Does 5.0 coyote performance improve with octane?

[HerbB]

Has anyone done instrumented tests of acceleration and economy with 91 octane vs 87 octane on an unmolested coyote engine? My experience is that you do not gain anything using fuel of higher octane than recommended by the manufacturer.

Sponsored

 

[Frogdog1]

Has anyone done instrumented tests of acceleration and economy with 91 octane vs 87 octane on an unmolested coyote engine? My experience is that you do not gain anything using fuel of higher octane than recommended by the manufacturer.

What instruments did you use to measure what data to draw your conclusion?

 

[ChitownStang]

93 octane will feel much stronger than 87.
Go E30 and you will consistently get max power from your coyote.
More octane = more timing.
computer figures it out on these modern 5.0’s
Why wouldn’t you want that?!

 

[Frogdog1]

93 octane will feel much stronger than 87.
Go E30 and you will consistently get max power from your coyote.
More octane = more timing.
computer figures it out on these modern 5.0’s
Why wouldn’t you want that?!

When Ford quotes horsepower numbers they state it is when using 93 octane. There has to be a reason they use 93 octane when measuring and stating HP numbers.

 

[noac]

Use 93+ top tier fuel

 

[Q6543]

Even better, people have done datalogs showing spark knock and timing being pulled from low quality 93octane, and then E30 no knock, full advance.

 

[Neggytive]

you are running what any engine builder would tell you is a LOT is compression for a street engine.

I don't know what the cylinder pressure numbers are, but they are up there.

What the tuning on these cars does is listen to the knock sensors, and when you are running 87 octane and getting on it I would guess there is some pre detonation going on and the knock sensors are taking timing out until there is no more pinging.

Time for torque, jet for HP is the old saying

If you watch any dyno guy, assuming they are not running lean, they keep advancing the timing until they get no additional torque, then back it off 2 degrees to be safe. Then they play with the fuel curve adding and subtracting to see what HP gains/losses they get.

If you are driving as if there was an egg shell between your foot and the go fast pedal, you can get away with low octane fuel, start stomping on it and you are going to want to feed it top shelf or let the computer pull timing out of the curve with the associated loss of performance

YMMV

 

[GrabberB]

High compression computer controlled engines like the Coyote will certainly perform better with high quality 93 octane fuel and beyond to a certain point. There is no argument or data that will ever dispute this fact. Old school (non computer controlled) high compression engines did not have the option to run low octane fuel.

There is no need for instrument tests to prove this fact. Certainly a computer controlled Coyote engine can run safely on low octane fuel if one is willing to accept lower performance. Running lower octane fuel such as 87 has additional downsides. Higher octane fuel contains additives that keep the fuel system and more cleaner.

Personally, I would never consider running 87 octane fuel in a Coyote engine. I installed a Whipple SC and have no choice to run less that 93 (91 for some depending on location in US). Again, I would not run 87 even without the SC.

 

[Mr Hyde]

Also if you live in a hot climate like the southern states. You WILL feel it. I either run an e30ish blend or use top shelf 93 and something like octanium by VP racing. Car seems to like those blends, Not run together of course.

 

[AZ_Ryan]

Has anyone done instrumented tests of acceleration and economy with 91 octane vs 87 octane on an unmolested coyote engine? My experience is that you do not gain anything using fuel of higher octane than recommended by the manufacturer.

You're experience must be based on older cars, where on-board computer controls did not adjust for timing and spark knock.

As mentioned by several people already, the Coyote not only does those things, but the factory HP numbers are determined using 93 octane fuel. Using anything less will reduce performance.

 

[LouG]

I alternate between our 95 (91) and 98 (93), the butt dyno can't tell a difference and fuel consumption is effectively the same.
The only reason I use 98 at all is that it's recommended by the manufacturer.

 

[D/\rK•650]

This may not compare exactly because its not a coyote 5.0 engine but I recently went on cross country drive from California to New Jersey and back , now this was in my previous car Nissan 370z that I sold to get my dark horse but I can tell you there is a definite difference on performance and mileage going from even 91 which is highest i can get here in California to 93 and 94 towards east coast "sunoco 94". The sunoco 94 is the best I ever felt that car run and the mileage was better that was a fact like a lot better. Around going from 3 to 400 per tank to 4 and almost 500 miles per tank. Hard to believe right ? Well it surprised me too.!

 

[HerbB]

Thanks for the responses above. I guess I asked my question incorrectly, but I got the answer I was looking for. I have a Jaguar V8 and the recommended octane is 91. If you feed it 93 or even 100 racing fuel, you are throwing money away - no performance change. If you feed it 87, the knock sensors will dial the timing back and degrade performance. Even though my Mustang GT specifies 87 on the fuel filler door, it appears that this does not unleash all the performance built into the engine, and the more octane you throw at it, the more it rewards with additional HP. It is rare to find fuel higher than 91 octane here in CA unless you go to race shops.

 

[Alan Applegate]

It is my understanding that the GT's V8 has 12:1 compression ratio. That fact alone, should tell any motorhead that higher octane equals better performance.

Similarly.... I've owned a lot of turbo'd vehicles, and every single one required premium if you expected long life and performance. My 2024 Eco-Boost is no exception!

If I could buy 100 octane pump gas, I would!

 

[Neggytive]

Octane rating is not a rating of power, it is a numerical expression of a gasoline's resistance to pre-detonation, or "pinging"

As you get higher cylinder pressures lower octane fuels will light off before the spark starts the burn, and that does really bad things to rods, bearings and even crankshafts.

Knock sensors will tell the ECU to pull timing out of the curve to reduce cylinder pressures and temperatures when you drive in such a way that causes pinging.

You are not getting any additional power because out of the fuel if you burn 93, what you are getting is the computer being allowed to add the maximum amount of timing the tune will allow, and that equates to torque and HP

A gallon of 87 octane gas has (within experimental error) the same amount of energy, measured in British Thermal Units (BTU's) as a higher octane fuel

Even if you fed it a steady diet of 100 0ctane fuel, the computer is limited by the tune as to how much timing and fuel it can provide.

This is a function of a lot of things, but the biggest one, besides keeping the rotating assembly from self destructing is complying with EPA EU and other government entities emissions limits. Letting the timing advance even if you had the fuel to resist pinging increases NOx emissions.

What are the real world effects of what gas you put in your car?

You really want to use a "Tier 1" or "Top Tier" gasoline that has an additive package that keeps the intake valves clean. You'll loose more HP from crudded up valves than lower octane fuel IMHO. Running a bottle of Techron in the gas a couple of times a year doesn't hurt either.

Sponsored