CX5 just keeps getting faster with age....

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2021 CX-5T AWD CE
This whole octane vs hp tradeoff seems very slippery to me.

I doubt Mazda has any way to directly measure octane of the fuel supply, so presumably any engine detuning occurs dynamically in response to detecting engine knock. The problem is that engine knock is dependent on many more factors than just fuel octane. So under non-challenging conditions, the engine probably doesn’t knock at all even on 87 (and makes the full 250-HP) while in challenging conditions (I.e., hot weather, heavy loads, high atmospheric pressure) I suspect some detuning might occur even with 93.

I’m guessing that Mazda’s HP derating numbers are some kind of overall average rather than precise outputs. Which means that using premium simply buys you more headroom to be able to make full HP in challenging conditions. Conversely, using regular probably gives you full HP in most conditions.

Doing a track day, towing a trailer over a steep pass, or racing around your favorite canyon roads? You’d probably benefit from premium. But trundling to work in traffic or cruising a flat freeway at 70? No benefit whatsoever. That’s my read of things.

- Mark
 
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2014 Ford Explorer Sport, 2009 CX9(Wife's)
That 0-60 time was the reason I started looking at the CX5 and was also the reason I purchased my 2014 Explorer Sport back in 2014.

BTW - when I drove the CX5, it was about 0F and I experienced the significant power loss as well. It was definitely related to intake air temp. When I parked it for a quick run into the store and came back out about 10 minutes later, it had noticeable more power for about 1 mile. After that, it was back to gutless until it hit 3rd gear and/or highway speeds. It could be a safety issue if you are expecting 250hp and instead you get 150hp (or whatever it was).
 
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CX5 GT-R
That 0-60 time was the reason I started looking at the CX5 and was also the reason I purchased my 2014 Explorer Sport back in 2014.

BTW - when I drove the CX5, it was about 0F and I experienced the significant power loss as well. It was definitely related to intake air temp. When I parked it for a quick run into the store and came back out about 10 minutes later, it had noticeable more power for about 1 mile. After that, it was back to gutless until it hit 3rd gear and/or highway speeds. It could be a safety issue if you are expecting 250hp and instead you get 150hp (or whatever it was).
100%. It is 100% purposeful and designed this way, and literally everyone with the stones to go out and actually test it, has concurred. Some people are still in denial, though.

That said, I really REALLY want to know: "WHY!?" I am sure there is a good reason, I wish Mazda would share it with us. Since it doesn't kill me on the highway speeds, I am not super mad about it, but it is a bit of a let down in an otherwise flawless execution. That said, it may well be related to the DPT setup in some way. I just want an explanation is all, and NOONE will supply it.
 

JackCastle

2020 CX-5 GTR
My CX-5 GT-R just turned 5K miles after 10 months of driving. I recently had the lift gate module recall performed. Upon receiving my car back from the dealer it feels much faster and quicker. It is becoming much more fun to drive.

I have always been using 93 octane fuel since I bought it. It feels like I have picked up 25-30 HP since the lift gate was updated.

My question:

Why does my car feel so much quicker?
  1. The dealer updated my ECU from Mazda when in for service
  2. The ECU finally calibrated itself to 93 octane after a battery disconnect at the dealer
  3. The gas station I just refueled at has better gas
  4. The car hit a break in milestone and finally started giving me full power
Thanks for replies, Jack
 
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CX5 2018 GT
was the battery disconnected?
that usually happens when batt is off for a while. Auto trans shifting adapts again since old adaptation is gone. during this phase it is perky :) unless you drive like maniac every day, eventually after some time it will get to what it was before.
 

JackCastle

2020 CX-5 GTR
was the battery disconnected?
that usually happens when batt is off for a while. Auto trans shifting adapts again since old adaptation is gone. during this phase it is perky :) unless you drive like maniac every day, eventually after some time it will get to what it was before.
Thanks, I did not know this.
Yes the battery was disconnected. I spoke with the dealer, they say that is all that was done.
I was told by Corksport a while back to disconnect the battery for the car to learn it was using 93 octane. I never did this until now.

It feels like I was only getting the 227 HP before, and now I am getting the 250 HP.

Hopefully it wont change back to how it was driving before.
 

ColoradoDriver

Gen-1 Kodo Design
Contributor
:
Denver, CO
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2014 CX-5 Touring
I don't know about actual times, but my CX-5 has only ever gotten more responsive to acceleration the longer I've owned it.

I've driven two Gen 2 non-turbos now (2019 GT and a 2020 Touring) and they both felt quite sluggish from stop by comparison.
 
Colder air is denser, hence higher mass of oxygen in every intake stroke of the engine. Anybody who's ever been a piston engined airplane pilot learns this very early in their pilot training and uses this to their advantage when flying in cold weather since we can manually control the fuel/air mixture with a knob in the cockpit.

The Skyactive engine computer knows this too and dynamically adjusts the timing, fuel injector mapping, and rate + amount of throttle opening in order to prevent cylinder pressures from rising too rapidly as anti-detonation measures since it's such a crazy high compression ratio for a gasoline car engine. We single engine bugsmasher pilots don't have to worry so much about that as our Lycoming and Continental air cooled 4-banger engines typically have no higher compression ratio than around 8.5:1 max, and many are only 7.0:1 plus in the past couple decades all we've been able to get for avgas is 100 octane low-lead, which is gross overkill of a high performance fuel for our 60-70 year old engine technology in our single engine propeller planes.

On a slight tangent, although I've only got 750 mile on my 2020 normally aspirated CX-5, and I've not measured this phenomenon just going by "seat of the pants" feel of acceleration, I honestly think my car is quicker and gets better mileage on 87 octane unleaded regular than it does on 92 octane premium unleaded. I've only tried running one tank of premium thru it yet though.... and this kinda makes scientific sense too because 87 octane regular has more BTUs of potential energy in it per gallon than 92 octane premium, and the Skyactive engine's quasi-diesel-like combustion system extracts a little more useful work energy more efficiently out of each power stroke than legacy 4-stroke gasoline engines. Thoughts?
 
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Ottawa, Ontario
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17 Mazda 6 GT
Percentage of ethanol content may have something to do with performance.
Ethanol doesn't have as much potential energy as gas does (roughly 30% less), but then again, it has a higher octane rating, so higher ethanol content will reduce engine knocking somewhat.
Try switching from high ethanol to no ethanol gas from tank to tank and see what happens. I'd be curious to know what the difference is for a turbo engine.
Catch-22.
 

ColoradoDriver

Gen-1 Kodo Design
Contributor
:
Denver, CO
:
2014 CX-5 Touring
Percentage of ethanol content may have something to do with performance.
Ethanol doesn't have as much potential energy as gas does (roughly 30% less), but then again, it has a higher octane rating, so higher ethanol content will reduce engine knocking somewhat.
Try switching from high ethanol to no ethanol gas from tank to tank and see what happens. I'd be curious to know what the difference is for a turbo engine.
Catch-22.
I've only ever found one gas station here that offers ethanol free gas.
 
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