When I put on 89 or 91, my gas consumption seems to be slightly worse. Also, there seem to be some sort of rattling noise when I'm stopped with the transmission set to D (e.g. foot on the brake at a red light), like the RPM idles lower than it should (I can't see because I have the base model which doesn't have a tach). Is it just me/psychological?
Is it just me, or does my 2014 Mazda3 like regular gas (87 oct) better than 89 or 91?
- Thread starter buliwyf
- Start date
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- San Diego, CA
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- 2014 Mazda3 S GT auto, 2008 MX5 6-speed
The Skyactive engine was designed to run on low octane fuel (87), so it should come as no surprise. However, I may add that it may be possible to avoid a power drop by using higher octane gas during very high ambient temperature conditions.
Like I've pointed out several times on these forums, most modern cars will automatically advance engine timing on higher octane gasoline. The Ford Source Book for my 2012 Focus specifically stated that the car would make more power on higher octane gasoline, and the difference was quite noticeable on 93 octane gas. I was hoping for a noticeable gain on the 2014 Mazda3, but it seems as though Mazda may have set a fairly low cutoff for timing advance.
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- San Diego, CA
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- 2014 Mazda3 S GT auto, 2008 MX5 6-speed
If the M3 manual does not include a similar statement, then you should assume that using higher octane fuel is a waste of money.
High intake air temps can result in predetonation and timing retardation. At least it did with many vehicles, 10-20 years ago.
High intake air temps can result in predetonation and timing retardation. At least it did with many vehicles, 10-20 years ago.
According to Road & Track, you should assume the other way around, most likely:
http://www.roadandtrack.com/go/news/new-technology/premium-fuel-futures
http://www.roadandtrack.com/go/news/new-technology/premium-fuel-futures
Just filled my tank with 87 oct this time around. It does sound "more relaxed," idling or accelerating. Again, might be psychological unless I do some "scientific testing."
Regarding the rattling sound, it seems to be the rad fan when it kicks in, and I'm at a full stop with the transmission at D. Kinda annoying since this is an "old car" problem, considering it's a 2014 with only 5,600 Km's on it.
Yeah it's funny these Variable Valve Timing engines. I once had a 1996 Nissan Bluebird with an old school SR20DE engine (cast iron block!). If I wanted more performance, I'd gas up with 93 octane and manually advance the timing a bit to 17 degrees. When I put on regular, I set it to the default 15 degrees. It's a shame what Nissan is doing right now considering they were really badass during the 90's. Then I had a 2012 Hyundai Accent with a 1.4L engine (not available here in Canada) with VVT. Engine knocks like crazy when I use anything lower than 89 octane.
Regarding the rattling sound, it seems to be the rad fan when it kicks in, and I'm at a full stop with the transmission at D. Kinda annoying since this is an "old car" problem, considering it's a 2014 with only 5,600 Km's on it.
Yeah it's funny these Variable Valve Timing engines. I once had a 1996 Nissan Bluebird with an old school SR20DE engine (cast iron block!). If I wanted more performance, I'd gas up with 93 octane and manually advance the timing a bit to 17 degrees. When I put on regular, I set it to the default 15 degrees. It's a shame what Nissan is doing right now considering they were really badass during the 90's. Then I had a 2012 Hyundai Accent with a 1.4L engine (not available here in Canada) with VVT. Engine knocks like crazy when I use anything lower than 89 octane.
During a 17 day vacation out west with my son, I was stunned to discover just how many western states have bad gasoline. Almost every car on the road today requires at least 87 octane gas. Some older cars can be damaged by running less than that. Newer cars WILL make less power on anything less than 87 octane. I just don't get it.
I would stick with the 85 octane. The sky active engine has a high compression ratio 13:1 which is one of the reasons gas mileage is what it is.
One of the issues with a high compression engine is the ignition point of the fuel. You want the fuel to ignite when the piston has fully compressed the fuel. The things that affect that are octane and heat.
One of the reasons the 2014 mazda has a long nose besides looking cool is it has a 4 - 2 - 1 exhaust manifold and I read this is to get heat away from the engine to prevent premature ignition.
Octane is the other thing that affects when the fuel ignites. So using a non recommended octane maybe affecting when the fuel ignites and may produce the pings and knocks.
It is my understanding that higher octane is not better fuel. It exists for engines that are engineered to use it.
I am not a car expert but this makes sense to me and usually bares out when someone says my car knocks and pings. You usually find out they are using regular when the car calls for premium.
The manual is you friend
One of the issues with a high compression engine is the ignition point of the fuel. You want the fuel to ignite when the piston has fully compressed the fuel. The things that affect that are octane and heat.
One of the reasons the 2014 mazda has a long nose besides looking cool is it has a 4 - 2 - 1 exhaust manifold and I read this is to get heat away from the engine to prevent premature ignition.
Octane is the other thing that affects when the fuel ignites. So using a non recommended octane maybe affecting when the fuel ignites and may produce the pings and knocks.
It is my understanding that higher octane is not better fuel. It exists for engines that are engineered to use it.
I am not a car expert but this makes sense to me and usually bares out when someone says my car knocks and pings. You usually find out they are using regular when the car calls for premium.
The manual is you friend
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- 2022 CX-5 Turbo
The long nose was from design/styling, not a mandate from manifolds.
There are youtube videos from Mazda that explains the design of Mazda3 when it was launched.
Look up "Dave Coleman Mazda3" on youtube.com
On fuel, stick with 87 octane in US.
Higher octane does not help when the engine does not need it.
The DI sprays cool the cylinders by cool fuel. Hence, compression ratio can be raised.
Energy content is slightly less per volume of fuel with higher octane (source, Wikipedia)
Pure chemistry.
There are youtube videos from Mazda that explains the design of Mazda3 when it was launched.
Look up "Dave Coleman Mazda3" on youtube.com
On fuel, stick with 87 octane in US.
Higher octane does not help when the engine does not need it.
The DI sprays cool the cylinders by cool fuel. Hence, compression ratio can be raised.
Energy content is slightly less per volume of fuel with higher octane (source, Wikipedia)
Pure chemistry.
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