We have in Ontario 87, 89, 91, 93 and 94 Octane, My car is only a weekend warrior so I run 94 Octane. Plus it's tuned to run on 94 but I might add another tune for 87 octane. Cuz it's frigging $2.00 a liter for 94 right now.
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Fox What gas do you run in your foxbody?
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Always run the lowest octane your car is tuned for. If you have a stock 5.0 you're fine with 87 will be fine and 94 won't do anything to help at all. Higher octane only means it will burn slower and is harder to ignite, thus it is better for higher compression or boosted engines as it will help prevent detonation. Every mustang with a modified engine will have different requirements based on the setup and the tune.
Kerosene, thinking about converting to moonshine, cleaner, cheaper and if the car breaks down you can still get drunk.... 
When I was stock, 87. Although over the years I found I needed to bump to 89 to prevent detonation even with stock 10 degrees of timing.
Since I've gone H/C/I, I've just changed over to 93 octane. I don't drive the car often enough to worry aout saving a few bucks. Until i get a tune and a sense of how she runs once optiized, not worth trying to run lower.
All my DD"s I run the lowest octane I can. Lower octane burns more completely and faster, but it's just that pesky detonation that makes this aspect such.
Since I've gone H/C/I, I've just changed over to 93 octane. I don't drive the car often enough to worry aout saving a few bucks. Until i get a tune and a sense of how she runs once optiized, not worth trying to run lower.
All my DD"s I run the lowest octane I can. Lower octane burns more completely and faster, but it's just that pesky detonation that makes this aspect such.
I was actually thinking of converting to propane that way if I brake down I can hookup the portable barbecue and cook a feast on the side of the road lolKerosene, thinking about converting to moonshine, cleaner, cheaper and if the car breaks down you can still get drunk....
I have stock heads and cam just an explorer intake with a SVT chip, 76 mm mass air , 70mm Tb, Black Magic Xtreme electric fan, full length Mac 1 5/8 longtube headers, Mac h Pipe with cats and super 44 flowmaster mufflers, with 3 inch flowmaster tails. with 4.10 gears, should I have it tuned for 87 octane you think? even though shes currently tuned to run on 94 octane and 91 octane and all I have to do is turn the SVT chip switch and select it for either tune.
The statement implies that an older motor is more likely to detonate.
This sort of thing can be the results of build up in the combustion chambers, introduction of oil into the air/fuel mix, some operating condition change, like altitude or temperature without the tune set correctly to compensate. Dirty fuel injectors with poor atomization can cause this.
I'm binge watching the oil geek guy on youtube andlearning a lot. Honestly, I'm not likely to do a bunch of oil analysis on my cars, but it's still interesting learning some of the science instead of listening to people recommend oils based off of nothing more than the fact that they never noticed a problem. Anyways, he said something on one I watched tonight about how high-calcium (detergent) oils, like Mobil 1 0W-40, which I like, can increase low rpm detonation. It's particularly not recommended with DI motors.
He also suggests only one additive for fuels and none for oils. If you're not using "tier 1 fuels" already, then no brand in particular, but specifically PAE (poly-ethyl amine, I believe) works best to keep injectors clean. I noticed oil getting through the PCV in black jack and buildup on the backs of some valves, and I think I'll pick some up and run it for a while to hopefully clean up the valves and combustion chambers a bit.
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Speaking of " Tier 1 " fuels, GM recommends Tier 1 diesel for my 20 Silverado 3 liter diesel engine....
Found two places in Colorado and a few in S. California that have it......... Probably not gonna happen...
Isn't the main contributor to detonation compression? I know todays fuel is alot different than the good stuff we had in the late 60's early 70's..
Most of my friends and I had Z28 camaro's then... The 70 LT1 engine came with 11.25 to 1 compression stock from Chevrolet... I can assure you it would not run on todays fuel...
Found two places in Colorado and a few in S. California that have it......... Probably not gonna happen...
Isn't the main contributor to detonation compression? I know todays fuel is alot different than the good stuff we had in the late 60's early 70's..
Most of my friends and I had Z28 camaro's then... The 70 LT1 engine came with 11.25 to 1 compression stock from Chevrolet... I can assure you it would not run on todays fuel...
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It all depends on what it is you are trying to accomplish here. I can only guess that your "problem statement" is the cost of the higher octane fuel but really in the end it's only a few bucks more a tank vs. likely hundreds for a tune. If you get an 87 tune you could safely run that gas but it is very likely you will have less performance as you'll need to pull timing to help ensure you don't have detonation problems if you're already tuned for 94.
I suppose there are many 'contributors' to detonation, and in the end its combustion temp/pressure & the fuel's detonation resistance.
I think 11:1 is borderline and in the next motor for Black Jack, I'm going to be a lot closer to that. But as long as you can pull spark, I would think you can make it work. I honestly don't know where the ability to pull spark on 93octane is always overcome by compression ratio. Then, there's the whole static vs dynamic compression... Everything gets technical and theoretical pretty quickly...
On 93, it may just be that there is a point where you have to pull so much timing with higher compression that you've lost power by adding compression, defeating the purpose.
I think 11:1 is borderline and in the next motor for Black Jack, I'm going to be a lot closer to that. But as long as you can pull spark, I would think you can make it work. I honestly don't know where the ability to pull spark on 93octane is always overcome by compression ratio. Then, there's the whole static vs dynamic compression... Everything gets technical and theoretical pretty quickly...
On 93, it may just be that there is a point where you have to pull so much timing with higher compression that you've lost power by adding compression, defeating the purpose.
Wonder what kinda power I would get with TSF 170 heads, my explorer intake with stock cam would make?
Cruze through this thread, find something similar, https://stangnet.com/mustang-forums/threads/guess-my-h-p-the-dyno-1-4-mile-time-thread.677534/
With the old twisted wedge 170s, I'm used to seeing around 300 to the tire. The GT40 intake is huffing pretty hard at or beyond that, which is due to not only CFM flow, but the long runner length.
So, it doesn't make much sense to aim beyond that point or beyond about 6k RPM with an unported explorer. To build a lot more, you should be porting & cutting/welding to reduce runner length.
One of many articles/sources on what is Detonation vs Pre-Ignition
Pre-ignition, Detonation & Knock
Understanding the difference between pre-ignition, detonation, knock and pinging. In this article, you will learn the difference between these combustion events and learn how to tune your engine to avoid them.
www.masterenginetuner.com
Basically detonation occurs in the end gases on the compression stroke and after the spark. PI occurs due to a hot spot that lights the AF off before the spark, right? A lot conflate the two.
Weird.
Nobody around here runs E10 in their small engines.
You see nothing by lawn care guys at the Ethanol Free fuel stations filling up their gas cans with a trailer full of small engine powered lawn/garden equipment.
Plus the occasional Hot Rod/Street Rod/Muscle Car/Performance Car fueling up.
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