TA 21 Engine Heat

For all cars made after 1945
Cavendish51
Posts: 15
Joined: Wed Aug 28, 2013 1:14 pm
Name: J. Simon Rigge

TA 21 Engine Heat

Postby Cavendish51 » Wed Jul 10, 2019 11:47 am

With the advent of warm weather, we have been uncomfortably hot in the passenger compartment of our TA 21 saloon. Has anyone solved this problem by facing the engine bulkhead, gearbox tunnel and floorboards with reflective or other heat-insulation materials?

RichardWallach
Posts: 376
Joined: Mon May 21, 2012 10:14 am
Name: Richard Wallach
Location: Melbourne, Australia

Re: TA 21 Engine Heat

Postby RichardWallach » Thu Jul 11, 2019 11:13 am

Simon,
He is Melbourne summer temperatures are quite often in the mid 30's. With my TA21 all I needed to do was to put insulating material under each front carpet. Nothing was needed on the bulkhead or transmission tunnel. In my case the heat issue was more exhaust pipe based than engine based. You can try a heat shield between the pipes and the floorboards if you have sufficient space to create an airflow.


Richard
Melbourne

Ernest Taylor
Posts: 7
Joined: Mon May 28, 2012 6:58 pm
Name: Ernest H Taylor

Re: TA 21 Engine Heat

Postby Ernest Taylor » Mon Jul 15, 2019 10:48 pm

Simon,
When the TA21-TC21/100 were built they had a highly effective insulating system to protect against heat from the engine and exhaust penetrating the cabin. The heat insulation system comprised the following components.

(a) Horizontal floor area.
• Heat shield/fire protection under the entire horizontal floorboard area formed by four sheets of 5mm thick asbestos-cement board; two sheets each side with a metal plate joining them below the forward cross-chassis member. The boards were a snug fit against the chassis and projected into the tunnel space by a small amount.
• A 20mm air gap between the asbestos-cement boards and the wooden floor boards. The asbestos-cement sheets were supported on pillars to give the required air gap.
• Wool carpet with sewn-in felt underlay above the floor boards, tunnel and gearbox casing.

(b) Inclined floorboards at passenger and driver’s feet, gearbox cover and tunnel
• Wool carpet with sewn-in felt underlay.

(c) Bulkhead.
• 3mm thick insulating board on the outside face.
• 12mm thick hessian backed felt on the inside.

The heat shield and air gap mentioned above is a vital safety feature. Without them escaping gases from the exhaust system can char the plywood floorboards and the draft from driving will fan the ignition process. Yes, it does happen and the result is a hole burnt in both the floor board and carpet as a minimum before you notice it.

I suggest the easiest solution is to reinstall the original heat insulation system using a modern equivalent of the asbestos-cement boards. Remember, Alvis knew best! I can vouch for the efficacy of the system in some of the world’s hottest ambient temperatures.

Check that there are no air gaps between the gearbox cover and floorboards otherwise these will let in drafts of hot air, likewise the pedals.

RichardWallach
Posts: 376
Joined: Mon May 21, 2012 10:14 am
Name: Richard Wallach
Location: Melbourne, Australia

Re: TA 21 Engine Heat

Postby RichardWallach » Wed Jul 17, 2019 12:57 pm

Ernest's comments are very relevant especially when the original exhaust system was in place. Unfortunately the life of the system was relatively short and today who knows what is in place and in particular how closely mounted the pipes are to the floor. Ernest is quite correct with respect to possible charring hence the fibro cement sheeting under the passenger side floor in particular. Over time the location of the mufflers also tends to change as well as their physical shape. This too can cause issues. If your system is due for replacement then it is worth having it carefully designed in order to maximize the floor gap. Stainless steel rear pipes will prolong the systems life as these tend to be the first to rust out.



Richard
Melbourne


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