im using the good gas
#41
10-10-2008 | 10:20 AM
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From: Houston TX
It may be the different additives that BP and Chevron put in, vs. the "cheapo" gas places that don't add stuff. Seems like I knew this once but I can't remember now. But there is a difference, and it's either that the gas is just cleaner at the large names, or they can put better additives in.
#43
10-10-2008 | 05:12 PM
my boyfriend swears that he gets considerably better gas mileage with Shell in his Mazda3 (he keeps spreadsheets). He claims the difference in gas mileage is more cost effective than cheapie brand gas, even though the initial cost is higher. When gas is expensive to begin with, the difference a few pennies makes is minimal when you look at how much you're spending overall.
Over my 20 tanks in my Fit, I have yet to see concrete results personally as there are so many other factors (changes in weather, 1st manual car etc).
#45
10-13-2008 | 11:20 PM
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Joined: Oct 2007
Posts: 2,304
From: Illinois
I just put Reg. gas in my fit and now my car idles at 900 rpm from 700 with primium. My mileage went down 10 percent. i just want to say that the fit has 10.4 compression and does has a map for it or the check engine would come on. timing is based on a lot of conditions and the ecm adjusts. the ecm is set for 14.7fuel ratio under most conditions. I have read a lot of manuals and ask tuners and they all agree. Primium gas burns cooler and longer not slower two different functions. If a fuel burns slower there is a better chance for pre-igntion. A engine timing is set by engine design from the factory. In the old days they would detune a car a few degrees and add more fuel so you would not blow it up. A car will make more power with a richer mixture. This link explains it in short Daytona Sensors LLC - Tech FAQ Engine Tuning
#46
10-14-2008 | 10:38 PM
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Joined: Oct 2007
Posts: 2,304
From: Illinois
There are about 90 different blends of fuel across the USA, They have ethonal in the fuel where I live which I try to stay away from. That is why I use BP Ultimate, I get the best mileage and least problems with. New cars will run on Regular but you have to take mileage and compare it to different Fuels to see which one works best in your car. If the fuel you use burns slow/incomplete you will not get good mileage and will build up sludge in the motor.
#47
10-14-2008 | 11:09 PM
no. the higher the octane teh higher ignition advance you could possibly use. but unless you advance the timing manually, which is doubtful, you are throwing money away
#48
10-14-2008 | 11:10 PM
It may be the different additives that BP and Chevron put in, vs. the "cheapo" gas places that don't add stuff. Seems like I knew this once but I can't remember now. But there is a difference, and it's either that the gas is just cleaner at the large names, or they can put better additives in.
"if i fill my tank with half shell v-power, and half, chevron w/ techron, would i have v-tech gas?
#49
10-15-2008 | 01:11 AM
give it up
I agree totally with you. They're wasting their money and any difference is the placebo effect. You and I are wasting our breath. They ought to buy the 87 octane and then say a prayer over it. It'd still be the placebo effect but their wallets wouldn't take a hit!
#51
10-15-2008 | 04:12 AM
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Joined: Oct 2008
Posts: 122
From: Central CA
You seem to be confused, so let me see if I can help.
About gasoline, octane rating measures one thing and one thing only: resistance to detonation (knock, or compression ignition). Higher octane fuel does not explode more powerfully, it contains the same amount of energy as regular gas. It is possible to have a high octane fuel that contains less energy than a lower octane fuel (diesel vs. gasoline is a good example of this).
About ignition timing, advance refers to the number of degrees before top-dead center that ignition occurs. More advance is required for lower octane fuels as obviously the closer to TDC the greater the compression and the greater the chance of detonation. Conversely, higher octanes can run with less advance, as they can come closer to TDC without detonating.
About ECUs and ignition timing: Detonation is bad for an engine. If you've ever looked at the pistons and heads of an engine that's been knocking, you'll see tiny balls of metal stuck to them that were blown off the combustion chamber during detonation. To think that the engine in any modern car is constantly reducing advance until it hears detonation is laughable and a recipe for an unreliable engine (not something that Honda is known for).
That's not to say that knock sensors don't exist or that the ECU doesn't adjust ignition timing, it just works the opposite of what you seem to think. A modern car has a default ignition map designed for its recommended fuel. When the knock sensor detects detonation, ignition advance is increased until it goes away. This allows a car designed for premium to run regular when no premium is available (the original purpose behind the system). It has the added benefit of keeping a car from knocking if the compression ratio changes (say, from carbon deposits building up in the combustion chambers).
Finally, you can't tell from a compression ratio alone whether an engine would benefit from higher octane fuel. Displacement, combustion chamber shape, number of spark plugs per cylinder and bore:stroke ratio have almost as much effect on detonation as compression ratio. But the real trump card is whether the ECU is programmed by default to take advantage of the higher octane; in the case of the Fit it is not, or significant MPG gains could be realized just by switching to premium.
About gasoline, octane rating measures one thing and one thing only: resistance to detonation (knock, or compression ignition). Higher octane fuel does not explode more powerfully, it contains the same amount of energy as regular gas. It is possible to have a high octane fuel that contains less energy than a lower octane fuel (diesel vs. gasoline is a good example of this).
About ignition timing, advance refers to the number of degrees before top-dead center that ignition occurs. More advance is required for lower octane fuels as obviously the closer to TDC the greater the compression and the greater the chance of detonation. Conversely, higher octanes can run with less advance, as they can come closer to TDC without detonating.
About ECUs and ignition timing: Detonation is bad for an engine. If you've ever looked at the pistons and heads of an engine that's been knocking, you'll see tiny balls of metal stuck to them that were blown off the combustion chamber during detonation. To think that the engine in any modern car is constantly reducing advance until it hears detonation is laughable and a recipe for an unreliable engine (not something that Honda is known for).
That's not to say that knock sensors don't exist or that the ECU doesn't adjust ignition timing, it just works the opposite of what you seem to think. A modern car has a default ignition map designed for its recommended fuel. When the knock sensor detects detonation, ignition advance is increased until it goes away. This allows a car designed for premium to run regular when no premium is available (the original purpose behind the system). It has the added benefit of keeping a car from knocking if the compression ratio changes (say, from carbon deposits building up in the combustion chambers).
Finally, you can't tell from a compression ratio alone whether an engine would benefit from higher octane fuel. Displacement, combustion chamber shape, number of spark plugs per cylinder and bore:stroke ratio have almost as much effect on detonation as compression ratio. But the real trump card is whether the ECU is programmed by default to take advantage of the higher octane; in the case of the Fit it is not, or significant MPG gains could be realized just by switching to premium.
#52
10-22-2008 | 08:14 PM
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Joined: Feb 2007
Posts: 689
From: Alabanana
Placebo Domingo
Although I have experimented with higher octane a couple of times in the Fit (to no advantage that I could tell), I normally run regular gas. What I'm trying to figure out is the difference between BP and Walmart gas. Regular gas, not premium.
#53
10-22-2008 | 10:37 PM
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From: Houston TX
I would like to cross-compare gasoline without ethanol to gas with ethanol. I HATE using ethanol it cuts my mileage and I am totally convinced it's going to screw up my engine too.
If I could move I would.
If I could move I would.
#54
10-22-2008 | 10:45 PM
stinking ethanol
I got in my gas vendor's face because of a sticker that suddenly showed up "may contain up to 10% ethanol" and he told me (he's really nice, I apologized) that they weren't even required to tell us if it was under 10%. I know it screws our mileage and suspect it might compromise our engine's integrity. It's getting hard to escape it!
#55
10-23-2008 | 12:31 AM
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Joined: Oct 2007
Posts: 2,304
From: Illinois
They change my Bp ultimate that I used to get 10 percent better mileage. I have been using their reg. lately with good results so far but it is getting colder so higher octane doesnt matter. I knew their premium was high denisity fuel that was about 83 percent carbon/hydrogen balanced, and burned extremly clean. I had a honda civic that got 35 regular and 38.5 premium over 4 years. Invigorate seems to be a very good additive but time will tell. I think it is law that they have to put Ethonal in all brands now and they could put up to 15 percent in because new cars can run it. This is my observations and what ive read and talk to people in the know. I got 38.5 miles last tank with a little premium. In the winter I expect to get 35 and I will be happy.
#56
10-23-2008 | 10:20 AM
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Joined: May 2008
Posts: 354
From: Saskatchewan
Waste of money............
#57
10-24-2008 | 12:19 PM
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Joined: Feb 2007
Posts: 689
From: Alabanana
Hatin' on ethanol
BUICK!
OK, there, I puked.
#58
10-24-2008 | 07:02 PM
Someone that spends HER life on FitFreak.net
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From: Houston TX
I hope someone in Congress grows a brain pretty soon and takes that corn out of our gas tanks. I know someone up there in Washington was trying to get that legislature reversed. I mean, do we really need to put corn in our cars while we stuff our own bodies with HFCS??? It isn't good for us and it ain't good for our machines either. But we grow so damn much of it...
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