CX-5 turbo high rpm on highway

Sorry I’m not an engineer or mechanic. That really didn’t help me understand my question. My thinking is that to make maximum torque which is said to be around 2100 rpms on this model because of the turbo it would need full boost to make that 310lbs of torque. Since that’s almost the same rpm at cruising speed (2-3k rpm). Wouldn’t that mean the turbo is fully spooled (full boost) up my entire highway trip. Maybe my thinking is all wrong, just trying to understand.
 
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Texas
:
'19 MX-5, '20 CX-5
Sorry I’m not an engineer or mechanic. That really didn’t help me understand my question. My thinking is that to make maximum torque which is said to be around 2100 rpms on this model because of the turbo it would need full boost to make that 310lbs of torque. Since that’s almost the same rpm at cruising speed (2-3k rpm). Wouldn’t that mean the turbo is fully spooled (full boost) up my entire highway trip. Maybe my thinking is all wrong, just trying to understand.

Yes, "full boost" is required to achieve 310 lb-ft of torque, but you don't need anywhere near 310 lb-ft of torque to maintain cruising speed. Boost pressure is controlled independently of engine speed.

Throttle opening, valve timing, ignition timing, injector pulse width, EGR, and other parameters are constantly adjusted to produce the desired amount of torque in the most efficient way possible. There are times when the throttle blade may be wide open even when you're pressing the accelerator pedal half way while the turbocharger is developing no boost IF that's the most efficient way to develop power at that given moment.

On modern, turbocharged engines, the acclerator pedal is actually a "torque request pedal" that commands many different systems to do different things to develop that requested amount of torque. The throttle blade is no longer directly connected to the accelerator pedal. Some systems, like BMW's Valvetronic technology, keep the throttle blade wide open at all times and use valve timing to control output while closing the throttle blade only as a failsafe device.
 
Yes, "full boost" is required to achieve 310 lb-ft of torque, but you don't need anywhere near 310 lb-ft of torque to maintain cruising speed. Boost pressure is controlled independently of engine speed.

Throttle opening, valve timing, ignition timing, injector pulse width, EGR, and other parameters are constantly adjusted to produce the desired amount of torque in the most efficient way possible. There are times when the throttle blade may be wide open even when you're pressing the accelerator pedal half way while the turbocharger is developing no boost IF that's the most efficient way to develop power at that given moment.

On modern, turbocharged engines, the acclerator pedal is actually a "torque request pedal" that commands many different systems to do different things to develop that requested amount of torque. The throttle blade is no longer directly connected to the accelerator pedal. Some systems, like BMW's Valvetronic technology, keep the throttle blade wide open at all times and use valve timing to control output while closing the throttle blade only as a failsafe device.
 
Thank you very much. That makes sense and also makes me feel much better about the longevity of my engine. I haven’t had a turbo since the 80’s (nightmare), I told myself the 2 things I would never purchase again was a turbo engine or CVT transmission but with all the advances in technology I thought I would be safe with a turbo in 2019.
 
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Texas
:
'19 MX-5, '20 CX-5
Thank you very much. That makes sense and also makes me feel much better about the longevity of my engine. I haven’t had a turbo since the 80’s (nightmare), I told myself the 2 things I would never purchase again was a turbo engine or CVT transmission but with all the advances in technology I thought I would be safe with a turbo in 2019.

Turbos for gasoline engines have come a long ways since then. They've been used on heavy-duty diesel engines that go millions of miles between rebuilds for decades. You used to find turbos on gasoline engines only in a small subset of performance cars. Now, turbos are standard on everything from $20,000 economy cars to $100,000 luxury cars. Turbos are standard in every Honda Accord and CR-V - two of Honda's most important vehicles - these days. Turbochargers themselves are pretty simple devices, so it doesn't take much engineering to make them reliable.
 

AVC

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'17 CX-5 Select
Although it's a 6 speed, it's usual for the ratios to be tweaked for a given model or engine. Maybe someone has that technical info for NA and Turbo. And, forget if anyone posted this, but the 2.5NA runs about 2300 RPM at 75MPH. And according to the dash computer, I get between 31 and 33mpg, averaging 65mph in 80% freeway/20% city.
 
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Texas
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'19 MX-5, '20 CX-5
The overall ratio (gear ratio * final drive ratio) is the significant number.

The difference in gear ratios between the two transmissions is less than 2% in 1st and 2nd and insignificant in 3rd through 6th.

When you factor in the final drive ratios, the overall drive ratio difference ranges from over -4% to over -6% (2.5L vs. 2.5T).

In 6th gear, the 2.5T will turn 4.4% slower than the 2.5L.
 
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CX5 GT-R
So does that mean if I’m cruising on the highway at a steady 65 - 70 mph and that equates to 2000 - 2500 rpm I’m at full or almost full boost my whole 60 mile drive? That seems like a recipe for poor gas mileage, short turbo and engine life.
No, under normal cruising you're in vacuum rather heavily. Its not making anywhere NEAR 300# of torque while you piddle along at 60.
 

