Turbo Engine - Please Educate Me How to Drive & Care

Joined
Jul 11, 2015
Messages
7,723
Location
New England
my wife did nothing special with her 2005 Subaru Legacy GT 2.5 turbo wagon she owned from new to 14yrs/240k miles. She changed oil every 4K Dino (the horror!) and simply drove it not hard nor easy. Not a single turbo issue.

Don’t believe cool down so many seconds or minutes stuff because most people drive sanely and slowly after hard because they pull into a parking lot/space slowly. Also don’t floor it cold and you are good.

My wife never warmed her car from work, just drove a 1/2 mile onto highway home.
 
Joined
Dec 15, 2002
Messages
1,336
Location
Simpsonville SC
Turbo "cool down" is to let it spin down to sane speeds. With more responsive smaller turbos these days that can happen as you drive to the house and pull into the garage. Plus, almost ALL modern turbo cars have water cooled snails and the auxilliary coolant pumps operate for several minutes after shut-off (thats the sound you hear running) to prevent galling the bearings or coking the oil.

Good call on shorter OCIs. Don't know about Mazdas, but most forced induction engines have higher fuel dilution and that, with some moisture, and EtOH, will kill the oil over a longer interval. And run it in sport mode from time to time to keep RPMs up and the smile on your face. Happy Motoring.
 
Joined
Feb 15, 2003
Messages
13,412
Location
Jupiter, Florida
Choose a quality synthetic oil of adequate viscosity, change it regularly. A really good way is to simply change every 5000 miles, on the "5's" 5000, 10,000, 15,000 etc.

This helps reduce the oil related issues that can happen with direct injection/turbo engines. Issues such as fuel dilution, excessive particulates, deposits on pistons/valves and so on.

Nothing else will make as much difference as the above. Drive it like any other vehicle. The cool down time happens during parking.
 
Joined
Jul 14, 2020
Messages
868
Location
California
Sparky, I use nothing but 91 octane in my CX 5. Gas is expensive here in Southern California, close to $5 a gallon lately but I don't drive much so it's not a big deal. I like getting the full power from the engine. One thing I really like about the Mazda 2.5L turbo engine is that it makes a lot of torque at low RPM's and I imagine that is partly due to how the turbo is programmed. I live in the mountains and make runs down to the nearby city for groceries, Home Depot, etc. With a good amount of cargo the car still pulls like crazy going back up the mountain and the transmission is well matched to the torque and horsepower curves.

I do give it an Italian Tuneup once in a while. A battery tender is not a bad idea if you don't drive it often, short drives won't keep the battery fully charged which will probably lead to shorter battery life.
 
Joined
May 17, 2021
Messages
1,800
Location
open range
Just drive it.

I use to drive turbo'ed vehicles for decades and never had to replace a turbo.
The only turbo related issue I ever had has been with a sticky VTG on a Diesel,
however your Mazda doesn't have a VTG turbo.
There's simply no need to idle before shutting off after normal driving in town.
Consider doing that when towing and climbing hills.
Thoroughly perform maintainance, use proper synthetic oils and filters and do
enjoy your car. OCIs of 5,000 or 6,000 mls sound quite reasonable to me.


I suppose I should floor DI engines once in a while to avoid carbon build up, tried to floor to hit the red line, but reaches the speed limit++ long before hitting the floor, any advice, please?

There is no need to rev it to redline. The inlet valve temperatures are what
actually matter to IVD. Just give it some boost at mid revs from time to time
and over extended periods of time.
Using oils with a high flashpoint and low Noack may likely help and certainly
doesn't harm.
.
 
Joined
May 6, 2005
Messages
8,890
Location
San Francisco Bay Area
The whole thing about a "cool down" is something that was for older turbos that are oil cooled. Especially if there's a lot of pressure and they're spinning. Letting it "cool down" at idle would supply oil to them while they were allowed to slow down. If they weren't, the bearings would get really hot with only a small amount of oil in the bearings, which would get really, really hot and the residual oil would turn into "coke".

