Honda Insight Forum banner

1 - 20 of 32 Posts
G

·
Guest
Joined
·
0 Posts
Discussion Starter #1
This is my first post here. The reason is, I have had nothing to contribute since getting my brand new 2004 CVT several months ago and visiting this site prior to this. But the time has come!

The weather here in NJ has been in the mid to low 40's for some time now and continues in this range. My mileage has been 50 - 52 mpg during this time.

Last week it was time to fill the Insight up. Having read a number of posts here regarding premium fuel, both pro and con, I thought I would give it a shot. I filled it up with SUNOCO ULTRA 94 octane and reset my FCD. After about 75 miles of driving the MPG was stabilizing between 68 - 70 MPG! After another week of driving 300+ miles, the MPG remains the same, 68 - 70 MPG! No difference in temperature, no difference in driving habits or terrain, essentially no difference at all... except the fuel.

Now I understand that there are all sorts of varying opinions regarding this issue, many with what seems to be a good 'scientific' basis or reasoning as to why this mileage increase can not be attributed to the type of fuel. But facts are facts. And I must engage in a psychotic break with the interpretation of reality to deny that use of this particular fuel does not have a dramatic effect on the increased mileage of the vehicle.

I would suggest strongly the use of SUNOCO ULTRA 94 to increase the MPG, or at least try it. For those who may use this fuel and do not have such success, you too must face the reality of your experience, but I would suspect that it has something more to do with engine performance issues than the fuel. Keep in mind, my vehicle is brand new (7.5K miles to date).
 

·
Premium Member
Joined
·
4,942 Posts
It will be interesting to read what your MPG is a year from now with several switches back and forth between fuel grades.

I more than suspect the biggest % in improvement is one or several other variables beyond brand and octane given your stated 25% improvement. Sadly, its simply the limitation of the chemistry of combustion. Unless Sunoco has _really_ found some liquid "magic" <VBG>.

Keep us posted :!: :)
 
G

·
Guest
Joined
·
0 Posts
Discussion Starter #3
Insightful Trekker said:
It will be interesting to read what your MPG is a year from now with several switches back and forth between fuel grades.

I more than suspect the biggest % in improvement is one or several other variables beyond brand and octane given your stated 25% improvement. Sadly, its simply the limitation of the chemistry of combustion. Unless Sunoco has _really_ found some liquid "magic" <VBG>.

Keep us posted :!: :)

OK. I'm a retired analyst. I've specifically outlined the dynamic factors and result. Could you please specifically outline the 'other variables' as to what could it possibly be, other than the fuel?

As for what will or will not happen over the next year -- such a point is diversionary and lacks relevance, for it fails to address the present issue of what has in fact happened now.
 

·
Premium Member
Joined
·
4,942 Posts
As analyst I hope you don't draw similar conclusions from the other data you have analyzed. I guess I'm "preaching" to the choir here but such an anomaly in such a short time frame cannot be considered a "fact" without supporting data. Where in relation to a standard deviation does this new data fall? Does this fact alone not give reason for doubt? Time will tell.

With that said its more of an anomaly that your MPG in the past was as low as you stated. Some of the early low figures can be attributed to the break-in wear of the engine and driver in order to attain maximum MPG. The "technical" issues in regard as to what _could_ scientifically and reproducibly explain this anomaly are many. And except in laboratory conditions cannot be reliably isolated. So I don't see the benefit of hypothesizing.

My opinion is that your earlier _low_ MPG was the anomaly, and that you will likely see many more MPG averages in this readily attainable range. :D

The "debate" of premium fuel vs. regular has been discussed in here ad nausium. One thread quite recently. Use the forum search feature if your interested. :)

HTH! :)

<Official road sign in Virginia in the early 70's>
"Everybody in favor of saving gas raise your right foot."
 
G

·
Guest
Joined
·
0 Posts
Discussion Starter #5
Hi SwordStroke:

___There is more variability then you think as it has been warming up in Edison, NJ. just as it has in most places in the Midwest over the last few weeks. Edison is the town I checked given I do not know of any other towns in NJ. off the top of my head? When I checked weather.com’s previous 7-day history, Edison had a 58 degree high last Tuesday in particular? You might believe that Sun 94 is the reason for a 35% increase in FE but there is not that much extra BTU content in any two comparable gasolines anywhere in the country! High Octane and low Octane fuels have very little Delta in BTU content between them with the lower Octane fuels actually being touted as having more in some cases. When driving a hypermile style as you probably are, there isn’t an ECU that would pull back timing given the lower RPM’s so it isn’t a higher Octane vs. lower Octane timing issue causing the increase either. Even if you happened to get your hands on some non-winter blend - lower oxygenated fuel (here in IL., we will not see it for at least another month), it is only good for a 3 - 4% increase at best. Let’s say you are forced like we are to use a 10% ethanol blend year round. If you happened to find or fill up with non-Ethanol based fuel, it is worth another 2 - 3% at best as well so that could not account for it either. Your 35% increase is by no means explained by using Sun 94 as that would be an impossibility imho. I have been proven wrong on far more then this occasion however ;)

