Will a bonnet scoop reduce heat in the engine bay?

**rick130** · 13th January 2018, 11:54 AM

Try this thread

Defender Engine Bay Heat - LH guard vent

**Fausto79** · 13th January 2018, 02:44 PM

That’s on deefers though. We are on the D1 forum. Would these side vents still apply?

I was trying to find a thermal imaging recorder and drive the car around to see under bonnet temperature and then fit spare bonnet with vents or louvres and see if it makes a difference. Turns out those cameras are about $7,000 and beyond, so that kills my experiment.

**rick130** · 13th January 2018, 03:41 PM

Originally Posted by Fausto79

That’s on deefers though. We are on the D1 forum. Would these side vents still apply?

Umm, someone asked to see the Deefer ones, but the principal is still the same.

Car underbonnet airflow is ordinary at best and older cars can't rely on ram air at speed to push air through the radiator as the under bonnet air appears to 'pack up', ie. it doesn't exhaust fast enough through the trans tunnel and out under the car.
E.g. Tdi Defenders and GU Patrols need the viscous fan to help push the air from under the bonnet at speed.
If the viscous clutch isn't working properly they both overheat under load at highway speeds.

To help extract the high pressure under bonnet region you need a bent in an area of low pressure and/or preferably laminar flow.

**Vern** · 13th January 2018, 04:00 PM

Originally Posted by Phil B

Vern
Any chance of more details on how you installed a Plazmaman w to a intercooler onto the 4bd1t please?
Thanks
Phil

Excuse the mess, have some things i will change in due time, but have attached some pics.
Intercooler sits on top of the motor, have a bosch electric water pump on the inner guard, and the biggest heat exchanger i could fit behind the grill.
The intercooler is the plazmaman 800hp series one.
The heat exchanger (550×430×50) needs to be as big as possible to reduce heat soak.

**Old Farang** · 13th January 2018, 04:30 PM

Originally Posted by Fausto79

That’s on deefers though. We are on the D1 forum. Would these side vents still apply?

I was trying to find a thermal imaging recorder and drive the car around to see under bonnet temperature and then fit spare bonnet with vents or louvres and see if it makes a difference. Turns out those cameras are about $7,000 and beyond, so that kills my experiment.

Infra Red temperature guns should be sufficient. Many different models and prices, but the cheaper ones would be good enough.

Infrared Thermometers & Laser Thermometers | eBay

**blackrangie** · 14th January 2018, 10:11 PM

Progress on dummy RRC Bonnet..thoughts

**Fausto79** · 14th January 2018, 11:05 PM

Aerodynamics of Road Vehicles: From Fluid Mechanics to Vehicle Engineering - Google Books

**blackrangie** · 15th January 2018, 12:27 PM

Originally Posted by Fausto79

Aerodynamics of Road Vehicles: From Fluid Mechanics to Vehicle Engineering - Google Books

Good article, RRC bonnet is very smooth and rounded at the front compared to those pics. In AU it seems we use the AC rather than fresh air most of the time..if not my window is down or my heater is on

**Phil B** · 15th January 2018, 04:27 PM

Originally Posted by Vern

Excuse the mess, have some things i will change in due time, but have attached some pics.
Intercooler sits on top of the motor, have a bosch electric water pump on the inner guard, and the biggest heat exchanger i could fit behind the grill.
The intercooler is the plazmaman 800hp series one.
The heat exchanger (550×430×50) needs to be as big as possible to reduce heat soak.

Thanks Vern
Do you have any before/ after EGT or pre / post intercooler temps?
Very interested.
Phil

**turtle** · 15th January 2018, 07:58 PM

Originally Posted by turtle

I have a 300TDI Disco 1 and one thing I have noticed is that the engine fan does not blow any air down the passenger side of the engine bay thus very little air movement on that side of the engine. All of the fan air exits on the drivers side and top and bottom.
Curious to know how you worked that out. Not arguing, asking.

Originally Posted by johntins

Curious to know how you worked that out. Not arguing, asking.

If you look at the fan on the 300TDI you will notice that the fan is offset to the drivers side by quite a bit. The air coming off the fan on the passenger side is blocked by the alternator, water pump and power steering pump. The air on the drivers side is not much better with the injector pump in the way. Air coming off a radiator fan doesn't exit the fan directly behind it, it usually exits in a radial pattern to the side of the fan thus very little air is thrown behind it in the 300TDI Disco's. Stick your hand behind the alternator while the engine is idling and you will feel very little air movement.

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