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Dakota Performance
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peedee
Dodge Dakota
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8/14/2004
06:35:46

Subject: RE: Save Gas
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When an engine, inclusive of its fuel -including but not limited to the delivery through to the exhaust-, ignition, and cooling system, etc, is modified by any means, whether factory or DIY, either or both the air/fuel, compression, or ignition timing changes or because of deposits. The reasons for this are obvious. The higher the air/fuel ratio, the leaner the mixture and the higher the compression. The higher the compression the more molecular heat produced. The higher heat, the more likelyhood of self-ignition -the same as how a diesel ignites-, so, higher octane fuel, being that it is LESS volatile- will resist self-ignition and the "system" will operate more in tune. HEAT is the THE factor here. The best thing about finding "better performance" with a higher octane fuel, is that you can now realize that something is amiss. Maybe it is intentional -by modifications for horsepower to economy, or maybe it is a problem with running a bit warmer because of a cooling system problem, or a thousand other reasons. Point is that once discovered you can now make a rational determination to allow "tuning" of the system and possibly allow the use of regular fuel. If you intentionally modified the system, and find that it will achieve its best economy with higher octane fuel, then that is - or MAY BE - the price of performance. Yeah, a NASCAR engine needs higher octane because of the way they are tuned. But if the economy -in a conventional system - is improved ONLY with the use of higher octane, then something is wrong, and changing timing, cooling, looking for an intake or exhaust restriction -outside of the factory design- is in order.
BOttom line is that regular fuel is regular, high octane is LESS volatile. Second name stations are inconsistent whenit comes to the advertized octane, and any tests should be performed with a major brand fuel, like Sunoco, Mobil, exxon etc. And stay away from BP for any performance test until you have tested the others. BP is blended like a second name brand.When higher octane fuel is used to correct or supress a condition, it will give better performance, but that is like drinking 2 gallons of coffee per day to perform better because you like to party all night. Attack the cause not the symptom.... Find the PROPER tuning point of your system and your engine will last longer too. When a system is not "tuned" it is causing the main component -the engine- to fight itself with every ignition stroke. So an untuned or non-synergistic system is beating bearings, burning oil, running hotter valves, leaving deposits......



peedee
Dodge Dakota
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8/14/2004
06:38:29

RE: Save Gas
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Oh yeah, I forgot to mention. Hybrid is CORRECT!



peedee
Dodge Dakota
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8/14/2004
06:54:14

RE: Save Gas
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Me AGAIN!! One thing to remember. Very important. Time of ignition -and I don't mean simply playing with the distributor or the equivalent- is THE most important factor of performance AND the highest consideration for determining/adjusting the power curve of a drive system. And that can be before TDC - TDC - or after. It is all dependent upon the rest of the system. Timing is contingent upon ALL components and ALL components have an effect on timing.



Bob Lincoln
Dodge Dakota
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8/14/2004
08:14:51

RE: Save Gas
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"The higher the air/fuel ratio, the leaner the mixture and the higher the compression." Here's the only flaw in peedee's argument. Compression is simply the volume of the cylinder when piston is at BDC, divided by volume of piston at TDC (assuming no leakage). But he is right, higher octane fuels are less volatile by nature of their chemistry, and less prone to pre-ignition. It takes more heat to ignite them.



Kevin
Dodge Dakota
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8/14/2004
16:38:30

RE: Save Gas
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Well,i was just trying to tell people that want more gas miliage what i have succesfully done with mid and premium. I will stick with my candle and let the RACE car guys know it all. If you are interested in this try it yourself and tell me the outcome.
Nice Talking To You Guys,

Kevin



peedee
Dodge Dakota
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8/14/2004
16:58:15

RE: Save Gas
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Bob, I agree with you 100% about the volume thing. But remember that that "volume" can be affected by many factors like the engines ability to draw air and fuel, exhaust the gases, and the specific lbs per cu ft of vapor in the air, the altitude, to mention a few. So "tuning" can be dynamic, dependent upon those and other factors. To get REAL critical we could even factor the change in cu inch because of expansion, but that is getting a bit ridiculous I agree.
Kevin, your info is appreciated. I wanted to clarify and explain the reasons for the difference that you experienced. Maybe not you, but many persons still believe that higher octane equals more explosive. They also don't realize the fact that an engine which performs better with different octane than another, specifically higher octane, does so for a reason, and sometimes that reason is not one so intentional by the designer/operator, etc. When I travel in the heat on long highway trips, but with reletively dry air, I get the best mileage with 89 octane. When I travel the same trip with the same air temp heat, but with humid or rainy conditions, I get the best with 87 octane. The higher humidity is increasing the compression, but the moisture is by default decreasing the volitility of the fuel. We all know that water cannot be compressed and it is wicked difficult to burn. Unless you have some sort of hydrogen/oxygen seperator in your truck. The difference is negligable but it is there. Usually 1/2 mpg or so. Certainly not worth the cost of the fuel, but any more than that can be a factor in the price per longevity of the engine system.



