Sorry if this has been covered... searched.
Took a ~320 mi. trip. Before I left, I filled up with 89. There was about 1/8 tank of 91 in the tank when I filled up. At the end of the trip, the low fuel light was not yet lit, and there appeared to be about 1/10 tank left. Every other time I've made the trip (using 91-93 octane as I always do), the light has come on just as I'm arriving at my destination.
Nothing about this trip was out of the ordinary... same average speed, used the A/C most of the trip, etc.
So I'm wondering if the lower octane had anything to do with this, or whether it was just a fluke. The PCM is supposed to retard timing if lower octane is used, which would lower MPG instead of raise it. Of course, I'm not convinced the stock timing is really "optimized" for 91+ octane anyway, but that's a different story.
Anyone else encounter this?
Lower octane is just silly, period.. though I am sure you don't want anyone to preach to you. You will get less mileage, and less power with lower than premium. Also, most people say that they don't worry about using less than premium as the computer will "simply" retard timing, etc, effectively relying on the knock sensor to not allow detonation from using an octane that is too low.
One thing about that is: you have to rely on the knock sensor. the sensor doesn't do anything until it has ALREADY detected knock/ping. Not good.
You are likely seeing headwind/tailwind.. elevation climb/elevation fall variances. unless you have performed this trip multiple times, and used premium from A to B once, then from B to A the next time, etc. (this eliminates the elevation change, temperature, humidity, pressure, and wind variances because you are using both grades in both directions...)
Simply put: you either had help (weather, elevation, etc) on one way, or you were driving slightly different in high expectations. Of note: you were likely causing damage the entire time.. joy joy!
Ray
Originally posted by Ray:
Of note: you were likely causing damage the entire time.. joy joy!
Ray
All though im not recomending low octane in an svt. I seriously doubt he did any damage to his motor driving 300 miles on low octane.
You mean: "I seriously doubt he did devestating or noticeable damage"... any wear, tear, or damage, regardless of extent, is still damage, and he was likely to have caused MORE excessive damage to his engine than during a 300 mile trip with premium.
Ray
so the SVT is set for premium... I didnt know that.
I can say that when I use premium, my mpg drops a tad [but it feels like the car has a bit more giddyup].
Not that I am an expert on this, but maybe your cars running really rich on premium and the lower octane is running a bit more efficient.
Originally posted by bensenvill:
so the SVT is set for premium... I didnt know that.
I can say that when I use premium, my mpg drops a tad [but it feels like the car has a bit more giddyup].
Not that I am an expert on this, but maybe your cars running really rich on premium and the lower octane is running a bit more efficient.
You're right. You're not an expert. 
Also your Cougar is programmed to run on regular so of course efficiency would drop with premium.
Also any one just randomly changing octane is going to have erratic results. The PCM is adaptive but it's not an "instant" change. It is a learned altering to the new setting/variable/change and it takes time. If you keep changing fuel and yes this can even mean different gas stations (i.e. brands of fuel blend) it will never run at optimum efficiency.
Trying something just once is NOT trying it. It's just being foolish really. If you really wanted to "test" a change you would reset the PCM after you filled up and drive several tanks on the same fuel to get any results worth mentioning.
My highly opinionated 2 cents on this commonly misunderstood topic. 
excellent, I coaxed an answer from the expert.
and I hope you werent referring to me with "trying", I never used that word. I've gone through extensive periods of using high octane [for no other reason than that work was paying for it and I wanted to spend as much of their money as possible]. So I can say I've properly "tested" the change and because work was paying for it, I also had to anally log my miles. The result was about 1mpg drop and the totally unscientific, gee the car seems a tiny bit quicker.
I'm all about efficiency and only post this in an effort to more accurately understand the details.
I did a test with this on another car of mine (accord). They are made to run with reg, but I filled up with prem every other for a month or so. I seemed to get better milage with the prem, and slightly better drivability. Perhaps this is more apparent with older cars as they start to develop carbon deposits etc in the intake and combustion chamber. In any case, the slightly better milage didn't justify the higher cost of the premium.
I always use premium in the SVT. It would be different if you could manually advance/retard timing in cases where lower grade is only available, but that is not possible with the duratec. I wouldn't put anything else besides premium in it. If anything you will have a cleaner and more efficient engine even after years of driving.
