reducing heat transfer from exhaust to cabin

[deQuincey]

hi, i recall this topic, including some last additions from @eriknetherlands

my quesion is now about heat radiation from vertical pipes against bulkhead,

i remember this picture of a plate that can be used and the part is from another bmw model

question now is that the orange attaching point seems to be 3cm away from car body,

considering that the position is given by the GEARBOX mounting point, it seems that the orange point rests open and with a big difference to the shape of the car body

so what is the consensus here about what to do to solve it ? maybe a longer stud and using a double nut assembly ? maybe create a welded support plate ?


2nd question: would it be a good idea to separate the plate from the body ? i.e. creating an air flow that disipates the heat

or cover the internal part of the plate with an insulating fabric or material ?


ideas are welcome

thanks

 

[Ohmess]

That is an e24 part. I have one in my car. Rather than trying to tightly attach the orange mounting point to the body of my car, I cut a polypropolene sway bar link bushing and pushed it onto the orange mounting point using the cut. This wedged part of the bushing between the shield and the body. I did not otherwise try to create space between the shield and the body.

 

[Luis A.]

deQ, I did not place a mounting on your red arrow but used two on the green arrow near the hand and then added two weld-on threads for the other two green arrows. Pics below. I think it was Erikinthenetherlands original idea.

In addition, I strapped on some high quality heat shields on the exhaust with about 1/2" of airspace in between. Pic shows the piece on the main silencer but I also added two other pieces going forward up to the downpipes. I don't have the skills to install the large BMW modified (I think E60?) pieces on the body of the car as others (SFDON) have shown and this works equally well, in my estimation.

 

[eriknetherlands]

As mentioned above, I indeed placed 2 pre-zinced weld nuts on the car's body.
But I used different mounting points as in your pic with green and orange arrows. I did not use the hole at the Orange arrow.

Here are some pictures of what i did.
I made a new hole in the heat shield, in a place that thought was ideal: at the side toward the engine.

First pic shows the one that is close to the engine, welded in place.
Lower in the picture you see a round circle with a cross in it, just next to the frame rails where the second weld nut will be attached. The weldnut close to the frame rails is used the already existing hole on the heat shield.

Using the gearbox mount as 3rd point is indeed convenient. I bought an additional slide nut from BMW for it.
In this picture you see why I have chosen these locations of the 2 other points; they create a nice triangle between the bolts, fixing the shield in a sturdy way.

Just in case someone wanted to use the same location for the new screw location I measured up the location of the hole; it at least worked for me.

 

[bavbob]

Does anyone have any before and after data to show this improvement is truly an improvement? Have all who have done this already maximized interior insulation? Also any improvement has to come at low speeds and high ambient temps, I bet at a certain threshold speed, conduction transfer to air far exceeds a heat shields contribution.

 

[rsporsche]

deQ, I did not place a mounting on your red arrow but used two on the green arrow near the hand and then added two weld-on threads for the other two green arrows. Pics below. I think it was Erikinthenetherlands original idea.

View attachment 144975View attachment 144976

View attachment 144977View attachment 144978



In addition, I strapped on some high quality heat shields on the exhaust with about 1/2" of airspace in between. Pic shows the piece on the main silencer but I also added two other pieces going forward up to the downpipes. I don't have the skills to install the large BMW modified (I think E60?) pieces on the body of the car as others (SFDON) have shown and this works equally well, in my estimation.

View attachment 144979View attachment 144980
View attachment 144981View attachment 144982
View attachment 144983

Luis - is that a pre-made heat shield ... or one you fabbed. if it is a pre-made unit, please share info as it looks quite good. if its one you made, what is the base material spec?

 

[Luis A.]

Scott, the material is by Vibrant Performance. It's a stiff well made material easy to shape. Very similar to the stuff found on OEM shields. I bought the large sheet (www.vibrantperformance.com/sheethot-tf-400-heat-shields-v1264/) and cut it to size for my 3 shields bending, sealing --by creating a small seam, the cut ends.

