I bought my red V6 MT Accord Coupe 2nite and while test driving it, the salesperson said that "Honda engineers" had told him that higher octane gas, ie premium unleaded vs. regular unleaded, made absolutely no difference in performance and was a waste of money.

2nite while browing the forum I read a comment from a member that stated that premium would give you "5 hp" more.

Any comments? Woud I really get "peppier" performance with 92 as opposed to 89? This is the only car I've owned in many years that didn't REQUIRE premium. I'm happy about that, but would pay more for more performance.

just try it next tank and see if you feel a difference.

After 26k on my car and many times switching back and forth on regular, mid and super I have found my car runs best on midgrade Chevron.

After 26k on my car and many times switching back and forth on regular, mid and super I have found my car runs best on midgrade Chevron.

i fully agree on chevron midgrade as one of the best fuel choices for the accord v6. i think the chevron super is overkill, since its 93 octane in my area and priced significantly higher than their regular. almost 30 cents on average is it the usual difference.

i have close to 9k on my accord and am averaging 26-28 mpg on 89 octane. this is with 70% city and/or suburban and 30% highway driving. with 93, i noticed the fuel economy is significantly lower, but with 87 the fuel economy is only slight lower than 89, but the price difference tends to make up for it. gas stations are one of my least favorite places to stop at.

chevron midgrade seems to be the best compromise for performance and fuel efficiency.

While running anything higher won’t damage the engine, it also won’t benefit from the higher octane. You should follow what is recommended by the manufacture.

Here's the funny thing, i am more apt to believe the manufacturers (honda nissan and porsche have all said its not bad to run on regular fuel, and honda and nissan both said running on anything higher will not improve performance.)

BUT, what if they are just saying that to make people believe their cars can do everything they say they can do with low fuel so people get the impression they are better cars that will save them on gas equaling performance as opposed to competitors?

i know it sounds like a conspiracy and i'm not one for those usually but...

ONE other thing, my girlfriend puts only 89 in her 1998 accord sedan automatic i4. she claims it not only runs better, but that it runs rough, idles rough, and even starts misfiring in the winter time on 87. the car has 157k miles.

Winter fuel is more different than just octane. So if you compare it must be in the same season's fuel.

I can tell the difference in mine with lower gas grades. I don't do my own fueling, so it's a "blind" opinion. Other than on trips, I'm not even in the car for most fill-ups.

In Winter the first stop light will be a little rough idling if he puts in a low grade fuel. It's consistent. After that, there's virtually no difference.

Which kind of octane for your car also depends on your driving style. If you're an economy driver, then higher octane is a waste of your pennies. If you're an infrequent driver, the higher octane is SUPPOSED to store better. I have no real proof of that, just experience from what fuel has been in the boat off season. And rumors. The average, mostly city driver, a little freeway SHOULD notice more of a difference than a primarily freeway driver.

The L4 is recommended to have "regular" gas.
The V6 will run on it too. HONDA recommends higher octane for their vehicles that tow. They also recommend it for some of their "sportier" Acuras that have the SAME drivetrain as a Honda. Logically there must be some reason when with the higher octane is the only difference an Acura has a higher HP rating.:dunno:

This time of year isn't the time to test the octane. Winter fuel has been put out at some places already & Hondas aren't happy with the stuff. You will get a few tanks of crappy running/idling. It happens every year. Don't panic. Most of them adjust themselves. :D

I bought my red V6 MT Accord Coupe 2nite and while test driving it, the salesperson said that "Honda engineers" had told him that higher octane gas, ie premium unleaded vs. regular unleaded, made absolutely no difference in performance and was a waste of money.

2nite while browing the forum I read a comment from a member that stated that premium would give you "5 hp" more.

Any comments? Woud I really get "peppier" performance with 92 as opposed to 89? This is the only car I've owned in many years that didn't REQUIRE premium. I'm happy about that, but would pay more for more performance.

hp gain or not, what you will notice is an engine knock if you lug it at all with the lower grade in it (atleast with a manual trans it does). that will disappear with the higher octane. it will run on either though. (funny fyi~the tl reacts exactly the same, lower grade, lug engine in the tiniest bit, knock. higher octane eliminates it. i believe our local acura dealer even said they put regular gas in all of their loaners and demo casrs..... so much for "requiring" the 92....)

