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