Greg
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8/14/2004
23:18:53

RE: Save Gas
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Actually I would say that everyone on here is correct in their own way... I personally pointed out that the higher octane will not burn faster, hotter, or always give you more power in my previous post... And Kevin pointed out that you should try the different octane levels to see just what is best for your motor... No motor is ever the same and they are all tuned the same from factory resulting in the different octane levels doing better and so forth...

Like you pointed out peedee my motor is tuned for the higher octane, but then again it always seemed to do better off of the higher octane even before all of the modding I have done to it...

I am kinda curious on one thing though since everyone on here supposidly knows tuning and all, just what kind of fuel mileage you are getting, since you all seem to know how to tune and all... The tuning actually brings me to another point here, you mentioned adjusting timing by turning the distributor, well your wrong ignition timing wise anyhow... Because all this will do is adjust your fuel sync timing... The crank sensor is how you adjust your ignition timing...

My motor is getting plenty of air in and out, not to metion that the fuel atomixation is acheived very well through the 4 port injectors... Has 180 tstat which alone gives me 2 octane points... 1 point higher octane for every 5 degrees dropage in temp... Infact the only real thing to be the resulting factor in more compression would be the .020" head shave and the fact that I'm getting lots of air into my cylinders thanks to extensive porting, extra valve angles, and runners being shortend...

You also have to realize as far as your tuning goes that in these fuel injected systems the only tuning that you can do is modifying sensors, and setting spark plugs to burn good and tan... There is no real tuning to be done other than that... It's not like fine tuning the jets on carburated systems...



peedee
Dodge Dakota
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8/15/2004
06:33:42

RE: Save Gas
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Greg, tuning is not limited to what you are speaking of. It is synergystic in that everything you or the factory engineers do will have an effect. If you read my posts you will notice that the word "tuning" is in quotes, and that the context of the post, more than a "carburator adjustment" is included in tuning. In the post where I use the word distributor this is what I wrote: Time of ignition -and I don't mean simply playing with the distributor or the equivalent- is THE most important factor of performance AND the highest consideration for determining/adjusting the power curve of a drive system. And that can be before TDC - TDC - or after. It is all dependent upon the rest of the system. Timing is contingent upon ALL components and ALL components have an effect on timing.

read that carefully. You have tuned your engine by shaving the heads, altering the intake system, injectors, etc. THAT is tuning. Tuning is NOT limited to "modifiying sensors". Tuning is synergystic. Also: altering the gap or using a different plug, is attacking a symptom. Something causing a lean or rich mixture or a plug heat situation corrected by adjusting or grading the plugs may be needed by engineering in certain circumstance, but is usually an aspirin approach. The cause is not addressed / the symptom is covered. You can adjust spark timing all you want, but if a deposit is causing pre-ignition then it would make sense to address the deposit. If an exhaust restriction is causing buned gases to remain in the cylinder, then a professionally tuned exhaust is in order. The same goes for the intake, fuel delivery etc. That is the context of my posts.Restrictor plates on "nascar" engines are and act of tuning. When one of them cracks a header during a race, they usually fall off the pace because the cracked header has altered the synergy/tuning of the engine system. When the switch was made to Sunoco fuel, teams had to alter the systems slightly because Sunoco performs a little differently than the other fuel they were using, even though it is the same octane rating. My truck likes sunoco more than mobil, but the difference is so slight it is not worth seeking out a sunoco station in my area. The main point - Octane requirement is indicative of tuning difference, whether that "tuning" is/was intentional, or is the result of a "malfunction" of a "part of the whole." So look to the system, be sure that the need is real and not the result of "something amiss", before addressing the symptom. If you look in my other posts, you will see my reference to the trips taken and the performance characteristics. Those are legitimate "symptoms" and the adjustment through the use of different octane is proper. That is just ONE example. your "mods" are another.