Originally posted by DemonSVT:
My highly opinionated 2 cents on this commonly misunderstood topic.
Well said.
Octane is a measure of knock resistance, nothing else.
Higher octane fuel is not any more powerful. It may permit an engine to generate more power if it is engineered for it.
Higher octane fuel burns slower (to reduce the likelyhood of knocking).
If you don't need it, there is no reason to pay extra for it.
There is more that can be said about the difference in fuel that is labeled regular and that is labeled premium, but you still really end up with DemonSVT's comments.
My friend was complaining about the price of premium the other day and I was like, ummm, don't you own a honda civic, why are you putting premium in it?
He said something about hearing it was better for your car etc. I told him that his car didn't need it and wouldn't run better on it, but I don't know if he payed much attention to me
And given that higher octane indicates higher knock resistance i.e. the gas is harder to burn, he was probably choking his engine with carbon the whole time. Not good.
It never ceases to amaze me how people won't follow their owner's manual. Like they are smarter than the teams of engineers that spend years developing these systems...oil level in the Duratec being the obvious exception
Octane has nothing to do with fuel economy...directly.
Pulling timing is not done at cruising speeds; rather it is done at light load to full throttle loads and is based on knock. When the throttle is reduced back to light cruise loads the timing should be the same or comparable.
Therefore, octane in this case has nothing to do with your fuel economy.
Originally posted by dutchie:
I did a test with this on another car of mine (accord). They are made to run with reg, but I filled up with prem every other for a month or so. I seemed to get better milage with the prem, and slightly better drivability. Perhaps this is more apparent with older cars as they start to develop carbon deposits etc in the intake and combustion chamber. In any case, the slightly better milage didn't justify the higher cost of the premium.
I always use premium in the SVT. It would be different if you could manually advance/retard timing in cases where lower grade is only available, but that is not possible with the duratec. I wouldn't put anything else besides premium in it. If anything you will have a cleaner and more efficient engine even after years of driving.
There are the same amount of detergents and cleaning additives in 87 octane as in premium. They just make more money on premium so they advertise the advantages more.
I'll say it again for emphasis: Running low octane fuel in a premium tuned vehicle for highway cruise speeds and load levels will likely do NOTHING to fuel economy. Chances are timing will only be 'pulled' on steep inclines.
Originally posted by warmonger:
and is based on knock.
unfortunately, you have to have HAD knock, before it can detect it.. this is my main problem with running less tham premium. Jim and I have discussed this at length, a few times now, and a WELL maintained vehicle may be able to run less than premium, but "well maintained" is like "I'm a great driver..."
99.9% of people think that, but are wrong.
AGGRESSIVE maintenance is required if you are going to run less than premium, at the least.
Ray
I am not saying that running a higher octane fuel in a car engineered for regular octane will give you better fuel milage. Fuel economy is determined by a number of variables, including the energy content of the fuel and the condition of your vehicle, neither one of which have anything to do with the octane level of the fuel. Two fuels of identical octane could have different energy content due to a difference in composition and therefore can give you different results.
I do know that for whatever reason in a couple of cars I have owned, in particular a 93 probe gt (which required reg fuel) 'seemed' to run better on the higher octane.
In the z, I adjust the timing with a switch (MSD) when a higher octane isn't available (it is built to run on 94). Retarded timing equals less power, and less available power equals more pedal....
Also the lower the octane number, the more explosive power it has. High-octane fuels burn slower, so a cooler burn. Cooler burning fuels mean less pinging and fewer emissions.
Using high-octane fuel in a vehicle that doesn't need it is just a waste of money....that's the bottom line.
the burn rate of the fuel doesn't mean it has more power or in your terms energy. Higher octane fuels use different structured molecules like branched chain hydrocarbons versus a higher percentage of straight chain hydrocarbons.
Benzene ring has 6 carbons, so pentane. Relatively speaking and definitely in low efficiency car engines, the small difference in structural changes affects available energy very little.
I doubt it affects the fuel economy at all!
Running high octane in a car designed for 87 is pointless. It is good to run 89 in a car designed for 87, but anything over that is pointless because the computer is set for 87. My dad runs 89 octane on his fleet of about 130 trucks (mostly F150s) because its proven to be better. They have a lot less problems running 89 then when they ran 87
Originally posted by warmonger:
the burn rate of the fuel doesn't mean it has more power or in your terms energy.
