I have been to Beartooth Highway a couple years back and one of my passengers told me that I should I use engine braking instead of just my vehicles brakes. Going down that mountain could burn my brakes if I do not engage engine braking. So the question is with 2014 LX 570, can I simply switch to sports mode and shift the gear manually that way? Will this cause any harm when using engine braking? Thank so much!
Can I use engine braking when going down hill? (2 Viewers)
- Thread starter Charlielj
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hoser
SILVER Star
That is exactly what you should do. I would also try to keep the RPM's under 4500.
- Thread starter
- #3
Thanks! It's my first time and I want to make sure I didn't cause any issue to the vehicle.
Always engine brake downhill. The bigger the mountain and/or the heavier you are, the more important this is. Engine brakes have infinite heat capacity. Caliper brakes and rotors can be overheated. At which point it can be a runaway vehicle situation.
The ECU will not allow you to do anything that will compromise the engine. Yes, use sport and downshift. The ECU does have engine braking logic but it will generally provide only a modest amount of engine braking automatically.
There is no such thing as needing to limit to 4500rpm (again ECU will protect things and not allow an overrev). Just as you can accelerate with the full rpm band to redline, you can decelerate with the full rpm band. The more rpm, the more engine braking. I have been in extreme grade situations, full vehicle and full trailer, 110°F temps, sitting in first gear at 5,800rpm redline. That was an extreme hill in Death Valley.
When towing or hauling heavy, downshifting is a critical skill. You can literally overheat and burn up the brakes in a single large grade, at which point it will be a runaway situation and emergency brakes won't be sufficient.
If you ever feel the brakes not responding with the same amount of braking force, that's the first sign you need to ease up on the caliper brakes to stay well away from what can be an emergency situation.
The ECU will not allow you to do anything that will compromise the engine. Yes, use sport and downshift. The ECU does have engine braking logic but it will generally provide only a modest amount of engine braking automatically.
There is no such thing as needing to limit to 4500rpm (again ECU will protect things and not allow an overrev). Just as you can accelerate with the full rpm band to redline, you can decelerate with the full rpm band. The more rpm, the more engine braking. I have been in extreme grade situations, full vehicle and full trailer, 110°F temps, sitting in first gear at 5,800rpm redline. That was an extreme hill in Death Valley.
When towing or hauling heavy, downshifting is a critical skill. You can literally overheat and burn up the brakes in a single large grade, at which point it will be a runaway situation and emergency brakes won't be sufficient.
If you ever feel the brakes not responding with the same amount of braking force, that's the first sign you need to ease up on the caliper brakes to stay well away from what can be an emergency situation.
Use any gear needed to go downhill without using the brakes at all. Shift multiple times as you find which gear limits speed just right. The programming won’t let you shift into so low a gear you over-rev the engine. If you try, it will just beep at you. And just to make sure you know how sport mode works, the transmission shifts normally, but only up to the gear you’ve selected.
What does the ECU do to protect the engine?
Like if the RMP’s get too high, will it switch the gear or something?
I have always been afraid to let the RPM’s get into the red when either accelerating or using the engine as a brake.
Edit: I mean beyond beeping at me as mentioned above.
Like if the RMP’s get too high, will it switch the gear or something?
I have always been afraid to let the RPM’s get into the red when either accelerating or using the engine as a brake.
Edit: I mean beyond beeping at me as mentioned above.
If you're moving at a speed too high for a particular gear (that would cause the engine to over-rev), it will not give you the gear you requested. E.g. if you try to shift into 2nd at 75mph it will simply not shift and beep a "don't be an idiot" warning at you. It's like the ECU's rev-limiter, but in reverse. If you're already in 2nd, it will hold speed at/below redline in my experience. I've never gone down a hill steep enough where I really had to test it though.
I usually engine brake on any significant hill, but use a combination of engine brake and friction brakes. The engine braking allows you to "go easy" on the friction brakes so you don't cook them. Brake pedal only needs a light touch. It's not really necessary to engine brake on short hills, but just a good practice and something I do out of habit on all hills of pretty much any size. I found the stock engine braking pretty weak, but 4.88 gears made it much more effective (not saying you need that, just an observation).
