91 vs 94

[LoneWolf77]

So most gas stations sell premium 91 in my area. I found one gas station that sells premium 94, but it costs more. Do you think I'd notice the difference at all between the two? 2020 Civic Sport.

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[Gotch]

Stock? No power gain. Probably Less fuel economy too given higher ethanol content.

 

[LoneWolf77]

Stock? No power gain. Probably Less fuel economy too given higher ethanol content.

Okay good to know. That's what I was thinking too. Thanks!

 

[ShuJam]

If it's a Sport hatchback, stick to 91. If it's a Sport sedan or coupe, you don't need anything more than 87.

 

[Vic_L]

Unless you have a tune that specifically asks for higher octane gas, it's not necessary.
91 Octane is recommended for the Sport / Sport Touring hatchbacks from the factory.
There are certain ECU tunes in the market for these Civics that specify to use 93+ octane fuel.

 

[jayy_swish]

Every model from the factory EXCLUDING the Si and Type R can use 87 Octane. Although 91 or 93, which ever is sold in your area, is recommended. Si and Type R are solely 91 or 93.

If tuned 91 or 93 is required for all models. Anything higher than 93 won’t be optimized in the vehicle. You would need a flex fuel kit to be able to go beyond 93 octane or receive a custom tune for a higher octane.

 

[Gruber]

Every model from the factory EXCLUDING the Si and Type R can use 87 Octane. Although 91 or 93, which ever is sold in your area, is recommended. Si and Type R are solely 91 or 93.

If tuned 91 or 93 is required for all models. Anything higher than 93 won’t be optimized in the vehicle. You would need a flex fuel kit to be able to go beyond 93 octane or receive a custom tune for a higher octane.

Not true at more than one point.

No civic requires premium gas. All civics can run on 87, including Si and R. For Sport and Type R hatchbacks, and for Si Honda recommends 91 octane premium.

You don't need a flex fuel kit to run more than 93 octane gas if that gas does not contain more than 15% ethanol. Higher than 93 octane gasoline does not have to contain more than 10 or 15 % ethanol or any lead.

 

[FlexRex]

This time i fully agree w @Gruber. A flex kit to run 94oct.. lmao.

 

[jayy_swish]

Not true at more than one point.

No civic requires premium gas. All civics can run on 87, including Si and R. For Sport and Type R hatchbacks, and for Si Honda recommends 91 octane premium.

You don't need a flex fuel kit to run more than 93 octane gas if that gas does not contain more than 15% ethanol. Higher than 93 octane gasoline does not have to contain more than 10 or 15 % ethanol or any lead.

Models with sport mode 91 is required. Yes a civic with sport mode can run on 87, but is not ideally suppose too. Your knock will go up in which case the engine will pull timing to adjust for 87 octane.

I am not talking about running straight pump gas for a flex fuel kit. I am talking about running higher octanes past pump gas, a ethanol+pump gas blend. Most places do not sell higher octane pump gas. California sells 100 octane in some locations and it’s about $9/ga, I don’t know about you but I would not pay that much when there is ethanol for way cheaper. Only option if you do not want to run higher pump gas for more $$$$ is to run poor mans fuel, in which case one will turn to E-85 to achieve higher octane. Which would require a flex fuel kit.

 

[Shred]

Not true at more than one point.

No civic requires premium gas. All civics can run on 87, including Si and R. For Sport and Type R hatchbacks, and for Si Honda recommends 91 octane premium.

You don't need a flex fuel kit to run more than 93 octane gas if that gas does not contain more than 15% ethanol. Higher than 93 octane gasoline does not have to contain more than 10 or 15 % ethanol or any lead.

If you have a Type R you will probably have knock issues if you run 87 long term.

https://www.civicx.com/forum/thread...o-give-us-more-power.52111/page-4#post-845937

 

[Gruber]

Models with sport mode 91 is required.

No, as the manual says, that you are quoting, and that I also copied myself in other threads, premium fuel is recommended by Honda. Accordingly, no text or review, or car description or specification in the entire internet ever classified any civic as a premium-required car. If you find such reference, please share. Whether it will occasionally knock or not (actually Honda admits it might) is a different matter.

