Mikey , would you agree that the majority of concern over letting turbos, on TDV8's cool, is wasted?

I appreciate high temps can turn the oil to dust in one sitting and destroy the turbo but....... really, how many FF drivers do this? For instance, driving down the M6 for a few hundred miles at 80mph will generate some decent transmission heat along with engine heat so everything feel warms but the turbos won't be much hotter than normal. Throttle opening at these speeds will be pretty low so no real heat developed (and no real HP).

The only time I worry about my turbos are after one of "THOSE" drives!!! You know the type of roads I live amongst and if I drive the 20 or 30 miles to the nearest civilisation in sport mode with my foot to the floor out of every corner and only lifting off when I need to brake hard for the next then I let them cool. Coming up the M6 at fast motorway speeds then pulling into the services doesn't bother me in the slightest - I just think how long I've pootled around the services before I get to the car park / fuel station.

I've had to have one turbo replace but ..... the fault was electrical, not mechanical. The actuator had lost its position monitoring and didn't know its ar5e from its elbow

Of course, I may be completely wrong and living on borrowed time

I make you right about the heat build up ,no one has posted how much boost the ff runs or a turbo graph ,I run a 400bjp Nissan skyline and that runs at 1.2bar the maximum output for this turbo is 420bhp so it's running at nearly the max and produces a lot of heat when I give the heavy right foot and I have always eased up in the last few miles to home and never had an issue with it, I don't tend to drive in sport and watching the revs for each gear change I can't see it being highly stressing on the turbos

1.2 bar? That's cute

RiccartonRR wrote:

Mikey , would you agree that the majority of concern over letting turbos, on TDV8's cool, is wasted?

I appreciate high temps can turn the oil to dust in one sitting and destroy the turbo but....... really, how many FF drivers do this?

May I suggest that is why turbo failure is so common?

I was even more curious about this after reading that article, so I graphed my temps with the IID

On the motorway, with lots of airflow, the engine oil temp was sitting around 87-88 degrees.

Leaving the motorway, and 2 miles of gentle town driving, the temperature actually increased to 93 degrees

After 60 seconds of idling, the temps actually increased to 95 degrees, and gradually reduced to 85 degrees after almost exactly 10 minutes...

But these temperatures mean all. Its EGT's and subsequent Heatsoak we need to focus on

It's much easier to prove my point on a car with a DPF, as these have EGT sensors fitted into the exhaust.

On an engine that is run upto temperature, and idling, you will see a temperature of around 150-170 degrees.
Whilst driving on the motorway, you will see somewhere around 270-300 degrees
Under full throttle, they climb to in excess of 500 degrees.

But the hottest part will always be where it exits the engine (at the manifold) then passes through the turbo, and then into the downpipe, so the temperatures at the turbo housing will be higher than these seen by the sensors...

It is the heatsoak in the manifolds and turbo housings that vapourize the oil

While this is an extreme case, and a petrol engine, and I dont expect a TDV8 will ever get this hot, but the theory is the same:

Click image to enlarge

Manifold is cooking hot, turbo is cooking hot, then it begins to cool from the downpipe back. The EGT's will always be higher is the turbo and manifolds, than the sensors downstream can monitor



By allowing the turbo's to cool down, you get rid of any excess heat, and the turbo slows down, minimizing how long it spins without any oil flow, and prevent heatsoak

Great post Mikey - very informative.  405 AB exec seats Baltic and Cirrus
93 RR Classic efi

Remember it's easier to get forgiveness than permission!

Gone in order:
4.4 TDV8 SE - gone to a good home
93 Classic hard dash Plymouth Blue
03 L322 Oslo Blue
2000 Disco TD5 ES Epsom Green
98 P38 Rioja Red
89 Classic Cairngorm Brown

Should really put some new batteries in my IR Thermometer, and take some readings...

Are the 3.6 turbos water cooled? Probably not given the exhaust is divided between two turbos.

My old Isuzu 3.9 turbo has hit 600 degrees post turbo briefly and will sit on 500 degrees EGT ok. But the GT2560 is water cooled. I know it's comparing apples & oranges.

If the ECU allows fueling/EGR which results in excessive EGTs, maybe a remap is required. ______________________________
Vogue tdv8 08MY poverty pack - wow

I believe they're oil cooled. Got - 2017 SDV8 Autobiography in Loire Blue
Had- 2008 TDV8 Vogue SE in Java black
Had - 2007 S/C in Stornoway Grey

The turbo's are oil cooled.

