91 or 94 octane gas.

[13GetThere]

I don't daily drive my Mustang, so it doesn't hurt that much to run premium (93 octane here) in it. I'm not picky about the station I pull up to as long as it's one that has a brand name such as BP, Ashland, etc..
I have a friend with a 2013 Mustang GT, and he only uses one brand of premium. His is also not a daily driver.
We may be wasting our money, but it's ours to waste.
Now if I daily drove my Mustang, I might be running regular. Right now the daily driver honor goes to my wife's Edge since she no longer drives; and it runs 87 octane.

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[sk47]

I don't daily drive my Mustang, so it doesn't hurt that much to run premium (93 octane here) in it. I'm not picky about the station I pull up to as long as it's one that has a brand name such as BP, Ashland, etc..
I have a friend with a 2013 Mustang GT, and he only uses one brand of premium. His is also not a daily driver.
We may be wasting our money, but it's ours to waste.
Now if I daily drove my Mustang, I might be running regular. Right now the daily driver honor goes to my wife's Edge since she no longer drives; and it runs 87 octane.

Hello; A possible advantage of some premium brands can be additive packages other than octane boosters. Might be worth a check on the additive packages.
My mother had a Pontiac sedan with the 3.8 V6. Made to run on 87 octane and could not take advantage of higher grades. She used 91 octane gas. I could not convince her such was a waste of money. She felt it must be better because it cost more. I do get that this is not what you say. You appear to understand well the situation.
A suggestion which might be worth consideration would be to find a place selling pure gasoline ( E0 I guess). You will pay more per gallon I think but there may be benefits to avoiding the ethanol (alcohol) blended into most fuels.
Might be a different can of worms but what i read says the alcohol fuels can have problems when they sit in a tank a while. I tend to run the E 10 mix thru my truck and car fast enough so that I do not ad additives. My mower gas is E 10 and sits a while so I put marine formula fuel stabilizers in the cans. Seems to help as since i started using the newer fuel stabilizers my older mowers do not need carb cleaning much at all. just a thought.

Nice thing about the newer Mustangs is while they do fine on 87 octane fuels, they also can take some advantage of the higher octane fuels.

 

[WildHorse]

They used the same engine with 87 & 91 pump gas

Yes, yes. It's obvious that engine wasn't built for 91 octane.

Technically 87 will make more power under very specific conditions, due to higher volatility. Low load, high RPM, low compression for example. Think Ford flathead. Higher octane will hurt performance.

Coyotes with its 11:1 / 12:1 compression will always make significantly more power with higher octane fuels.

Period.

 

[sk47]

Yes, yes. It's obvious that engine wasn't built for 91 octane.

Hello; I will have to look at the episode again but think it was built for octanes above 87. They mentioned concerns about the 87 octane runs. But you bring up a point worth checking out.

 

[sk47]

Yes, yes. It's obvious that engine wasn't built for 91 octane.

Technically 87 will make more power under very specific conditions, due to higher volatility. Low load, high RPM, low compression for example. Think Ford flathead. Higher octane will hurt performance.

Coyotes with its 11:1 / 12:1 compression will always make significantly more power with higher octane fuels.

Period.

Hello; The engine was a Blueprint Engines crate motor. An LS 3. 6.2 liter. Blueprint 259 heads. 10.7 to 1 compression. Advertised at 531 HP & 495 lb.-ft torque. So, 1.4 less compression that the Coyote's 12:1 or 0.4 down from 11:1.

The dyno Steve stated the engine was obviously designed to run on 91 octane. For the 87 runs He first went into the map of the holly EFI and took out 5 degrees of timing and then creeped up on "that" (timing) until it made best power. He stated that 87 in this engine was probably not the best idea

I imagine the Blueprint engine builders might require or recommend 91 octane, but do not know. They got away with 87 in a few dyno runs apparently by being careful with ambient cool temps and not having loads or extra strains other that the dyno load.
My take is the tested engine is a 91 octane pump gas engine they were careful with when using 87. All three stated they would not run the engine on the street with 87. I cannot refute or confirm what you say myself, only relay what was in the episode.

 

[WildHorse]

Hello; The engine was a Blueprint Engines crate motor. An LS 3. 6.2 liter. Blueprint 259 heads. 10.7 to 1 compression. Advertised at 531 HP & 495 lb.-ft torque. So, 1.4 less compression that the Coyote's 12:1 or 0.4 down from 11:1.

The dyno Steve stated the engine was obviously designed to run on 91 octane. For the 87 runs He first went into the map of the holly EFI and took out 5 degrees of timing and then creeped up on "that" (timing) until it made best power. He stated that 87 in this engine was probably not the best idea

I imagine the Blueprint engine builders might require or recommend 91 octane, but do not know. They got away with 87 in a few dyno runs apparently by being careful with ambient cool temps and not having loads or extra strains other that the dyno load.
My take is the tested engine is a 91 octane pump gas engine they were careful with when using 87. All three stated they would not run the engine on the street with 87. I cannot refute or confirm what you say myself, only relay what was in the episode.

