Can you answer this question on behalf of a mate? He owns an RS Focus and has the usual worries about letting it cool down, I had the exact same thing with my scoob but soon got over it.

Can anyone provide some technical info on the reasons against the need for a turbo timer please?

Cheers all

 

If you race your car everywhere you may want a turbo timer. If you can restrain yourself and drive gently for the last mile or so you can just switch your engine off once you park up!

Basically drive off boost for the last part of your journey and no problems!

 

I have heard someone on here mention before that modern cars cool themselves once the ignition is shut off. Any technical answers?

 

well most modern cars may keep the fan running to cool the engine but the idea of a turbo timer is to keep the engine running so as to cool the turbo. I thought the only way to cool a turbo was just to run the car on tivk over for a bit. Obviously by switching the engine off your not doing that.

 

The turbo is cooled with the engine off, the header tank sits above the turbo so natural convection (is that the right word?) will cool the water jacket.

 

but the water isnt flowing when the engine is turned off!?

 

it does in this case, the hot water rises and the cold water decends naturally. much like the principal of a lava lamp

 

Oh, but that's not to say if you stop it after a lap of silverstone it'll be sufficient. It's a 'within reason' thing

 

water boils at 100 degrees C as I'm sure you know.

The problem with turbos and engine shut down is the oil burning off and leaving deposits on the shaft (cokeing).

Without flow the water in the core of your turbo could easily boil, that why on some modern cars the coolant is circulated after engine shut down.

Alex

 

I removed mine - I'm pretty sure any such device would alter your alarms CAT1 status. I'd rather keep my insurance valid, reason enough.

The GReddy one on my car worked with the alarm but as soon as the countdown had finished, it unlocked the doors.

 

I bought mine as an add-on module for the alarm so it arms whilst the turbo-timer's running and I can walk away.

 

Ah - I'd heard some Clifford alarms can do this.
Probably a much more better alarm then mine.

 

Yeah, when I bought the car it had a dodgy Scorpion alarm that didn't work properly so I replaced it. As a basic system it was a bargain but, adding that module and an impact sensor, the price jumped up pretty quickly.

 

And the interesting - or bloody shocking - thing depending on your point of view is that my old '93 Clio 16v had an anti-percolation pump on it even back then, yet Subarus AFAIK don't. In case you're wondering the AP pump basically was an inline electric pump in the bottom radiator hose that would energise if you'd switched off and the fans were running. What a great, obvious idea.

 

Slight correction to info above, Water boils at approx. 100 Deg C at Atmospheric pressures, the cooling system will be under pressure thus increasing the boiling point. I always thought that it was a good idea to cool down to allow the Turbo to be cooled by the oil, stop the oil cooking in the extremely hot Turbo internals and also allow it to slow down to protect the bearings. I normally drive at a lower pace, short shifting the gears for a mile or so from stooping the car and allow it to idle for a Minute before switching off.

 

A modern synthetic will survive a lot higher that 100c before carbonising. If you start boiling water in the cooling system you'd notice pretty quickly with the pressure cap spewing steam all over the place So the water jacket can't exceed the temp that water boils at, at the pressure the the pressure cap lifts at. In practise it doesn't get that hot.

 

Scooby Turbos ain't oil cooled

 

No one has really said if you should have one or not here?

Imoa i think they are a waste of money, drive slow for the last mile and switch off.

I heard running the car at idel is not even good enough to cool the turbo down anyway? But as i said "I heard"

 

I have my rad fans turned onto max (I have a over ride) drive a few miles off boost, thn park up and idle for about 3 minuites, this gets my oil temp down to nearly 80 deg
Which is the normal temp i usually start to use boost after warming up.

 

Turbo timers may be illegal now, I believe the New Edition of the Highway Code states that it is illegal to leave any car running unattended unless it is for the purpose of diagnosis of a fault. Think this was mentioned on the last episode of Fifth Gear..............

 

I thought they said it wasn't illegal but unadvisable.

 

Lats face it, you only ever leave it running, on yoyur drive or in a carpark, so cant really get into trouble.

 

Not to mention the fact it is not always practical, i.e pull off a motorway and into a petrol station... I doubt the person behind you will be happy if you sit at the pump for a few minutes cooling your engine without getting out and using the petrol pump.

With the exception of the above example, I always just calm my driving down when I know I will be coming to a stop soon. I personally think turbo timers are a waste of money unless you are on track or driving a very highly tuned car with a huge turbo.

 

I let the turbo timer run whilst I'm filling up. If the missus is in the car I lock the doors and leave the engine running.

 

They are oil lubricated though

 

Its all common sense - don't drive like a Loon for the last mile after you have come off the motorway and a steady 4000rpm. If you do, park over somewhere between the slip road and home/petrol station and let it cool down.

In reality driving at 2000rpm and 30/40mph is probably cooling your engine/turbo better (due to air throgh the rad and faster movement of coolant/oil) than sitting still for 3 minutes.

 

Waste of time IMHO, just drive the last 1-2 miles steady. Oh you cant have cat 1 status on ya security with one either (to the letter of the law)

 

I don't see why not - the Clifford turbo timers are integrated into the system,(unlike other third party devices) so it's impossible to do anything to the car whilst the turbo timer's running that you couldn't do when it's not. The alarm is armed and if you try and drive away the engine cuts out.

 

You fill up with petrol with the engine running....

 

I've said this before, but most of us live in residential areas so the last mile or two, if driven sensibly as it should be for these areas, will be sufficient to cool things down. You only have to be off boost BTW, not necessarily crawling along at 1500rpm..

Newage scoobs do have a percolating cooling system, but as said this has it's limits..!

So basically, if you live in a built up area don't drive like a dic3head and all will be well..