Pretty much any new turbo is water and oil cooled. It might make sense to let it cool down a little if you're coming right off of the freeway and stopping at a gas station next to the exist, but these days it doesn't matter as much. The cooling system will always draw hot coolant from the turbo housing to the reservoir - what's called a thermosiphon and that keeps the bearings from overheating. The reservoir has to be higher though, and most turbocharged cars these days will have a high reservoir located towards the front. Not sure what happens if one parks downhill, but I guess that's a consideration in the design.



Not sure exactly how Mazda does it, but Subaru typically has this really visible metal tank and the coolant fill is supposed to be via the high tank and not the radiator.

I found it for the Mazda, and the coolant fill (and apparently high tank) is tucked next to the engine cover. Notice that the non-turbo versions have an actual radiator cap, while the 2.5T has a cooling system cap located closer to the engine.


07030300-kfusa01-005.png
 
Joined
Mar 4, 2017
Messages
24,774
Location
...
The whole thing about a "cool down" is something that was for older turbos that are oil cooled. Especially if there's a lot of pressure and they're spinning. Letting it "cool down" at idle would supply oil to them while they were allowed to slow down. If they weren't, the bearings would get really hot with only a small amount of oil in the bearings, which would get really, really hot and the residual oil would turn into "coke".

Pretty much any new turbo is water and oil cooled. It might make sense to let it cool down a little if you're coming right off of the freeway and stopping at a gas station next to the exist, but these days it doesn't matter as much. The cooling system will always draw hot coolant from the turbo housing to the reservoir - what's called a thermosiphon and that keeps the bearings from overheating. The reservoir has to be higher though, and most turbocharged cars these days will have a high reservoir located towards the front. Not sure what happens if one parks downhill, but I guess that's a consideration in the design.



Not sure exactly how Mazda does it, but Subaru typically has this really visible metal tank and the coolant fill is supposed to be via the high tank and not the radiator.

I found it for the Mazda, and the coolant fill (and apparently high tank) is tucked next to the engine cover. Notice that the non-turbo versions have an actual radiator cap, while the 2.5T has a cooling system cap located closer to the engine.


07030300-kfusa01-005.png



Another thing Mazda incorporated for the turbo SkyActiv is EGR cooling. If the OP looks under the front of his car he will see part of that apparatus.




And here is a video that explains it well.


 

Sparky16

Thread starter
Joined
Sep 27, 2020
Messages
201
Location
Vancouver, WA
I found it for the Mazda, and the coolant fill (and apparently high tank) is tucked next to the engine cover. Notice that the non-turbo versions have an actual radiator cap, while the 2.5T has a cooling system cap located closer to the engine.


07030300-kfusa01-005.png

Thanks for the great explanation on how the Turbo works.
Lucky for me, my driveway is very stiff uphill, I was wondering if it might adversely effect the cooling, I can breathe much easier, appreciated.


Another thing Mazda incorporated for the turbo SkyActiv is EGR cooling. If the OP looks under the front of his car he will see part of that apparatus.




And here is a video that explains it well.




I noticed that cooling fins, thought it was trans cooler, thanks!

Thank s to all contributing great advices, these are exactly what I wanted to know, much appreciated. (y)(y)(y)
 
Joined
May 6, 2005
Messages
8,890
Location
San Francisco Bay Area
Thanks for the great explanation on how the Turbo works.
Lucky for me, my driveway is very stiff uphill, I was wondering if it might adversely effect the cooling, I can breathe much easier, appreciated.




I noticed that cooling fins, thought it was trans cooler, thanks!

Thank s to all contributing great advices, these are exactly what I wanted to know, much appreciated. (y)(y)(y)

I'm not an expert on this, but I remember hearing about the thermosiphon effect. The video from Garrett shows that they recommend the housing be mounted where the coolant inlet hose is at least 20º lower with respect to the outlet hose. It's supposed to draw lower temp coolant from the radiator up to the hotter coolant in the upper tank.

Cool down did a lot of different things though. It still might make sense even with water cooling if it's too hot. When the oil flow is cut off, it's just the residual oil there to lubricate the bearings. So obviously it gets hot because the bearings still transfer the heat to what little oil is left. There's energy in the turbo spinning, so cooling it down will minimize that energy when it's shut off. And turbo housings can literally glow orange, so it can be a good thing if it's that hot when shutting down since the hotter it is, the more likely that the residual oil is going to coke up. However, turbos almost never coke up any more because of water cooling.



