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Not wishing to opena can of worms, but are they worth it?????
I always run one on high boost petrol turbos... but with the much lower EGTs on a diesel is there muhc point? AS long as the turbines are turning over and normal "idle speed" on turn off??
all turbos need to have cooled before switching them off regardless off engine size or fuel used.
it doesnt matter how much boost you have.
if you look at cummins turbos it gives you pictures of what happens.
cant write a full come back now(lol) but seriously if you dont have a turbo timer, you should be waiting alength of time relative to distance travelled/ time engine has been on/ how hard the turbo has been working, before switching off.
diesels are higher compression than petrols, so i would expect higher exhaust temperatures. this would be an even bigger reason to have a turbo timer.
I run one on my supra as after a hard drive the manifolds glow yellow and the turbos glow cherry red.... but after that sort of drive I drive a few miles taking it easy anyway... the surf I dont bother, I just give it a couple of secs to make sure it is not turning fast and turn off...
if you took a IR temp probe and measured the exhaust temp around the manifold and turbo area it would still be bl00dy hot. not enough to glow though. if your exhaust glows then i would be leaving it ages! in this worst case like glowing, they say to let it tick over until the engine fans kick in. this means that the heat has got so far as to soak into the cooling system causing thats temp to rise and start off the engine fans, then you should wait until the engine fans switch off. this would mean that the fans have removed the heat from the cooling system, at this point this is as cool as the engine is going to be without moving.
the heat of combustion is very hot. what they say is the damage is not done when switching off the engine, its when you next start it up that does the damage. they say that if you switch it off without letting it cool first, the oil surrounding the turbo can crystalise then when you start back up those crystals prevent new oil from flowing for a little while, and the crystals also just cause extra friction on the bearings.
i personally leave mine ticking over too long, but only because im parranoid of anything going wrong, and i couldnt afford any big repairs. saving for a house and all that business
this is the first car ive had with a turbo. im used to propper power with twin carbs etc :p mates import impreza had a timer. we needed it then! http://www.holset.co.uk/files/4_3_3_...%20heating.php
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