What information are you referring too?
Feedback after 2 full tanks of 89 in my MS3
- Thread starter camrycev6
- Start date
What information are you referring too?
I would like to see any case where this is the truth. If you have done your research (and I have), there is no indication that using 89 verus 93 will cause anything but less gas mileage and less power (Both of which I have witnessed empirically.) on newer cars that have control over timing, A/F mix, RPMs, etc.
I am well versed on the chemistry and laws of physics on this one, so you will have to give me something solid. What I am requesting is more than a simple statement with no facts or data to back it up. I have done not one... but two full tanks with no ill effects.
I am sorry, do you have some statement from the Mazda engineers that stated what you did? Could it be that to meet the specs quoted by Mazda you have to use 91 (Per the manual) mean something different?
Could it just be as plausible, that if you use less than 91, you won't get the stated HP and gas mileage? I can see those two reasons as being very important reasons for Mazda to state 91. Can you honestly sit there and tell me that Mazda build zero tolerance into the engine as to cause catastrophic failures (burning a hole in a cylinder) because you ran gas that was say 90.7 or 90.2? (You have to assume that with the sheer volume of gasoline distributed that grades have small variances.)
I am going to do a third tank in the name of honest science. If you are going to just spout off vague statements with indefinite timelines with nothing to back them up, I am afraid it means very little. I could do the same with some easy examples:
If you speed all the time, eventually you will get a ticket. Well maybe, but how long, and why? (Speeding, or because you have a broken tail light?)
If you stand outside long enough, eventually , you will get wet. Well maybe, but how long, and why? (Rain, sweating in the sun, or because someone throws water on you?)
I think you get the point.
And finally, I am not trying to belittle you, I really just want to keep this discussion factual and withhold the scare tactic statements that lack any evidence.
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Not quite true. Using lower octane can result in engine knocking. However, there are a lot of factors involved that can prevent this. Here is just one of many explanations:
Autoignition that is responsible for Knock ( which is what the Octane
rating scale measures under the engine test conditions ) usually occurs
*after* the spark has fired the fuel/air mixture. The timing of the spark
is not required to describe the ability of the components of the end
gases to autoignite, other than the desired flame front has obviously
not reached those end gases under the knock rating engine test conditions.
Minimum autoignition temperatures is usually measured in a flask on
a hot plate, and no ignition source is involved - other than the hot walls of
the flask. Flame propagation rates in hydrocarbon/air mixtures do not
change much between individual family members usually found in petrol.
Flame propagation rates are very affected by the extremely hot, pressurised,
and turbulent conditions in an engine, hence the use of totally different test
methods to determine the actual octane requirement of engines.
If the fuel/air had ignited *before* the spark, then it would have been
considered *preignition* ( which starts the pressure pulse on the
piston before it should - whereas knock superimposes additional
pressure pulses on top of the normal pulse ). Autoignition does not
usually happen ahead of the spark, provided the spark is reasonably
timed, because it's the hot, turbulent, highly-compressed, fuel-air
mixture near Top Dead Centre that is the breeding ground for knock.
Under ideal conditions, the end-gases gases should be almost ready
to autoignite when the desired flame reaches them, and some engine
management systems with knock sensors can advance the timing
to incipient knock, and then retard the timing slightly. If the spark is
advanced, there is more time for the end-gases to autoignite, so by
retarding the ignition, the opportunity for the end gases to reach
the autoignition point is decreased.
If a fuel is used that can reach a higher temperature before autoigniting,
then the spark can usually be advanced if necessary, but there still is
an optimum advance value for each engine speed and load that is
determined by the engine design.
So as you can see, there are a myriad of factors that could cause knock, auto-ignition, and pre-detonation. We are talking about a small difference in octane in an engine with a sophisticated computer control system. (When compared against cars from 20 years ago.) The computer will adjust for the lesser octane (up to a point) reducing pressure, increasing RPMs (which reduces pressure), and / or altering the timing. This does not mean you are going to burn up your engine. It just means you engine is less efficient, which I have conceded from the very beginning. I just don't like boogey man stories that lack honest research, scientific data, and empirical evidence.
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- 2002 BJFW, 2007 BK3P, 1979 SA22C, 2005 BK3P
i would like to know the post combustion exhaust temps. i am betting they will be higher, and higher exhaust temps on a forced induction vehicle signify a long term reliability problem.
yes, the computer does, can and will make alterations through the knock sensor and retard the timing map in order to keep the engine safe. it is not designed for Joe Customer to be able to run cheaper gasoline. if it were, the alterations would be far more sophisticated than what they are (and believe me having seen the maps, they aren't) and not designed as a safety measure for bad gas or the wrong gas.
on an engine which is not turbocharged or supercharged i might agree with you on some of your points. but if we are being empirical, unbiased and factual about the matter that cannot be ignored. any reputable turbocharging firm that engineers its own setups will tell you that the highest possible octane is required. we can argue the limitations of the stock ECU and what it will do all day long. those capabilities and limitations will not address the mechanical properties of what is, frankly, a higher compression forced induction engine. the turbo is already forcing hot air into the engine and the combustion process needs to be as cool and rich as possible. the combustion process regardless of what the ECU does or does not do, what the engine should have for longevity and efficiency is a totally different argument.
yes, the computer does, can and will make alterations through the knock sensor and retard the timing map in order to keep the engine safe. it is not designed for Joe Customer to be able to run cheaper gasoline. if it were, the alterations would be far more sophisticated than what they are (and believe me having seen the maps, they aren't) and not designed as a safety measure for bad gas or the wrong gas.
