This is the first time I have ever owned a car with a turbo but I am unsure how it operates. All I know is that it spins with exhaust gases and power comes in from 1500 rpm. Now, is is continually spinning while the engine is running but leashes its power at 1500 rpm upwards when the throttle is opened for acceleration. What is the turbo doing when I am cruising at 70 mph? Also, there is no turbo 'sneeze' these days.

The turbo will still be spinning at 70mph but not as much boost. On my 1.6 TDi when you go full throttle and it kicks in at 1700rpm peaks at 23 psi then holds just over 22psi till about 4000rpm then it tails off.

 

At 70mph on cruise control its normally at 12psi of boost.

25 minutes ago, edbostan said:

This is the first time I have ever owned a car with a turbo but I am unsure how it operates. All I know is that it spins with exhaust gases and power comes in from 1500 rpm. Now, is is continually spinning while the engine is running but leashes its power at 1500 rpm upwards when the throttle is opened for acceleration. What is the turbo doing when I am cruising at 70 mph? Also, there is no turbo 'sneeze' these days.

 

The turbo is spun by the exhaust gas exiting the cylinders, the other end of the turbo is located on the air intake and compresses the air so is higher density in the cylinders, the more air (including oxygen) in the cylinders the more power can be generated.

 

Turbo always runs, you will forget it is even there.

However when cruising, the electronics that govern the fuel injection tend to dominate the process, allowing fuel to be used more sparingly, the inlet pressure can be reduced by a waste valve. 

Edited 19 March, 20188 yr by SurreyJohn

Thank you for both replies. I now understand the workings of the turbo. Manufacturers add these gizmos without educating the users. An explanation in the driver's handbook would be useful as driving with a turbo does influence driving technique as I have found.

14 minutes ago, edbostan said:

Thank you for both replies. I now understand the workings of the turbo. Manufacturers add these gizmos without educating the users. An explanation in the driver's handbook would be useful as driving with a turbo does influence driving technique as I have found.

with a turbo, when you park you car at the end of journey let the engine idle for about a minute; so the turbo  still has oil being feed to it while it "spools down" and starts to cool (they get very very hot.) this practice keeps the turbo's bearing's in good condition and will prolong the life of it.

Edited 19 March, 20188 yr by Ju1ian1001

^^^ Or maybe do not bother, as Stop / Start came about and 1.2 TSI's do just fine being driven and stopped as designed without the need to sit with the engine on after reaching your destination on UK NSL roads,, even if pulling into Motorway Service stations.

 

Any turbo issues being reported are the actuators on some, and that has nothing to do with not leaving the turbo to run a while.

After it’s turned off the oil still gets pumped around the turbo to cool it you can hear it. 

There is a water pump running if required.

Interesting points. I drive like Miss Daisy so the turbo is not put to any strenuous use. I must say though that when I drove through the Alps with high altitudes I left the engine running to allow it to cool down slightly before turning the engine off as I don't know if the cooling fan still runs for a time after switch off. On a previous alpine trip with a Fiat Multipla I turned the engine off after a long climb and quickly turned it back on when I heard hissing from the expansion tank. Lesson learned.

Edited 19 March, 20188 yr by edbostan

15 hours ago, AwaoffSki said:

^^^ Or maybe do not bother, as Stop / Start came about and 1.2 TSI's do just fine being driven and stopped as designed without the need to sit with the engine on after reaching your destination on UK NSL roads,, even if pulling into Motorway Service stations.

 

 

or is "the engine has just been given a hammering" one of the "don't stop this time" conditions for the auto stop start?  

Only car I've had with auto stop start was my wife's Toyota (non turbo).  On several 80 mile runs down the M1 to Junction 26 it always surprised me that the auto stop/start never operated at the junction traffic lights.  I concluded that it needed to keep the coolant circulating to remove the heat soak.  Similarly a turbo engine may use the same logic to keep the lubrication going to the turbo.

19 hours ago, edbostan said:

Thank you for both replies. I now understand the workings of the turbo. Manufacturers add these gizmos without educating the users. An explanation in the driver's handbook would be useful as driving with a turbo does influence driving technique as I have found.

 

I've owned 4 turbo cars (3 diesels and 1 petrol) and have driven countless other company pool cars and rental cars.  Can't say I've ever driven any of them specifically differently on account of the turbo.  They are just bits of the engine that are there and (hopefully!!) work.   

19 hours ago, Ju1ian1001 said:

with a turbo, when you park you car at the end of journey let the engine idle for about a minute; so the turbo  still has oil being feed to it while it "spools down" and starts to cool (they get very very hot.) this practice keeps the turbo's bearing's in good condition and will prolong the life of it.

 

Been driving petrol and diesel cars with turbos (and superchargers) since 1996 and have never let one idle after driving it. I just drive them normally enjoying the smooth power from 1500 rpm to the redline which is brilliant compared to the peaky power delivery a modern 16 valve petrol gives (Hondas are about the worst). In all that in and probably 30,000 miles the only problem we have had was a vacuum pipe that was crimped during manufacture and that was in 1996.

 

The only concession I make is to change the oil every 12 months even on cars with long life/variable servicing. The correct oil and filter is under £30 DIY so its daft not to.

 

Just drive it normally and enjoy.