Thread: Defender Engine Bay Heat - LH guard vent

I found a pic:



I measured ambient temps of approx 65 Celsius on the hot side of the engine bay in the puma. Details >>here<<.
Even heat soak up to 75C reduced to approx 45-50C once the car was underway and there was some airflow. This shows that there is sufficient airflow in the factory design to evacuate engine bay heat.

I don't think underbonnet temps and airflow, on balance, are a huge concern from what I've measured. Remember with the frontal area of a defender, there would have to be a heap of ram-air effect in the radiator area and the ducting which surrounds it.

That being said, any budding scientists should get busy with a simple water manometer to measure the high and low pressure zones of a defender. Get some data! From what I've read above, the methods employed for testing have been a little subjective ('air feels hot'), and although there would be some correlation between coolant temps and engine bay airflow, there is a few other variables there which might be at play (ambient temps, traffic conditions, vehicle speed, etc) and skewing the results. To play devil's advocate, my measurements may not be telling the full story of what ambient air temps are seen lower in the engine bay (ie directly in the wash of the radiator fan).
For my vehicle, I'd get more data before cutting a stonkin' big hole in the guard.

Water manometer: bit of wood, clear tube, and graduations in mm.

Attach open ends of hose to where you wish to find a pressure differential, read mm graduations from the zero point, and you have a pressure differential in mm H2O (1mm H2O = 9.80665 Pa = 0.0014psi)

Magnehelic gauges are dirt cheap these days too, we've all gone electronic with pressure measurements, so a Magnhehelic can be had for next to nix.

It's what I was going to use to prove or disprove my theory, moot point now as I think I went for the very last drive in the old girl today....

I've got a cheapo indoor/outdoor temp gauge on the intake pipe, so I could probably cover the vents and measure before and after.

Only downside is the intake is on the opposite side of the turbo, so it won't be entirely accurate.

thanks guys, just done the mod take van out this weekend. looks cool

Would a 200tdi guard with the factory outlet on the left be ideal? Bit hard to get though now I'd imagine.

It would be cool to modify one of these wolf style air intakes to be a vent IMG_1413.jpg do you guys think it would work the same ?

Originally Posted by Ranga

Would a 200tdi guard with the factory outlet on the left be ideal? Bit hard to get though now I'd imagine.

That's how Serg found how much air could flow from that area as his mates 200Tdi had the stock intake removed and is now just a vent.
As it had no doors he was able to reach out and feel all the hot air pouring out as they drove across a paddock at 40km/h

The vents are pretty easy to come by.
If you fitted a 200tdi vent,
I don’t think any casual observer would even know it wasn’t factory fitment.
IMO looks a whole better than some offerings, even if not factory recessed into the guard
https://images-na.ssl-images-amazon....8L._SX355_.jpg