got better gas mileage using premium in a regular car

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42 minutes ago, FlatBrokeRacing said:

To my knowledge there are no vehicles that are static 13:1 compression off the assembly line, ...

Mazda CX-5 2016, what is that then?  They say 13:1 on the spec sheet, but is that "not the whole story"?

[Zodiark1593]

2 minutes ago, FlatBrokeRacing said:

Using 91 octane in a vehicle which does not require it will not harm fuel consumption, the reasoning behind this is the specific gravity of the fuels and the "motor octane" of the fuels are too close together for there to be a noticeable difference.

 

Not going to delv into the other side of your factors here. but there is alot more alterations than just ignition timing (intake air temperature, coolant temperature, oil temperature, elevation, general health of the engine all play factors as well as many others).

 

there are no special measures for reducing intake temperatures, or exhaust gasses. Variable valve timing is one of the big factors in moving the torque curve around in order to make more low end torque on small engines without sacrificing high RPM horsepower, this plays into efficiency but is not the real answer. Modern vehicles can get away with higher compression due to direct injection. 

I was referring to the Mazda Skyactiv engines that use a, rather twisted exhaust manifold, though I concede that I didn't consider Direct Injection as well. 

 

Turbocharged engines of course use an intercooler to reduce the temperature of the intake charge. I didn't delve much further than what I specified as I'm typing on a phone at the moment.

[flibberdipper]

13 hours ago, Ganz said:

Similarly you won't save money by buying flex fuel (E-85) because you get lower gas mileage.

Odd exclusion to this seems to be my dad's P71. Makes noticeably more power, sounds totally different (much deeper and raspier), and mileage gets a healthy boost from 15-16 up to 18-20.

[Zodiark1593]

Just now, Ryan_Vickers said:

Mazda CX-5 2016, what is that then?  They say 13:1 on the spec sheet, but is that "not the whole story"?

From what I understand, the Skyactiv engines sold to Europe are 13:1, while the American variant is 12:1. Though this may have changed recently.

[FlatBrokeRacing]

4 minutes ago, Ryan_Vickers said:

Mazda CX-5 2016, what is that then?  They say 13:1 on the spec sheet, but is that "not the whole story"?

thats cool if they have finally broken that barrier! I'm not 100% up into current gen import engines, but i would say with Direct injection and variable valve timing it should be very do-able with a very good bump in torque!

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13 hours ago, Ganz said:

Most premium fuel will yield higher mpg but costs more.  But you will never save money by buying premium if you are solely looking for prices/miles.  Similarly you won't save money by buying flex fuel (E-85) because you get lower gas mileage. You buy premium (or flex fuel) for the other potential benefits. Premium being healthier in the long run for your engine and flex fuel being more environmentally friendly.

 

Just my two cents anyway.

Well my understanding is just that:

1. contrary to what the name might suggest, premium gas is not "better", it just so happens that it tends to be used in nicer cars
2. You should use what the manual recommends regardless: going lower is not good but higher is not good either, or at least won't help
   • A an extension of this, you'll get the most efficiency and power with using what it recommends

idk if that's all true but that's my understanding

[FlatBrokeRacing]

4 minutes ago, tmcclelland455 said:

Odd exclusion to this seems to be my dad's P71. Makes noticeably more power, sounds totally different (much deeper and raspier), and mileage gets a healthy boost from 15-16 up to 18-20.

physically impossible to get better economy on e-85 fuels, while the power may come around (most all 2006+ P71's had dual fuel ecm's in them) so the performance bump is very possible. however the economy aspect to that, if you knew the physics and fuel specific gravities behind that its just not possible.

[captain_to_fire]

2 minutes ago, Ryan_Vickers said:

contrary to what the name might suggest, premium gas is not "better", it just so happens that it tends to be used in nicer cars

Unleaded and diesel all the way

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3 minutes ago, FlatBrokeRacing said:

physically impossible to get better economy on e-85 fuels, while the power may come around (most all 2006+ P71's had dual fuel ecm's in them) so the performance bump is very possible. however the economy aspect to that, if you knew the physics and fuel specific gravities behind that its just not possible.

