Tdi Intercoolers shroud design

[Ardo92]

Hey fellow Landy nuts! 😁
Have you ever noticed that on Tdi and maybe TD5 the intercooler airflow is actually blanked from the radiator shroud?
I wonder why that is the case, any idea?

[Blknight.aus]

do a teltale test on it with the engine running,

its not.

[Ardo92]

do a teltale test on it with the engine running,

its not.

How is the airflow not effected?

[AK83]

Hey fellow Landy nuts! 😁
Have you ever noticed that on Tdi and maybe TD5 the intercooler airflow is actually blanked from the radiator shroud?
.....

Tdi and TD5 radiator/intercooler setup are different.

Sounds like you're referring to the Tdi side by side design.
TD5 is a stacked design.

Like Dave says ... not restricted.
Remember fan is pulling the air, pulls air faster than gets forced through at 100k/h on the open road!
So the blank area behind the IC isn't a restrictor in the way you think it is, it's a diverter where the only way for the air out is to go via the fan.
Ignoring minor leakage losses.

The only reason I say that the fan is pulling more air through than being forced through at 100k/h is:
(note I have a Disco tdi, not defer, but fan/rad are the same, but grilles are different!)
Recently I forgot to install the viscous fan after some work. On a test drive up and down the freeway, coolant sat at just above what I normally see on the aftermarket gauge.
The actual coolant values are: Fan On = 78°C (very consistently, sometimes 79°C) Fan Off = 83°C (ambient about 20-ish, at night)

After the test drive, I got home, installed fan again, back to 78-79 on the coolant temp gauge again now during the day.
Only reason I can reconcile those differences is that the fan has to be pulling more air through than is being forced through at speed, otherwise it don't make sense.
IF!! ... the fan then has more pulling power than forced air at 100k/h(lets call that a typical speed) .. then the blanked area behind the IC isn't a restriction, it's an assisting diverter(for the fan).

[Ardo92]

So if that is the case, it is fair to say that spotlights in front of the grille won't effect cooling since the air is sucked in from the viscous fan?


Tdi and TD5 radiator/intercooler setup are different.

Sounds like you're referring to the Tdi side by side design.
TD5 is a stacked design.

Like Dave says ... not restricted.
Remember fan is pulling the air, pulls air faster than gets forced through at 100k/h on the open road!
So the blank area behind the IC isn't a restrictor in the way you think it is, it's a diverter where the only way for the air out is to go via the fan.
Ignoring minor leakage losses.

The only reason I say that the fan is pulling more air through than being forced through at 100k/h is:
(note I have a Disco tdi, not defer, but fan/rad are the same, but grilles are different!)
Recently I forgot to install the viscous fan after some work. On a test drive up and down the freeway, coolant sat at just above what I normally see on the aftermarket gauge.
The actual coolant values are: Fan On = 78°C (very consistently, sometimes 79°C) Fan Off = 83°C (ambient about 20-ish, at night)

After the test drive, I got home, installed fan again, back to 78-79 on the coolant temp gauge again now during the day.
Only reason I can reconcile those differences is that the fan has to be pulling more air through than is being forced through at speed, otherwise it don't make sense.
IF!! ... the fan then has more pulling power than forced air at 100k/h(lets call that a typical speed) .. then the blanked area behind the IC isn't a restriction, it's an assisting diverter(for the fan).

[Blknight.aus]

So if that is the case, it is fair to say that spotlights in front of the grille won't effect cooling since the air is sucked in from the viscous fan?

depends on the size of the lights and where they are.

if the lights are big enough they create an air dam up the front that lowers the air pressure behind them in front of the radiator/front shroud, the fan then has less air to bite on so overall airflow decreases exponentially as things like blade slip (aka cavitation) come into play at higher RPMS.

The front shroud raises the air pressure immediately in front of the radiator which means at speed the fan in pulling in from a higher density of air.

in low range and at low speeds its pretty much moot.

[Ardo92]

I see now. Thanks! Makes sense!


depends on the size of the lights and where they are.

if the lights are big enough they create an air dam up the front that lowers the air pressure behind them in front of the radiator/front shroud, the fan then has less air to bite on so overall airflow decreases exponentially as things like blade slip (aka cavitation) come into play at higher RPMS.

The front shroud raises the air pressure immediately in front of the radiator which means at speed the fan in pulling in from a higher density of air.

in low range and at low speeds its pretty much moot.