End of 93 Octane???
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So your manual does specify premium.
Backing off...
I feel ya, let the hoarding commence....
JHZR2
Staff member
Does the manual spec "premium" or does it spec "93 octane"?quote:
Originally posted by GeaugaFletcher:
So your manual does specify premium.
Backing off...
At the end of the day, knowledge into the engineering of the controls system is the ONLY way that one can say for certain what octane the engine was designed for (and remember, its also at what condition set). Butt dynos, MPG logs, even real dynos and similar are only so good... without seeing the design specs of the sensors, the code for the controls and the logic of the ECU, one is only guessing.
I'm not saying that your car ont do 8250 RPM or whatnot, Im not saying that it doesnt absolutely need 93 octane... Im just saying that claims without real knowledgeinto the design are just guesses.
JMH
On my 220 mile trip to work and back (2 hours there 2 hours back) I've had time to compare 91 octane and 87 octane in my 2.2L Ecotec (04 Pontiac Sunfire). I do have a knock sensor.
91 Octane sounds better and feels better when going up the mountains @ ~90% engine load in comparison to 87 octane. (My imagination? - possibly). Real test would be to have co-worker fill up my gas tank and not tell me the cost or octane... I should try that...
91 Octane usually gets +2-3MPG as 87 octane but on several occasions I've gotten same MPG (wind?).
91 Octane sounds better and feels better when going up the mountains @ ~90% engine load in comparison to 87 octane. (My imagination? - possibly). Real test would be to have co-worker fill up my gas tank and not tell me the cost or octane... I should try that...
91 Octane usually gets +2-3MPG as 87 octane but on several occasions I've gotten same MPG (wind?).
JHZR2
Staff member
I wonder what the advance limit actually is for such a setup. I have a dinan chip inmy E30 318i M42 engine, and it must have 91 octane or better. I tried a little bit of 89 once as an experiment, and anything more than 1/4 throttle would knock... fair enough, it really does need 91+... however, there has to be a finite limit of what octane it will take before it hits its max advance. Otherwise I dont think it would ever actually learn a proper advance setting and adapt correctly to the conditions.
For example, I learned from a saab engineer how the trionic 8 system works on my 04 9-3. The system is CAPPED at aqdvance for 90 AKI. What happens is that the engine originally defaults to the timing for 87 octane fuel (its actually set up for the euro numbers, but they translated them for the US system). If no knock is sensed, it will advance the timing just up to the threshhold of knocking. This way the engien maximizes power under the use of any fuel. However, when it hits the advance programmed for 90 octane fuel, it stops advancing, so I could put in 91, 93, sunoco ultra 94, etc., etc. and still have the same power output. However, if a significant knock is sensed during operation, the advance will revert to the default 87 level, and then have to advance slowly but surely forward again, to adapt to the new fuel in the tank.
For the BMWs that we both have chipped and enjoy driving, I have to believe that there is a similar cap. There has to be a limit for them as well before the advance gets too far ahead and other bad things happen in the engine. What that cap is, I dont know, and wish I did
JMH
JHZR2
Staff member
What makes you so sure of your loading point being 90%? Are youi comparing a power/rpm chart, power specific fuel consumption chart or similar??? I tried the same thing in my 98 Chevy pickup, but without the same results in terms of sound or economy...
I am starting to believe that where you buy premium fuel (more specific to premium, but surely relevant to all purchases) makes a BIG difference. This has to do with throughput of the fuel at the station... premium fuel isnt always a big seller, especially compared to regular.
Some of the best premium gas Ive bought (in terms of calculated MPG and the totaly meaningless butt dyno) came from a very busy wawa gas station... That place got multiple deliveries a day, and had at least 20 pumps (40 cars at a time)... It ran 24 hours, I believe.
Must be some fresh fuel!
JMH
I have a ScanGuage. It has an Engine Load % option. As for power/rpm chart don't have one to compare accuracy. I hope it is accurate
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As for fresh fuel - our gas statinos out here where I live are constantly full - sometimes have to wait awhile to get gas.
It better be fresh for +$3.00/gal!!!! lol
As for fresh fuel - our gas statinos out here where I live are constantly full - sometimes have to wait awhile to get gas.
It better be fresh for +$3.00/gal!!!! lol
Wawa gas works ok for me too.
My G35 pings on 93, if I run 91 the car feels like if I give it any gas I will do damage. My race bikes are also built to run on 93.
I hope that we can keep our 93 here in florida.
I hope that we can keep our 93 here in florida.
Chevy recommends 93 octane for all forms of the Corvette.
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