Diesel vs petrol

SauRoNZA

SauRoNZA

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Drifter said:
I never let my car idle before I leave in the mornings. Start up and take it easy till ideal operating temps are reached.
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If you generally don't drive like a vark it not too much of a problem.

For me it's easy at the moment because I start the car, then load the baby and then let the wife drive off so it has a wee bit of warm up time.

If I left it up to her...
 
Dan C

Dan C

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Drifter said:
I never let my car idle before I leave in the mornings. Start up and take it easy till ideal operating temps are reached.
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This, I'm sure it's better to get it to a good temperature as soon as possible.
 
Pitbull

Pitbull

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ice_cubes said:
:D
Hi Pitbull, guilty as charged. Decided to get rid of that memory by getting a new set of wheels :)
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Congrats :)

New life and new beginnings. Wishing you all the best. Diesel is the wise choice, being a Merc even more so. You'll be extremely happy.
 
ice_cubes

ice_cubes

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SauRoNZA said:
You don't need to wait for it to get to temperature or anything like that, especially not with Unleaded cars, but especially now that you have a Turbo it's a good idea to just give it at least 30 seconds to a minute to circulate before driving off.

At the very least if you cold start and drive off don't nail it for the first few kilometers.
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I'll have to change my morning routine...I usually load everything -> start car -> drive off. I will start the car and then load everything before driving off *sigh*
 
M

Mr.Jax

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SauRoNZA said:
Actually you are both sort of wrong and sort of right.

Power actually doesn't exist. It's a calculation based on torque...not a measurement.

So without Torque you can't really have power :).


But more correct would be stating that Power = Top Speed. Torque = Sleeping a Caravan with a car full of people and luggage going up a hill and hardly noticing.
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Yup, power (at a specific RPM) is a calculation of torque at a specific RPM. ( Torque (N.m) x Speed (RPM) / 9.5488 = KW at said RPM )


Diesels have a lot less "power" because the torque band is quite "narrow" (at high RPM a diesel has very poor torque output because diesel burns too slow).
 
C

Colin62

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AntennaMan said:
The reason for idling before switching off is to let the turbo cool off. During operation, especially when driving on the highway, the turbo spins up and reaches incredible rpm's. This generates a lot of heat and the turbo will become red-hot.
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Not really. It's because the turbo spins at speeds of up to 250 000 rpm, and if you switch off the engine, the oil is no longer being pumped, so the turbo spins for a while as it slows down with no lubrication on it's bearings.
 
ice_cubes

ice_cubes

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AntennaMan said:
An Audi mechanic friend of mine told me that most turbo failures he saw was due to the bushes "burning through". Alternatively the turbo will just disintegrate.

It is possible to install a "turbo protector" on some diesel engines. This device keeps the oil pumping through the turbo even after the ignition has been switched off. Some, not all, modern diesel cars come with a similar system pre-installed.
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Is it that buzzing sounds that continues long after the car has switched off?
 
M

Mr.Jax

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Colin62 said:
Not really. It's because the turbo spins at speeds of up to 250 000 rpm, and if you switch off the engine, the oil is no longer being pumped, so the turbo spins for a while as it slows down with no lubrication on it's bearings.
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Well, that's almost correct.

What actually happens is that if the turbo is very hot and you switch off, the existing oil in the bearings basically 'bakes'; this clogs up the oil feed through the bearing. The bearing eventually can't be lubricated/cooled adequately and seizes.

So, its really all about the heat and not really the spinning down with no oil flowing.


..or so I've been told by the guys in the know.
 
ScottulusMaximus

ScottulusMaximus

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Mr.Jax said:
Well, that's almost correct.

What actually happens is that if the turbo is very hot and you switch off, the existing oil in the bearings basically 'bakes'; this clogs up the oil feed through the bearing. The bearing eventually can't be lubricated/cooled adequately and seizes.

So, its really all about the heat and not really the spinning down with no oil flowing.


..or so I've been told by the guys in the know.
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Technically it's a bit of both, however most modern diesels have turbo protection of some sort to keep the oil flowing. Around town(stop/start) don't worry about letting it idle but always good practice to let an engine calm down after a long freeway journey(even petrols)
 
F

Fiekus

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In 2006 I bought a BMW 320D and loved it. Then in 2010 I "fell" for the 125i Coupe and while it was awesome (sound and speed), I visited the petrol station roughly every 10 days...13L/100km. This year I got myself the 220D and man am I happy...Diesel for me :)
 
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