My 2004 WRX has over 170K miles on it. It isn't without problems, but I've never had a problem with the turbo.
 
Joined
May 17, 2021
Messages
1,800
Location
open range
What you see behind the lower grille is the Intercooler to
increase efficiency, power and torque.
EGR cooling has little to do with that and also little effect
on turbo temp. EGR cooling is implemented to reduce NOx
emissions. It's common on Diesel engines for two decades.

Videos of red glowing turbos aren't helpful. This happens at
full throttle for some extended period of time, not so when
driving on a freeway. The OP's turbo will most likely never
ever see such temperatures.
 
Last edited:

Pew

Joined
Mar 12, 2018
Messages
2,265
Location
IL
I wouldn't worry about a turbo getting hot enough to glow red - you're doing some highly illegal stuff there for a very long time if you manage that on the streets and by that point you'd probably be worried more about the cops.

I also wouldn't worry about letting it cool down before shutting off the engine unless you like to do multiple 0-100 pulls down your street straight into your driveway.
 
Joined
May 6, 2005
Messages
8,890
Location
San Francisco Bay Area
What you see behind the lower grille is the Intercooler to
increase efficiency, power and torque.
EGR cooling has little to do with that and also little effect
on turbo temp. EGR cooling is implemented to reduce NOx
emissions.
Videos of red glowing turbos aren't helpful. This happens at
full throttle for some extended period of time, not so when
driving on a freeway. The OP's turbo will most likely never
ever see such temperatures.

I'd note for anyone reading this that intercoolers only cool the charge air that's blown into the engine from the turbo, since the whole idea is to get as much air as possible into the engine. Engines are really just air pumps really, where the amount of fuel is supposed to match the amount of air where there should be as little unburned fuel and unused oxygen as possible. Aren't the terms rich or lean?

And the intercooler can have different locations. That version obviously gets air from the grill, but quite a few use hood scoops - especially Subaru turbos, where the intercooler sits horizontally and is fed directly by the hood scoop, and even sealed to some degree to make sure as little air as possible bypasses the intercooler. Doesn't seem to be working in this case though where these guests seemed to have made a home of the hood scoop and intercooler.

bees-nesting-in-subaru-wrx-sti-intercooler-are-not-cool-87646-7.jpg
 
Joined
Nov 29, 2021
Messages
4,509
Purchased a 2019 Mazda CX-5 with 2.5L Turbo engine, my first vehicle with Turbo engine, need some help from experienced folks.
I've read "not to drive until the engine has warmed up", "don't shut-off the engine right away", need some clarification on these two more than anything else.

Just a few minutes ago, the car starts right up idling at around 1,450 RPM, goes down to 1,200 after 30 seconds, took full 1 minute to reach 1,000. After 3 minutes it's hair below 1,000 RPM. The ambient temperature was 42℉. I usually drive off after 30 seconds of idling, but the OM says, "After starting the engine, let it idle for about 10 seconds". I then drive 25MPH for 3-4 min to reach 45MPN zone street.

The OM also says, "After driving at freeway speeds or up a long hill, trailer towing for a long time, idle the engine at least 30 seconds before stopping it. Otherwise, the turbocharger could be damaged". I have to drive 25mph before reach my driveway, do I still need to idle 30 seconds before turning off the engine?

Please feel free to give any and all advices so I can get clear idea , as I'm hoping to keep this CX-5 for 15 years/150,000 miles or longpassion, feeling, and zoomve with passiom,
Drive with passion, feeling, and zoom-zoom.

Use the manufacturer recommended oil grade and you will be fine.
 
Joined
May 6, 2005
Messages
8,890
Location
San Francisco Bay Area
Just thinking about it with a new post. Everything is really just based on the ideal gas equation:

PV=nRT


Pressure x Volume = Amount of air x Ideal gas constant x Temperature.

A turbo is usually regulated to a maximum boost pressure. So if you want to get in more air, then reduce the temperature, where:

n = PV/RT

Since the maximum pressure is regulated and volume doesn't really change, the only thing that can boost the amount of air molecules is to lower the temperature.
 
Top