I usually engine brake on any significant hill, but use a combination of engine brake and friction brakes. The engine braking allows you to "go easy" on the friction brakes so you don't cook them. Brake pedal only needs a light touch. It's not really necessary to engine brake on short hills, but just a good practice and something I do out of habit on all hills of pretty much any size. I found the stock engine braking pretty weak, but 4.88 gears made it much more effective (not saying you need that, just an observation).
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kcjaz
SILVER Star
Really? I didn’t know that I thought it just stayed in whatever gear you selected. When I’m wheeling in ascending anything fairly steep, I always put it into first gear when I’m climbing. When climbing in first and shifting into second, the rpms always drop. I guess it’s just means the ECU prefers second (lower rpm) in that situation. I generally like higher rpms (1500-2000) when slowing crawling my 8500 lbs up a steep trail as I figure this helps with engine cooling in that situation.
On a separate note, I applaud the OP for asking the question and also the respondents who clearly answered his question in a non-condescending way. A lot of car forms are not this way. Well done.
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One should/can use engine braking on any descent. But one does not necessarily need to down shift. I get lots of miles out my brakes (and better gas mileage) by simply taking my foot off the accelerator on descents and coasting. 9/10 when traveling at highway speeds and I see intermitant brake lights ahead I just let off the accelerator, that slows me down enough that I rarely have to brake. Though my foot is ready to brake if needed. In addition, it is worth noting that one should pump the brakes rather ride the brakes. If one ever wants to know what hot brakes smell like, wait at the bottom of any hwy that goes up to a ski resort. I guarantee there will be multiple vehicles coming down with hot brakes.
Lol, we stayed at a hotel in Silverthorne once, right next to I-70 at the bottom of the Eisenhower/Johnson tunnel hill. The whole hotel parking lot reeked of cooked brakes and you could even catch a whiff inside 
FrazzledHunter
SILVER Star
On our recent mega-trip out West I actually got adept at multiple downshifts when going downhill so as to keep the RPM's at 4K-4.5K and under. I also learned to up-shift at just the right time at hill's bottom so as to get a "run shot" and the next up-hill climb as I hated to floor it just to maintain 45mph!!!
It became instinctive after a while, listening to the engine purr. I just had to remember back to my old days of driving manual transmissions.
It became instinctive after a while, listening to the engine purr. I just had to remember back to my old days of driving manual transmissions.
hoser
SILVER Star
4500 rpm certainly is not the limit but I still recommend it to the OP. It gives leeway for another downshift, if needed. Less noise, less vibration. Why not just have a nice conversation with your co-driver instead of staring at the tachometer. If at redline, and the decline gets steeper, you can exceed redline if you don't brake. Redline is 30% higher rpm. Not going to break anything but 30% more wear on water pump, oil pump, etc.
Steepest road grade I've been on with my trailer is the Sonora Pass. 26% grade at some points!
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I drove that I-70 pass for the first time in my truck a couple years ago. Drove it in my V70 R about five years ago. It's no joke.Lol, we stayed at a hotel in Silverthorne once, right next to I-70 at the bottom of the Eisenhower/Johnson tunnel hill. The whole hotel parking lot reeked of cooked brakes and you could even catch a whiff inside
I just slip gear selector into S, which typically goes into 4th gear at highway speeds, and I play the game of how little I can use my brakes to control the descent speed. If necessary and available, a quick tap of the gear selector shifts to 3rd gear. All while "talking" to the other drivers to quit using their brakes. It pains me to see drivers follow each other so closely on the decent.
My family has grown accustomed to the gear shift and rpm rise sensation, so they no longer question why the engine runs at higher rpms. Time will tell if my daughters retain the knowledge for when they drive mountain passes.
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I get what you're saying and in typical use, this may help calibrate some expectations.
Like caliper brakes, we don't generally say not to use more that 50% braking for example. You use what you need to be safe.
Engine braking is the same. When towing heavy enough, engine braking even in first gear may need the full rpm band to avoid overheating the caliper brakes. Especially at elevation where the air is thinner. I've
even used used low range in some really steep sections.
Coming from the sports car would, going deep into corners late braking with heavy engine brakes is also a thing. My fault and for indulgent entertainment but I can still overheat and eat up some good pads.
One caveat I would offer is to watch engine breaking on slick, snow covered descents. In those situations I use manual braking so I can control any skid.