Relatively speaking and definitely in low efficiency car engines, the small difference in structural changes affects available energy very little.
I doubt it affects the fuel economy at all!
For a car programmed to run on low octane (87) fuel running high octane fuel will lower efficiency.
The slower burn rate & later point of ignition coupled with the smaller amount of ignition timing (later to initiate the flame front) will give less time to adequately burn the fuel. (in effect it's like retarding timing) Therefore the engine has lower efficiency which means less power & mileage.
I'm adding that in case you meant it both ways instead of the SVT, for example, retarding the timing curve to run lower octane fuel. Mileage will drop a hair but you are right it will be very minor at best. (once the PCM adjusts) However the torque (and subsequent HP) drop off will be notable. A good tuned chip is proof of that. Timing curve is EVERYTHING. 
Yeah the bottom line is to use what is recommended. I have a friend that wastes money using 93 in his motorcycle that only needs 87. (and we have tested it). Just follow the guidelines........it does suck that we have to use 93 when the gas prices are so darn high!
Is there a reason nobody has mentioned compression ratio in this discussion? You run a certain octane based on your compression ratio, not based on timing. Ocatane is the ability of the fuel to resist combustion under compression. If you run cheap fuel in a high compression engine the fuel will ignite before the ignition lights it strictly from being compressed. That is detonation. You can cause detonation by advancing your timing because it ignites the fuel before the optimal time in the engine's stroke.
9.8:1 is the cuttoff for running 91 octane pump gas at sea level. Higher compression than that you need to start thinkin about race fuel. I am not sure what these contours have, I don't have one, YET, but I doubt they require 91 octane unless you are right at sea level. The higher in elevation you are the less air going into your engine wich lowers compression in the cylinder, so you can use cheaper fuel.
If you run high octane where you don't have the compression to get it to ignite, you are wasting fuel and potential energy in the wasted fuel every time the cylinder fires. Resulting in lost power and fuel mileage.
If your car gets better mileage on the cheap stuff, and the "seat-of-your-pants" feel is better, run it, that means it works better. Higher elevation and lower humidity will allow you to run cheaper fuel.
Wait... your first post's synopsis is this:
You don't own a contour and don't know the compression ratio. (FWIW: the most SVT's are 10:1)
You state that anything over 9.8:1 requires "race fuel"
, but somehow the engineers at SVT state premium is fine for our 10.1 (or higher!!)
You finished up saying that we should always go by our "seat of the pants" feeling BECAUSE that MEANS its working. Never mention that just because something FEELS right, doesn't mean you don't need to tune, etc (granted fuel is not going to affect air:fuel, etc, but your general premise is flawed..)
Nice.. but I think I'll file this away under "whatever..."
Ray
Originally posted by Port:
Is there a reason nobody has mentioned compression ratio in this discussion? You run a certain octane based on your compression ratio, not based on timing. Ocatane is the ability of the fuel to resist combustion under compression. If you run cheap fuel in a high compression engine the fuel will ignite before the ignition lights it strictly from being compressed. That is detonation. You can cause detonation by advancing your timing because it ignites the fuel before the optimal time in the engine's stroke.
9.8:1 is the cuttoff for running 91 octane pump gas at sea level. Higher compression than that you need to start thinkin about race fuel. I am not sure what these contours have, I don't have one, YET, but I doubt they require 91 octane unless you are right at sea level. The higher in elevation you are the less air going into your engine wich lowers compression in the cylinder, so you can use cheaper fuel.
If you run high octane where you don't have the compression to get it to ignite, you are wasting fuel and potential energy in the wasted fuel every time the cylinder fires. Resulting in lost power and fuel mileage.
If your car gets better mileage on the cheap stuff, and the "seat-of-your-pants" feel is better, run it, that means it works better. Higher elevation and lower humidity will allow you to run cheaper fuel.
Compression ratio is too simplistic of a concept to make a full determination about octane.
The most critical element is cylinder PRESSURE. Cylinder pressure is determined by much more than just compression ratio. Cylinder presseure is effected by compression ratio, valve timing, ignition timing, combustion chamber shape, port configuration, number of valves, any restrictions in both the intake and exhaust systems, fuel quality, fuel mixture, flame propagation, flame temperature, engine load, and so on.