I personally stick to the recommendation of Honda. If I noticed a difference I would buy higher octane gas. I think 4 cylinder cars or cars that are pinging on lower octane gas would benefit. Just don’t use unknown or independent oil companies that you don’t know how they blend their products.

Being in Southern California our gas is blended differently then the rest of the US, so I would venture to say that it also depends on the climate and state your in. Thus greatly effecting performance. We have pretty much perfect weather year round here, so worrying about knocks and pings in the winter are moot.

The only difference overall is what is done by the gas co when they create their blend of gas for the consumers.

I remember there was something on the Discovery channel about oil and gas distribution, which basically confirmed that its at the last step at the refinery that differentiates one brand from another as they are all using the same distribution system to refine the oil.

Science, Marketing or Psychological? Pick your blend!

I bought my red V6 MT Accord Coupe 2nite and while test driving it, the salesperson said that "Honda engineers" had told him that higher octane gas, ie premium unleaded vs. regular unleaded, made absolutely no difference in performance and was a waste of money.

2nite while browing the forum I read a comment from a member that stated that premium would give you "5 hp" more.

Any comments? Woud I really get "peppier" performance with 92 as opposed to 89? This is the only car I've owned in many years that didn't REQUIRE premium. I'm happy about that, but would pay more for more performance.

The HONDA sales REP is absolutely talking TRASH. YES the Accord will make 5HP more IF you put Higher Octane 92/93. I have DYNO Results (http://www.driveaccord.net/forums/showthread.php?t=13801) to prove it.

Now will you feel a 5HP difference while driving? Probably not. I would settle on Mid Grade i.e 89 and although the accord can run on 87 I would not suggest using the lowest grade fuel.

I ran 85 in my Accord V6 for the time I owned it. It did run a little smoother and as Anysia said...it won't ping when you lug the engine (6MT owners only need to worry about this).

The TL hated anything less than premium and ran like crap without it. It is a waste of money for the I4, but to some, there are improvements in the V6. For me...I'd use regular as you won't feel 5HP...and I'd put money on that. Use the money you save from using the regular fuel and buy better tires. That is where you will see some improved performance. The premium fuel in the Accord really doesn't make sense.

It's not unusual for higher mileage cars to benefit from higher octane, which could explain why an I4 with 157k runs better on midgrade.

I have never noticed any difference putting premium in a car that calls for 87 octane. I have noticed the difference putting 87 octane in a car that calls for premium.....a negative difference.

Octane ratings dictate the basic property in fuel that makes them resistant to pre-ignition the result of which is detonation. Without getting into brain swelling tech info, the fuel burns slower. The result is less knock ( which the computer listens for to determine engine timing) and increased performance due to allowable increase in ign timing etc. In the old days of hi compression, hi octane leaded fuel reduced knock on Hi Comp engines, but these engines had inefficient cylnder head designs and limited ignition timing control, not to mention limited ability to mix fuel/air efficiently of the broad range of operating characteristics (load, eng speed etc). Remember the 08 accord uses 10.5:1 compression now

The HONDA sales REP is absolutely talking TRASH. YES the Accord will make 5HP more IF you put Higher Octane 92/93.
I have DYNO Results (http://www.driveaccord.net/forums/showthread.php?t=13801) to prove it.

Now will you feel a 5HP difference while driving? Probably not. I would setlle on Mid Grade i.e 89 and although the accord can run on 87 I would not suggest using the lowest grade fuel.

Have you done a dyno pull on 87 octane?

Have you done a dyno pull on 87 octane?

I havent but this guy did using Regular 87 gas...

FULL article here (http://www.vtec.net/articles/view-article?article_id=719873)

those numbers don't look right.

My g/f will only run 92+ in her new TSX as the owner's manual recommends. I'm trying to get her to put a tank of 89 in it to see what happens, but she's not too interested.

