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- San Antonio, Texas
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- '15 CX-5 Miata AWD
Yea, if you run e85 in an engine not mapped for it, of course it will run like s*** lol.
Premium gas
- Thread starter chckboy5
- Start date
I gave up using Consumer Reports as a source of reliable information long ago.
Your concern with phase separation with fuels blended with ethanol exposes a basic misunderstanding you have of the problem of phase separation. The fact is, pure gasoline without alcohol can absorb almost no water. This means that even the small amount of water that enters your tank in the form of vapor will phase separate and sit at the bottom of your tank where it can cause corrosion and other problems (remember, the fuel pump is at the bottom of your tank). With ethanol blended fuels that vapor will be absorbed into a homogeneous mixture and harmlessly burned along with the fuel.
If you want to learn from a real expert on the subject, a petroleum engineer, this link may be eye-opening:
http://www.google.com/url?sa=t&rct=...5dIzzBGPLxLbj1kFQ&sig2=yIrpiCmYWPxpyGXsfn9XGg
To think this was never a problem until ethanol is wrong. Ethanol actually solves the very problem you speak of unless you have an even bigger water problem in which case it would be even worse in ethanol free fuel. But don't believe me, read the link above from the engineer who says E10 is unlikely to ever become saturated enough for separation to occur from water vapor. On the other hand, non-ethanol gasoline has this water separation issue from the get-go.
If you were pointing out minuses that actually existed, I would agree with you. But you appear to have very basic misunderstandings of the "problems" you claim exist with ethanol fuels.
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In regards to if there is any benefit to running higher octane fuel, initially, I would have said no.
But, now...maybe.
Over on the Mazda 6 (same engine) forums, they have a pretty good thread about it.
http://forum.mazda6club.com/2-5l-i-4/296745-can-we-get-better-hp-mpg-higher-than-87-octane.html
Most of it is just anecdotal. However, one guy dynoed his car once on 87 octane, and then again on 91 octane. There was no power difference. However, what he found was that at 91, the car was leaner at start, and gradually got richer as the pull went on. 87 octane was the exact opposite (it would be interesting to see how 89 would have faired.) Looking at the graphs, theoretically, one may achieve better fuel economy on 91 octane than 87 (cruising around town vs WOT.)
But, now...maybe.
Over on the Mazda 6 (same engine) forums, they have a pretty good thread about it.
http://forum.mazda6club.com/2-5l-i-4/296745-can-we-get-better-hp-mpg-higher-than-87-octane.html
Most of it is just anecdotal. However, one guy dynoed his car once on 87 octane, and then again on 91 octane. There was no power difference. However, what he found was that at 91, the car was leaner at start, and gradually got richer as the pull went on. 87 octane was the exact opposite (it would be interesting to see how 89 would have faired.) Looking at the graphs, theoretically, one may achieve better fuel economy on 91 octane than 87 (cruising around town vs WOT.)
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You only use what the manufacture tells you too.
There is quite the common misconception that higher octane somehow give you more power in your vehicle or "cleans" the engine out.
Higher octane has a higher combustion point. It actually acts like a cooling agent in forced induction vehicles. When you try to put more air (turbo, supercharger) in a confined space (engine cylinder) the air particles get excited and create a lot of heat (this is why those vehicles have intercoolers). Hotter air is damaging to the engine for a lot of reasons but most notably, it can cause pre-detonation. What this means is that if the cylinder temp is hotter then it's supposed to be, you can have the gasoline prematurely ignite before the piston gets to TDC (top dead center). This is VERY bad because it will cause knocking in the cylinder. That knock is actually the piston hitting and marring the cylinder wall. End result could be catastrophic i.e. broken rod or piston, etc. Vehicles today have knock sensors to prevent this from happening. When the computer senses knock, it automatically reduces the timing in the engine which in turn reduces the overall power output.
So, the higher octane actually cools the cylinder temps in FI vehicles and is made specifically for those vehicles or ones with high compression ratios.
Long story short, higher octane then what the manufacture recommends is a waste of money and it has no added benefits for your CX 5.
There is quite the common misconception that higher octane somehow give you more power in your vehicle or "cleans" the engine out.
Higher octane has a higher combustion point. It actually acts like a cooling agent in forced induction vehicles. When you try to put more air (turbo, supercharger) in a confined space (engine cylinder) the air particles get excited and create a lot of heat (this is why those vehicles have intercoolers). Hotter air is damaging to the engine for a lot of reasons but most notably, it can cause pre-detonation. What this means is that if the cylinder temp is hotter then it's supposed to be, you can have the gasoline prematurely ignite before the piston gets to TDC (top dead center). This is VERY bad because it will cause knocking in the cylinder. That knock is actually the piston hitting and marring the cylinder wall. End result could be catastrophic i.e. broken rod or piston, etc. Vehicles today have knock sensors to prevent this from happening. When the computer senses knock, it automatically reduces the timing in the engine which in turn reduces the overall power output.
