Been here a while and the board is a great wealth of info, great forum.
I have an '04 QC Hemi and the manual states the truck is designed for 87 and will run ok on it, but 89 will perform better. It then goes on to state using anything higher is not recommended, and may actually hurt performance. I bought my Ram in March, and never used anything but 89.
Here is my dilemna, I recently stopped at the station I always use, the only pumps working were for 93 octane. I filled up anyway and certainly did notice a change in performance.
My Ram is running like a Raped Ape on it!! I am almost through a whole tank, and MPG is still in the same range, but the trucks performance seems so much better, especially off the line.
Is this just a ploy by Dodge to avoid the better performance, and avoid heavier beatings on their warranty incurred by the increased fun factor the higher octane gives this truck?
What octane do you all run? How is your performance?
So, I tried the 93, didn't notice any increase in milage or performance. @ first I thought the 93 was making it run better, but after a few days, the thrill was gone, mileage the same. 87 sucked. Performance and mileage was gone.
higher the number value, the stronger the resistance to detonation (knock, ping). The higher the number value, the stronger the resistance to detonation. Putting a higher octane gas will not help performance in any way unless you were experiencing some minor detonation with a lower grade of gas, which would be picked up by knock sensros and caused the PCM to dial back the ignition timing, which in turn would result in less power.
The reason the manufacturer explicitely states to not use a higher octane gas is that the computer was not programmed for it with an appropriate mapping. It will not hurt anything, but is a waste of money.
I could not even get a chirp from the tires off the line when I punched it, they light up now.
If I rev to 1K, I sit and spin till the limiter dumps me down.
Is it possible that cooler weather conditions are affecting my performance, to this extent?
The only other thing I can think of it being is my power plant finally broke in completely. I don't know about that though, I have about 8,700 miles on it, shouldn't I be passed the breakin stage already?
It says you are in South Beach (I live just outside Winter Haven, in Polk County).
Heat is the most likely answer... It's hot this time of year here in Florida, so the heat will cause some minor detonation under hard accleration and load, and I am 99% sure the PCM uses a knock sensor so, when it hears one or two knocks, it will dial back the ingition timing, but the higher octane fuel will help prevent that detonation and the computer doesn't dial back. It could be something else, but it is beyond my knowledge as to what.
As for break in, it is definately fully broken in by now.
I do not know what the cause of my performance increase is, but the only changes have been in gas and ambient temp, but I have definitely seen much better performance.
If I run anything but 93 in my TA it hesitates and chugs like crazy.
'07 TRD 4X4 V6 Tacoma
ARE LSII bed cover
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422 rwhp / 441 rwtq -- Ran 11.00 @ 122 (daily driver)
I wonder if there is an old folks home for old motorheads like me!
Oh, and GlenB probably hit the nail on the head... If the ambient air temps were warmer when you used a lower octane fuel, it's the air temp above all else... I can;t recall the equation, but every 1%F drop in ambient air temp nets x% of increase in power.
Oh, and GlenB... ALL IC engines "love" cool air.
While I thought gains were the gas, the good news is, I can still get the performance from 89 which is about 20 cents a gallon cheaper here.
Gas quality is a posibility as well. The 89 octane from one station could out perform 89 Octane from another. Its not all the same stuff and you should do your best to find out where the higher quality fuel can be had. Some get the octane value by adding additives and there are MANY differnet additives that can effect the octane reading so your not always getting the SAME 89 octane fuel....
SPEED SAFE, AIR RAM
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i used to run strictly 91 octane, one day said phuck it i'll try 87.....i've noticed no different performance or mpg from 91 to 87....so i'm strictly running 87 now
can't wait for superchips to put out there 04 programmer so i can run there 87 performace program
2004 5.7L Quad Cab
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Awaiting Install:Thorley Mid's
In other words, if your vehicle requires 87 at sea level, In denver, at 5280ft (1mi.) up, it only requires 85., and if 89, then there it requires only 87, etc.
Remember, higher octane does NOT produce more power... Racing gas is higher octane to help stop detonation (ping, knock), which would otherwise occur in high compression racing engines and/or under heavy loads.
In a factory stock compression engine, unless the engines experiences detonation regularly (due to various factors, such as advanced ignition timing, higher compression, hot ambient conditions, etc.), there is no advantage or reason to use a higher octane fuel... it is merely throwing away money.
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