___For your own future tracking and ours, might I suggest that you open up your tank over tank data to the world?

Honda Insight

___With this real world hybrid mileage DB/tracking tool, you can help explain a great tank vs. mediocre tank with weather, temperatures, drive time, traffic congestion, and an area for notes on each tank that help others see what is actually changing on your day to day driving routines vs. a guesstimate of I was receiving XX.X and am now receiving XX.X …

___By the way, I only use BP, Shell, or Speedway Regular Unleaded 87 Octane gasoline’s in all of my vehicles. The Ford Ranger has averaged 28.6% greater then EPA highway estimates all winter here just north of Chicago and the Insight 5-speed averages 45.7% greater then EPA highway estimates in the summer. I too would love to see another 35% on top of what I am currently receiving but I highly doubt you could average 137 mpg throughout the summer months in an Insight 5-speed using Sun 94. Now do you understand why I am suggesting that this type of increase is an impossibility?

___Give your Insight and its tank over tank FE data some time to settle out. I was just posting to an HCH owner here in the Chicago area that saw a 5 mpg increase per his FCD over any of his previous tanks last night. The same reasoning applies as above. It is a temperature and traffic related issue for him (he finally hit the Interstate) and we are finally beginning to see some highs in the low to mid-50’s where it was in the low to mid 20’s to mid 30’s for most of the last 6 weeks. After a few months, you will learn what it is that is changing your own Little Beauty’s FE (you would be surprised what driver experience has to do with it ;)) just as we have all learned how to drive our Little Beauty’s for all they are worth when called upon to do so.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:1tkjo7fk][email protected][/email:1tkjo7fk]
 

·
Registered
Joined
·
65 Posts
While a little unrelated, I have noticed some consistent variation in gas brands. I've filled up using Exxon/Mobil gas and averaged 57mpg and alternated it with Shell gas consistently and gotten 61-62mpg. Both 87 octane. Other brands like Chevron and Arco give me 58-60.

What may be a factor though is the refinary from which the gas came. I've tried to use different shell locations and gotten similar results but I have yet to use different Exxon/Mobil locations.

Also changes in driving style like slowing down have given me higher tanks. Right now I've been averaging a little less than 65MPH and pulling just under 70MPG -- on Shell gas. Usually I do 70-75MPH and get 60-65MPG.
 

·
Registered
Joined
·
2,448 Posts
Where are you located that you have 94 octane fuel? The regular grades available to me are 87,89 and 91 (used to be 92, but that was before I could drive).

I know in the past I've always said use premium, but this last week I filled with 87 just for a change and I gotta say I haven't noticed any difference (there... I said it).

Still, the service manual says something to the effect of for best mileage and performance use 91 or higher octane fuel. I think there would be slightly less difference with the CVT with it's lower compression ratio. I wounder what the CVT non US owners manuals say. I believe the German, Japanese, and UK owners manuals say to use whatever their equivelent to 91 octane is. I think in the end YMMV is just something to stick to.

Continuing to ramble on here, I think if there is any difference in mileage it's deffinitely not enough to offset the higher cost of premium fuel.
 

·
Registered
Joined
·
162 Posts
OK... lets be honest hear... if you use higher octane fuel. You are not getting better performance. There are two effect that the higher octane will have.
1) More advanced timing = more hp, better combustion
2) Prevents detonation at current timing (detonation is bad!)

Since there is no way a properly functioning insight engine is going to be having detonation issues at all, anywhere within its rev range. The higher octane is doing nothing but costing you an extra 20 cents per gallon.

For those guys who now have turbo insights, thats a different story. They will need higher octane, because bosting your engine effectively increases your compression ratio alot, and you may have issues with detonation!

Thats my $0.02
 

·
Premium Member
Joined
·
4,389 Posts
One variable not mentioned is the possibility that the 94 octane is also not mixed with ethanol whereas the lower octane fuel is a mix. I live in CT but near the MA border. Most 87 octane gas in CT is reformulated with ethanol whereas the gas in MA can be non reformulated based on where it is purchaced. I do see some MPG difference between the ethanol gas and the straight gas, but because on my more aggressive driving, cannot quantify the difference.
 