I've never ran anything but 87 in my '94 Accord EX but I put 93 in my last two fill-ups and it made a HUGE difference in so many ways (e.g. much quicker acceleration, quicker start-ups in the morning, a *slightly* higher mpg rating). I doubt I am going to continue to waste money on that until I trade her in, but I do think I will try 89 in it the next time around.

any car with a compression ratio of 11:1 must go on premium.

ive noticed a difference in my engine, but it might be due to the engine breaking it (only has 1100 miles on it. 2008 accord sedan)

My g/f will only run 92+ in her new TSX as the owner's manual recommends. I'm trying to get her to put a tank of 89 in it to see what happens, but she's not too interested.

I've never ran anything but 87 in my '94 Accord EX but I put 93 in my last two fill-ups and it made a HUGE difference in so many ways (e.g. much quicker acceleration, quicker start-ups in the morning, a *slightly* higher mpg rating). I doubt I am going to continue to waste money on that until I trade her in, but I do think I will try 89 in it the next time around.

i advise against it.

what happens with a higher ratio engine is using lower grades in cars like your gfs tsx will cause knocking. immediate effects are: notable degrading performance,worse gas mileage.

while back in the day knocking would kill an engine, modern technology made it that it doesnt happen immediately, but keep doing it long term and you might just pay for it (engine wise).

i cry a little inside when i see bmws,lexus,acruas at gas stations putting 87 or 89 in their tanks (which is why i will never own either used).

after using 93-94 octane (Shell or Sunoco) for years , using plus grade in my new 08 is still a refreshing price break and Ill stick to 89 in the coupe unless 87 goes up to 4$ a gallon

Mercedes from 89-95 years used a crazy retarded CEL EZL to dumb down the firing on cylinders for US spec cars... they realized crazy americans would still try to put in 87 crap ...

you can get away with it for a tank, but the performance and idling of the engine from what ive heard is still hideous with 87 ... id never venture lower than 91 in a high compression engine car like a benz.

Octane ratings dictate the basic property in fuel that makes them resistant to pre-ignition the result of which is detonation. Without getting into brain swelling tech info, the fuel burns slower. The result is less knock ( which the computer listens for to determine engine timing) and increased performance due to allowable increase in ign timing etc. In the old days of hi compression, hi octane leaded fuel reduced knock on Hi Comp engines, but these engines had inefficient cylnder head designs and limited ignition timing control, not to mention limited ability to mix fuel/air efficiently of the broad range of operating characteristics (load, eng speed etc). Remember the 08 accord uses 10.5:1 compression nowWow, someone that actually understands the capability of modern computer controlled engine management systems! Of course the other issue is whether or not you could “feel” the difference in the seat of your pants, unlikely!

Ah! The never ending debate continues everytime we see a new Accord generation rolling out. Well, here are my thoughts:

1. It takes a few gas tanks of the good stuff (high octane) to notice any difference in performance. One tank won't do anything... and yes there are noticable performance changes.

2. First thing you notice after a few high octane gas tanks is the knock sound is down by a lot (shell and petro Canada, especially petro Canada 94 oct makes the engine run more quiet, still don't know why).

3. You stick to higher octane gas and your engine won't need de-carbonizing as much as you fill up with the recommended octanes. Higher octane gasolines have enough detergent in them to keep carbs out!

... or at least this is what I have discovered over the past 10 years with a '98 v6 and a '03 v6. However now we have a new engine here. The 3.5 with cylinder deactivation. That part is what scares me. No idea how lower or higher octanes will react in that engine with that mechanism of deacticating cylinders. No idea how timing may or may not change due to higher octane and how timing is related to the cylinder deactivation. Lots of questions, no answers yet.

(you ask all that a sales guy you are wasting your time)

Maybe do this:

"regular" I-4 : 87 octane
High Output hp I-4: 89 octane
V-6: premium

That was easy................

Octane ratings dictate the basic property in fuel that makes them resistant to pre-ignition the result of which is detonation. Without getting into brain swelling tech info, the fuel burns slower. The result is less knock (which the computer listens for to determine engine timing) and increased performance due to allowable increase in ign timing etc. In the old days of hi compression, hi octane leaded fuel reduced knock on Hi Comp engines, but these engines had inefficient cylnder head designs and limited ignition timing control, not to mention limited ability to mix fuel/air efficiently of the broad range of operating characteristics (load, eng speed etc). Remember the 08 accord uses 10.5:1 compression now
Good thing I kept reading the posts. I was going to post my input that is JUST AS YOU POSTED. From my experience, modern GM vehicles have TWO timing tables (High & Low Octane). The usage depends on detonation. From the first start of the engine, the ECM/PCM selects higher of the two. If no knock (pre-detonation) is detected, that table is continually used. However, if knock is detected, the ECM/PCM selects the Low Octane table to use for ignition timing. This is known as Knock Retard. This is done without a driver's input so to optimize fuel burning (along with a slew of other things). I'll try to remember to post a screenshot of my HPTuners software that shows the two different tables.

