My life in the slow lane: Turning a z71 4x4 335I into something respectable.

[patsbimmer1]

Chris Welter said:

I have been thinking about that a lot recently and have been trying to come up with a solution. I thought about wrapping the headers since they are stainless but don't really want to deal with stressing the materials out with excessive heat and cracking them. It is looking like ceramic coating will be the best option but I've had crap luck with that in the past and it is rare it stays nice for long. Time will tell, might run them unfinished and insulate everything around them.. Hood louvers may be warranted..

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I think coatings and reflective tape are usually the most popular options.  Louvers are an option but I know off the shelf options aren't always effective due to pressure variances caused by air flow over the hood/under the body compared to under the hood.  I remember a trick from my 240sx days was to shim the hood so it lifted the rear of the hood up an inch or so to increase airflow under hood.  I know I had read a pretty in depth article about why this worked with data from thermocouples to support it.  I can't find it right now but i'll keep looking.

[Chris Welter]

patsbimmer1 said:

Chris Welter said:

I have been thinking about that a lot recently and have been trying to come up with a solution. I thought about wrapping the headers since they are stainless but don't really want to deal with stressing the materials out with excessive heat and cracking them. It is looking like ceramic coating will be the best option but I've had crap luck with that in the past and it is rare it stays nice for long. Time will tell, might run them unfinished and insulate everything around them.. Hood louvers may be warranted..

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I think coatings and reflective tape are usually the most popular options.  Louvers are an option but I know off the shelf options aren't always effective due to pressure variances caused by air flow over the hood/under the body compared to under the hood.  I remember a trick from my 240sx days was to shim the hood so it lifted the rear of the hood up an inch or so to increase airflow under hood.  I know I had read a pretty in depth article about why this worked with data from thermocouples to support it.  I can't find it right now but i'll keep looking.

I would be interested to read that article if you do find it. I know that with the N54 if you removed the Ecu cover and that shelf that goes over the engine the amount of heat/air that poured out onto the windshield was unreal. Provided rain or washing the car at that point was prohibited but for hot weather and drag racing it worked out well. A good thing though is the wiring and all the heat sensitive components are away from the pipes for the most part now. BMW left the steering shaft hole for the right hand drive cars in the left hand drive chassis and installed insulated plug, that plug gave me a hole to run my Dominator wiring, it was almost meant to be..

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[Jdesign]

Chris Welter said:

I have been thinking about that a lot recently and have been trying to come up with a solution. I thought about wrapping the headers since they are stainless but don't really want to deal with stressing the materials out with excessive heat and cracking them. It is looking like ceramic coating will be the best option but I've had crap luck with that in the past and it is rare it stays nice for long. Time will tell, might run them unfinished and insulate everything around them.. Hood louvers may be warranted..

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Heat wrap will give you better fuel consumption, better turbo spool and wont heat everything in the engine bay to a million degrees. Make sure you get a good brand and soak it in water before you apply it. There is a lot of opinions about wrap on the internet, but if done right it makes a drastic difference. The stuff doesn't exist because it doesn't work. The only way I could see a manifold cracking would be due to weight and vibration without being properly supported. Ceramic coating is nice and I have had it on non-turbo manifolds before(mostly hondas) and it seemed to hold up fine. My issue with it is cost and effectiveness. Besides that though it also looks better than a mummy wrapped manifold.

[Chris Welter]

Jdesign said:

Chris Welter said:

I have been thinking about that a lot recently and have been trying to come up with a solution. I thought about wrapping the headers since they are stainless but don't really want to deal with stressing the materials out with excessive heat and cracking them. It is looking like ceramic coating will be the best option but I've had crap luck with that in the past and it is rare it stays nice for long. Time will tell, might run them unfinished and insulate everything around them.. Hood louvers may be warranted..

Sent from my HTC6545LVW using Tapatalk

Heat wrap will give you better fuel consumption, better turbo spool and wont heat everything in the engine bay to a million degrees. Make sure you get a good brand and soak it in water before you apply it. There is a lot of opinions about wrap on the internet, but if done right it makes a drastic difference. The stuff doesn't exist because it doesn't work. The only way I could see a manifold cracking would be due to weight and vibration without being properly supported. Ceramic coating is nice and I have had it on non-turbo manifolds before(mostly hondas) and it seemed to hold up fine. My issue with it is cost and effectiveness. Besides that though it also looks better than a mummy wrapped manifold.

I suppose you are probably correct. I need to take the application into context too. This is strictly a street/strip car. My initial reservation about wrap was it was bad because they material cannot vent the heat that it absorbs and heat cycles badly causing expansion and contraction problems and cracking as well as becoming brittle because of the temps. However this being a street/strip car and not a dedicated track car, it will be hard pressed to run hard enough for long enough to cause a problem. What brands do you recommend? Reccomended process or tips?

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[Daggerty]

A lot of times with stainless exhaust cracking is if it wasn't back purged when it was welded, to much weight on it without enough support, or welding the exhaust hangars directly to the car.

[Jdesign]

THIS^!^!^!^!^

As far as brands go, the high end stuff with titanium and Lava rock is all going to do a good job. DEI, Ledaut, brands are some good ones. I used DEI on my down pipe on my 1JZ and it works amazing. Its the same stuff we used on all the cup cars and it works great. DEI also offers a few different styles or "levels" so you can get something that will work best for you. Just make sure you do a really good job installing it.