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The mkiv Supra Owners Club

Warming the car up


Underworld
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I've read that you should leave the car 5 mins before and after driving. Is it ok to take the car at 1-1.5k rpm for the first 5 mins rather than leaving it idling? Because A) im too impatient, B) traffic round my area is dog slow.:question:

 

I dont mind putting the turbo timer on for 5 mins when im getting out.

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Warm up time is mainly to do with the viscosity of the oil... at low temps it is thick and gooey and doesn't provide the protection that the engine needs when it runs at high revs.

Once the oil is up to temp then it is much more fluid and can flow in and out of all the gaps much better, and provides the engine with the lubrication that is required for the full rev range.

 

Cool down time is more to do with the spinning of the turbos.... once you turn the engine off the oil supply to the turbos is cut off. Generally speaking if you've just been on boost then it takes about 2mins for the turbos to gradually reduce revs to a safe level whereby the oil suply can be cut of (ie. engine shut down).

 

Thats the way I understand it anyhow.

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I thought it was the temperature of the metal of the turbos rather than them actually spinning!!!

 

And as for warm up time, I'd leave it longer than 5 minutes before giving it a 'proper' thrashing, luckily the motorway always used to be at least 10 mins away from my house! :D

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I'm no expert I must point out but my understanding was that the bearings of the turbos were supplied with oil and if they are still spinning [the turbos that is] at high revs when the engine is shut off then the bearings loose their oil supply and you get metal-on-metal friction which rapidly stops the spinning turbos impellas.

By allowing time for them to reduce revs through air and oil friction down to say a few hundred rpm rather than a number of thousand rpm then the 'damage' is no where near as bad (from what I understand).

I believe that turbos spin upto something like 15K-20K rpm is that right?

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I heard it was more like 80k!!! But I'm only going on rumour as well.

 

What I mean is that they only spin on spool with exhaust gas, so by your theory you'd only need to give them 10 seconds to spin down before you could 'safely' switch off, whereas the 5 minute theory lends itself much more towards the 'temperature' idea.

 

:D

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Turbo's can spin in excess of 100k rpm, very very quickly. If you turn the engine off whilst the turbo's are still too hot, you will scorch the oil inside them that is no longer moving and being cooled. Hence you get lumps of burnt oil all over the engine, not a good thing!

 

5 minutes is far too long to leave an engine idling, you won't do it any favours at all. Don't drive the car straight away from a cold start, but 15-20 seconds imo is enough to get the oil round places to drive off. Try not to give the turbo's any stick until well after the coolant gauge is at normal temperature, oil takes longer to warm up than coolant.

 

A couple of minutes idling after a thrash is plenty long enough to leave it to save any damage. Never turn straight off though, and a couple of miles of gentle driving will be enough instead of idling for a minute or two.

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Guest gzaerojon
Anyone who thrashes an engine from cold is a goon :)

 

 

lol i've not heard that word in ages since my dad used it when he explained how a group of kids fishing next to him were using a float the size of a football :blink:

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It is the temp that is the problem with the turbo, not the speed it's spinning at.

 

Unless you have a ball bearing turbo, then you also have the issue of the turbo spinning very very quickly. You can hear them spinning for a minute or two after turning the engine off quite often. This also needs decent oil flow..

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Guest dee_rz

J specs have water and oil cooled turbos so the turbos pretty much have no need to be warmed up but it's still worth doing if the turbos were only oil cooled you would need to let the oil warm up at least 30 seconds or 1 min + but in terms of engine warm up it is fine to warm up by driving the car just as others said don't rag (drive hard) keep below 3.5 rpm and fast reving till about 4-5 mins and then fun can begin, on cool down toyota do have recormendations wrote down somewhere as to how long you should let the car cool down if you don't have a turbo timer.

1 min if slow driving has been done

2 mins for a semi hard run

3 mins cool down when you have driven the car very hard (tracking, dragging etc or sprited drive)

 

:)

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