Effect of 93 octane

[flewism]

2 Strokes and the boat 4 stroke I/B-O/B get 93 octane, everything else run on 87 octane. No eco-boost engines 5.0 f150, 5.7 hemi 1500, and two 4 cylinders commuter freeway SUV's.

 

[Molalla1]

I use it in everything I own (CX5; F150; 60 Impala, mowers, saws, blower, etc.) and never buy anything with ethanol in it unless it's an emergency.

Have you made up for your '60 in the lead department?

 

[deserteagle71]

Owner's manual for my F150 with the 3.5 Ecoboost recommends 93+ octane for heavy towing or any other situation where the engine is going to be working hard.

 

[RalphVa]

I double checked the Mz3's CR = 13.0 in owner's manual, because I figured you guys probably wouldn't believe it.

Strange thing is I usually access the owner's manual online on the Mazda site because it's easier than running out to the garage and pulling the paper manual (with not much search capability), etc.

Well, they required me to change my password. Did that. THEN they REQUIRED a mobil (e.g. smart) phone #, which I don't have, as they would then send a code to it, and I'd have to input that code to get back on. I'm out, because we only have dumb phones, e.g. emergency ones that my wife and I use to talk to each other or for emergency.

Ralph

 

[dodge man]

We rented a SUV to drive to Colorado, I do not remember the model but I saw in the owners manual where it said it has a 13.5 compression ratio, which is very high.

 

[KennyG]

Compression Ratio is just a volume calculation. Knock is dependent on actual cylinder pressure, among other things. Valve timing affects how high the pressure gets for a given compression ratio. Engines with variable valve timing or lots of overlap can have high compression ratio without knock. Injection timing and spark timing can also affect knock.

 

[Dftodd]

The only new truck I bought was an 04 F150. Came with a sticker on the dash stating the truck was designed to run on the lowest octane available. Using higher octane fuels would actually lower the gas mileage.

That sticker was the gospel for that truck. I could always tell if I let someone borrow that truck and they filled it with high octane fuel thinking they were being nice The miles driven between fill up would drop by 1/4.

 

[Clark6x20]

I have been an ASE master automobile tech, Michigan master automobile tech with 18 years as a drivability tech in a Ford dealership.
Octane is the resistance to burn. The higher the number the more resistance to ignite. I have seen well meaning people who used high octane fuel tow their vehicle into the dealership in very cold weather because it will not start. The engine is typically flooded badly the oil is contaminated with fuel, many times the plugs will need to be replaced. My advice is to use the fuel recommended by the manufacturer.
Do not use alcohol blends in seasonal equipment. Alcohol blends start to break down in 30 days it has very poor shelf life.

-Todd

 

[fatjay]

I have been an ASE master automobile tech, Michigan master automobile tech with 18 years as a drivability tech in a Ford dealership.
Octane is the resistance to burn. The higher the number the more resistance to ignite. I have seen well meaning people who used high octane fuel tow their vehicle into the dealership in very cold weather because it will not start. The engine is typically flooded badly the oil is contaminated with fuel, many times the plugs will need to be replaced. My advice is to use the fuel recommended by the manufacturer.
Do not use alcohol blends in seasonal equipment. Alcohol blends start to break down in 30 days it has very poor shelf life.

-Todd

Finally someone with sense. I said this on page 1. Resistance to explode, high compression engines have a habit of detonation before TDC because the combination of heat and pressure makes lower octane fuels explode before spark is introduced at TDC. It has nothing to do with computers.

 

[Clark6x20]

Many computer controlled vehicles have a piezoelectric sensor commonly referred to as a knock sensor. This typically will detect pre-ignition (spark knock) and ****** the timing to prevent engine damage. I’m sure that is what the previous poster was referring to. You can run a higher octane fuel and see better performance in some situations where your engine is under heavy load especially a turbocharged unit.
-Todd

 

[snymat68]

Stick or auto? We have auto. I dislike the way it interacts with the slow timing of the throttle-by-wire. I step on the gas pedal, nothing happens, so my brain says "step harder', but in that instant of brain-to-foot time, the throttle catches up with my initial step, and it ends up pushing it too far, the car accelerates faster than you want, and it jerks your neck. I know there's some tunes out there that can clean that up. Just deciding if I want to go that route.

Stick (6 speed). No throttle lag unless I'm having brain lag. :laughing:

 

[kcflhrc]

Look near the filler neck, there will be a big sticker that says minimum octane rating. Climate has a lot to do with it. I think based on theory colder climates like Michigan and warmer climates like say Arizona are night and day difference in what octane you can get by with. With that said. My wife has a 2019 VW Tiguan R-Line which has a 4 banger with a turbo. She says she can notice a difference between 87 and 91 octane so her car get's premium to keep her happy. Recommended is 87. Personally, I don't care, I never drive the thing. My 2015 Nissan Titan with 315 HP runs just fine on the recommended 87 octane.

 

[dalola]

All the studies I have ever read including car owner manuals say that it is a waste of money and could actually be detrimental to the engine to use any higher octane than what the OEM recommends. This does not include engines that have been made into dragsters by highly modifying them like dalola did to his truck.

lol... my truck is far from a dragster! it's my DD, tow vehicle, family road-tripper, and winter survival tool. It's also 100% factory stock sans the tune. I get to the track a couple times a summer just for fun.

I have also read you get a benefit in the F150 both the eco-boost and the 5.0 of using higher octane and even E85. The problem is does it offset the cost? Does slightly more power and slightly better fuel mileage offset the cost? I doubt it.

When I drive rationally (which is honestly 99% of the time...), I see about a .5-1mpg bump on 93, so it isn't a cost effective move at all. I just find the whole tuning thing fun & interesting. I'm currently running an 87 tow tune through the winter, which is an excellent all-around drivability tune. Nice low end torque with smooth delivery, and saving money running 87 fuel again. I typically only run the 93 perf tune in the summer, when I'm out playing with the Mustangs. :cool2: