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N56629
Dodge Dakota
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2/02/2005
13:06:33
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 Subject: RE: Higher octane vs. factory programming?
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"ok, who's to say that your engine isn't tuned for omptimum performance at 87 octane?"
If you are not capable of making any decisions based on your own observations, you should stick to driving stock cars and following the instruction in your manual.
"Your did it backwards. We both understand that running to low of octane will effect the performance. That doesn't mean running to high of octane will increase performance."
Now talk about doing things backwards. No one has yet claimed that running higher octane will make any difference except in an individual car.
What it does say is that if your octane rating is lower than optimum the engine management system can compensate for it. Usually it does this by retarding the timing. Is that how you get optimum performance from your vehicles?
Can you tell us how an individual would know their engine is compensating for too low of octane? Maybe they might think they have sluggish performance or poor gas milage? If they try a higher octane and some of this improves, might it not indicate that the computer has been compensating for too low of octane?
The only difference between you and me is that you are advising people to absolutely not try a higher octane rating base solely on what the manufacturer claims and I say go ahead, try it and make your own decision.
Btw, what makes you think that 92 or 94 octane is optimum for your vehicle?
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justdoit
Dodge Dakota
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2/02/2005
13:21:58
| RE: Higher octane vs. factory programming?
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if it feels good, do it... if you feel your performance is better running on 89 or 91 octane and you don't mind spending the extra 10-20 cents per gallon, do it... if you feel you're getting better gas mileage, do it... I've noticed recently that my performance and gas mileage improves significantly if I drive around in a positive frame of mind. that's gotta be worth something...
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N56629
Dodge Dakota
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2/02/2005
13:24:19
| RE: Higher octane vs. factory programming?
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"I've noticed recently that my performance and gas mileage improves significantly if I drive around in a positive frame of mind. that's gotta be worth something..."
If it doesn't say so in your owners manual, it can't possibly be true.
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hybrid
Dodge Dakota
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2/02/2005
14:17:34
| RE: Higher octane vs. factory programming?
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Alright, I don't think we'll ever see eye to eye so I'm just going leave it at that. The reason I know what octane MY car needs is due to dyno tuning. I've tuned with pump (92) gas and high octane (100)because thats what I had in the tank the day of the initial tune. I ran about 100 octane (110 + 92 = out to about 100 octane) because the last time I ran the car it was hot out, and I was running a lot more boost then what the car was tuned for prior. I ran a little excessivly on the octane to leave me a safety margin. My last tune was done on 95 octane, we specifically tuned the car to run on 95 octane (+/- a tad...Fortunatly for me I have COMPLETE control over my engine's state of tune, I can tune it to run on pump gas or race gas. Thats how I know what octane I need to run....many trips to the dyno.Not what "feels" right
It's been nice chatting with you, no hard feelings but we obviously have our own oppinions.
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hybrid
Dodge Dakota
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2/02/2005
14:28:32
| RE: Higher octane vs. factory programming?
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BTW, I'm NOT advising people to absolutly not run higher octane. For a stock vehicle there is no reason to run higher octane then whats recomended. Run it if you like, hope you enjoy paying more for fuel then you need to.
"ok, who's to say that your engine isn't tuned for omptimum performance at 87 octane?"
If you are not capable of making any decisions based on your own observations, you should stick to driving stock cars and following the instruction in your manual"
please explain that to me,as it makes no sense. I'm talking about a STOCK car being tuned for the fuel that the manufacture recomends. Your talking about making decisions based upon my own observation???? So is the manufacture wrong? Do they tune it for 91 octane but use the computer to de-tune the motor? I don't understand your statement...
I'm fully capable of making my own decisions, but what doest that have to do with octane and engine tuning???
My car doesn't have a manual...it's a mut. It's not as fast as it is because I don't know what I'm doing...Lots of research and trial and error.
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N56629
Dodge Dakota
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2/02/2005
15:46:05
| RE: Higher octane vs. factory programming?
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"So is the manufacture wrong? Do they tune it for 91 octane but use the computer to de-tune the motor?"
I think most people already believe that the manufacturer doesn't tune for maximum performance. Do they de-tune some engines? Absolutely!
"Lots of research and trial and error."
That's pretty much what I'm supporting. If higher octane doesn't show measurable gain either by testing at the track or on the road, don't keep using it because it's a waste of money. If you want to try it, go for it.
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hybrid
Dodge Dakota
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2/02/2005
22:44:39
| RE: Higher octane vs. factory programming?
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Wow, we agree om something.......
****"Lots of research and trial and error."
That's pretty much what I'm supporting. If higher octane doesn't show measurable gain either by testing at the track or on the road, don't keep using it because it's a waste of money. If you want to try it, go for it."*******
A dyno Is also a great tool, IMO it's a bit more accurate then using an ass dyno at the track or on the street.
Yes you are correct some cars are detuned from the factory, but I doubt your dodge dakota/ram/durango, your moms toyota 4runner,celica,camry, or your neighbors silveraldo, explorer, daiwoo, etc is detuned from the factory. Some sports cars are detuned too meet strict emission standards.
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N56629
Dodge Dakota
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2/03/2005
07:00:48
| RE: Higher octane vs. factory programming?
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"Yes you are correct some cars are detuned from the factory, but I doubt your dodge dakota/ram/durango, your moms toyota 4runner,celica,camry, or your neighbors silveraldo, explorer, daiwoo, etc is detuned from the factory."
You are right, on Dakotas they do that after you buy. It's called the death flash or something. It takes care of the annoying pinging that you get once in awhile when running 87 octane and the computer can no longer compensate for it. It retards the timing even more and certainly reduces hp.
That's why I occasionally run 89 octane. This seems to be especially true during the summer. I've also been known to throw in a gallon or two of 100 if it's pinging on the last fill-up. Now I could just mindlessly follow the manual, continue to stick with 87, go and complain to the dealer and insist that they detune my engine more than it already is or run 89 octane.
Most people don't want to spend a lot of money or time on dyno testing their daily drivers which likely make up over 90% of trucks here.
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hybrid
Dodge Dakota
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2/03/2005
13:10:07
| RE: Higher octane vs. factory programming?
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Does anybody know what causes the pinging? Is the death flash a band-aid fix or is because the engine does run to much timing?
Sounds like in your case the extra octane is to prevent pinging, not to improve fuel economy or performance..
The 4.7 has a knock sensor huh??? what rpm range is it effective? The one in my car disables after 5k rpm to prevent false retardation of the timing due to engine noise (redline is 8,250)
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N56629
Dodge Dakota
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2/03/2005
16:57:17
| RE: Higher octane vs. factory programming?
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"Sounds like in your case the extra octane is to prevent pinging, not to improve fuel economy or performance.. "
Ask yourself if pinging improves or degrades fuel economy and overall performance.
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Kowalski
GenIII
2/03/2005
18:35:33
| RE: Higher octane vs. factory programming?
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Pinging is caused when the mix ignites explosively - factors include low octane, heat, high loads, high compression, too much ignition advance, and carbon deposits. Your mixture should ignite with a flame front that pushes down on the piston rather than hitting it like it was struck with a hammer - that would be the ping. The 4.7 does not have a knock sensor; except in the HO version. 4.7s don't seem especially vulnerable to pinging, and part of the reason for that is their aluminum head with its ability to efficiently conduct heat away from the combustion chamber. Even with the extra spark advance I have from my custom PCM flash, my 4.7 will not ping under normal conditions with 87 octane. The only time I need to run higher octane is for the extra load of heavy towing. It would be very unusual for most 4.7s to ping.
Lead, follow, or get out of the way
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hybrid
Dodge Dakota
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2/03/2005
23:17:35
| RE: Higher octane vs. factory programming?
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Your not improving it, just restoring it.
It's improved from the degraded state that it was before.
It's like saying that you'll gain 10hp by doing a tune-up, when in reality your restoring the power that was lost by the poor state of tune that your motor was in...
I know all about detonation, I've had my run-in with it and have researched it. I can link you to a cool picture of detonation happening. Not the aftermath, but actual pictures of detonation happening in a controlled environment.
Detonation is dangerous when it's uncontrolled.
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N56629
Dodge Dakota
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2/04/2005
06:59:48
| RE: Higher octane vs. factory programming?
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"Your not improving it, just restoring it.
It's improved from the degraded state that it was before."
I don't know about you but most people might consider restoring power an improvment. As far as the "poor state of tune" goes, it is the computer that causes it. This is why Dodge goes with the "death flash." Some vehicles don't need the death flash, it is built in. You would never know that your computer is compensating for pinging caused by too low of octane.
Again, the manufacturers octane recommendation is only that, a recommendation. It might correct most of the time but you have to judge whether or not it is in your individual case.
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Kowalski
GenIII
2/04/2005
16:24:09
| RE: Higher octane vs. factory programming?
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You seem to misunderstand the "death flash" if you think it is built in. It is a flash that reduces spark advance (and performance) that dealers flashed into some vehicles when people complained. Not built in to any of our trucks; and there is no way the 4.7 would be able to compensate since it doesn't have any knock sensors (except for new HO 4.7).
Lead, follow, or get out of the way
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gen1dak
Dodge Dakota
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2/04/2005
18:02:12
| RE: Higher octane vs. factory programming?
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Hey hybrid, did you notice that I put "carbons up" in quotes? That's because it came straight from my Mopar Performance Engine manual, where they address the subject. Also, if you doubt this is a legitimate issue, why then, did you, in the next sentence, cite SeaFoam or steam cleaning as methods of dealing with the very same issue?
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hybrid
Dodge Dakota
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2/04/2005
20:56:52
| RE: Higher octane vs. factory programming?
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Here we go.
I don't doubt that carbon build-up can raise the compression, I've seen it before. But it's not going to raise it from say 8.5:1 compression to 9.5:1 compression.
I mention the seafoam and water method as preventative manintenance and a cheaper alternative to spending $.20 per gallon more eatch time you fill up.
If your have to run higher octane because your engine is so gummedup with carbon, and would rather pay for the higher fuel, be my guest. I myself would rather spend a few bucks on a water bottle and water then a few hundred on higher octane fuel..You shouldn't have excessive carbon build-up on a young motor (20-30k) generally carbon build-up becomes an issue with high mileage cars.
Bottom line is, do as you like, it's your truck and your money.
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N56629
Dodge Dakota
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2/05/2005
10:43:31
| RE: Higher octane vs. factory programming?
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"You seem to misunderstand the "death flash" if you think it is built in. It is a flash that reduces spark advance (and performance) that dealers flashed into some vehicles when people complained."
What part of "AFTER you buy" didn't you understand? Does that sound like I thought that it was "built in?" The "built in" reference above refers to the stock computer's ability to compesate for a range of gasoline. If your computer can not compesate then you get the "death flash" from the dealer.
Actually, unlike some other vehicles, I don't believe the Dakota's computer is capable of compensating and your only choice is to use a higher octane or get the death flash.
This simple fact seems to support my contention that the manufacturer is willing to walk a fine line between what octane they can recommend and what octane will give best overall performance.
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N56629
Dodge Dakota
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2/05/2005
11:08:35
| RE: Higher octane vs. factory programming?
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"I mention the seafoam and water method as preventative manintenance and a cheaper alternative to spending $.20 per gallon more eatch time you fill up.
If your have to run higher octane because your engine is so gummedup with carbon, and would rather pay for the higher fuel, be my guest."
Here's a couple of more fallacies. One, not everyone pays .20 more a gallon for 89. I rarely see more than .10 and at least once a week get it for the same price as 87. Two, you don't have to fill your tank with the next higher grade to benefit. They really do mix, you know.
And of course that old fallacy that the manufacturer makes perfect products and their recommendations for fuel and lubrication are the final word.
Don't port that tb or manifold and definately don't vary your suggested octane rating by even a half a point, because you simply can't improve on facatory recommendations.
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Kowalski
GenIII
2/06/2005
08:43:31
|  RE: Higher octane vs. factory programming?
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N56629 - nowhere in the post I replied to does it say anything about "after you buy". My point is that with the aluminum heads, the 4.7 is quite tolerant of lower octane fuel. You get 89 octane for the same price as 87 ? I find that claim unbelieveable, I've always seen a price difference between the grades at every gas station I've ever been too. Got to raise the BS flag on that one.
hybrid - You ask what causes pinging, and when I respond you claim to already know and offer to explain it to me ? WTF ? You seem to think carbon deposits cause detonation by increasing compression. Actually, they cause detonation by creating hot spots that can pre-ignite the fuel before the spark plug does.
This is the last post I will make to this thread - you two beauties deserve each other. BTW, my ported TB works great.
Lead, follow, or get out of the way
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N56629
Dodge Dakota
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2/06/2005
10:18:59
| RE: Higher octane vs. factory programming?
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"You get 89 octane for the same price as 87 ? I find that claim unbelieveable, I've always seen a price difference between the grades at every gas station I've ever been too. Got to raise the BS flag on that one."
What do you want? A picture the next time it goes on sale?
"You seem to think carbon deposits cause detonation by increasing compression. Actually, they cause detonation by creating hot spots that can pre-ignite the fuel before the spark plug does."
Pre-ignition and detonation or pinging are not the same thing. You can have one without the other or you can have both. You can have carbon deposits and not have pre-ignition.
"This is the last post I will make to this thread..."
After a comment like that, I would run away too. Well, maybe not, I would be man enough to admit that I was wrong.
Just so this mis-information doesn't get passed along as truth, here is the difference between detonation and pre-ignition.
Detonation can be caused by:
Lean fuel mixture
Fuel octane too low
Improper ignition timing
Lugging
Carbon deposits
Excessive milling of heads or block, which will increase compression ratio.
Pre-ignition can be caused by:
Carbon deposits that remain incandescent
Spark plugs too hot a heat range
Spark plugs not firmly seated against gasket
Detonation or the condition leading to it
Sharp edges in combustion chamber
Valves operating at higher than normal temperature because of excessive guide clearance or improper seal with valve seats.
Overheating
Ignition crossfiring. Induced voltage in spark plug wires that run parallel to each other for long distances
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