Originally posted by Port:
Is there a reason nobody has mentioned compression ratio in this discussion? You run a certain octane based on your compression ratio, not based on timing. Ocatane is the ability of the fuel to resist combustion under compression. If you run cheap fuel in a high compression engine the fuel will ignite before the ignition lights it strictly from being compressed. That is detonation. You can cause detonation by advancing your timing because it ignites the fuel before the optimal time in the engine's stroke.
9.8:1 is the cuttoff for running 91 octane pump gas at sea level. Higher compression than that you need to start thinkin about race fuel. I am not sure what these contours have, I don't have one, YET, but I doubt they require 91 octane unless you are right at sea level. The higher in elevation you are the less air going into your engine wich lowers compression in the cylinder, so you can use cheaper fuel.
If you run high octane where you don't have the compression to get it to ignite, you are wasting fuel and potential energy in the wasted fuel every time the cylinder fires. Resulting in lost power and fuel mileage.
If your car gets better mileage on the cheap stuff, and the "seat-of-your-pants" feel is better, run it, that means it works better. Higher elevation and lower humidity will allow you to run cheaper fuel.
Wow. This is just a simple Ford forum.
Despite this fact, you'll get eaten alive here with random posts like this. On import car forums... 
maybe, maybe not.
You can't just determine octane requirements based on compression.
BTW, I ran 91 octane on my 10.2:1 motor with 6 pounds of boost in 100 degree Arizona weather That was the end of May, early June to be exact. So as far as I'm concerned I've OWN3D your azz on that one.
What was that again.... oh yes, you were talking out your arse.....
By the way, fuel igniting before the spark plug ignites it is called Preignition. Yes there is a term for it and it isn't detonation. If it is just slightly off from the appropriate amount of timing then it manifests itself as pinging. If it manifests too early then it can detonate.
Detonation is caused when the gas pressure of the burning fuel elevates too soon before the piston reaches top dead center and overcomes the piston force that is compressing it when it is ignited before top dead center. This results in knock and damage. The gas pressure tries to overcome the piston pressure as it comes up...somethings gonna break.
This can be caused by preignition, high temps, or bad fuel. All of these possibilities are affected by high compression.
You can just plain set your timing too far in advance and cause detonation with no hint of preignition and still have nothing to do with compression ratio.
BTW, timing your car right means you initiate burn with the spark plug well before the piston is at TDC in such a way that the gas expansion creates the max pressure right as the piston passes TDC.
Originally posted by DemonSVT:
Originally posted by warmonger:
the burn rate of the fuel doesn't mean it has more power or in your terms energy.
Relatively speaking and definitely in low efficiency car engines, the small difference in structural changes affects available energy very little.
I doubt it affects the fuel economy at all!
For a car programmed to run on low octane (87) fuel running high octane fuel will lower efficiency.
The slower burn rate & later point of ignition coupled with the smaller amount of ignition timing (later to initiate the flame front) will give less time to adequately burn the fuel. (in effect it's like retarding timing) Therefore the engine has lower efficiency which means less power & mileage.
I'm adding that in case you meant it both ways instead of the SVT, for example, retarding the timing curve to run lower octane fuel. Mileage will drop a hair but you are right it will be very minor at best. (once the PCM adjusts) However the torque (and subsequent HP) drop off will be notable. A good tuned chip is proof of that. Timing curve is EVERYTHING.
This is very sketchy. In principal you are correct for significantly different grades of fuel, however, in terms of available pump grade gasolines it isn't applicable. A car tuned for 87 octane will run the same on 87 through 93 and probably even upwards towards 100 octane. It definitely won't run less efficient, it just won't see any benefit from it.
Now when you talk about running gasoline and then later methanol or propane or a fuel that is VERY different in its octane and power capacity, then yes, I think you'd be correct.
Originally posted by Port:
9.8:1 is the cuttoff for running 91 octane pump gas at sea level. Higher compression than that you need to start thinkin about race fuel. I am not sure what these contours have, I don't have one, YET, but I doubt they require 91 octane unless you are right at sea level. The higher in elevation you are the less air going into your engine wich lowers compression in the cylinder, so you can use cheaper fuel.
SVT Contour:
Compression ratio: 10.0:1
SO are you saying that all of us NEED race fuel? get your facts straight buddy.