For mounting I used the mounting kit(s) from DEI: https://www.designengineering.com/heat-shield-mounting-kit. Supply your own high quality SS large hose clamps.

@bavbob , I did notice a substantial reduction in floor warming. A quick and dirty test from the driver's seat is to feel with your right hand the large passenger seat belt securing floor bolt that is directly exposed to the hot exhaust. Pop off the plastic bolt cover and feel the bolt. It is now barely warm whereas it used to be objectionably hot.

I'm no thermal transfer PhD but my observation is that transfer of radiant heat (as it is from the exhaust to the car floor) is not so much dependent on airflow or air temperature. Just like you can feel the sun's (radiant) warmth on a cold (air) day, so does the radiant heat transfer to the car floor in spite of cold air temperatures. Of course, high and/or cold airflow will then cool off the steel floor but the heat transfer has already happened.

Bottom line, I now f eel no warmth emanating from the passenger floor area and all I have is the factory insulation and carpets.

Hope that helps.

 

[sfdon]

Does anyone have any before and after data to show this improvement is truly an improvement? Have all who have done this already maximized interior insulation? Also any improvement has to come at low speeds and high ambient temps, I bet at a certain threshold speed, conduction transfer to air far exceeds a heat shields contribution.

Radiant heat occurs even in a vacuum.

 

[deQuincey]

Radiant heat occurs even in a vacuum.

oh yesss, that is why the sun is comming !!!!

 

[rsporsche]

Scott, the material is by Vibrant Performance. It's a stiff well made material easy to shape. Very similar to the stuff found on OEM shields. I bought the large sheet (www.vibrantperformance.com/sheethot-tf-400-heat-shields-v1264/) and cut it to size for my 3 shields bending, sealing --by creating a small seam, the cut ends.
View attachment 145017
For mounting I used the mounting kit(s) from DEI: https://www.designengineering.com/heat-shield-mounting-kit. Supply your own high quality SS large hose clamps.
View attachment 145016

@bavbob , I did notice a substantial reduction in floor warming. A quick and dirty test from the driver's seat is to feel with your right hand the large passenger seat belt securing floor bolt that is directly exposed to the hot exhaust. Pop off the plastic bolt cover and feel the bolt. It is now barely warm whereas it used to be objectionably hot.

I'm no thermal transfer PhD but my observation is that transfer of radiant heat (as it is from the exhaust to the car floor) is not so much dependent on airflow or air temperature. Just like you can feel the sun's (radiant) warmth on a cold (air) day, so does the radiant heat transfer to the car floor in spite of cold air temperatures. Of course, high and/or cold airflow will then cool off the steel floor but the heat transfer has already happened.

Bottom line, I now f eel no warmth emanating from the passenger floor area and all I have is the factory insulation and carpets.

Hope that helps.

many thanks Luis ... this helps a lot. we all appreciate your sharing of good information

 

[daicos35]

guys, I recall as well, and note the very helpful shield from the e24 as above, that works closer to the footwell per se.

I also remember an oem part from an e12 I believe , that is effectively a bolt on, that is used further down the transmission tunnel. Does anyone know what I am talking about, or is this another one of my fever dreams? I cannot find the part number!

 

[Cornishman]

DeQ
I don’t like the idea of insulating the gap with a fabric as it is in a good place to get wet and if the car is not used it will stay wet for some time.

Once there is a consensus on the best way to do this I am in. I drove my right hand drive, with the heat from the exhaust next to my leg, for over three hours yesterday and it was hot.

Calling all craftsmen, Can someone make a really good heat shield kit and sell it?

 

[deQuincey]

DeQ
I don’t like the idea of insulating the gap with a fabric as it is in a good place to get wet and if the car is not used it will stay wet for some time.

Once there is a consensus on the best way to do this I am in. I drove my right hand drive, with the heat from the exhaust next to my leg, for over three hours yesterday and it was hot.

Calling all craftsmen, Can someone make a really good heat shield kit and sell it?

Thank you