What type of gas 87 or 91

[SKINNIE]

You bought the wrong car if you're deciding to run 87 to save money on gas at the pump.

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[J_D]

If I recall correctly from my FK8 days, the Bosch ECU is programmed to reach torque targets based on throttle position and RPM. It uses the air charge to do math. It will not make more power if you use a higher octane than what the torque targets were designed with. In the FL5 that is 91 octane.

The knock retard strategy (again, IIRC) is:
press gas pedal -> low octane will knock ->car pulls timing/reduce knock
However when you let go of the pedal it forgets everything and does it again next throttle press
So you can use 87 in a pinch, but long term stick to 91+, as you will continually hit the cycle of knock then reduce and repeat.

For reference the DE5 ITS has a slightly more aggressive tune than the FL5. It requires 93+ as written on its gas cap, vs. the FL5's 91. I have to check Honda's base maps to see if it's due to increase torque targets or the pop and bangs.

Edit: added default torque limits. Seems ITS is a bit higher after 4000 RPM. Below that Type R is slightly higher. My guess is the 93 octane helps with higher rpm increased torque targets

 

[MYK20C1]

Hello All,

I wanted to see what other people are using for gas. Where I live, 91 if available is 1.25$ more a gallon. I am not tracking the car. Is there any big downsides to using 87. Also if they don't have 91 they have 93. What is best to use in that situation as well? Money is tight and the 1.25 per gallon will help as long as I am not hurting the car. Thanks for your input.

I have used 87 with an octane booster that is cheaper than paying for 91 or especially 93 but not sure how accurate their advertised boost might be! I have tried this and have not experienced any knock so should be good if you are not stomping on the gas!

 

[TypeRD]

I have used 87 with an octane booster that is cheaper than paying for 91 or especially 93 but not sure how accurate their advertised boost might be! I have tried this and have not experienced any knock so should be good if you are not stomping on the gas!

Yeah, I think that’s a very reasonable strategy in areas where 91+ is a lot more expensive than 87. What would be interesting is if you could actually see and compare the knock data using 87 vs 87 w/ octane booster vs 91+.

 

[optronix]

This thread is even worse than the all-seasons thread. WTF is happening.

 

[spectre186]

Buys 45k Type R…I need to save $1 a gallon. Dude if finances are that tight you bought the wrong car. Do what the manufacturer recommends.

I just don’t get some people…And to top of all off you talk about not driving it hard. Honestly sounds like you bought the wrong car.

 

[qingcong]

I don't think trying to save money by going to 87 is a wise choice. You will probably get worse MPG and maybe something will crap out earlier than expected. My friend's Mustang's spark plugs went bad at like 20k due to him using 87 instead of 93. I'm guessing there will be slightly more frequent instances of knock (even with the computer trying to manage it) which will put more stress on the components in general, resulting in worse long term outcomes.

If you get lower MPGs using crappy 87 gas, you won't get the savings you want. Say you get 2 MPGs worse, that's about 30% lower savings than if you assumed you could get identical MPGs - you think you're gonna save $12 over a 300mile tank, but you're actually saving $8. That can easily be made up by not drinking a Starbucks coffee or 2. Plus you get the peace of mind that your engine won't grenade itself unnecessarily.


Assuming the same MPGs

Assuming 2MPG difference

 

[fordsucks]

I don't think trying to save money by going to 87 is a wise choice. You will probably get worse MPG and maybe something will crap out earlier than expected. My friend's Mustang's spark plugs went bad at like 20k due to him using 87 instead of 93. I'm guessing there will be slightly more frequent instances of knock (even with the computer trying to manage it) which will put more stress on the components in general, resulting in worse long term outcomes.

If you get lower MPGs using crappy 87 gas, you won't get the savings you want. Say you get 2 MPGs worse, that's about 30% lower savings than if you assumed you could get identical MPGs - you think you're gonna save $12 over a 300mile tank, but you're actually saving $8. That can easily be made up by not drinking a Starbucks coffee or 2. Plus you get the peace of mind that your engine won't grenade itself unnecessarily.


Assuming the same MPGs

Assuming 2MPG difference

Not to talk down to person you're responding to but this is something people rarely every sit down and calculate and its always interesting to really break down gas cost vehicle:vehicle. The money savings are almost always not enough to justify whatever choice someone is trying to make

Very regularly done by dealerships trying to sell a hybrid for $10k more to squeek out 5-8mpg more, unless you're a medical courier or uber driver you're never getting the ROI for that $10k extra spent. And the majority have no issue at all spending extra thousands on the more reliable car/suv but then they're willing to use cheap oil and gas to save a few hundred a year at best.

 

[menikmati]

Buys 45k Type R…I need to save $1 a gallon. Dude if finances are that tight you bought the wrong car. Do what the manufacturer recommends.

I just don’t get some people…And to top of all off you talk about not driving it hard. Honestly sounds like you bought the wrong car.

But muh MPG.

 

[WhoCares]

I use any gas 87 or + octane from usually Murphy in Florida. I owned numerous cars over the years from 1972 onward, last count more than 130. Driven the vehicles in some 70 countries plus all 48 lower states. Never worried or noticed any of my cars complaining on my fuel choice. I even put 5 gallons (in desperation) diesel in a 1990 ZX twin turbo in 1991 going through Romania do to having no other choice. The car made it to my next fill up with no repairs, or complaints . As couple of our wealthier members injected? If you worry about fuel price you should not own the car? Really? I do worry, and have always worried about how and where I spend my money. I guess according to the few if you own a $45,000 +- car you should be at minimum, as wealthy as they are when average car price in USA is $47.000+? You own the car you are doings just fine plus you made a excellent choice both financially and as a knowledgeable car buyer on a Honda product they build good cars plus hold their value period. Now go "Enjoy the car" don't worry about the car which will be fine with any fuel choice from any brand from 87 octane onward. Will it perform better on one brand to another or the higher the octane? Arguable? maybe? Definitely, negligible when you concider all the variables.

 

[HKSpeed]

Money is tight and the 1.25 per gallon will help as long as I am not hurting the car.

No response from anybody here will change your tight money situation. Do what you gotta do to survive.

In terms of hurting your car, I suppose laying off boost and driving slow would minimize long term damage.

 

[TypeRD]

No response from anybody here will change your tight money situation. Do what you gotta do to survive.

In terms of hurting your car, I suppose laying off boost and driving slow would minimize long term damage.

That’s possible. But laying off boost and driving it slow all the time can cause more carbon buildup too. Yes, it can be cleaned off, but it’s yet another thing to consider.

 

[HKSpeed]

Is the Type R engine direct injected?

 

[spectre186]

So you drive it slow with 87 and low boost…again, makes my point, you bought the wrong car. Just trade it in for something that’s made for 87 that gets good gas mileage, like the new civic hybrid.

 

[Clark_Kent]

Is the Type R engine direct injected?

Yes.

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