So, the higher octane actually cools the cylinder temps in FI vehicles and is made specifically for those vehicles or ones with high compression ratios.
Long story short, higher octane then what the manufacture recommends is a waste of money and it has no added benefits for your CX 5.
MidwestCX5
Member
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- 2015 Mazda CX-5 GT AWD w/ Tech
I switched back to 93 octane a few weeks ago and the CX-5 is much more tolerable. The throttle response is improved, the transmission doesn't have to downshift to make it over the hill by my house, and mpg (25mpg hwy) has not decreased even with the more spirited driving. I find the engine noise with 93 octane to be less bothersome when the cruise control is set in the high 80s/low 90s, and the car feels much more refined when idling (much less vibration & shaking).
mazdadude
ZOOOOOOOOOM ZOOOOOOOOOM
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- '16.5 Mazda CX-5 Touring
Would love to find some 93 in CALIFORNIA... (wow)
One thing that people forget, is that it will take some time to get the highest octane number in your tank and to the motor. It also takes several drive cycles to get the engine computer adapted to the highest octane rating.
Imagine you run 87 octane...you decide to try 91 octane, your 15 gallon tank fills up with 12 gallons of 91octane and adds to the remaining 3 gallons of 87 octane in the tank.
you are not running 91 octane fuel yet...but rather a mix of 80% 91 octane and 20% 87 octane. Giving you a 89 ish octane? Now over the course of a few drive cycles the motor adapts to the 89 ish octane.
now it is time for another tank of fuel, you fill up again with 91 octane, giving you a mix of 80% 91 octane and 20% 89ish octane...now you have 90ish octane... Now over the course of a few drive cycles the motor adapts to the 90ish octane.
now it is time for fuel tank #3, you fill up again with 91 octane, giving you a mix of 80% 91 octane, and 20% 90ish octane... now you are very close to a 91 octane fuel. And over the next few drive cycles, the motor adapts to the 91ish.
So as you can see, it takes a while for both the fuel mix to rise, and engine to adjust to it. You can not try it for just a single tank, and expect an accurate result.
That's spot on. Auto critics always test new vehicles with the recommended fuel and if 87 octane caused vibration and shaking they would have mentioned that in the numerous published reviews over the years. If 87 octane causes vibration and shaking then either the fuel doesn't meet spec or there is something wrong with your engine.
You can fill-up with 93 octane at Northern Lights Energy just north of where you live in Redding. But there is no benefit in a North American spec CX-5 and it would be a complete waste of money.
This is true for some vehicles but not most vehicles. The CX-5 will not run more aggressive ignition maps than those suitable for 87 octane. In other words, it's not designed to run on the ragged edge of the knock sensor and putting higher octane than 87 will not improve performance or MPG. In fact, performance and MPG could be slightly lower due to the fact that higher octane fuels tend to have slightly lower amounts of embodied energy.
This is completely different than (for example) my Volvo S80 with the original T-6 engine (straight six with twin turbo). The Owners Manual states any fuel higher than 87 octane is suitable, but it recommends 91 octane for the best performance and MPG. And the difference is quite noticeable the few times I have filled up with lower octane 87. Less power and lower MPG. As long as I run the tank nearly empty it doesn't take multiple tanks to notice the differences, it's immediately apparent within the first few minutes.
But the North American CX-5 cannot take advantage of fuel with higher than 87 octane. The one time I filled with premium I was actually slightly down on power and mpg. While the NA spec CX-5 cannot capitalize on higher octane, it can automatically take advantage of fuels with higher embodied energy. If you want slightly more power and MPG, fill up with ethanol free fuel. Because it typically has higher BTU content (unlike most higher octane fuel which has less BTU's/gallon) the engine can go further on less fuel as the oxygen sensor readings cause the ECU to lean the mixture. Because higher octane fuel typically has lower BTU content, this will not occur (or it will happen slightly in the opposite direction causing lower mpg's than 87 octane).
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- San Antonio, Texas
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- '15 CX-5 Miata AWD
Engine is constantly adjusting intake/exhaust timing based on knock. So if you run a higher octane and can get more power from the same RPM. If you really want more power on any octane, then a tune is the way to go..
Some cars work this way, a stock CX-5 has fuel/ignition/valve timing maps that are designed to not cause knock on 87 octane. If it detects knock it's because the fuel is not to spec or there is a faulty sensor, etc. The CX-5 does not constantly advance these parameters just because it's not knocking.
Of course if you change the software and run premium there is more potential. But not with a stock engine.
