Under Bonnet / Hood Insulation

[AndrewA]

Have looked at a few 410's now and some of them have insulation on the engine side of the bonnet and some don't!
Mine has none.
What should it have and what have others done/what product have they used and has it been beneficial?
Thanks
Andrew

[Roger Morrall]

I fail to understand why one might wish to insulate the underneath of the bonnet and keep even more heat in. The usual plaintiff V8 cry is connected with getting rid of the heat, not keeping it in. Also bear in mind that the hotter the air the engine is ingesting the thinner it is so the less power is available to you. I believe you’d get something like 20% less ooomph at 90C as compared to 20C. I’d be most interested to know if I’ve misunderstood some fundamental point.

[Thor]

Under-bonnet insulation is more often to reduce noise getting back to the cabin via the windscreen, but it is probably not all that significant on a 410. The foam is often protected from heat by a foil covering.

I would agree that it is probably not to be recommended for a V8 Bristol, but if you do want something like this look at the products of 'Noise Killer Acoustics' and 'Dynamat'.

[AndrewA]

Thanks for the replies gents which confirm my thoughts - I was just wondering!
I can see how it would add to/create higher temperatures so that's not a great idea and the car isn't noisy so there doesn't seem any point.
Car already has dynamat in selected places inside the car under the carpet (previous owner) and I've used that in other cars and fund it beneficial, but looks like I'll be leaving the bonnet well alone - thanks.

[John Keighley]

Andrew,

Mine doesn't but the engine is very quiet anyway so I would most probably not bother.

John K.