And why would you use 91 when you could get 93 or even 94
Damn it. Everyone got to make fun of the ignorant fool before I could.
Greg, I don't mind giving you the points.. You know I'm here for ya when you aren't around to jump on someone..
Ray
I can see that you are some bench-racing fools. There is a saying we use in racing, "you can beat 75% of the competition in the shop", I think you guys just got your "arse" handed to you. I would love to get lined up next to one of you guys.
Run 14:1 in one of your contours with pump gas and see if you can get your timing to take care of that, and then tell me that compression has nothing to do with octane rating. Compression ratio is not too vague. You need someplace to start. Then you can take into factor air temp, elevation, humidity, barametric pressure, the whole bit. Did you miss that lecture when Vin Deisel was pulling a wheelie with only one rod left in the block?
I said at 9.8 you need to start THINKING about running race fuel. I didn't say your motor would shell if you ran pump gas with 9.9:1 compression. 9.8 and 10 are pretty close to the same number if you guys arn't too familiar with decimals and math. Why do you think ford doesnt build all of its motors with 12:1 compression? Because the proper fuel is expensive and a little hard to get ahold of. Most of you arn't ever at sea level, so you dont have enough air to get that kind of cylinder pressure anyway. And forget about engineers, they don't have a clue what is going on. There head is burried too far in their calculator to do any good. They probably can't screw in a light bulb without doing a few calculations on how much resistance the friction on the threads is going to give them.
And the comment about running boost in Arizona, the air is hot, which makes it very thin, and also has very little humidity, which makes it even thinner. So you running that "massive" boost you are so proud of is probably only making your contour run in arizona like a stock one would run at sea level.
Lay off the "Fast and Furious" movies, you might learn something and get a little faster.
I happened to be AT sea level with my 10.25 (or whatever it actually is) for over 2 years. Does that mean that I am defying logic?
Personal insults directed at the entire community (familiar with decimel/math, etc) are not the ways to get us to listen to, accept, or even talk about your "theory" there.
I suggest returning to whatever "shop" you came from, reading up a little bit, and returning when you can intelligently discuss whatever thoughts you may have, instead of insults..
Ray
Let's lock this thread. Nothing useful is happening now.
Originally posted by Big Jim:
Let's lock this thread. Nothing useful is happening now.
Please. This ignorant fool doesn't even understand basic tuning, adaptive computers, technology 20 years old, and common items of that nature.
Damn trolls. They have no life of their own... 
Originally posted by Port:
Did you miss that lecture when Vin Deisel was pulling a wheelie with only one rod left in the block?
Originally posted by Port:
Lay off the "Fast and Furious" movies, you might learn something and get a little faster.
Way to contradict yourself. 
You sir, are wetauded 
Mark
so i guess my hairly modded regular V6 cougar in Savannah, GA(lol pretty much below sealevel
) with 87 gas spraying a 75 shot should be blown up...and its got 108,000 miles to boot? NO! the motor is running just dandy ARSE! lol
oh and BTW it doesn't have 87 in it anymore i just sprayed it that one time with that gas...then i went and filled up with 93 ever since.
i bet 100 bucks that if we met this guy in person he would not act this way! i could see all of us surrounding him in a corner and saying "SO, WHAT DID YOU SAY WAS WRONG WITH PUMP GAS IN A 10:1 COMPRESSION MOTOR?" (with a Vin Diesel voice ofcourse) lol
Couple followups:
- The 320 mi. trip is from my place to my Mom's house, and I've made the trip probably 25 times in all types of weather. And yet the fuel mileage is always almost exactly the same. IMO I can eliminate weather from the equation.
About the only other non-PCM variable I can think of is that I somehow got an extra-full fill. This is unlikely, though, since I always use the same method when filling up.
- Other than timing, are there any other parameters that the PCM supposedly adjusts in response to octane?
Well I just got a lesson in octane, checked into this one out of curiousity and went to school. Let me throw you fuel experts a bone. I run a Mondeo V6 Dual fuel system. Runs Premium on the gasoline side and compressed natural gas [via a Bugatti System] I can switch back and forth from fuel to fuel, ie: leaving the city and entering the Autopista and switch over to gasoline. [ I use CNG primarily in the city because it's inexpensive and it burns very clean]In either case I detect no difference in performance. And the engine seems very smooth on either.
