Thread: Bonnet vents

I don't think it looks bad.

The bonnet is usually sound insulated so cutting holes in the top will send revs through your windscreen. Then there's the rain water dripping into your engine bay when its parked up.

Apart from looks I can't think of any reason why you would put vents in the bonnet instead of the side wings.

Originally Posted by mudder110

hi all quick question probably been asked before, ive all ways let my 300tdi idle for about two or three minutes.before I drive off.
longer in winter its got 355,000ks up uses no oil, am going around Australia next year
is letting it idle to warm a bad idea? was contemplating a rebuild did replace the head gasket at 220,000 advice appreciated cheers

I always move off steady and let the engine warm up on the road. But I don't load it up too much until the engine reaches it's working temperature.

The only time a engine needs to idle for a while after starting ( that's to warm the oil before moving off ), is when the air temperatures are really cold or below freezing IMHO.
.

To reduce the heat in a Defender cab that has not any airconditioning, how effective is the side vent in dumping some of the heat?
.

Originally Posted by manic

I don't think it looks bad.

The bonnet is usually sound insulated so cutting holes in the top will send revs through your windscreen. Then there's the rain water dripping into your engine bay when its parked up.

Apart from looks I can't think of any reason why you would put vents in the bonnet instead of the side wings.

Na my bonnet never had insulation, I got it mostly because I like the look of it.
I am putting in a side vent as well.

Hi All

Saw a Defender Td5 a few weeks ago
Wearing a standard to small Subaru Wrx bonnet scoop
positioned towards the back of the bonnet just in front of the ridge in the bonnet.

Pulled up and had a quick chat with the gentlemen
He told me he did it to help push cool air down the front of the firewall which helps the air conditioning to work more effectively and push the heat from the engine bay out under the car.
He also said that according to the computer the engine is running between 3 - 6 degrees cooler on the open road due to better air flow.
The other advise he gave me was to put heat shield ( dynamat ) on the floor panels to reduce the heat coming up through the floor.

Cheers

Steve

I like the idea of side vents but I'm cautious.

Some manufactures go all out to design engine bays and the air flow through them. Small changes can make big differences. Doing it wrong can have a negative effect. I know that the bull bar is probably the biggest negative thing I have done to mine but I don't want to make it worse by adding side vents than might reduce the air being drawn down under the vehicle.

As an example of negative effect. Those full width mud/stone flaps that people often put across the rear of vehicles to stop stones and mud being thrown up over the trailer/caravan are known to increase diff and transmission temps as the the air pressure in increased in front of the flap and air flow reduced.

Vehicle aerodynamics are bloody complicated.

Happy Days.

Look at the gap between bonnet and guards - no need for vents on there at all - especially on a diesel..

However, if you like the look that's your prerogative.

Originally Posted by joel0407

I like the idea of side vents but I'm cautious.

Some manufactures go all out to design engine bays and the air flow through them. Small changes can make big differences. Doing it wrong can have a negative effect. I know that the bull bar is probably the biggest negative thing I have done to mine but I don't want to make it worse by adding side vents than might reduce the air being drawn down under the vehicle.

As an example of negative effect. Those full width mud/stone flaps that people often put across the rear of vehicles to stop stones and mud being thrown up over the trailer/caravan are known to increase diff and transmission temps as the the air pressure in increased in front of the flap and air flow reduced.

Vehicle aerodynamics are bloody complicated.

Happy Days.

Its shaped like Lego. A standard 110 has the aerodynamics of a house brick. Besides could a 110 achieve a top speed to benefit from any aero kit?

Sent from my ZTE T809 using AULRO mobile app