Yeah ethanol is ~2/3 the energy density of regular gasoline iirc, and so any addition of ethanol is just going to make the mixture slip from what gas would have been to something less.

 

That said, the energy density of the fuel indicates the best you could do... but you won't necessarily unlock all of it perfectly; I wonder if it would be possible to tune an engine so exactly (so badly?) that it actually ran better on a certain blend o ethanol than straight gas?

[Zodiark1593]

1 minute ago, FlatBrokeRacing said:

thats cool if they have finally broken that barrier! I'm not 100% up into current gen import engines, but i would say with Direct injection and variable valve timing it should be very do-able with a very good bump in torque!

You should take a look at the Mazda Skyactiv line of engines. They've been around since 2012. The Mazda 3 with a Skyactiv-G engine can achieve 40 mpg. Yes, VVT and DI are crucial components here. Power is nothing to write home about, at 155HP or so for the 2.0L one. Lower rev limit than the older MZR-L 2.0 (148HP), but better torque and fuel economy.

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7 minutes ago, Zodiark1593 said:

You should take a look at the Mazda Skyactiv line of engines. They've been around since 2012. The Mazda 3 with a Skyactiv-G engine can achieve 40 mpg. Yes, VVT and DI are crucial components here. Power is nothing to write home about, at 155HP or so for the 2.0L one. Lower rev limit than the older MZR-L 2.0 (148HP), but better torque and fuel economy.

idk about you car enthusiasts but for me I think getting more torque and getting it sooner matters more to the general feeling of responsiveness and power than pushing the HP to crazy levels.  Few if any people will push their car to the redline or anywhere near it on a regular basis, which is where you actually get that rated HP, and so how it performs in the 1500 - 3500 rpm range is a lot more important imo.  We used to have a TDI Jetta before the recall and while the HP was nothing special (140 iirc) the torque (236 iirc) was unreal for an engine that size (2 L).  The turbo lag was not fun but once it kicked in it would whip your head back lol and the way it could climb hills with a heavy load and not downshift... it was nice

Oh yeah and the efficiency... they claimed it would do 4.6 L/100km on the highway and we saw as good as 5 in real world tests... idk how many cars can do that even today, 7 years later.

[flibberdipper]

8 minutes ago, FlatBrokeRacing said:

physically impossible to get better economy on e-85 fuels, while the power may come around (most all 2006+ P71's had dual fuel ecm's in them) so the performance bump is very possible. however the economy aspect to that, if you knew the physics and fuel specific gravities behind that its just not possible.

¯\_(ツ)_/¯

 

Unless for some retarded ass reason the ol' confuzer (aka computer) has no idea what is going on (which I wouldn't put past this car) it would tell ya that it's getting marginally better mileage on E85. Either way it's still cheaper to run so can't complain there.

[Zodiark1593]

1 minute ago, Ryan_Vickers said:

idk about you car enthusiasts but for me I think getting more torque and getting it sooner matters more to the general feeling of responsiveness and power than pushing the HP to crazy levels.  Few if any people will push their car to the redline or anywhere near it on a regular basis, which is where you actually get that rated HP, and so how it performs in the 1500 - 3500 rpm range is a lot more important imo.  We used to have a TDI Jetta before the recall and while the HP was nothing special (140 iirc) the torque (236 iirc) was unreal for an engine that size (2 L).  The turbo lag was not fun but once it kicked in it would whip your head back lol and the way it could climb hills with a heavy load and not downshift... it was nice

To be honest, I prefer a decent NA car to a Turbo can on the windy hills, namely when the road is wet. When I had my old Volvo, the turbo would kick in, and the front tires would slip more than intended around prolonged bends. With my Mazda, I can pretty much brush along that slipping point, and make small adjustments to my turn with the throttle while holding the wheel steady.

 

Though that 200 ft/lbs at ~1900 rpm from the Volvo was pretty great. If it had the manual, it would most likely be faster than the Mazda in everything but wet roads. For a wagon, it handled quite well. I don't miss the sub-24 mpg though, not on my long commutes.