Hello All
I have just fitted the insulation, which I bought from Minisport it comes in 4 sections ,fits right up to the panel edges I am concerned this insulation may cause engine overheating on hot days. Has anyone used this type of insulation ?
Allen

I have used some kind of under bonnet insulation for years. It seems to quieten the sounds and have never had any overheating issues either.

I too have used a four piece sound insulation bought from MinSport and fitted it four years ago.

No problems with overheating - I'm in Perth and it has survived our summers here.

Why would it cause overheating?

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1963 Morris 850 Smoke Grey
1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
5/72 Clubman Gt

The insulation will reduce the amount of hot air leaving the engine compartment as the insulation fits right up to the edge of the bonnet, this means the insulation will sit on the guard and windscreen flanges reducing air flow, when you close the bonnet you can see it.
Allen

I seem to remember reading that the wheel arch space was a natural low pressure area (if compared to the front grill area when moving) so the hot air would be drawn out of the engine bay together with the help of the fan. A lot of heat must go down the back of the motor and under the car too.

Agreed.
If I recall there were some Mini's that had a seal in the gutter at the rear edge of the bonnet too.

_________________
1963 Morris 850 Smoke Grey
1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
5/72 Clubman Gt

Modern cars with turbo installations can have problems with excessive heat in the engine bay and resort to putting louvres in the bonnet and even lifting the rear edge of the bonnet to flow hot air out (probably illegal and contrary to ADRs).
Doubt this is a serious problem for most minis though.
I don't think the original design relied on the poor alignment of the bonnet panel to assist much in cooling.
Scoop's comment about the seal is right; the roundnose minis had a strip of sponge rubber glued into the gutter below the windscreen (helped in the rusting process). Later clubman styles had a strip that pressed over the edge of the rear gutter - maybe to stop the bonnet vibrating.