So who is using regular gas in these cars?

[alvav]

It's not the octane that gives the extra power. The higher octane will simply resist knocking more, thereby allowing the engine to perform as it was designed. So, no the octane does not generate more power. But it does allow the engine (or engine tune) to reach its potential. So it is "indirectly" responsible for additional power. That's why there's aftermarket tunes for 93 octane (or even higher). They assume the higher octane (effectively a higher resistance to knock), thereby allowing a more agressive tune. So, again, it's not the higher octane gas containing more power. It allows a more agressive tune due to a higher knock resistance, thereby allowing the engine to make more power.

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[Fountainhead]

I only run 93 in my CTR.
But, think of ALL the cars that "require" 93 "Only" in rental fleets/and leases. You think for one second that anyone is going to put 93 in a rental/lease? No way.
So thousands of rental/leased cars are happily getting the shite beat out of them (because it's a rental/lease) and I haven't yet heard of anyone saying "Oh my rental/lease/car quit today because I put 87 in it instead of 93", lol.
I err on the side of caution in many ways with my CTR and as others have said the extra few cents a gallon is nothing compared to a blown engine-oh wait, the rentals/leases are blowing up?
I plan on keeping my car for many years but I guarantee you there are literally thousands upon thousands of cars sold by off-lease and rental agencies to customers that run them for years after the "87 only" years of rental/lease.

 

[jrow3]

It's not the octane that gives the extra power. The higher octane will simply resist knocking more, thereby allowing the engine to perform as it was designed. So, no the octane does not generate more power. But it does allow the engine (or engine tune) to reach its potential. So it is "indirectly" responsible for additional power. That's why there's aftermarket tunes for 93 octane (or even higher). They assume the higher octane (effectively a higher resistance to knock), thereby allowing a more agressive tune. So, again, it's not the higher octane gas containing more power. It allows a more agressive tune due to a higher knock resistance, thereby allowing the engine to make more power.

This is a very good answer. It's also why putting 91 in your base model civic will not increase it's power. Because none CTR/Si models are tuned for 87, putting in 91 doesn't do anything because the engine is not designed to use the potential that 91 offers it. Higher octane allows for a more aggressive tune of your car. From the factory most "performance cars" recommend you to use 91 and tune the car accordingly. It would be similar to if 93 was offered in every gas station. Your CTR could USE 93, but it wouldn't see any difference from running 91 because it was not tuned to utilize the potential 93 has.

The basic rule of thumb is, you can always run a higher octane than the car was designed for without issue, but you're just wasting money. If you run anything lower you will see a reduction in performance (from the recommended octane) as the engine will pull timing. In very rare cases lower octane fuel can cause issues if the engine doesn't pull timing quickly enough (it takes a bit to "learn" what fuel is being used based on how it monitors the combustion process).

To echo what others have said, put in what the engineers designed the car for and if once in awhile you have to use regular there should be no issue as the engine can compensate, however if you plan to regularly use 87 I would suggest a tune so the engine doesn't have to "figure it out" every time and thus you reduce any risks associated with knock.

 

[HondaFan2017]

No way, unless I am stranded somewhere! If I afford this car I can afford the best gasoline.
I buy only Shell V-power(Racing 100 in Germany). Official EU octanic rating is 98/100. However I know someone from the testing lab and routinely this gasoline tests at 100-105. Sometimes up to 110. This means US octanic grade 95-100-105. Also V-Power has no ethanol.
Gas in Europe is expensive though, 4$/galon the cheapest.

 

[zsak]

I only fill up diesel gas only! As the price is always green to be more eco friendly!

 

[stevessvt]

I only fill up diesel gas only! As the price is always green to be more eco friendly!

Mines electric. I put AA batteries in the back flap.

 

[FifStreet]

I have put "regular" gas 87 octane in my CTR twice. Both times at a gas station where the recommended octane wasn't available. I noted no change in the behavior of the car. I didn't drive it hard, just drove it conservatively until I used up some of the fuel and then added 93 octane to mix it in the tank.

Since then I carry a bottle of octane boost for this situation.

For some reason 91 is rarely available in my area so I'm often mixing 87 and 93 when I fill up or alternating every fill up. Its annoying , lol.

 

[FifStreet]

91 is the same gas as 93, but at higher altitudes the octane content of the gas is lower so they have to relabel it.

Just fill it with 93. You're probably getting closer to 89 octane with this weird split thing you're doing.

I understand that most middle grades of gas are mixed at the station anyway. So who knows what we actually get anyway?

 

[Jpierro79]

Do not put anything less than 91 octane in the air or the type r. Yes timing will be pulled due to knock sensing. Do you really want to risk under boost full on detonation. Detonation is like chucking dynamite in a cylinder. Fuel doesn’t explode under compression it burns at a controlled rate. Boost is like high compression the fuel will auto ignite under enough pressure burning without spark. It doesn’t matter how much timing you take out. You will damage your engine. I’m not getting into more details most won’t understand just don’t do it!!! just look up fuel detonation vs burn

 

[tinyman392]

Do not put anything less than 91 octane in the air or the type r. Yes timing will be pulled due to knock sensing. Do you really want to risk under boost full on detonation. Detonation is like chucking dynamite in a cylinder. Fuel doesn’t explode under compression it burns at a controlled rate. Boost is like high compression the fuel will auto ignite under enough pressure burning without spark. It doesn’t matter how much timing you take out. You will damage your engine. I’m not getting into more details most won’t understand just don’t do it!!! just look up fuel detonation vs burn

I thought the FK8 had control over both timing and boost. In theory, couldn’t it avoid the entire knock issue by lowering boost and pulling timing. By doing that the fuel wouldn’t be under as much pressure and would have less chance of pre-igniting.

 

[kefi]

Absofuckinglutely do not unless it's an emergency, and if you do, do not floor it. Ever. Contrary to what many are saying here, our ECU's don't magically know that you're running lower octane. It's a corrective action for AFTER knock (and potential damage) has already occurred due to the lower octane. Not only that, but at least for our ECU, knock retard tends to reset every time you fully let off the throttle. This essentially means that you're going to be constantly knocking. If you go up to 6000RPM and let off and reapply, boom, your knock retard from earlier RPMs is gone and you're in a bad spot.

I'm not sure how well the stock tune takes 87, but I can imagine it won't be very happy.

 

[Kevindust]

I got the perfect answer.

Don't get the CTR or the SI if you are considering using regular gas on them.

I guess that your next question will be if you can use base civic tires because the CTR ones are so expensive.

I agree with you. Yet, this forum is half full of people that are replacing the summer performance tires with all season tires for daily use in Southern Regions.

DON'T GET THE CTR OF YOU ARE CONSIDERING USING ALL SEASON TIRES.

(The one exception is the Michelin AS3+, which magically outperforms at least 50% of other summer performance tires while maintaining an AS rating.)

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