Rev Limit

[Pitter]

I noticed when changing gears manually on my Signature with turbo that engine power was reduced at a tad under 6000 rpm i.e. just under red line. I imagine this is a safety feature designed to protect the engine from over reving. Correct?

 

[Silly Wabbit]

4k-5k is the range you want to stay at for power. Check out the dyno chart over here

Torque curves for 2.5L Mazda engines

Cx5 turbo gains a ton. Pulls up to well past 6k and looks amazing.

www.mazdas247.com

 

[sm1ke]

I noticed when changing gears manually on my Signature with turbo that engine power was reduced at a tad under 6000 rpm i.e. just under red line. I imagine this is a safety feature designed to protect the engine from over reving. Correct?

The rev limiter is part of what protects the engine from over-revving, but without seeing a video of what the revs look like when you approach red line, I can't tell if its just the power drop off or something else. Can you get someone to take a video, or put your phone in a shirt pocket and record what the RPM gauge does?

 

[Pitter]

Thanks I'll try that.

 

[Akera]

I came across this issue today. In sport manual mode and the trans changed up around 5000 rpm.
It redlined around 6,300 so I don't understand why it does this? Surely these engines are not that fragile, are they?

 

[sm1ke]

I came across this issue today. In sport manual mode and the trans changed up around 5000 rpm.
It redlined around 6,300 so I don't understand why it does this? Surely these engines are not that fragile, are they?

Can you explain what you mean when you say "the trans changed up"? Do you mean it shifted into the next gear?

 

[ColtX-5]

Engine power in the turbo falls off above the torque peak when you run 87 octane. The power rating is 227 vs w50 on 93 octane.

The rev limiter is a hard stop to increasing revs, like the motor blew up.

 

[zroger73]

I noticed when changing gears manually on my Signature with turbo that engine power was reduced at a tad under 6000 rpm i.e. just under red line. I imagine this is a safety feature designed to protect the engine from over reving. Correct?

Correct. The safest maximum speed for this engine is 6,300 RPM according to Mazda. Naturally, there's some unpublished safety factor built in, but we don't know what that is. When approaching redline, the throttle will begin closing for a smooth cutoff unlike some engines that will abruptly cut spark and fuel above a specific engine speed resulting in jerky power delivery and drivetrain shock.

This engine develops peak horsepower at 5,000 RPM on 87 or 93 octane and peak torque at 2,000 RPM (87) or 2,500 (93). There's no point in winding the engine out all the way to 6,000 RPM where there is less power available than there is at 5,000 RPM - this is why the transmission automatically upshifts well before redline and why you should, too, for maximum performance.

 

[Akera]

Can you explain what you mean when you say "the trans changed up"? Do you mean it shifted into the next gear?

Yes it shifted up around 5200rpms in manual mode without me touching the steering wheel paddles.

 

[sm1ke]

Yes it shifted up around 5200rpms in manual mode without me touching the steering wheel paddles.

Was that with Sport mode on?

 

[Akera]

Was that with Sport mode on?

Yes it was and in Manual mode.
Never had a car do this so far from the redline.
It may be more efficient to change up a gear lower but i'd like to make that decision myself.
My S550 Mustang will bang the rev limiter if you let it.

 

[cz5gt]

If you are in manual mode, it won't shift up or down. If you are in sport mode, yes it could but that is not manual mode.

 

[zroger73]

Perhaps this will help clarify. There are actually three modes:

Sport mode - This is activated using the rocker switch to the left of the shift lever. In Sport mode, the transmission will upshift later and hold a lower gear. The throttle will become more sensitive. The transmission will still shift automatically. The downside is more engine noise and lower fuel economy.

Manual mode - This is activated by moving the shift lever to the left while in D. You can then manually select a gear using either the shift lever or paddle shifters. Invalid gear requests will be ignored. The transmission will downshift automatically as you come to a stop. The transmission will also downshift automatically if you press the accelerator past the detent position. Otherwise, the engine will hold the selected gear and will not upshift automatically, but the engine's rev limiter will keep it from going past redline by closing the throttle.

Manual mode (temporary) - This is selected in Sport or "normal" by pulling a paddle shifter to temporarily choose a lower gear such as when engine braking is desired. "M" appears on the instrument cluster beside the shift indicator just as it does in manual mode, but unless the shift lever is in the manual mode, the vehicle will override the chose gear.