Fine then. Wasn't optimized for higher octane.

If you ever do finally get a coyote, try it for yourself instead on relying on clicks for views.

 

[engineermike]

I only know of one case where lower octane made more power, but it was a very specific scenario and sequence of events. It was a 10.5/1 LT1, cam, ported heads, etc. The car sat for 6 months with 93 in the tank. When he finished the build and dyno'd it, it made more power than expected and more than anything similar. He was expecting even higher numbers on fresh gas, but was never able to replicate the initial numbers. I ran it by a fuels-blending Chemist, who explained that the volatile light components that help with cold starting likely flashed off/evaporated over the 6 months. This lowered the octane, but the heavier components left behind had a higher energy density (think diesel). The engine didn't really need the octane, so the result was more power. That said, if you buy 87 at the pump, it has the lower-energy light components so it will cold start, so you don't get this same advantage.

There was a good test years ago in Car Craft IIRC, where they tested various pump gases and brews of octane booster, then did a C16 test. The engine was some modified Chrysler carbureted V8 and compression was under 10/1. There were small differences in the pump gas concoctions, but the surprise came on C16. It made more power than all the pump gases, and it did it with less timing. This is the day I learned the difference between MBT and BLK timing. The explanation was that the C16 was a more-refined, narrower range blend of hydrocarbons which burned faster. This lowered MBT, which translates into more power. It didn't need the octane at all, but still made more power due to the faster burn rate.

That said, it needs to be understood that burn rate, energy content, and knock resistance are all different properties. The combination of the 3 matters, and it affects different engines in different ways.

 

[sk47]

Fine then. Wasn't optimized for higher octane.

If you ever do finally get a coyote, try it for yourself instead on relying on clicks for views.

Hello; I get the test engine was not optimized for 110 or 116 octane used in the test, but apparently was for 91 octane pump gas.

Not sure what set you against my posting of a relevant series of dyno tests which specifically address the question of octane making power, but so be it. I am interested in the subject and felt the information is on point, clicks are not a part of my motivation.

 

[K4fxd]

This lowered MBT, which translates into more power. It didn't need the octane at all, but still made more power due to the faster burn rate.

And this should kill the myth of high octane gas burning slower.

 

[GL95]

Hello; I get the test engine was not optimized for 110 or 116 octane used in the test, but apparently was for 91 octane pump gas.

Not sure what set you against my posting of a relevant series of dyno tests which specifically address the question of octane making power, but so be it. I am interested in the subject and felt the information is on point, clicks are not a part of my motivation.

Because you're comparing a 10.7:1 LS engine that is not optimized for 91 to a 12:1 coyote that automatically optimizes timing

It's not relevant

 

[WildHorse]

clicks are not a part of my motivation.

No, I mean those youtube vids.

With the right spec'd out camshaft & cylinder heads, you can run 15:1 CR on 87 all day long and make WOT only power. Everywhere else it's gonna suck.

But that's not the point here, is it ?

Silent knock, is a type of knock that occurs below the audible frequency range, typically below 5 kHz. Silent knock can be caused by a variety of factors, including low-quality fuel, low-octane fuel, excessive cylinder pressure, or improper engine tuning. Unlike audible knock, silent knock may not be detected by the driver or even by the engine's knock sensor, making it a potentially more dangerous problem.

With a high performance engine, always go with high performance fuel.

 

[glockholiday]

For my 2019 the Ford literature stated 460hp (93 octane). In the owners manual it says minimum 87 octane. My take on that is the car can adjust tuning enough to not ping on 87 but if you want the full 460hp run 93. I notice a 1-2mpg increase running 91 over 87 and that cancels out the price difference so I run 91. If I could get anything higher in AZ I might occasionally run it. Theres one station in the valley that sells 95 and 100. I filled up with 100 one time and didn't notice a difference in seat of the pants or mileage.

 

[WildHorse]

My take on that is the car can adjust tuning enough to not ping on 87

it will knock on 87. Just check your tuning device if you have one.

it'll knock with 91 as well.

When 94 was available in my neck of the woods, you'll have to try really, really hard to get it to knock on 94.

With E30, zero knock, it won't happen.

 

[sk47]

And this should kill the myth of high octane gas burning slower.

Hello; In the Engine Masters TV show they came to the same conclusion that high octane fuel does not burn slower.

 

[WildHorse]

Hello; In the Engine Masters TV show they came to the same conclusion that high octane fuel does not burn slower.

Very easy to test. Get 200ml of 87, and 200ml of 91/94.

Put in separate ceramic bowls.

Light both at the same time & see which burns out first.

Disclaimer: Take every precaution. Use a well ventilated area away from
other flammables. Have a fire extinguisher rated for liquids on hand.

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