Greg
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8/15/2004
21:29:47

RE: Save Gas
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That's all very true, which is part of the reason why it is beneficial to keep proper check up on all systems and is also the reason why I use high quantities of fuel system cleaners to keep carbon deposits gone and injectors operating at maximum ability... You are also right on all gasolines not being the same which is just another reason to try different octanes to see just which one is the "purest"... Infact some states or stations will charge more for the premium gas, but it is identical to the regular supplied through the regular pump...

All I'm trying to say is that switching to a different octane may be better even if there is no obvious cause for needing the higher octane... If you try it and there is no advantage then why use it???



dkota_rt
Dodge Dakota
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8/15/2004
22:15:58

RE: Save Gas
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If you all are so concerned about saving gas, then buy a 4 cyl. or a 1.8 VW diesel. Don't buy a V8 and then wonder what you can do to save gas. This is like buying a 25,000 sq. ft Mansion and then asking for advice to cut down on heating and air conditioning bills. Use your brain.



hybrid,
Dodge Dakota
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8/16/2004
03:39:11

RE: Save Gas
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Sorry Iwas away on a fishing trip so I wcouldn't keep up with the post, So now I'm dead tired and about ready to pass out for about 12 hours so I will keep it short and simple.

Peedee, You are correct, I was agreeing with your whole post as I read it, the part about compression caused me to pause for a second because you didn't explain the differences between static compression and dynamic compression. Like my motor, it's running 10.2:1 static compression, add 13psi and the dynamic compression has gone up drastically. I cant remember the formula off the top of my head, but with my set-up at 10psi my dynamic compression was somthing like 15.6:1.
I also want to point out "greg" I don't claim to know tuning per-say, but I have an ok understaning of tuning,the concept of tuning, and what goes into tuning a happy motor. I would also like t point out, while the motor I do the tuning on isn't a dodge or a v-8, but, the concept is the same air/fuel in....exhaust out. Gasoline engines are just big air pumps, the more you pump in the more it pumps out.
Also greg, i'm not sure about our motors, but fuel injected engines in general require a lot more attention when it comes to tuning, there is a lot more to tune then the basic parts you mention, A lot more. I have a fully programable engine management system in my car, I can change any aspect of my tune at any give time (granted I have a laptop hooked up and emulator,chip burner,etc) I can chage everything from the injector pulse width (to alter air/fuel ratio) to timing advance/retard of any given amount (.68 degree per psi of boost If I wanted). Closed loop and open loop settings. You name it, it can be changed, hell we spent about an hour (after it was tuned and had a good bas map set) just playing with the idle adjustments (electronically) altering air/fuel ratio, timing,rpm,etc trying to get my 756cc injector to idle like my stock 240cc injectors did. You can adjust tip-in (or whatever you like to call it) so rite when you step on the gas it accelerates instantly instead of having a pause or hesitation while it figures out what to do. A lot can be changed, I can add pretty much any size of injector and make my car run like stock, change the tuning maps for any change I make to the motor (larger exhaust, retune,larger t/b retune instead of allowing the stock ecu to figure out that it "thinks" the engine needs).....
I'm done for the night, no hard feels to anybody, not trying t anger or upset anybody, just felt as though some things should be clarified.



peedee
Dodge Dakota
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8/16/2004
07:39:11

RE: Save Gas
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Dakota rt, my 25,000 square foot mansion in the hamptons just got an oil delivery the other day and I found out that the delivered oil is of a lower quality than the other companies around the area. So, now I am using 5% more fuel to heat the house, and, most importantly, the oil pump, burner, sensors, and flue are dying a premature death. Please advise! Should I not worry about the savings because i am arrogant enough to own a biga$$ house, or should i try to maximize my potential while doing the best i can to take care of my equipment? I guess the other alternative would be to use the same oil company, but purchase a smaller house.... What the heck, it would just be a crappy little house so who would care about savings and longevity and stuff.



hybrid
Dodge Dakota
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8/16/2004
13:51:29

RE: Save Gas
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Hey peedee, I had a very simular problem like the one you described except I had a 250sq ft mansion in the Comptons, and when the power company shut off my power I vacated the house (shows them) insead of paying them. Now who got the last laugh...lol.
I like your thinking.



kevin
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8/20/2004
16:53:12

RE: Save Gas
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higher octane in the second test=18mpg(No Change From Regular)
I am going to let it go to E and try mid grade again.

Kevin

P.S. It did work once though, I dont want to hear any, i told you so, bullpoop



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