Originally posted by DemonSVT:
Damn trolls. They have no life of their own...
WTF, a troll? Good one.
Originally posted by Y2KSVT:
Way to contradict yourself.
You sir, are wetauded
Mark
I guess you missed the sarcasm. My bad, I should have realized it was a little over your head. He didn't actually give a lecture before the wheelie, besides how scared of the car he was, I was just commenting on how rediculous the movie is, and how you all seem to live by it. If you stop watching it, and actually go out and learn something, you might be a little better off. You get it now?
BTW, what was up with loosing the floor pan in the Eclipse when the manifold pressure got too high?
Originally posted by Ray:
I happened to be AT sea level with my 10.25 (or whatever it actually is) for over 2 years. Does that mean that I am defying logic?
Personal insults directed at the entire community (familiar with decimel/math, etc) are not the ways to get us to listen to, accept, or even talk about your "theory" there.
I suggest returning to whatever "shop" you came from, reading up a little bit, and returning when you can intelligently discuss whatever thoughts you may have, instead of insults..
Ray
Well, you were the first one to jump all over my arse about my "theory" and file it away under "whatever". Pretty rude about it too, so how do you get off tellin me who to insult and who not to?
AGAIN, I did not say you would blow your motor if you ran pump gas with 10:1 compression, I said any more than 9.8 you need to THINK about running a better grade of fuel. Again, 9.8 is pretty close to 10, I guess you still havn't got that part. That is why Ford did't build more than 10:1 compression into your engine. Or could they not get timing to handle any more compression?
Originally posted by 99cougar:
so i guess my hairly modded regular V6 cougar in Savannah, GA(lol pretty much below sealevel ) with 87 gas spraying a 75 shot should be blown up...and its got 108,000 miles to boot? NO! the motor is running just dandy ARSE! lol
oh and BTW it doesn't have 87 in it anymore i just sprayed it that one time with that gas...then i went and filled up with 93 ever since.
i bet 100 bucks that if we met this guy in person he would not act this way! i could see all of us surrounding him in a corner and saying "SO, WHAT DID YOU SAY WAS WRONG WITH PUMP GAS IN A 10:1 COMPRESSION MOTOR?" (with a Vin Diesel voice ofcourse) lol
So your sayin since you couldn't comprehend how to build any reliable power into your engine, you hooked up a bottle and a button and went to town? And you think you know enough about engines to actually talk about them? Not to mention you sprayed with 87 in the tank. Way to go. Running 7's yet? And if you were literate enough to read and understand my post, I didn't say you couldnt run pump gas in a 10:1 motor.
Originally posted by DemonSVT:
Originally posted by Big Jim:
Let's lock this thread. Nothing useful is happening now.
Please. This ignorant fool doesn't even understand basic tuning, adaptive computers, technology 20 years old, and common items of that nature.
Damn trolls. They have no life of their own...
I sure would have a problem running a 650hp/630ft-lb motor on methanol if I didn't understand basic tuning huh?
Originally posted by Viss1:
Couple followups:
- The 320 mi. trip is from my place to my Mom's house, and I've made the trip probably 25 times in all types of weather. And yet the fuel mileage is always almost exactly the same. IMO I can eliminate weather from the equation.
About the only other non-PCM variable I can think of is that I somehow got an extra-full fill. This is unlikely, though, since I always use the same method when filling up.
- Other than timing, are there any other parameters that the PCM supposedly adjusts in response to octane?
Wow, seems like the ocatane rating may have something to do with performance and fuel economy according to cylinder pressure. Whadda ya think guys? Or does his experiment bend the rules of your logic? How hard headed can you be, actual hard results, and you tell him, along with me, no way. Sounds about right.
Originally posted by Port:
1. 9.8:1 is the cuttoff for running 91 octane pump gas at sea level.
If you run high octane where you don't have the compression to get it to ignite, you are wasting fuel and potential energy in the wasted fuel every time the cylinder fires. Resulting in lost power and fuel mileage.
2. Wow, seems like the ocatane rating may have something to do with performance and fuel economy according to cylinder pressure. Whadda ya think guys?