on an engine which is not turbocharged or supercharged i might agree with you on some of your points. but if we are being empirical, unbiased and factual about the matter that cannot be ignored. any reputable turbocharging firm that engineers its own setups will tell you that the highest possible octane is required. we can argue the limitations of the stock ECU and what it will do all day long. those capabilities and limitations will not address the mechanical properties of what is, frankly, a higher compression forced induction engine. the turbo is already forcing hot air into the engine and the combustion process needs to be as cool and rich as possible. the combustion process regardless of what the ECU does or does not do, what the engine should have for longevity and efficiency is a totally different argument.
xboxlivemonkey
Member
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- 03.5 Msp
its stupid to test 89 octane on a car that is equipped with a turbo . so what if the knock sensor can adjust teh timing , it still prevents you from driving with a turbo . you might as well not drive the speed 3 get a reg. 3
FrequentFlyer
Member
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- 2008 CWP Mazdaspeed3
I didn't say anything about the quality of the gas or damage. I have no problem with you testing the tolerances of your engine, go for it. As long as you stay out of boost, thus not raising your effective compression ratio, you should be okay with your fuel test. But staying out of boost defeats the purpose of having a forced induction car imo.
You want this to be factual yet you have not method of logging any type of information or data of your vehicle, other than it still starts and drives. You state that so far you have seen no ill effects. Have you even pulled the plugs to see what condition/gap they are in? So if you want to start blabbing on about what you have come up with in theory, don't ask me to waste my time to try to convince of your not so intelligent idea. As far as "do you have a written statement from the mazda engineers" yea it says it right on the inside of the gas door, "Premium Unleaded Only" thats good enough for me. You wanna run 89 get a Regular 3/6. Here's an idea for a more useful thread. do a poll of what poeple with ms3/ms6 run 89 91 or 93 and see what you get.
MikeHTally
Member
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- 2008.5 Speed3, 2006 Chrysler 300C, 2003 Ram 1500
93 is a bit cheaper here. I filled her up today @ $4.10/gal at Costco.
Crypt0wind
Member
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- 2007 MS3 GT
I'd filled up with some 91 from Speedway before a road time. I alway use Mobil 93, love the Mobil speed pass (RFID) tag
Well that one speedway 91 tank shudder and coughed every hard acceleration. On ramps it felt like fuel cut. Just never did this with Mobil.93 I replaced the empty speedway tank with Mobil 93a nd added Lucas Fuel Treatment. Problem solve!!!
Cheap gas is really not worth the problems, Modil 93 for life...
Well that one speedway 91 tank shudder and coughed every hard acceleration. On ramps it felt like fuel cut. Just never did this with Mobil.93 I replaced the empty speedway tank with Mobil 93a nd added Lucas Fuel Treatment. Problem solve!!!
Cheap gas is really not worth the problems, Modil 93 for life...
perfect. youll be here for the 100+ weather lol jk you will be happy to see the prices have gone down a bit.
Paid $3.99 for 93 today.
im moving now..
Fair enough, and I certainly respect your opinion on this. Unfortunately, I have no plans to run long term (1000's of miles) tests with 89. I guess we won't know unless something happens, but I doubt two tanks of 89 caused any serious damage. I tell you what, if something does go wrong, I will jump right on here and tell everyone. (I had planned to anyway) That way I could say for sure it had an effect on the engine. For now, I remain unconvinced that there are not safety tolerances that engineers do (and in most industries - must) account for. As far as pulling plugs and doing other tests (as jville) suggested, I have no intention of getting that invasive. First, I am not that curious, and I don't have the time. I wanted to simply see if the engine acted strange / performed poorly. My initial results were no. Can I say conclusively that no damage was being done? No. Can you say conclusively that damage was being done? No. Even if you were *certain* I was doing damage, you could by no means give an extent of the damage. If could take months (major problem) or years (minor) to show up. That is certainly important to consider as well.
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Wait. Did you even read my original post? I drove the car exactly how I would drive it with 93 in it. That means I was constantly in my turbo / boost. I drive my car fairly hard from time to time, and again if you read my post, the difference between 93 and 89 was very subtle at best. I drove a regular 3 for almost a year before getting the speed3. I can assure you, they weren't even remotely the same, octane rating be damned.
I did the exact same test in my 325i. I lost 1.5 MPG with 89 octane. The car ran no different. It wasn't worth it. I went back to 93 octane.
I do find that getting gas at shell nets me another MPG vs. gas at a discount place. I'm one of the lucky ones who's relatively unphased by current gas prices. So a few extra pennies a gallon isn't a deal breaker for me.
Thanks for giving it a shot camryce. It's a good test to see what we can run in the car. In the event of another major oil disruption, I'd like to know *if* I can run other octane levels if 93/91 isn't available. During Katrina, we had no high test at several stations locally.
I do find that getting gas at shell nets me another MPG vs. gas at a discount place. I'm one of the lucky ones who's relatively unphased by current gas prices. So a few extra pennies a gallon isn't a deal breaker for me.
Thanks for giving it a shot camryce. It's a good test to see what we can run in the car. In the event of another major oil disruption, I'd like to know *if* I can run other octane levels if 93/91 isn't available. During Katrina, we had no high test at several stations locally.
Ghost Rider
Banned
I'll spend the extra .20cents per gallon for (93 octane) no matter what the gas prices do. I prefer the piece of mind knowing I'm putting in the manufactured recommended fuel in my vehicle. To do otherwise just seems…well dumb IMO. Of course in a crisis if you have no choice you could put in a lower octane, it says this in the owners manual. However, it's certainly not recommended.
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- 2002 BJFW, 2007 BK3P, 1979 SA22C, 2005 BK3P
there is one thing which has not been mentioned; if mazda for any reason feels that you ran anything other than 93 with regularity in this car, they are within thier bounds to void the warranty.