A remap will not help with heatsoak, and EGT's

Last year when we renewed both turbos I fitted EGT probes to each manifold of the wife's RRS TDV8. Probes are fitted in the manifolds (which are ceramically coated inside and out) before the turbo.
They are still there, but I hardly ever take the display out of the top cubby to look at it.

(Yes I know this is the FFRR forum, but I thought you may be interested in the results. )

The tests we did were done with MTR 19" mud tyres on the vehicle, which would have induced quite a bit of drag.I will repeat the tests with the current street tyres if anyone cares.

At idle it sits at about 170-200, general driving at 120-140kmh it's 400-500, and it easily gets to 700 if you spank it.

Comes down really quick though, 700 to 200 within 15 sec.

Spanked her up the hill 160 and reached 800 fast but that's about the max.

Vehicle had a fairly aggressive remap and still had the standard intercooler at that stage. I noticed about 350 on cruise at 130 the other day, so I think the road tyres plus new cooler has brought it down a lot.

In light of these actual EGT readings, it seems prudent to quote myself from the previous page, just to remind ourselves...

Mikey wrote:

Cam-Tech-Craig wrote:

If you were running a race car into the pits then YES that statement is correct but ITS A TDi RANGE ROVER FFS! Who in there right mind is going to sit there and let the car tick over for 10 mins beginning & ending of every journey! Do RR owners not have better, more important things to do with their lives?

And we are not talking about 10 minutes of idling. We are talking 60-90 seconds

I have reason to believe the coated manifolds make the readings slightly higher though. I saw the same in my D2 TD5 where I ceramically coated the manifold too.

Anyway, good advice - let them cool a bit.

Or if you can, slow down the last coupled of minutes to your destination, and it will save you idling at all.

Last edited by Baben on 1st Sep 2015 9:57am. Edited 1 time in total

I was led to believe the very same. The ceramic coating does not let as much heat "soak" into the cast manifold/turbo casings

Thanks for some real world data. Very interesting top end EGTs, cooling rates and impact of changes.

What cooler did you change (oil or inter cooler), and what did you fit.

More air and/or less fuel generally means lower EGTs. Less air and/or more fuel means higher EGTs. I can see a malfunctioning EGR reticulating more exhaust and therefore less air would increase EGTs, which makes sense for clearing the DPF so long as the turbo is not already experiencing high EGTs.

Maybe a EGT gauge with an alarm and two probes pre turbo is the safeguard required to warn of an EGR malfunction. ______________________________
Vogue tdv8 08MY poverty pack - wow

Mikey wrote:

In light of these actual EGT readings, it seems prudent to quote myself from the previous page, just to remind ourselves...

Mikey wrote:

Cam-Tech-Craig wrote:

If you were running a race car into the pits then YES that statement is correct but ITS A TDi RANGE ROVER FFS! Who in there right mind is going to sit there and let the car tick over for 10 mins beginning & ending of every journey! Do RR owners not have better, more important things to do with their lives?

And we are not talking about 10 minutes of idling. We are talking 60-90 seconds

rar110 wrote:

Baben wrote:

Last year when we renewed both turbos I fitted EGT probes to each manifold of the wife's RRS TDV8. Probes are fitted in the manifolds (which are ceramically coated inside and out) before the turbo....

At idle it sits at about 170-200, general driving at 120-140kmh it's 400-500, and it easily gets to 700 if you spank it.

Comes down really quick though, 700 to 200 within 15 sec.

Spanked her up the hill 160 and reached 800 fast but that's about the max.

Vehicle had a fairly aggressive remap and still had the standard intercooler at that stage. I noticed about 350 on cruise at 130 the other day, so I think the road tyres plus new cooler has brought it down a lot.

Thanks for some real world data. Very interesting top end EGTs, cooling rates and impact of changes.

What cooler did you change (oil or inter cooler), and what did you fit.

More air and/or less fuel generally means lower EGTs. Less air and/or more fuel means higher EGTs. I can see a malfunctioning EGR reticulating more exhaust and therefore less air would increase EGTs, which makes sense for clearing the DPF so long as the turbo is not already experiencing high EGTs.

Maybe a EGT gauge with an alarm and two probes pre turbo is the safeguard required to warn of an EGR malfunction.

My EGR's are blanked off.
Fitted my own design huge intercooler.

EGT alarms are available. Its just a pain to lift the body to fit an EGT probe