The same exact wording word for word is used in the hatchback manual, which includes Type R. Instead of "Models with SPORT mode" it has"Models with the label PREMIUM RECOMMENDED". Indeed, both Sport hatchbacks and the Type R hatchback have on the fuel door the same label saying "PREMIUM RECOMMENDED."

When I say the premium fuel is recommended, not required, I mean what the manufacturer says, not what a guy on a forum says. I don't know whether my car would knock on regular, because I never tried regular, and I currently don't have such plans. I expect that at the right conditions it would. That doesn't change the fact that it's a premium-recommended car.

 

[BriteBlue]

I recall from a few years ago the Ford Fusion Sport was advertised having 325HP. But it wasn’t highly advertised that was when using 93 octane. I remember this MotorTrend article where they tested the car in CA which only has 91 octane available.
https://www.motortrend.com/cars/ford/fusion/2017/2017-ford-fusion-sport-ecoboost-first-test-review/

I also remember that somewhere this was mentioned in a manual or brochure, but in fine print. Doing a quick search I found this. In the fine print at the bottom it states 325HP with 93 octane.
https://www.ford.com/cars/fusion/models/fusion-sport/

I’ve seen something similar regarding the Ford F150 EcoBoost V6 & found this.
The use of 87 octane fuel saw a decline in boost for the EcoBoost engine by 1.9 psi.
https://fordauthority.com/2019/08/is-premium-fuel-better-in-an-ecoboost-ford-f-150/

That doesn’t mean using 93 octane in an engine designed for 87 octane is going to give you more power. However if 91/93 is recommended but the engine is designed to be able to run on 87 octane, maybe you’re taking a hit in horsepower by using the lower octane.

Here’s a quote I saw somewhere. “The engineers made the engine capable of running on 87 octane, that is different than recommending it.”

The question is how much is the timing pulled back & how much is boost reduced when using the lowest capable of running octane vs. the recommended octane?

 

[gtman]

I remember a while back when Hondata co-founder Doug first did testing on the then new 2017 Sport Hatchback. He was asked why he thought the car produced more hp and tq than the other hatchbacks. His reponse was that a slight increase was from the different exhaust but the majority came from the 91 octane gas recommendation. He said the stock hatchback tunes were essentially identical on all models.

 

[Gruber]

The question is how much is the timing pulled back & how much is boost reduced when using the lowest capable of running octane vs. the recommended octane?

This is a great question indeed, and lacking a clear manufacturer information, it can be only answered by measurements. Obviously, the decision to make a car "premium only" is loaded for a manufacturer, because it tends to put off many potential customers. It also increases the cost of fuel numbers on the label. Actually, all the civics with "Premium recommended" do have the cost of fuel numbers on the dealer labels based on the current prices of 91 premium. But then "you can still use regular." So they avoid "premium only", unless the car is targeted squarely at the market segment that shouldn't care, or even want a "premium only" car. It is also linked to the nominal power specifications they choose for each trim.

Strangely, my salesman swore he was not aware the hatchback sports were "premium recommended" and he was not able to explain why they have bigger $$ numbers on the labels. It was news to him.

So beyond a butt dyno, and hearing noises, exactly how many hp a Si/CTR loses by using regular gas? How many hp a regular non-sport 1.5T gains by switching to premium?

 

[BriteBlue]

Here's a Car and Driver article where they compared regular to premium.
https://www.caranddriver.com/features/a28565486/honda-cr-v-vs-bmw-m5-ford-f-150-dodge-charger/

It does make wonder if a vehicle's computer can adjust timing & boost in both negative & positive directions. If the system can adjust for lower octane can it also adjust for higher octane, within reason? I don't know how tightly the octane number is controlled. If it varies +/- 1%, does a vehicle's computer make adjustments in either direction in order to optimize fuel economy, emissions, or power?

If 91 octane is used in a basic 1.5L Civic will the computer increase the boost in order to help optimize efficiency? If so, it's probably so small it's not worth the cost of using premium gasoline, but is there any boost gain at all?

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