune. You can almost balance a penny on the engine it runs so smooth! My other thought is that the fuel pump is crapping out at the top end, when it needs the most fuel. Running lean will cause spark knock as well. I was going to change it this summer anyway because I HATE being stuck in the middle of nowhere, and it's got over 100k miles on it. I know, I know...

There's yet another possibility that is the harmonic balancer has slipped on the rubber, making your 12 acuallu 16 or more.
This is true, and I've had this happen on a few Ford motors before. However, when setting the timing using those bad balancers, the timing marks would shake back and forth a bit. These DON'T at all. Even if it is lying, it's not by much; it gives me a good reference to go from, and it's consistent from time to time when checked. :toothless I'll be checking its accuracy this week after final exams when I'm home with a dial micrometer and a degree wheel, along with everything else I haven't been able to touch this semester (ball joints, shocks, U-joints, diff & X-fer lube, etc).

[/HIJACK!!!]
 

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I run 85, it is the regular fuel at higher altitude. Just jumped to $2.67/gal today, so there is definitely no reason to be spending more than that for the higher octane rated fuels.
 

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87 works fine in both of mine.
 

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Rick3373 said:
I run 85, it is the regular fuel at higher altitude. Just jumped to $2.67/gal today, so there is definitely no reason to be spending more than that for the higher octane rated fuels.

i'd kill for 2.67/gal, it's up to 2.99 here in chicagoland. right across the border into indiana (i live a hop, skip, and a jump from the border) it is 2.89/gal.

that's for the cheap stuff, which is the only thing i will run.
 

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I run the cheapest 87 around. For the mustang i get 91, but the bronco doesnt need that high octane. So it gets the cheap stuff.
 

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Discussion Starter · #20 ·
Yeah ill probably end up putting mid grade or 87 in it... i got a job workin minimum wage right now, lol. Cost me bout 100 bucks to fill it up when it was runnin on E and i threw in 92 octane... Gas prices just jumped up too within the last week or so... Damn washingtons prices of gas :(
 
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