1. You have contradicted your first statement yourself at least twice.
Just to pick one manufacturer, Ford, has several engines at 9.8 to 10.3 to 1 that run on 87 octane fuel. I mean that's what is recommended to run. That's not including any of their vehicles tuned for premium that are capable or running lower octane fuel.
Several folks have run 11.25 to 1 hybrid 3L's on 87-89 octane fuel. Even some using ethanol blended fuel with all it's drawbacks.
Your ignorant statement that certain compression ratios automatically require higher octane fuels is missing the rest of the equation entirely. Compression ratio is just one part of the formula/puzzle.
Just the timing curve alone throws all of your statements into the garbage. It's as simple as this; "BUILD A NEW TIMING CURVE" That easily trumps compression ratio.
Your way of thinking is very 50's and 60's. That's a polite way of saying it's horribly out of date and mistaken.
Not only that but the engine in this post is 10 to 1 and most discussion revolves around engines with a range of 9 to 1 - 11.3 to 1 CR. Yes that includes supercharged and turbo charged engines so it encompasses cylinder pressures much higher the typical NA engines.
2. Octane is ONLY a fuel's resistance to preignition. It has little to do with the fuel's stored energy and performance or efficiency ability. Higher octane will "ALLOW" (not generate) use of higher cylinder pressures, leaner fuel mixtures, and/or greater ignition timing so the engine can make more horsepower. It's called tuning. A higher octane rating itself does not make more power or efficiency.
This same TUNING is why running more octane then needed can decrease the efficiency of the engine. The engine is not "TUNED" to run with fuel of a significantly higher flash point and slower burn rate.
Most cars now days that require premium are backwards adaptable to run lower octane fuel. (That's that technology you do not seem to know about based of your posts btw) However adaptive timing trim is caused by the engine experiencing pre-ignition or detonation and adjusting itself. (timing retard)
And we still need to lock this thread.
Originally posted by Port:
Originally posted by Y2KSVT:
Way to contradict yourself.
You sir, are wetauded
Mark
I guess you missed the sarcasm. My bad, I should have realized it was a little over your head. He didn't actually give a lecture before the wheelie, besides how scared of the car he was, I was just commenting on how rediculous the movie is, and how you all seem to live by it. If you stop watching it, and actually go out and learn something, you might be a little better off. You get it now?
BTW, what was up with loosing the floor pan in the Eclipse when the manifold pressure got too high?
Dude. It's a movie. Get a life.
To respond to your other foolish posts:
1.) No one was bench racing here. That is when someone claims they can beat you with such and such mods without proof of time slips or video or actual track head-to-head.
2.) You are plain wrong about the compression and the fuel requirements. Modern engines designed for natural aspiration are runing 9.8 on the low end and up to 10.5:1 on the high end. 20 years ago 8.8:1 was considered low and high was considered 9.5 or 10:1 Now days 11:1 is considered high and 9.7 is considered low. Times change. Cylinder head design improves, electronics improve, even fuel composition is altered.
3.) You came on a contour board, a car that runs 9.7:1 stock compression from 1995 and runs on 87 octane with no issues, and claimed we needed race gas at 9.8. Even to imply that we needed to "look at it" at 9.8 is just showing you are ignorant of new engine design. Hell its old news now, this engine is TEN YEARS OLD! THe SVT motors are 10:1 and 10.2:1 stock. They recommend 91 octane but it will run with 87 by pulling back timing as necessary.
4.) My car runs "massive boost" at 6-10psi because I have a 10:1 compression ratio motor. So far I have run 12psi on 93 octane and no problems. For this motor that is massive boost. That 6psi I pulled 300 Horsepower at the wheels in that weather. For 8.5psi I pulled 328 Horespower at the wheels. All on 91 and 93 octane respectively. THe dyno graphs are posted on my site.
Oh, and 1/4 mile times are also posted. As I stated, I OWN3D your ass on that one.
5.) I could post a dyno with A/F data showing 14:1 at the tailpipe on 92 octane and no issues. In fact, it was hosted long ago by someone and may still be up. I'm not going to waste my time because the boosted graphs on 91 octane are sufficient to prove the point.
6.) You sir deserve a 
for you foolish posts. You are a troll. I wouldn't waste my time on you alone, but this topic may come up again and next time I want to see people to tell you to search.
Get educated by reading instead of watching the fast and the furious for you lectures. Grasshopper.