Manual and manual (temporary) mode can used in either "normal" or "sport" model.

This can get really confusing for drivers who don't fully understand each mode. My 2019 RDX took a while to figure out. It had a pushbutton shifter that had PRND and S (sequential mode) positions, paddle shifters, and four drive modes (Snow, Comfort, Sport, and Sport+) resulting in many combinations of shift behavior. Sequential ("manual") mode only became manual when you pulled a paddle shifter and would still upshift automatically near redline unlike the CX-5. Otherwise, S mode was more like Mazda's "sport" mode, but only for the transmission - the rest of the car (dampers, steering, throttle, sound) didn't change. Those parameters only changed when you chose a different drive mode (i.e. Comfort or Sport+).

 

[sm1ke]

Perhaps this will help clarify. There are actually three modes:

Sport mode - This is activated using the rocker switch to the left of the shift lever. In Sport mode, the transmission will upshift later and hold a lower gear. The throttle will become more sensitive. The transmission will still shift automatically. The downside is more engine noise and lower fuel economy.

Manual mode - This is activated by moving the shift lever to the left while in D. You can then manually select a gear using either the shift lever or paddle shifters. Invalid gear requests will be ignored. The transmission will downshift automatically as you come to a stop. The transmission will also downshift automatically if you press the accelerator past the detent position. Otherwise, the engine will hold the selected gear and will not upshift automatically, but the engine's rev limiter will keep it from going past redline by closing the throttle.

Manual mode (temporary) - This is selected in Sport or "normal" by pulling a paddle shifter to temporarily choose a lower gear such as when engine braking is desired. "M" appears on the instrument cluster beside the shift indicator just as it does in manual mode, but unless the shift lever is in the manual mode, the vehicle will override the chose gear.

Manual and manual (temporary) mode can used in either "normal" or "sport" model.

This can get really confusing for drivers who don't fully understand each mode. My 2019 RDX took a while to figure out. It had a pushbutton shifter that had PRND and S (sequential mode) positions, paddle shifters, and four drive modes (Snow, Comfort, Sport, and Sport+) resulting in many combinations of shift behavior. Sequential ("manual") mode only became manual when you pulled a paddle shifter and would still upshift automatically near redline unlike the CX-5. Otherwise, S mode was more like Mazda's "sport" mode, but only for the transmission - the rest of the car (dampers, steering, throttle, sound) didn't change. Those parameters only changed when you chose a different drive mode (i.e. Comfort or Sport+).

Very helpful. It seems that having it in Sport mode overrides the Manual mode, which is what I suspected.

In my experience with the CX-9 (and as a few CX-5 owners have reported in the past), Sport mode doesn't change throttle sensitivity. I could be wrong, but I've played with it a lot and as far as I can tell, it doesn't.

@Akera, if you put it in Manual mode with the Sport mode off, you should be able to "bang the rev limiter" as much as you want.

 

[zroger73]

Very helpful. It seems that having it in Sport mode overrides the Manual mode, which is what I suspected.

@Akera, if you put it in Manual mode with the Sport mode off, you should be able to "bang the rev limiter" as much as you want.

Sport mode and manual mode are mutually inclusive.

When the shift lever is the M (manual) position and a gear is manually selected using the shift lever or paddle shifters, the engine will "bang the rev limiter" whether or not sport mode is on.

In my experience with the CX-9 (and as a few CX-5 owners have reported in the past), Sport mode doesn't change throttle sensitivity. I could be wrong, but I've played with it a lot and as far as I can tell, it doesn't.

The CX-5's owner's manual says only, "When the sport mode is selected, vehicle's response against accelerator operation is enhanced." It doesn't specify how "accelerator operation is enhanced". A blog on a Mazda dealer website says, "Sport mode increases the throttle response of your Mazda while also adjusting the shift points of your automatic transmission." This statement implies sport mode results in changes to the transmission and throttle.

The service information doesn't seem to go into detail, either. I've reached out to my Mazda PR rep for confirmation.

 

[sm1ke]

Sport mode and manual mode are mutually inclusive.

