Premium gas gives 2-3 more horsepower in turbo models (confirmed by Honda rep)

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Ryude

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My brother's BMW has an ECU that automatically adjusts for octane. Several users posted dynographs of a completely stock 335i with e85. It gains 20-30whp. And more automakers are implementing this type of algorithm. It's simply an outdated method of thinking to say octane doesn't do anything.
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CEXT

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Oh I understand exactly what I am talking about. Meanwhile you are dancing around with some semantics on 'top tier' gasoline and stuff you overheard from some salesman at Honda as your factual basis for using high octane gasoline.

General response from automakers? No, it is the mechanics of modern cars and they all work the same way without exception.

There is absolutely no benefit...zero, zip, nada, zilch...to using a high octane fuel on a modern car that is designed to run on regular gasoline and recommended by the manufacturer. And this is a scientifically proven fact over and over again.
You can't tune a car to run exactly on 87 octane. You can tune it to accept a minimum octane rating of 87. And that doesn't mean there won't be any benefit from higher octane. Even fuel quality varies from brand to brand, summer to winter, and whether or not there was higher octane in the hose before you filled up. All modern ECUs can adjust to the fuel used, more so to protect the engine from pinging.
 

ArnoldLayne

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You can't tune a car to run exactly on 87 octane. You can tune it to accept a minimum octane rating of 87. And that doesn't mean there won't be any benefit from higher octane. Even fuel quality varies from brand to brand, summer to winter, and whether or not there was higher octane in the hose before you filled up. All modern ECUs can adjust to the fuel used, more so to protect the engine from pinging.
The modern cars are tuned to run on a range of octane with 87 being minimum and I believe I clearly stated that in my post.
That being the case, a car designed by the manufacturer to run on 87 octane gas won't offer any distinct advantage if you pump 91 octane. And Honda is not using any 'fuzzy logic' like some other post mentions. The knock sensors which are controlled by ECU drives the whole mechanism and every modern car that has a ECU uses the same mechanism with their own proprietary implementation of it.

A higher octane fuel was beneficial in older cars in the pre 1990s when knocking was an issue when the engine got old. That problem virtually do not exist on modern engines and how modern cars control the fuel injection and ignition process.

Unless your engine is tuned to work the best on high octane gasoline (performance cars and other luxury cars which demand high octane gas per mfr), there is no advantage to using high octane gas.

That is the science and fact. You can choose to believe whatever else it is you like and that does not make it the reality.
 

CEXT

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The modern cars are tuned to run on a range of octane with 87 being minimum and I believe I clearly stated that in my post.
That being the case, a car designed by the manufacturer to run on 87 octane gas won't offer any distinct advantage if you pump 91 octane. And Honda is not using any 'fuzzy logic' like some other post mentions. The knock sensors which are controlled by ECU drives the whole mechanism and every modern car that has a ECU uses the same mechanism with their own proprietary implementation of it.

A higher octane fuel was beneficial in older cars in the pre 1990s when knocking was an issue when the engine got old. That problem virtually do not exist on modern engines and how modern cars control the fuel injection and ignition process.

Unless your engine is tuned to work the best on high octane gasoline (performance cars and other luxury cars which demand high octane gas per mfr), there is no advantage to using high octane gas.

That is the science and fact. You can choose to believe whatever else it is you like and that does not make it the reality.
If you put 85 octane in your car, the engine will ping and the ecu will retard timing to prevent detonation. If you fill up with 87 octane again, the ecu will recognize that and advance the timing to match; it won't get stuck at the 85 octane timing. Conversely, if you put 91 octane in the tank, the ecu will advance timing further. Yes, the ecu will only advance timing to a point, but you don't know for sure that Honda put a hard cap on the timing advance at 87 octane. There would be no reason for any car manufacturer to do that. There is a minimum timing and a maximum timing and rarely is the limit right at 87. The ecu having the ability to advance timing does not affect the performance/efficiency with 87 octane, since the ecu will calibrate to the optimal timing anyways. You're statement may hold true for older or lower performance vehicles that aren't high compression or turbocharged--like a corolla or something.
 

ArnoldLayne

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Dude you have been proven to be empirically wrong on this subject, give it up. Not all manufacturers use dumb ecu's that don't adjust to octane. Honda has been using fuzzy logic in their ecu's since around 2003. There is a volume of evidence that shows most Honda engines gain HP with higher octane fuel. It was about 10hp at the wheels going from 87 to 91 in my 04 Accord. Not only was it stated right in the owner's manual, but tested and confirmed by multiple independent sources.
No I haven't. Just because you sing Kumbaya to the tune of others without having a full comprehension of the process.