·
Registered
Joined
·
1,032 Posts
If the manual suggests the use of 91 octance ( :?: Does it? I don't have my car yet.) could it not be that the knock detection system is capable of retarding the ignition timing to make 87 octane acceptable, at the cost of a small amount of power?
 

·
Registered
Joined
·
2,448 Posts
The us manual says 87 octane, the rest of the world's suggests higher. As far as I know there is no major difference in the drive train's umong different sections of the world. The Insight's knock sensor is more than capable of adjusting the timing for 87. You don't need to use premium.

This should explain it better:

http://www.insightcentral.net/KB/faq-dr ... ml#GasType
 

·
Registered
Joined
·
1,240 Posts
I have tried premium in my CVT and didn't notice any increase in mpg. But then again we only get 91 octane in California.
 

·
Premium Member
Joined
·
1,631 Posts
As many people here (as well as myself) seem to doubt a 25% increase
in fuel economy as "facts are facts" I only have this to offer. You can
draw your own conclusions of facts if you are still able to read this post.

JoeCVT - Just your average CVT owner
 

·
Premium Member
Joined
·
4,942 Posts
joecvt said:
You can draw your own conclusions of facts if you are still able to read this post.
Well, my curiosity got the better of me.

Without inviting any type of debate, political or otherwise, the only conclusion that I draw from the above statement as it relates to this thread is confusion :!: :?:

What am I missing :?:

p.s. if you have to get political a PM is preferred but don't expect a reply of anything more than "OK." :)
 

·
Premium Member
Joined
·
679 Posts
Doesn't 'knock' have to occur to have the sensor start to make adjustments to prevent it?

If so, then putting fuel into your car that is 'managed' by the anti-knock technology is just reducing the damage vs. no such technology, but you are still damaging your engine because of the fact that you have to have some detonation take place in the first place before the 'management' step in to stop it. Unless the car says, 'hey, I think knock might start to happen in the future, so I will do things to make it impossible'... Is there some little clairvoyant seer under the hood for this kind of prediction? If so, my little guy must have fallen out.

In any case, I can't imagine that Honda designed the car such that as a stock car for sale for street use it would knock at 87 octane, when most street cars are using that octane. I don't believe that the Insight engine should knock at 87 for those reasons, not on account of detailed engineering understanding a priori.

I believe that the anti-knock sensor is for when real problems come around, and it is not expected to be triggered (virtually triggered) all the time to manage 87 octane gas. Maybe sometimes gas is sold at 87 but is really not because of some weird processing snafu, then anti-knock saves you.
 

·
Premium Member
Joined
·
4,942 Posts
Sorry Figgy,

A knock sensor works backwards vs. what it's name implies. AFAIK all engines equipped with knock sensors use the sensors to allow timing advancement to the knock tolerant point. The Insight is not an exception.

Agreed the name is counter intuitive, the name for the knock sensors function should be a timing advance sensor. But it was derived from how it accomplishes this task, listen for spark "ping" which is a reflection of timing advance. The back door approach. Done primarily due to the fact that you can only "know" if you've gone too far in timing advance when you've got too much "ping". And is was discovered to be relatively easy to tune a piezoelectric crystal to become "excited" in the spark ping frequency range signaling too much timing advancement.

Engines equipped with such a sensor can dynamically adjust the ignition timing based on the fuel or blend(s) of fuel in the tank, compression decrease (due to wear) or increase (due to abnormal carbon deposit build-up), load, altitude and probably a couple more I can't think of right now.

AFAIK the knock sensor is continuously "active" and monitored. The fuel management program is always testing the limit up to a defined point of knock that would begin to cause engine damage. Its also likely limited via software for emission purposes where knock tolerant timing (advance to just before the knock "damage" limit) would otherwise cause emissions to exceed limits.

HTH! :)
 

·
Premium Member
Joined
·
679 Posts
Them thar engineers sure are smart!

I guess my idea about the pixies and fairy fortune teller was a bit off?

Why didn't they call it 'pre-knock condition super safety sensor', darn it.
 

·
Premium Member
Joined
·
4,942 Posts
Not quite sure of how to understand this. Didn't see a %~) emoticon (or something similar). Maybe :arrow: :mrgreen: :?: :p

Don't feel too bad. All the knock sensor posts in here to date have been from the name intuitive perspective (backwards).
 
1 - 20 of 32 Posts
Top