Do you mean a custom tune? Do you know a suggested vendor with 'tunes' on offer to otherwise stock owners? I'd check it out: but there had better be some before/after dyno runs backing up claims.
A number of vendors offer custom tunes and all claim to make more than stock HP, they claim the exact amount is dependent on other mods like exhaust, intake, turbo, etc. No doubt a tuner with the same resources as Mazda corporation could produce maps that safely provided a little more power if you were willing to run premium. The gains would be very small on the top end and mostly noticeable as a bit more torque. Gains beyond this (from premium fuel primarily as there is little to be had from different exhaust/intake) would likely compromise the engine (for example unwanted carbon deposits that could then lead to detonation and other problems) and/or emissions and drivability issues.
The truth of the matter is the automobile market is very competitive in recent years and manufacturers put a lot of time, money and effort to be more competitive in terms of performance, MPG and reliability. They have extensive engineering and development talent and equipment at their disposal and, if they leave a wee bit of performance on the table you can bet they have a competitive reason for not extracting that last little bit. A small garage tuner could never hope to understand all the technical issues the team that developed the engine has "tuned around". The explanation that cost cutting prevented them from optimizing power doesn't make sense when you realize that a more aggressive ignition or valve timing/fuelling map does not cost the manufacturer one penny more (unless it causes engine damage under warranty or gives them a reputation for unreliable cars down the road).
But, yes, most independent tuners who make good money selling "better" software have some dyno charts floating around to support their claims. But they often hem and haw when you try to pin them down to specifics. In my opinion, for the potential gains, it's a fools game. It's not going to turn your CX-5 into a performance vehicle and the issues of carbon deposits with direct injection may just turn around and bite you in the ass.
MFR's very frequently 'leave performance on the table', as you put it, for various marketing reasons, not due to any engineering concern. Fuel economy and use of regular fuel are of course considerations in this line of reasoning as is product positioning. I know of three specific cases myself and wonder what it takes to 'tune' the 2L in the CX3 to output the same HP/Tq as the 2L in the M3 making a 4rth.
Whether it's worth it or not is a matter for the consumer to decide, and the marketplace to respond with.
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The CX-3 2.0L has 9 less HP than the Mazda 3 2.0L due to a more compact exhaust manifold. It has less efficient cylinder scavaging because there was not room for the regular Skyactiv header.
This is an engineering constraint and Mazda couldn't simply "tune around it". I'm not sure what you're getting at here.
I think you just helped make my point
There is indeed some performance 'left on the table' in the CX3 too. There are compromises and they can be exploited. Sometimes as easy as new performance maps alone, but frequently coupled with intake and exhaust. I consider those relatively easy 'bolt on' mods part of the 'tuning' process.I'd be curious to know if the decision to go to market with a restrictive exhaust was an engineering decision alone.
I think you just helped make my point
I'd be curious to know if the decision to go to market with a restrictive exhaust was an engineering decision alone.
The Skyactiv header required too much room to fit in the engine bay. Getting the last 9 HP would have required moving the engine forward which would have involved a whole host of other compromises. If you want to "exploit" that, be my guest.
mazdadude
ZOOOOOOOOOM ZOOOOOOOOOM
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- '16.5 Mazda CX-5 Touring
Yes the very first skyactiv 2.0L motors that were released by Mazda into the OLD 2012 Mazda 3's were skyactiv's, but due to the space restrictions, they had to use a detuned exhaust manifold, and not the preferred skyactiv exhaust manifold.
The CX-5 released in 2013 was the first chassis that Mazda had designed to accept the large skyactiv exhaust manifold.
The Mazda 3 and Mazda 6 released after the 2013 cx5 were also designed to accept the large skyactiv manifold.
The recently released CX-3/Mazda2 and Mazda Miata/MX-5 do not have the space or room for the large 2.0 skyactiv exh manifold, as those chassis were designed for the 1.5 Skyactiv motor. Thus is the reason they had to forgo the preferred 2.0 sky exhaust manifolds, as there was not the physical space for the skyactiv exh manifold after shoehorning in the larger engine platforms.
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GJ-Molestor
Banned
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- 2011 BMW 528i, 2015 Mazda 6, 1995 Nissan Maxima Manual
it doesnt matter. ethanol free fuel improves performance and effciency. the engine will run better and sound smoother without it.
Being in the great white north, I can attest to that first hand.
I have a snowblower that sits for eight months a year.
The first year I had it, I filled it up with 87 octane regular gas (10% ethanol). Ran like crap.
The float kept getting hung up as well, and it would stall out.
I had to clean it out and drain the tank.
Started using premium 93 gas with no ethanol, and it has run perfect for the last three winters.
I still siphon the tank in the spring, plus I add some stabilizer in the left over gas, and then run it until it empties and stalls.
Good to go in the fall.