I know, I know... that's a GM experience, but I'm sure Honda's very similar (if not the same).

*edit*

Found a screenshot online of someone's High Octane table. The Low Octane table is formatted the same (obviously) but will have values about 3 - 5 degrees lower in stock form. Most performance tuners will set both tables the same in order to trick the ECM/PCM into using the same values no matter which table is used.

http://www.hptuners.com/forum/attachment.php?attachmentid=1961&d=1160405967


Hope this helps with visuallizing. :thmsup:

However now we have a new engine here. The 3.5 with cylinder deactivation. That part is what scares me. No idea how lower or higher octanes will react in that engine with that mechanism of deacticating cylinders. No idea how timing may or may not change due to higher octane and how timing is related to the cylinder deactivation. Lots of questions, no answers yet.

(you ask all that a sales guy you are wasting your time)

Isn't the purpose (and actual function) of shutting down cylinders mean no electrical power to coils for spark & no fuel feed from injectors in those respective cylinders, but balanced fuel & ignition to minimize engine noise (to prevent sounding like it's "misfiring")? :dunno:

i advise against it.

what happens with a higher ratio engine is using lower grades in cars like your gfs tsx will cause knocking. immediate effects are: notable degrading performance,worse gas mileage.
It will still knock w/ 89, though? And I'm not quite sure her mpg could get any worse...although I am pretty sure a lot of that has to do with the way she drives her. ;)

Isn't the purpose (and actual function) of shutting down cylinders mean no electrical power to coils for spark & no fuel feed from injectors in those respective cylinders, but balanced fuel & ignition to minimize engine noise (to prevent sounding like it's "misfiring")? :dunno:

On top of that, it uses a solenoid to unlock the cam followers on one bank from their rockers, so the cam follower floats freely while the valve springs keep the valves closed. Its kind of the opositve of vtek. Below a certain rpm level it shuts 3 off by closing all valves and not allowing any air in or out. Not sure how the damn thing doesn't explode!

... my point was that now that we have essentially a 3 cylinder engine, the old theory of higher octane is better may not be valid anymore for many reasons. Your back 3 cylinders on the v6 that get cut off when the CVM kicks in may end up a lot more "new" than the front 3 that work all the time. So, you have 3 old and 3 new cylinders both receiving the same octane gas. Weird. The Odyssey people say they never experience any issues, too early to tell?

Below a certain rpm level it shuts 3 off by closing all valves and not allowing any air in or out. Not sure how the damn thing doesn't explode!
From what? I would guess any existing exhaust gases (burned fuel) would be scavenged from the cylinder thru the head's exhaust port before closing. If there's no vapor/liquid resistance, then there's no ill effect of compressed whatever, right? :dunno:

As for cylinder wear on half the engine, I doubt that's true (IMO). The crank will still turn, thus forcing the connecting rod to push the piston through it's normal cycle. The only thing you're not getting is the air/fuel thrown in the cylinder. :yes: :thmsup:

I would be interested in a dyno run on an 03- 07 model 2.4l with regular vs midgrade vs premium fuel to see what (if any) differences, positive or negative, were noted.

I recall reading that the Honda engineer that developed the 3.0l V-6 said it would develop 10 more horsepower (at the crank I assume) on premium. What about the the 4 holer? If I read the article correctly the V-6 "brain" is sophisticated enough to realize the difference in octane but the four banger is not. Thoughts on this folks?

those numbers don't look right.

Those Dynapacks are weird.

