I know I've touched on this subject before, but is it really necessary to let an Impreza idle for a long period before driving off? I first noticed it when one of my neighbours acquired one and he used to allow it to idle for 10 minutes or more. Another neighbour has now also got one and he allows his to idle for some time, although admittedly not for as long as the other neighbour. I can't see the point of having an Impreza for everyday use if you have to do that. If I started my car at the same time as these neighbours I'd be long gone by the time they got to drive off, so their power advantage would be completely wasted.
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L\'escargot.
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No. its not necessary at all. A few moments of idle (whilst you put on seat belt, adjust heating) is enough to allow oil to get around the turbo etc. Once you drive off then ideally keep off boost (i.e. keep the revs down) until the oil has warmed up a bit - just a mile or two.
Presumably these guys are trying to warm the cars up so they can hammer them as soon as they leave the driveway.
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I would say not.
All turbo cars I've owned, I start them and let them idle for a minute or so to get the oil circulating then drive off keeping the revs down until the water temperature guage gets up above 80-ish.
Same when stopping. Drive the last few miles home off boost and let it idle for a minute or so before switching off.
I only let it idle longer if pulling into a service station/area after a fast run to let things cool down before switching off.
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In fact allowing it to idle before leaving isn't going to warm the car up anyway. Also leaving it to idle will cause heat soak as there in no cooling onrush of air. Heat soak kills power on turbo cars. What they are in fact doing is wasting petrol, making their car slower and causing excess wear in the vital start up period.
They're idiots.
Also a mile or two isn't enough to allow for warming on any car let alone a turbo Impreza. I'd say more like 5 miles minimum as backed up by the oil temperature guages I had fitted to all my Imprezas.
Leaving the car to idle after a hard run is of course good practice with any turbo car to prolong life.
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I'd add that the water temperature guage gets upto temperature well before the oil. In my Imprezas, Audi, VW and every other marque I've owned fitted with oil temp guages.
I wouldn't rely on that as a way of telling if the engine is warmed up.
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>Leaving the car to idle after a hard run is of course good practice with any turbo car to prolong life.
But as Gmac says, there are very few situations in normal driving where you can go straight from high-speed, on-boost use to an engine-off stop. Even trundling into a service area, negotiating the chicanes and reversing into a parking space is enough to cool things down in most cases, isn't it?
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I don't agree. After a few hours at 90mph thirty seconds coming into the petrol station isn't going to be enough to allow the turbo oil to do it's job of cooling it down. You run the very real risk of it overheating and carbonising and thus shortening turbo life.
Personally I leave it to idle for at least a minute.
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Why do you monitor the oil temperature OldHand ?
I know VW and Audi used to fit these as standard to their performance models but generally found the oil settled at about 10 degrees warmer than the water temp.
What does it matter if the oil takes a little longer to get upto temp. ? Is that not why we have multi-grade oils so they work through a range of temps.
Is general engine temp. and oil pressure not more important ?
Not baiting here, genuinely interested in why oil temp. is monitored.
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I just use the oil temperature as a guage of whether the car as a whole has warmed up. There's more to warm up than just the engine or coolant system as I'm sure you know.
If the engine oil is upto running temperature then it's likely that everything else is as well.
As far as the multi grade argument goes I thought it was the case that the oil still lubricates and protects better at running temperatures than when it's cold.
I guess what it comes down to is mechanical sympathy and not wanting to flog a high tech piece of engineering.
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So does that mean that every time someone with a turbo car pulls in for petrol you have to sit outside the petrol station idling for minutes while everyone else just goes and fills up, pays and leaves before you've managed to get near the pump. Imagine that would make every trip rather tedious especially if you had to do it in Tescos, going to visit friends....The advantage of getting their quickly is sort of negated...
Is it possible to get any device that can manage the idle/cooldown process automatically? ie you "switch off" and the car idles until a device finally shuts it down a few minutes later?
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Is it possible to get any device that can manage the idle/cooldown process automatically?
Yes, a 'turbo timer'.
www.blitz-uk.co.uk/Product-26.aspx
I was at a filling station a few weeks ago and a lad in a modified Impreza turned up, got out with the engine still running, locked the car remotely and went in to buy a paper. I'd heard of them but that was the first time I'd seen one being used.
;o)
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First time I've heard of an Impreza driver buying reading material - unless he just needed it to mop up an oil leak.
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I just use the oil temperature as a guage of whether the car as a whole has warmed up. There's more to warm up than just the engine or coolant system as I'm sure you know.
I personally just use the water temp and oil pressure as good pressure and normal water temps. are the usual indicators all is well. I've never had an engine or turbo blow.
If the engine oil is upto running temperature then it's likely that everything else is as well.
Can't argue with that though the twenty mins. or so it can take for this to happen can be as long as, or even less than, some peoples entire journeys. Guess these are the people who don't care or know about your later point of mechanical sympathy though twenty minutes can easily cover a ten mile plus commute (if you live outside the SE of England).
As far as the multi grade argument goes I thought it was the case that the oil still lubricates and protects better at running temperatures than when it's cold.
