Cooling system works better with splash guard fitted?

[lukeADE335i]

Hi all

Over the weekend I re-fitted the plastic splash guard under the engine and the front brake ducts, which I haven't run on the car in 3 years since doing my M30 swap. Surprisingly, the car now appears to be running cooler? This seems counter-intuitive to me as the guard restricts airflow into the engine bay and I'd left it off deliberately thinking that it would help with keeping the engine cool.

Does anyone have an explanation for this?

The only thing I can think of is that by restricting the airflow under the car, the fan is actually working more efficiently as there's less turbulent air behind the radiator?

Cheers
Luke

[marshallnoise]

Hi all

Over the weekend I re-fitted the plastic splash guard under the engine and the front brake ducts, which I haven't run on the car in 3 years since doing my M30 swap. Surprisingly, the car now appears to be running cooler? This seems counter-intuitive to me as the guard restricts airflow into the engine bay and I'd left it off deliberately thinking that it would help with keeping the engine cool.

Does anyone have an explanation for this?

The only thing I can think of is that by restricting the airflow under the car, the fan is actually working more efficiently as there's less turbulent air behind the radiator?

Cheers
Luke

This makes sense though. Fans are more efficient when they have a shroud as well. Apparently, the designers of cooling systems know what they are doing in spite of our best efforts to improve on them.

Since I haven't ever seen this splash guard you speak of, what does it look like?

[Bearmw]

I run the plastic shield as well under the belief that I have improved aerodynamics (and improved air flow into the radiator and being evacuated from the engine compartment).