Link to article on this topic.
http://www.canadiandriver.com/articles/jk/060118.htm

RTexasF,

Dynos can vary several horsepower with identical runs. A dyno has inherent variances and we can't perfectly control all the environment variables. Correction factors usually have a large (relatively speaking) ± that has to be factored into the uncertainty of the result. There would need to be dozens of runs to discern any small power increases at all & even then the operator may still have too much influence on the results. This is why the dyno charts showing one oil gained a few hp are crap and are approaching the lamest rung on the ladder of marketing. It is the precise reason why I won't purchase Royal Purple - more telemarketing junk.

RTexasF,

Dynos can vary several horsepower with identical runs. A dyno has inherent variances and we can't perfectly control all the environment variables. Correction factors usually have a large (relatively speaking) ± that has to be factored into the uncertainty of the result. There would need to be dozens of runs to discern any small power increases at all & even then the operator may still have too much influence on the results. This is why the dyno charts showing one oil gained a few hp are crap and are approaching the lamest rung on the ladder of marketing. It is the precise reason why I won't purchase Royal Purple - more telemarketing junk.

Thats very true but if you could see a difference in timeing advance between 87 and higher at a constant speed/load/throttle %, I think that would prove you should get slight performance gains just as a affect of CPU programing.
I bet the timing curves advance's into the knock sensor input , as modern timing is pretty aggressive to get the most out of the engine. So running higher octane "should" help stop knock sensor from kicking in much (though this would need testing to see if so) .
run a scan tool monitoring the data and see if any changes show, you would still have to make sure air/water temp is close in both tests .

RTexasF,

Dynos can vary several horsepower with identical runs. A dyno has inherent variances and we can't perfectly control all the environment variables. Correction factors usually have a large (relatively speaking) ± that has to be factored into the uncertainty of the result. There would need to be dozens of runs to discern any small power increases at all & even then the operator may still have too much influence on the results. This is why the dyno charts showing one oil gained a few hp are crap and are approaching the lamest rung on the ladder of marketing. It is the precise reason why I won't purchase Royal Purple - more telemarketing junk.

I understand the variances which is why several runs are made to obtain an average. I wouldn't consider changes of 1 or 2 horsepower significant but I know of no other way to check for differences or effectiveness of a given modification/octane. It is still the standard (be that good or bad) for tuning used to determine horsepower.

I'm not disagreeing with you, I simply don't know of any other way to determine horsepower at the wheels so the "dyno run" still prevails.

RTexasF,

Dynos can vary several horsepower with identical runs. A dyno has inherent variances and we can't perfectly control all the environment variables. Correction factors usually have a large (relatively speaking) ± that has to be factored into the uncertainty of the result. There would need to be dozens of runs to discern any small power increases at all & even then the operator may still have too much influence on the results. This is why the dyno charts showing one oil gained a few hp are crap and are approaching the lamest rung on the ladder of marketing. It is the precise reason why I won't purchase Royal Purple - more telemarketing junk.We are on a role lately with logical information!

Typically back to back dyno pulls result in lower readings due mostly to HEAT buildup that cannot be effectively eliminated from the dyno area. So the variance in results of back to back pulls of +/- 3% or so is meaningless. The BEST dyno I know of is still the ¼ drag strip. Variances are still a factor, but horsepower & torque numbers mean nothing unless you can effectively get the power to the ground.

I don't know anything about the J35Z2/3, but the J30A4/5 definitely gains some power running premium gas. And if the old engine does, why shouldn't the new one?

Anyway...

Last winter, I used an Auterra dyno scan tool to log ignition timing advance in my 2007 Accord V6.

The first runs were using 87 octane. In order to ascertain the ignition timing advance with the engine going all out, I made several WOT runs through 1st and 2nd gear. I noted the timing curves, intake air temp, and coolant temp, and then filled up with 93 octane after completely draining the tank of 87.

I drove about 500 miles on 93 before conducting the 2nd set of tests in order to give the engine computer time to adjust to the higher-octane fuel. I picked a time with nearly identical weather conditions as during the first set of runs, and went at it.

My results weren't astounding, but they definitely proved that the J30A5 ran somewhat more aggressive ignition timing on 93 octane. As I did WOT runs from 0 to 70, I was able to compare the timing advance between the two grades of gas from as low as 2500 rpm all the way to the redline.