I thought it was different grades were for different conditions. Thiner at low temp to get round the engine quicker and start protecting, thicker at higher temps to stay on surfaces with closer tollerances.
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It is true that the oil temperature is a more accurate indicator of internal engine temp than water temperature. However it is not normally necessary to wait for the engine to fully warm up - this might take 20+ miles in winter. Modern oils do a pretty good job of lubricating, just give it a few miles and it should be OK, perhaps a bit further in the winter.
Incidentally, I believe that turbo-timers are not legal in UK, nor are remote-starters. Something about leaving the engine running on an unattended car.......
As regards shut-down, well modern turbo's do run very hot, up to 1000degC in the extreme, however most are now water-cooled and this keeps the bearing temperature down so there is little chance of oil burning on the shaft, especially with a modern fully-synth oil. I therefore don't think you have to worry too much about extended idling after a hard run, just give it a minute or two to slow down.
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I don't bother - the second owner can worry about it :-)
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There does seem to be a lot fuss/hype about turbos.
Use good quality oil and filter and change regularly.
allow engine to warm before full power applied. Ok to drive away as soon as car started and seat belts put on etc.
See advice sheets that come with turbos, and/or talk to turbo specialists will second this.
Allow to cool at idle for 30 seconds after a prolonged high power drive, or for a few seconds after normal drive. Approach to motorway petrol pumps at non turbo speeds will be sufficient to do this.
Neglect oil, use full power too soon = problems, otherwise should be ok for years.
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I suppose I should have asked in my original post whether it was recommended by the manufacturer to let a turbo car idle before driving off. If it was I wouldn't buy one. I want a car that I can drive off in as soon as the engine has been started not one which has to be molly-coddled.
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L\'escargot.
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Cue the Maestro with the non turbo Perkins Prima :)
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I think these guys are very mis-informed.
Idling the car is a very bad thing to do. Especially for more than 5 mins and thats in traffic when the car is warm. The imbalance of air intake during the combustion process whilst idling creates condensation from the un-burnt fuel on the cylinder walls. This residue eventually makes it way into the oil sump and reduces the oil's effectiveness as a lubricant and therefore reduces the life of the engine oil. You know how important oil is in a modern engine especially a turbo-ed engine.
Newer turbo's these days dont use the oil babbitt bearings of the past which could coke and seize up if you suddenly turned the engine off. Oils these days are also resistant to coking so turning your engine off straight away shouldn't cause too many problems, however doing this will slightly shorten the turbo's life. It is best to take it easy, stay off boost - no more 1.6k rpm to allow the turbo to cool before you stop if you dont want to sit for a minute or 2 letting it cool.
I drive a Toyota t180 which is fairly quick with a decent sized turbo - i always allow the turbo to cool for around 1 minute at driving between 30 and 60mph. THis allows any spinning inertia to dissipate and for the bearings to cool and to prevent heat soaking. This should maximize the life of the turbo and allow the car to run more efficiently. THe idle time is increased to near 2 minutes for motorway driving above 70mph as the turbo is constantly working. I would also recommend for cars with bigger turbo's lets say, BMW 335d, Impreza's for example to idle longer around 2mins but no more.
Turbo health is very important because if they go they will usually take the whole engine, cat and maybe other bits with it. Its is also a good idea to take the car up to max revs through the gears where possible to clear out burnt particulate from a diesel engine. With regards to idling before you go, 10 - 15sec should be more than adequate if you must, just to get the oil circulated, there is no way idling a car warms it up! Get into the habbit of starting the car as soon as you get in. You will be doing other things and by the time you are ready to go the oil will be fully circulated. Take it easy, keep off boost until your oil / engine is warm on the gauge.
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My car manual has no precautions for starting a turbo engine and the following for turning off:
Precautions for turning off a turbo engine (3S-GTE engine)
After high-speed or extended driving, etc., requiring a heavy engine load, the engine should be allowed to idle, as shown in the chart, before turning off.
Driving condition and required idling time
Normal city driving - Not necessary
High-speed driving
About 80 km/h (50 mph) - About 20 seconds
About 100 km/h (63 mph) - About 1 minute
Steep mountain slopes or continued driving above 100 km/h (63 mph) - About 2 minutes
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The time for idling is on a freezing day when you have already driven a few miles and have the choice to switch off and re-start... better to keep things toasty warm. Especially for a diesel which takes longer to heat up, and burns less fuel when idling.
I am not a fan of those cars which switch off the engine every time you stop momentarily, at least if the car is not yet properly warmed up I think it is counterproductive.
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I've never taken any silly precautions with any of my Turbo'd cars, and in the combined 500,000+ miles I've driven in them, I've never had any issues with any of them.
I guess I've just been lucky?
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I do try and let my 1.9TD ZX idle a minute or so before turning off. Sometimes I get back late and the neighbours probably hear the noise, but that's life I suppose - I have to live with their barking dog so they'll have to live with my engine idle.
The problem I have is that I live on a 40mph busy main road (average speed: 50...). I usually have to accelerate quite hard in to a gap in traffic to get out of the drive. I am a bit stuck really then, as I don't have much choice but to use the Turbo just after turning the engine on. I do keep off of the power, after that, until the engine has warmed up.
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