When the shift lever is the M (manual) position and a gear is manually selected using the shift lever or paddle shifters, the engine will "bang the rev limiter" whether or not sport mode is on.

Akera says he had the car shifter in Manual mode with Sport mode on, and he was not able to redline the car. So Akera was mistaken and the car was not in Manual mode, or Sport mode overrides Manual mode and automatically shifts the engine, or there is something else going on.

It's entirely possible that the throttle sensitivity changes, but in my (admittedly limited) experience, if it does change, it's imperceptible. Thanks for reaching out to your rep, hopefully he/she's got some answers.

 

[zroger73]

Akera says he had the car shifter in Manual mode with Sport mode on, and he was not able to redline the car. So Akera was mistaken and the car was not in Manual mode, or Sport mode overrides Manual mode and automatically shifts the engine, or there is something else going on.

It's entirely possible that the throttle sensitivity changes, but in my (admittedly limited) experience, if it does change, it's imperceptible. Thanks for reaching out to your rep, hopefully he/she's got some answers.

Yeah, sorry - I intended to assert that earlier. I believe @Akera had sport mode on and manually selected a gear using the paddles shifters without the shift lever being in the M position or had pressed the accelerator past WOT (until it clicks). If so, this would explain why the transmission upshifted before redline even when a gear was manually selected.

I do notice (or at least seem to notice) an increase in throttle sensitivity in sport mode. However, I'm usually driving aggressively in sport mode (i.e., WOT or launching using the brakes from a dig). If I can't get confirmation from my rep, I'll connect my data logger and compare the relationship between throttle angle and accelerator pedal position in sport and normal modes. That might be tricky, though, because vehicles with electronic throttle control are constantly altering throttle mapping based on many variables (i.e. reduced sensitivity for gentler driving at parking lot speeds, increased sensitivity when the A/C compressor clutch is engaged, etc.).

One thing I've noticed about my CX-5 is that acceleration runs are inconsistent. I've had better acceleration runs on 87 than 93 and on warmer days than cooler days in some instances - just the opposite of what you'd expect. It just seems to vary its demeanor at times and I've not been able to narrow it down to a specific set of conditions. Another reviewer (Alex on Autos or TheTopher on YouTube, perhaps?) noticed this same thing.

 

[CX-5um]

The Skyactiv turbo is built for torque and tuned to short shift to get to lower rpms for max MPGs. Just run it hard and don't worry about breaking it. Mazda capped it due to preserving mpgs plus there's not much power up there.

The Skyactiv gas engine in the Miata redlines to 7500 RPMs mainly from lighter pistons and connecting rods plus better spring valves. Wider throttle body to gulp more air. Plus of course it has a sportier tune.

 

[zroger73]

The Skyactiv turbo is built for torque and tuned to short shift to get to lower rpms for max MPGs. Just run it hard and don't worry about breaking it. Mazda capped it due to preserving mpgs plus there's not much power up there.

The Skyactiv gas engine in the Miata redlines to 7500 RPMs mainly from lighter pistons and connecting rods plus better spring valves. Wider throttle body to gulp more air. Plus of course it has a sportier tune.

Indeed. Having both a 2019 MX-5 Miata and 2020 CX-5 Signature in the fleet, I can confirm that the engines in these vehicles have very different characteristics. The 2.5T in the CX-5 loves the 2-5K range. the 2.0L in the MX-5 loves to rev to 7.5K. The CX-5 develops lots of torque at low RPMs while the MX-5 develops lots of horsepower at much higher RPMs.

 

[Akera]

I believe @Akera had sport mode on and manually selected a gear using the paddles shifters without the shift lever being in the M position or had pressed the accelerator past WOT (until it clicks). If so, this would explain why the transmission upshifted before redline even when a gear was manually selected.

Hi, I had the car in sport mode and the shift lever moved across for manual mode.
I haven't tried it in normal mode with the lever across in manual as I don't normally drive it that way.
I've raced and rallied for more years than I'll admit to so I can feel when an engine has passed it's power curve and it's time for another gear. It's just I was surprised with the CX5 that it didn't give me the option to feel that for myself and seemed to short shift on me.
I rarely take an engine to redline as I can feel it's not necessary .
Like this car more and more though..just need some sway bars