I found that, with 87 octane, ignition timing advance dropped to as low as 12* at 2500 rpm and then reached a plateau of about 23* at 5000 rpm on its way to a definite peak of 24.5* at 6000 rpm. All of the runs were within a degree of each other throughout the powerband, and the peak timing was 24.5* every run.

On 93 octane, the peak only rose a fraction to 25*(there was one run that peaked at 26.5, but the others were steady at 25), but the timing advance in the low-end and mid-range increased dramatically. Whereas the timing advanced dropped to as low as 12 degrees on 87, it never fell below 19 degrees on 93, even at a low 2500 rpm. The curve was much flatter, and the peak was less defined, with a steady 25* of peak timing advance spanning from about 4500 rpm to the redline. On the run with the 26.5* peak, that peak came at 6000 rpm while the rest of the curve from 4500+ rpm was still around 25*, so I disregarded that run as it was an outlier as far as peak timing advance was concerned.

To be sure that all things were equal, I also measured the intake and coolant temps during the runs. The average intake air temp for both sets of runs was about 95 degrees F, and the coolant temp during all of the runs was right around 180 degrees F, give or take a few degress. I wanted to make the comparison as fair as I could in order to obtain the most accurate results possible.

All in all, I concluded from my testing that the J30A5 does indeed benefit from premium gasoline, especially in the low-end and mid-range. I don't know how much power each degree of timing advance is worth, but the extra 7* of timing advance at 2500 rpm when using 93 has to be pretty significant. I can definitely feel the extra low-end on the ole' butt dyno when running premium, and overall the engine behaves in a much more refined manner. When run on 87, my V6 feels and sounds like it's in pain. It pings at low rpm during high-load situations and feels kinda rough at idle and during acceleration. With 93 in the tank, it smooths out quite a bit and the pinging disappears. Based on my experience with the J30A5 on regular 87 octane, I don't see how Honda can confidently recommend 87 octane for this engine. Surely, they know better than anyone that this engine HATES low octane gas, and with a 10:1 compression ratio, why shouldn't it?

It will still knock w/ 89, though? And I'm not quite sure her mpg could get any worse...although I am pretty sure a lot of that has to do with the way she drives her. ;)

why get a tsx if youre not going to care for it the way it should be?


atleast sell it to someone who will. i cry when i see nice cars driven to shit because logic sometimes escapes people (ie, buy a 40k car but cry at $3.50 for premium)

The K series I4's are just a half point or so shy of the compression of a V6(sans the TSX motor), so why shouldn't WE be pumping at least 89 in ours? I had one tank of 87 in my car... from the dealer. Its only seen 89 since I've owned it and maybe a little E85 once in a while to cleanse the system.:thmsup: Thats a totally different subject in its own, though.

E85??? how does the car run on that fuel???? :eek:

is it able to run properly with that? almost like GM's flex-fuel cars???? :dunno:

I don't know anything about the J35Z2/3, but the J30A4/5 definitely gains some power running premium gas. And if the old engine does, why shouldn't the new one?

Anyway...

Last winter, I used an Auterra dyno scan tool to log ignition timing advance in my 2007 Accord V6.

The first runs were using 87 octane. In order to ascertain the ignition timing advance with the engine going all out, I made several WOT runs through 1st and 2nd gear. I noted the timing curves, intake air temp, and coolant temp, and then filled up with 93 octane after completely draining the tank of 87.

I drove about 500 miles on 93 before conducting the 2nd set of tests in order to give the engine computer time to adjust to the higher-octane fuel. I picked a time with nearly identical weather conditions as during the first set of runs, and went at it.

My results weren't astounding, but they definitely proved that the J30A5 ran somewhat more aggressive ignition timing on 93 octane. As I did WOT runs from 0 to 70, I was able to compare the timing advance between the two grades of gas from as low as 2500 rpm all the way to the redline.

I found that, with 87 octane, ignition timing advance dropped to as low as 12* at 2500 rpm and then reached a plateau of about 23* at 5000 rpm on its way to a definite peak of 24.5* at 6000 rpm. All of the runs were within a degree of each other throughout the powerband, and the peak timing was 24.5* every run.

