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Dealing with heat under bonnet

26 Nov 2018, 10:09pm
Hi all,
If you have not seen my build thread you will not have seen my Tribute Kobra with a twist.
I have had the bonnet scoop deleted (as they say somewhere) and so the air flow above the engine has less option to escape.
I’ve had the car painted and will be using it soon again. If I was concerned about the heat what would be a good way of deflecting/reflecting heat?
Underside of the bonnet is flow coated (grey not black) if that makes a difference to what would stick.
I’m not overly concerned but better safe than sorry etc
Dave
27 Nov 2018, 5:36pm
The adhesive gold foil stuff
29 Nov 2018, 9:38pm
Cheers.

Will look at suppliers

Dave
29 Nov 2018, 11:09pm
I really don't think you will have a problem. The Z3 didn't have a vent and the slot in a Cobra bonnet isn't big enough to let much heat out when the car is at a stand still. When your on the move the air flow through the front grill and over the engine will take most of the heat with it.
30 Nov 2018, 7:59am
Lucky@LeMans wrote:
I really don't think you will have a problem. The Z3 didn't have a vent and the slot in a Cobra bonnet isn't big enough to let much heat out when the car is at a stand still. When your on the move the air flow through the front grill and over the engine will take most of the heat with it.


Thanks. After getting it done I’m paranoid about issues. I drive it home Monday so picks on my build thread will follow.

Dave
16 Dec 2018, 2:30pm
would exhaust manifold heat wrap stuff help?
16 Dec 2018, 4:56pm
Car photographer wrote:
would exhaust manifold heat wrap stuff help?


it might do yes. There is a gap above the beemer straight six and the bonnet so i will take a look. Now that it has been painted i was a bit paranoid. I bet I am worrying unnecessarily.

will keep an eye on things during the winter and look at options in the spring.

Dave
16 Dec 2018, 8:43pm
Instead of deflecting or reflecting the heat away, what about ducting some more in? Just a thought...
16 Dec 2018, 9:12pm
Nostromo wrote:
Instead of deflecting or reflecting the heat away, what about ducting some more in? Just a thought...


Good point. But dammit I have spent time cleaning up the front and having less intakes. It does have a dirty great mouth grill though so I could see how to influence how that comes in if required.

Thanks for the suggestion

Dave
19 Mar 2019, 9:24pm
Is the radiator masked around the sides so that the air has to go through it and not around it?
19 Mar 2019, 10:20pm
Dpaz wrote:
Is the radiator masked around the sides so that the air has to go through it and not around it?


Hi, it is not as such no. But given the mouth is the only inlet most would go that way. Will take a look next time it’s out to see if I can direct it more so.

Dave
20 Mar 2019, 8:56am
The air goes through the rad, then round the edges and back in. Turbulence. Mask it off and you make a cleaner airflow through the engine room.
20 Apr 2020, 5:31am
Hi Dave P, not sure whether you sorted the heat scenario, however just for info for all I fitted the original z3 bonnet heat blanket using self manufacturer or clip fittings. Reduced the heat that amassed into the bonnet significantly and it is now cool to touch even after 20mins idling on the driveway....hope it helps someone.
20 Apr 2020, 8:05am
Welshkiwi wrote:
Hi Dave P, not sure whether you sorted the heat scenario, however just for info for all I fitted the original z3 bonnet heat blanket using self manufacturer or clip fittings. Reduced the heat that amassed into the bonnet significantly and it is now cool to touch even after 20mins idling on the driveway....hope it helps someone.


Thanks for the suggestion. As it has turned out so far my concerns have not been warranted. So far it cools well and I have not noticed any heat build up.

Purely panic attacking post an expensive paint job. 18 months later and no paint-grp issues to note.

Loving your build by the way.

Keep safe

Dave
12 Nov 2025, 2:30am
[USER="6514"]DaveP[/USER] I have this problem on mine. Z3-based 275. It was ok in UK, but I think a warm (27°C) trip to Le Mans cooked the alternator. The temperature when I lifted the bonnet was extreme.

My plan is to use ducting similar to brake ducts. I hope that I don't have to add louvres to the bonnet, but I will if I have to.