2018 93 octane questions

inglimer

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I understand that the 18's are tuned for 93. How much are you losing on 91?
Plenty of 93 stations(BP) in my area, but not always the case everywhere you go.
Thanks.
Jack
 

dre256

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460 horsepower rating is on 93 octane. 91 it's hard to say how much you will lose, comes down to how much timing the knock sensors are setup to pull back on. If I had to guess 5-ish horsepower. That does suck there now setup for 93 octane for people in some new England areas and out west like California. Everything use to be based off of 87 or 91

Fuel is the wild west, even 93 might not really be 93. Could be a little higher or lower. Even E-85 I believe is aloud to vary as low as 70
 

RED09GT

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With Direct Injection, there is a lot less time for pre-ignition to occur, you probably do not lose much. I haven't run across any testing on this and it probably will have less of an effect than the coolant and oil temperature does.
 

RocketcarX

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91 and 93 are interchangeable, they just use lower octane rated fuels at higher elevations.
 

LarryJM

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If you watch the timing pull on a SCT Tuner, I would say all Coyote Mustangs are tuned for 93 gas. Some of the people here are saying I am misunderstanding that active timing pull built into the ECU. Meaning it will jump to about 25 degree at WOT and will pull back to as low as 18 degrees at 6800 rpm. The Ford rep says that is the knock sensors at work but some of the people on this thread say it's the standard Ford programing that can be modified by your local IT guy that drives a bike to work.
 

RocketcarX

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If you watch the timing pull on a SCT Tuner, I would say all Coyote Mustangs are tuned for 93 gas. Some of the people here are saying I am misunderstanding that active timing pull built into the ECU. Meaning it will jump to about 25 degree at WOT and will pull back to as low as 18 degrees at 6800 rpm. The Ford rep says that is the knock sensors at work but some of the people on this thread say it's the standard Ford programing that can be modified by your local IT guy that drives a bike to work.
For a guy who claims to have PHD you sure are dense
 

JJ427R

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I can usually only get 91 in my area, hence my 2010 I have a 91 octane tune. I run 93 when I can but I really don't notice any difference, however the wife recently put in about half a tank of 87 (she's too used to her car) and I got a P0171 code for system lean bank 1. Since refueling with 91 code has not returned.

I have also compared several gas stations in my local area with my 2003 F250 Van and have found I get my best mileage with Shell gasoline. and with 91 octane I get almost 2mpg better mileage compared to 87. If gas is cheaper and I'm doing highway driving the extra cost is worth it, at $4.00 a gallon like it was a couple years ago, not so much....
 
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LarryJM

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For a guy who claims to have PHD you sure are dense
It's the Ford guy with the PHD. The issue is here, does the advance pull from 3500 to 6850 rpm hard wired by a hard wire program with no input of the knock sensors or is it a micro second by micro second update by the active input of the knock sensors? Two ways to think about it.
 
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RocketcarX

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It's the Ford guy with the PHD. The issue is here, does the advance pull from 3500 to 6850 rpm hard wired by a hard wire program with no input of the knock sensors or is it a micro second by micro second update by the active input of the knock sensors? Two ways to think about it.

It's both. The stock spark tables are conservative to say the least, that's why a tune is worth 30 horsepower, most of the found power is in adding spark.
Now, if the car detects knock, it will pull timing, it also runs it though a temperature modifier so if ambient air or coolant temps are high the spark is retarded even further.
The car is not constantly adjusting spark to find knock, it runs it's programmed spark table and IF knock is detected the car pulls timing to prevent damage. 9 out of 10 driving situations on 91/93 octane you will never generate spark knock with the stock timing tables so the only time the knock sensor is active would be to prevent damage.
 

LarryJM

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So your saying there is a spark table for 50 degree weather and a spark table for 100 degree weather? Would that be 10 degrees apart for say 13 spark tables from Detroit winters to Phoenix summers? It's my understanding everything is real time by the micro second. From Cam Position to EGT to Spark Advance to Spark Knock to Crank Position to RPM to Octane. Then when the Cams are turned in to each other at 108 degree lobe separation you get high rpm HP and when turned out to 114 degree to each other you get low end TQ.
 