On 93 octane, the peak only rose a fraction to 25*(there was one run that peaked at 26.5, but the others were steady at 25), but the timing advance in the low-end and mid-range increased dramatically. Whereas the timing advanced dropped to as low as 12 degrees on 87, it never fell below 19 degrees on 93, even at a low 2500 rpm. The curve was much flatter, and the peak was less defined, with a steady 25* of peak timing advance spanning from about 4500 rpm to the redline. On the run with the 26.5* peak, that peak came at 6000 rpm while the rest of the curve from 4500+ rpm was still around 25*, so I disregarded that run as it was an outlier as far as peak timing advance was concerned.

To be sure that all things were equal, I also measured the intake and coolant temps during the runs. The average intake air temp for both sets of runs was about 95 degrees F, and the coolant temp during all of the runs was right around 180 degrees F, give or take a few degress. I wanted to make the comparison as fair as I could in order to obtain the most accurate results possible.

All in all, I concluded from my testing that the J30A5 does indeed benefit from premium gasoline, especially in the low-end and mid-range. I don't know how much power each degree of timing advance is worth, but the extra 7* of timing advance at 2500 rpm when using 93 has to be pretty significant. I can definitely feel the extra low-end on the ole' butt dyno when running premium, and overall the engine behaves in a much more refined manner. When run on 87, my V6 feels and sounds like it's in pain. It pings at low rpm during high-load situations and feels kinda rough at idle and during acceleration. With 93 in the tank, it smooths out quite a bit and the pinging disappears. Based on my experience with the J30A5 on regular 87 octane, I don't see how Honda can confidently recommend 87 octane for this engine. Surely, they know better than anyone that this engine HATES low octane gas, and with a 10:1 compression ratio, why shouldn't it?Peak total timing rarely changes, but a pickup of 7* of initial timing at the lower end of the Rpm scale where peak torque numbers are affected should result in a measurable gain in torque.

Thanks for the breakdown!

Surely, they know better than anyone that this engine HATES low octane gas, and with a 10:1 compression ratio, why shouldn't it?


I don't know that it really means anything today. Our '03 Corolla 1.8l has the exact same compression ratio. It's an economy car and intended for 87 octane, actually 85 or above is stated. There has to be more to it overall than compression ratio.

why get a tsx if youre not going to care for it the way it should be?

atleast sell it to someone who will. i cry when i see nice cars driven to shit because logic sometimes escapes people (ie, buy a 40k car but cry at $3.50 for premium)
Well as I stated earlier, she is the one babying it and taking care of it w/ 93+ gas. I just wanted to do a little experiment w/ it, that's all. My comment on her MPG was because she drives the performance car, well, like a performance car (unlike me who absolutely babies cars) and gets a lower MPG than I do.

So don't worry, logic hasn't escaped us and no one is crying over the higher price of the gas. :wave:

i filled half tank with 89 over 87 and i noticed greatly difference in engine noise and performance compared to when i put $20 in regular on my EX.


im going to stick to mid grade from here on out.

i filled half tank with 89 over 87 and i noticed greatly difference in engine noise and performance compared to when i put $20 in regular on my EX.
im going to stick to mid grade from here on out.



The effect was purely psychological. 89 octane is a 50/50 blend of 87 and 93. With that in mind your 89 over 87 MIGHT have raised the octane to 87.1.

I always thought octane rating referred to "resistance to detonation"?

Meaning, 93 octane is "harder to burn" than 87 octane? MAybe I need to go back to science class........:(

which is correct...having said that.

Back to using higher octane with "our" Honda engines...87 is fine and the performance boost you feel is most likely in your head.

I always thought octane rating referred to "resistance to detonation"?

Meaning, 93 octane is "harder to burn" than 87 octane? MAybe I need to go back to science class........:(

Talk about a weird coincidence: My g/f got an Acura magazine in the mail yesterday and there was a whole section dedicated to caring for Acuras. One part of the article talked about how some owners are putting in less than 91 octane in them. "In one word: don't" is what the article said, and then it goes on to talk about what happens to the engine if you use less than 91 in them.

