Subject: [Healeys] ducting

From: J Armour <[email-masked]>
Date: Thu, 8 Jan 2015 00:16:32 +1100

>Kees
>My understanding is that at speed a fan is not required.
>Geoff clearly states that it is the recirculation of hot air that has
>already passed through the radiator matrix that must be avoided
>especially 
>at low speeds - thus the installation of close fitting sealing ducts.
>Fans fitted in front of a radiator that originally has not had suitable
>allowance for the area blocked by the fan and its supports will decrease
>the cooling surface area.
>It is always easier to such air into a low pressure area than to attempt
>to blow it through a matrix and into an area which if restricted by a
>closed engine bay close to the ground will be inefficient.
>
>Works cars were usually fitted with vents in the front fenders to reduce
>under hood air pressure allowing more air to pass freely through the
>radiator.
>
>Controlling engine temperature is all about heat transfer. First a clean
>inner surface of the head and block casting, maximum wetted surface area
>ie. No crud build up in the bottom of the water jackets ( note how far
>down that huge lump of cast iron that the water does not go so any

  crud build up can leave the surface area exposed to water reduced.)
>
>Clean cores in the radiator and good condition inside of tubes for water
>flow and clean and maximum outer area exposed to the air flow to gain
>maximum heat transfer. Also the thermostat must be operating as designed.

 A dirty surface of cast iron will reduce the efficient transfer of heat
into the water
>
>Addressing only one of these areas will not necessarily solve the
>problem. 
>And as Geoff said a bigger radiator and fan may not be the best solution
>
>
>
>Joe
>
>On 7/01/15 7:59 PM, "Oudesluys" <[email-masked]> wrote:
>
>>The ducting will mainly be of use during driving, not at stop and go
>>traffic. The only thing it may perhaps do is to keep the recirculation
>>of hot air more or less in check, but do not be to sure about that. The
>>only thing that will help is an electric fan very near or fixed to the
>>radiator.
>>Kees Oudesluijs
>>
>>

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