Heatshielding Bonnet Inner

[Jeemy]

I don't know if anything particularly is wrong.

I have the Piper ceramic downpipe, and a rebuilt turbo. It should all be as cool as it can be; equally I guess the black coating outside the downpipe means it radiates heat pretty sharpish.

Basically in the picture here I have cracking on the bonnet interior.

Its due to heat stress, you can feel the heat after a short drive. I have a new heatshield but in brilliant lotus style, the circled area is exactly above the turbo and downpipe i.e. the hottest point of continual stress to the bonnet, has no facility for shielding.

I've been advised (I was intending on stripping the whole bonnet inner and refinishing it perfectly) to put some self-adhesive matt silver material on this to disperse the heat and protect the bonnet, and cover the cracks (to be sanded smooth).

Anybody else have this problem or any thoughts?

[Steve A]

I've got the same set up, using only the top part of the the heat shield, I am monitoring
the situation and have been looking at sticking something on the bonnet in this area,
but haven't seen anything that has caught my eye (cheap enough ).

[Elannewbie]

Hi Gods

I too have the same cracking problem on the underside of my bonnet. I have toyed with the idea of applying an aluminium self adhesive foil to the localised area but fear the heat with just melt the adhesive. My other thoughts are to either:-
1. Bond a piece of aluminium or titanium to the area in question (still to find an appropriate high temp epoxy) or,
2. Still using either Ali or titanium but mount it on lugs that are bonded to the bonnet so there is a gap between bonnet and shield.
The only problem with both options is that the heat will still "soak" into the bonnet structure.

Any additional thoughts and ideas would/will be greatly received.

Kind regards

Grahame (not a god!)

[HJ2]

Hmmmzzz I sure hope this is not my future....

It is not clear who has the OEM heatshield and who has not!
Jeemy, your setup is like mine, but i have not got the ceramic coating. I do however installed the turbo heatshield back in position You can see it in one of the last pictures here:
forum.lotuselancentral.com/viewtopic.php?f=31&t=21482

My bonnet looks new! And when hot I drive it like a mad man
Also I usually do a cooling down before parking the car. Make sure all the heat is out of the turbo. I always assume everybody does that but it might help saving your bonnet if you didn't so far

[Elannewbie]

I have a completely standard set up i.e the turbo heat shield is still fitted to the vehicle.
I also let the turbo cool sufficiently before switching the engine off. Only thing I can think of is if I have been stuck in traffic the temp gauge reads halfway when I switch the engine off, but then again the car has not been driven hard in this instance.

[CalElan]

Maybe fitting the lower ranged temp sensor may help by turning on the engine fans sooner to help dissipate the build up?

[Elannewbie]

I have considered fitting the lower rated temp sensor so that the fans come on earlier and also the modification to add an "in cockpit" switch so the fans can be turned on manually - both mods would help greatly when sitting in traffic. I still think a heat shield on the underside of the bonnet could/ would be beneficial, I just haven't come up with an ideal solution yet!

Regards

Grahame

[Elannewbie]

Just been on demons tweeks web site and found a self adhesive backed heat shield. The blurb said it can shield against radiant heat to a temperature of 1000 degrees C. I'm not sure how to add a link but the product is COOL-IT Adhesive backed heat shield, demon tweek part # NIM13575.

I hope the product works - will post results with pics here in due course.

[CalElan]

I have considered fitting the lower rated temp sensor so that the fans come on earlier and also the modification to add an "in cockpit" switch so the fans can be turned on manually - both mods would help greatly when sitting in traffic. I still think a heat shield on the underside of the bonnet could/ would be beneficial, I just haven't come up with an ideal solution yet!

Regards

Grahame

Mine has the lower temp cut-in and incidentally I also fitted a manual fan override switch this last weekend. Not used the car since but I already feel the peace of mind!
I find the car takes a while to come up to temp but once at temp sitting in traffic makes it rise pretty quickly.

let us know how you get on with the shield..

[Elannewbie]

Hi

I have good news and bad!

The good is the insulation matting works very well... The bad is - the pictures I tried to upload will not upload whatever I do, believe me,tried everything! Anyway...

The matting did not cover the whole area (under bonnet support structure) in one piece. As this structure is in effect a 'top hat' section. The matting has to be cut into sections, and applied to the bonnet so as to cover the last applied piece with a little overlap this probably will not make much sense in this thread but, if you look at the area to be protected and then logically think the best way to apply the matting everything will be fine. I found that by making card templates of all the areas I needed to shield I could 'map out' the sequence of installation. It helped to tape all the templates in place to the bonnet. With the card templates taped to the bonnet use masking tape mark the ends and edges of the templates - this will give you a datum to use when you stick the matting in place. Remove the card templates and transfer the shapes to the matting. Cut the shapes out the matting and apply the pieces to the bonnet remembering the mapping out sequence I mentioned earlier. I gave an overlapp of approx 3 mm and I only needed 3 templates.

[CalElan]

How are you measuring how well it works? Is the outside of your bonnet cooler?
Do you have a link to what you used?

[Elannewbie]

Hi Cal

Oops I see what I did there! Sorry, made a bit of an error. When I stated that "it seems to work very well" that was completely unfounded. I have no accurate way of measuring the difference in temperature now the matting is fitted. What I meant by the statement was:- given that the bonnet support structure is a series of curves and double curves, I was very pleased with the ease of application of the matting. I'm not sure the best way to definitively say "yes" the matting has worked, I'm not going to peel it off to see if the cracks have grown!

I did try an add a link to the store where I purchased the mat but, I don't know how to do it...
The store is called DEMON TWEEKS and the product is COOL-IT (12" * 24" cost approx £40)
I guess you must have similar Motorsport retail outlets in the U.S.

Kind regards

Grahame.

[Elannewbie]

Cal, if you pm me with your email address I'll be happy to email the pictures I have to you.

Regards

Grahame.

[chrisP]

I have had a similar heat matting attached under the bonnet for years, just over the turbo. It seems to have worked well and as it was not self adhesive, i used an impact adhesive to bond it on - no problems to report.

Regards
Chris