Octane ratings dictate the basic property in fuel that makes them resistant to pre-ignition the result of which is detonation. Without getting into brain swelling tech info, the fuel burns slower. The result is less knock ( which the computer listens for to determine engine timing) and increased performance due to allowable increase in ign timing etc. In the old days of hi compression, hi octane leaded fuel reduced knock on Hi Comp engines, but these engines had inefficient cylnder head designs and limited ignition timing control, not to mention limited ability to mix fuel/air efficiently of the broad range of operating characteristics (load, eng speed etc). Remember the 08 accord uses 10.5:1 compression now

This is as I understand it. I once read a comment by an automotive engineer in which he explained that because of the low compression of cars designed around low octane gas, if you use a higher octane it forces the monitor electronics to attempt to compensate resulting in worse overall performance and engine wear not to mention thinning out your wallet.

Just keep in mind that Honda designs their engines for 87 octane, and the Acura engines for 91 octane.

Talk about a weird coincidence: My g/f got an Acura magazine in the mail yesterday and there was a whole section dedicated to caring for Acuras. One part of the article talked about how some owners are putting in less than 91 octane in them. "In one word: don't" is what the article said, and then it goes on to talk about what happens to the engine if you use less than 91 in them.

Ever since my car drove off the lot, I've always put 93 octane in it. I don't mind the extra 0.30 since I'm used to it anyways. I really don't think it would hurt the engine at all as some would say, but maybe there could be some long-term benefits? I plan to keep this car until it dies out, so I'll report back to you guys in 10 years on the benefits :D.

Talk about a weird coincidence: My g/f got an Acura magazine in the mail yesterday and there was a whole section dedicated to caring for Acuras. One part of the article talked about how some owners are putting in less than 91 octane in them. "In one word: don't" is what the article said, and then it goes on to talk about what happens to the engine if you use less than 91 in them.

Propaganda cow pies :)

My 96 Integra GSR "requires" premium gas according to Acura, it had 9.5 years of 87 octane regular gas while I owned it and drove for a couple of hundred thousand kilometers, never had a problem.

I don't take it easy with the car, but I don't abuse or lug it either, i.e. wait until the engine is warmed up before driving it hard.

Modern engines have detonation sensors to "listen" to detonation under heavy, and the fuel control computer will retard the ignition spark just a bit to reduce/eliminate the pinging.

I can only speak for myself that a high strung GSR engine lived quite happily on a diet of 87 octane gas, and felt as strong the day I sold it as the day I bought it.

no not psychological. i could feel the car being rougher on 87 than 89.


i didnt combine 87 and 89. i waited till i was .01 gallons left before i put half tank of 89. car feels smooth and quiet.


im going to stick to 89 simpply because.

Your prerogative of course. If it feels better to you that's all that matters.

Propaganda cow pies :)

My 96 Integra GSR "requires" premium gas according to Acura, it had 9.5 years of 87 octane regular gas while I owned it and drove for a couple of hundred thousand kilometers, never had a problem.

I don't take it easy with the car, but I don't abuse or lug it either, i.e. wait until the engine is warmed up before driving it hard.

Modern engines have detonation sensors to "listen" to detonation under heavy, and the fuel control computer will retard the ignition spark just a bit to reduce/eliminate the pinging.

I can only speak for myself that a high strung GSR engine lived quite happily on a diet of 87 octane gas, and felt as strong the day I sold it as the day I bought it.

I guess you never heard any pinging under load conditions.
pinging under steady load is very bad thing and will cause damage over time.
now if you only hear or get slight ping in transition loads in part throttle/low rpm thats not so bad as its only a sec or so not heavy loaded.

I have replaced many pistons because of detonation issues, its a real killer on turbo cars, broken lands. broken spark plugs etc, its like hitting top of pistons with a hammer ;-).

Now Honda not turbo or anything but still pretty high compression ratio, I would never use gas that pings under load, its just not worth it, and retarding the timing is not great either on engine.

I would use whatever the manufacturer states the min octane rating, if you want to try higher to see how it runs, it shouldn't hurt at all.
The higher grades will have better additives added so that can be side benefit besides octane rating

anyway just my opinion.

any car with a compression ratio of 11:1 must go on premium.

ive noticed a difference in my engine, but it might be due to the engine breaking it (only has 1100 miles on it. 2008 accord sedan)

You are correct, its all about the compression ratio and since the V6 Accord's compression ratio is 10.5:1 it will run just fine on 87 octane, just like it says in the owners manual. :)