AVC

:
'17 CX-5 Select
In 6th gear, the 2.5T will turn 4.4% slower than the 2.5L.

So if that 2.5T is supposed to turn SLOWER in 6th, and the OP said he was over 2500RPM at 75, then it suggests either his tach is off, or his trans isn't in 6th, or in 6th but not in full lockup?
 
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I was wondering the exact same thing. I have put it in manual on the interstate to confirm (at least by the dash) that it is in 6th gear and turning 2500 rpm at a steady 70 mph.
 
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Texas
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'19 MX-5, '20 CX-5
So if that 2.5T is supposed to turn SLOWER in 6th, and the OP said he was over 2500RPM at 75, then it suggests either his tach is off, or his trans isn't in 6th, or in 6th but not in full lockup?
I was wondering the exact same thing. I have put it in manual on the interstate to confirm (at least by the dash) that it is in 6th gear and turning 2500 rpm at a steady 70 mph.

In 6th gear with the TCC fully locked:

The 2.5T with 19" wheels and OE Toyo tires will turn:
1,911 RPM at 60 MPH or 2,230 RPM at 70 MPH or 2,389 RPM at 75 MPH.

The 2.5L with 19" wheels and OE Toyo tires will turn:
2,000 RPM at 60 MPH or 2,333 RPM at 70 MPH or 2,500 RPM at 75 MPH.

The 2.5L with 17" wheels and OE Yokohama tires will turn:
2,019 RPM at 60 MPH or 2,356 RPM at 70 MPH or 2,524 RPM at 75 MPH.
 
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Pueblo county CO
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CX-5 Sport 16.5 6M
I remember Consumer Reports use to list the RPM @60mph which is useful to know.
I'm trying to remember the specs on my 2.0L w/6MT but I've never written them down.
About 78mph @ 3000 RPM maybe 22xx @ 70.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
In 6th gear with the TCC fully locked:

The 2.5T with 19" wheels and OE Toyo tires will turn:
1,911 RPM at 60 MPH or 2,230 RPM at 70 MPH or 2,389 RPM at 75 MPH.

The 2.5L with 19" wheels and OE Toyo tires will turn:
2,000 RPM at 60 MPH or 2,333 RPM at 70 MPH or 2,500 RPM at 75 MPH.

The 2.5L with 17" wheels and OE Yokohama tires will turn:
2,019 RPM at 60 MPH or 2,356 RPM at 70 MPH or 2,524 RPM at 75 MPH.
But the final ratio is different between FWD and AWD. FWD is taller.
 
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Texas
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'19 MX-5, '20 CX-5
But the final ratio is different between FWD and AWD. FWD is taller.

Good catch. Jeez, Mazda has lot of variations! I come from "Hondaland" where things are simpler. :)

So...

Gear ratio * final drive ratio * tire revolutions per mile = engine RPM at 60 MPH

6th gear ratio is 0.599 on the 2.5L and 0.600 on the 2.5T.
Final drive ratio is 4.325 on the 2.5L FWD, 4.624 on the 2.5L AWD, and 4.411 on the 2.5T.
Tire revolutions per mile are 722 on models with 19" wheels and 729 on models with 17" wheels.
 

AVC

:
'17 CX-5 Select
2017 2.5L NA FWD; 2200 RPM @ 70mph, 2360rpm @ 75mph, according to scan tool. 19" rims, A36 tires, with 4mm tread depth.
 
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Gozo

2020 Mazda6 2.5T
The RPM’s seem about right. I have a 2020 6 2.5T and runs at 2250 @ 70mph on flat highway.
 
:
Florida
:
2021 CX5 Signature
No.

An internal combustion engine is typically most efficient at wide-open throttle where pumping losses are the lowest, but that's also the point of the highest fuel consumption as well.

Let's say an engine is 45% efficient at 100% load at WOT and 25% efficient at 20% load at part-throttle.

The engine may consume 10 gallons of fuel per hour at 45% efficiency at 100% load, but only 2 gallons of fuel per hour at 25% efficiency at 20% load. Even though the engine is less efficient at part-throttle, your fuel consumption is lower.

An electric furnace is 100% efficient meaning that all of the electricity that goes into the unit is converted to heat. A gas furnace is typically 80% efficient because 20% of the heat produced by the flame is exhausted outdoors. Still, a gas furnace costs less to operate because the cost per BTU is lower.
And the gas heat feels much, much warmer than the electric heat..😁. Sorry lived up north and worked for a natural gas distribution and transmission company for many years.
 

erhayes

Contributor
:
CX5 Reserve
At a cruising speed of 75, I think there is little or no turbo boost. Only when you ask for ore power. Ed
 
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2021 CX-9 Sig
:
2014 CX-5 GT
At a cruising speed of 75, I think there is little or no turbo boost. Only when you ask for ore power. Ed

And are people really getting 22-23 on the highway in a CX-5 turbo? I averaged 24.4 MPG in my 2018 CX-9 and would routinely get 27-28 MPG on the highway with cruise control set to 79 mph.
 
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