There is no such thing as a dumb ECU. The fact that you are throwing around 'dumb ECU' and 'fuzzy logic' demonstrates you have no idea of how the ECU in combination with knock sensors work on modern cars (and yes, I can emphatically state they all work the same and burn a range of octane rated fuels) but you are the guy in the mob who can yell and scream with no substance.

Can you provide links to these alleged 'independent sources' you cite?

This is an independent test performed by Car and Driver on a Honda Accord, Dodge Ram & Ford Mustang with 87 and 91 octane fuels. And this is their finding on the Honda Accord specifically with 91 octane fuel

The Accord took a tiny step backward in power (minus 2.6 percent) and performance (minus 1.5 percent) on premium fuel, a phenomenon for which none of the experts we consulted could offer an explanation except to posit that the results may fall within normal test-to-test variability.

Rest of the test article and conclusion here

http://www.caranddriver.com/features/regular-or-premium-test-results-page-2

I am an engineer myself so don't try and bs your way thru to win an argument with words like 'fuzzy logic' and 'dumb ECU' when you have no comprehension of how it works.
 


ArnoldLayne

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If you put 85 octane in your car, the engine will ping and the ecu will retard timing to prevent detonation. If you fill up with 87 octane again, the ecu will recognize that and advance the timing to match; it won't get stuck at the 85 octane timing. Conversely, if you put 91 octane in the tank, the ecu will advance timing further. Yes, the ecu will only advance timing to a point, but you don't know for sure that Honda put a hard cap on the timing advance at 87 octane. There would be no reason for any car manufacturer to do that. There is a minimum timing and a maximum timing and rarely is the limit right at 87. The ecu having the ability to advance timing does not affect the performance/efficiency with 87 octane, since the ecu will calibrate to the optimal timing anyways. You're statement may hold true for older or lower performance vehicles that aren't high compression or turbocharged--like a corolla or something.
There is no hard cap on timing from Honda and most of these cars are designed to work with a range of gasoline (e.g: 87-93)

That said the issue under discussion is the power and performance gain on a high octane gas (allegedly). Honda recommends 87 octane gas as the de facto fuel and while 89/91/93 octane fuels will work without issues, they do not offer any distinct advantage in terms of performance or efficiency.
This general myth on 'premium fuel' has been debunked several times in the past decades.

If this car would perform optimally with 91 octane gas rather than 87, Honda would be sure to mention it as the 'recommended fuel'. Several Luxury cars (Lexus, BMW et al) specifically recommend 91 octane fuel though the car would work fine on 87 but 91 is recommended by the mfr.

Not the same case here.
 

CEXT

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There is no hard cap on timing from Honda and most of these cars are designed to work with a range of gasoline (e.g: 87-93)

That said the issue under discussion is the power and performance gain on a high octane gas (allegedly). Honda recommends 87 octane gas as the de facto fuel and while 89/91/93 octane fuels will work without issues, they do not offer any distinct advantage in terms of performance or efficiency.
This general myth on 'premium fuel' has been debunked several times in the past decades.

If this car would perform optimally with 91 octane gas rather than 87, Honda would be sure to mention it as the 'recommended fuel'. Several Luxury cars (Lexus, BMW et al) specifically recommend 91 octane fuel though the car would work fine on 87 but 91 is recommended by the mfr.

Not the same case here.
Honda will never have 91 as the recommended fuel for a non-performance civic. Like you said, "past decades". I don't know how that is relevant to a new 1.5T that makes more power than some older V8 engines. New cars need very high cylinder pressures (whether through compression ratio or forced induction) to achieve the fuel economy number that they do. This historically requires premium fuel, but with direct injection, and very precise timing management, new engines are able to push timing to the brink of detonation without pinging on regular fuel. Give it higher octane fuel and the engine doesn't need to be as conservative with timing.
 

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You can't tune a car to run exactly on 87 octane. You can tune it to accept a minimum octane rating of 87. And that doesn't mean there won't be any benefit from higher octane. Even fuel quality varies from brand to brand, summer to winter, and whether or not there was higher octane in the hose before you filled up. All modern ECUs can adjust to the fuel used, more so to protect the engine from pinging.
You are correct. We observe a variation in Knock Control based on:
  • Water temperature
  • Driving style (cruise or full throttle)
  • Gas station filled up at

Variation in Knock Control makes consistent power runs difficult. Today on the dyno with a 1.5 Civic turbo we had Knock Control variations from 77% to 86% all on 91 octane fuel resulting in differences of 5-8 HP with no tuning changes.
 