JJ427R

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There is a product called Race-Gas that is a race fuel concentrate that can be blended with pump gas and mixed up to 112 octane. They have some great information on their website regarding octane, ratings, and blending their product. I also recommend calling them on many of the questions above.
I am going contact them myself. I've used it previously in a 95 octane mix, I want to know how high in octane I can actually go on my Roushcharged 4.6? There is a point where too much octane actually decreases power or causes engine damage.

http://race-gas.com/

I just got off the phone with race gas, they recommend not going above 95 octane for my situation without having a custom tune done.
I did notice a bit of a difference when I used this product, smoother idle and had a bit more power, I'm trying it again in a 95 octane mixture at BIR sept 10th. I'll post what I think about it. They actually sell this at BIR now.....
 
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LarryJM

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Well what at least some people are saying for the Coyote ECU, if the timing at 3500 RPM is 25 degrees advance and the timing is 18 degrees advance at 6500 rpm, it will ALWAYS be that curve unless it's very cold or hot outside or some other factor like maybe a tank of 85 octane gas that the knock sensors hate. The ECU will never learn to go to 27 degrees advance and stay there with 100 octane gas.
 

RocketcarX

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So your saying there is a spark table for 50 degree weather and a spark table for 100 degree weather? Would that be 10 degrees apart for say 13 spark tables from Detroit winters to Phoenix summers? It's my understanding everything is real time by the micro second. From Cam Position to EGT to Spark Advance to Spark Knock to Crank Position to RPM to Octane. Then when the Cams are turned in to each other at 108 degree lobe separation you get high rpm HP and when turned out to 114 degree to each other you get low end TQ.
There is one spark table, "modifiers" are used to refine the spark output, think of these modifiers as a filter. These modifiers are mostly temperature and load related. The hotter it is or the more load the computer sees the more spark will be retarded to keep the engine from being hurt. The knock sensors are for worst case senarios, and will often cause a code to set if they detect knock, because knock indicates a real problem, wether it be poor fuel quality or a mechanical failure.
Everything is controlled in real time, but the basis is the tables preprogrammed into the ECU which are modified using inputs from the cylinder head temp sensor, ambient air temperature, mass air flow, etc.
 

RocketcarX

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Well what at least some people are saying for the Coyote ECU, if the timing at 3500 RPM is 25 degrees advance and the timing is 18 degrees advance at 6500 rpm, it will ALWAYS be that curve unless it's very cold or hot outside or some other factor like maybe a tank of 85 octane gas that the knock sensors hate. The ECU will never learn to go to 27 degrees advance and stay there with 100 octane gas.
This is correct
 

LarryJM

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Last year I purchased a SCT 4x unmarried tuner for a Raptor Truck for $100. It had 5 customs tunes of which none could be used for my 2014 Mustang GT. When I called SCT, the guy on the phone tried very hard to sell me a $125 custom tune for the Mustang to add to the SCT. When custom tunes are on the SCT, the canned tunes are locked out. I asked him what happens if I just reset the SCT. He said he didn't know. He did know by sending him $125, that would solve my problem. Then I talked to a Ford guy who worked for Mercedes Benz at one time. He had a PhD in something and he hates tune guys who are really bicycle riding IT guys or so he says. Two main things he hates. Setting the timing at WOT at 27 degrees and disabling the Knock Sensors because they are always going to be going off at the timing. In any event, I did finally reset the tuner to stock and it came back up after a few minutes to "as shipped" condition with all the canned tunes for the Mustang GT. I also updated it with the available online free software. The SCT has a monitor only section with user selected readouts. I pick RPM and Advance. Driving along the road, the advance is all over the place from almost zero to as high as 40 degrees. Get on it from 3500 to 6500 at WOT on 3th and the advance jumps to 25 and slowly drops to about 18. With that I decided not to change the existing program and sold the unit for $200.
 
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