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Hondata

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Hondata's core driving ethic is education. We like our potential customers to be informed and smart. So, here is today's lesson on octane and performance. From Honda's press release http://news.honda.com/newsandviews/article.aspx?id=9236-en:

In Civic Hatchback Sport and Sport Touring models that are designed to benefit from premium unleaded fuel, output jumps to 180 horsepower at 5,500 (6MT) or 6,000 (CVT) rpm. Torque output crests at 162 lb.-ft. between 1,700 and 5,500 rpm when equipped with the CVT. For Sport models equipped with a 6-speed manual transmission, the peak torque rating increases to 177 lb.-ft.

What, might you ask, did Honda change in their computer code the achieve this increase in power?
Answer: Nothing. The ECU code and data relating to performance is the same as the in the lower horsepower turbo Civics.

So, unless there are hardware changes we are unaware of, it would seem that the increase in power is due exclusively to the use of the higher octane fuel.
 

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The Accord took a tiny step backward in power (minus 2.6 percent) and performance (minus 1.5 percent) on premium fuel, a phenomenon for which none of the experts we consulted could offer an explanation except to posit that the results may fall within normal test-to-test variability.

Rest of the test article and conclusion here

http://www.caranddriver.com/features/regular-or-premium-test-results-page-2
Looks like we are not finished for today's education.

This article is 15 years old and has little relevance to the modern direct injected Honda 1.5 turbo engine and computers. Knock control processing is very processor intensive and was pretty primitive in computers 15 years ago. Modern vehicle computers can process knock on an individual cylinder basis. This was not the case in Honda ECUs in 2001. Today the knock processing is an order of magnitude or two better.


There is an explanation for this power difference. To reduce knock, 91 octane has a slower burn rate than 87. A slower burn rate delays the time the flame front hits the piston. This is the same as retarding the ignition timing a little. This ignition retard could result in a power loss. In this test the power could have been restored by tuning the car.
 
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planedoc

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I feel like the whole point of 2 - 3 hp is moot as its not something you're ever going to feel and will fall in the realm of "margin for error". You're going to pay a lot more for 91 - 93 octane gas, with virtually no benefits and likely lower gas mileage.
I am pretty sure it won't get lower gas mileage on premium. I realize it is a very different engine, but the mechanics at similar, and physics are physics. I had a 2007 Toyota FJ Cruiser with the 4.0L V6. On 87 octane, it ran fine, I couldn't detect any difference, BUT, it routinely, repeatedLy, averaged 16-17 mpg. On 92 octane, the highest they sell in my state, driving the very same daily commute, it repeatedly averaged 20-21 mpg. This is from the pump, not the dashboard. That is 20% better mileage, for fuel that costs 10% more.
 

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You get 40.8-41 MPG out of a car that is rated 42 MPG on Highway?(under ideal driving conditions in the lab, mind you)

Where exactly do you drive?

I am curious to hear from anyone else who gets 41 mpg on the Honda Civic.
Attached is a photo of the mileage I took. Slightly lower as I had a little fun driving over the weekend. When I get back up to the 40.8-41 I will take another picture for you if you require further proof..........

Honda Civic 10th gen Premium gas gives 2-3 more horsepower in turbo models (confirmed by Honda rep) IMG_0264.JPG
 

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Furthermore,
It's not all highway driving.
 

ArnoldLayne

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That is quite impressive at 40+ mpg. I average about 31 mpg on about 80-85% city driving and I drive on eco mode mostly.

I barely have 3200 miles on mine over 11 months and haven't taken it on a long highway trip yet. Mostly city driving plus some freeway driving.

I bought it as my second car/gas engine backup.
 

ArnoldLayne

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I am pretty sure it won't get lower gas mileage on premium. I realize it is a very different engine, but the mechanics at similar, and physics are physics. I had a 2007 Toyota FJ Cruiser with the 4.0L V6. On 87 octane, it ran fine, I couldn't detect any difference, BUT, it routinely, repeatedLy, averaged 16-17 mpg. On 92 octane, the highest they sell in my state, driving the very same daily commute, it repeatedly averaged 20-21 mpg. This is from the pump, not the dashboard. That is 20% better mileage, for fuel that costs 10% more.
It also won't get you higher mpg on premium so all things being equal, I don't see the justification to pay 25-30c per gallon extra for premium gas. This engine is not one of those that is designed to work best on premium fuel.

So regular gas at $2 per gallon and premium at 2.30ish, you have to see a 15% mpg improvement to justify using premium gas and there is zero evidence to support that.
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