The Cal-look Lounge

I have never wrapped a header to help keep heat down in the engine compartment.  For those who have, what are the pro's and con's of doing so?  I am making some special tin to hopefully help deflect heat away from my exhaust and wondered if I should wrap it while I have the motor on my engine stand.

I've heard some stories about them trapping moisture and rotting out the metal.  I live an an ULTRA DRY heat area (Arizona) and don't think it would be a problem. However, I will be doing road trips and there is where some inclement weather could come up.

Let me know your opinions.

Rick M

why not get a full stainless header from CB Performance and you can forget about the corrosion problem?

  I've heard the moisture concerns as well. Also that wrapping keeps the headers hotter internally helping with scavaging ability. But I've also heard of the increased temps ending up making the headers brittle and more prone to cracking. I have no personal experience though.

   I believe it would keep the internal temps higher and help with scavaging maybe giving a slight gain or benefit it also would keep temps down around the outside of the header, but I also believe the concerns about the moisture trapping and the possibility of becoming more prone to cracking. It's a give and take I'd say what are you doing it for? looks or performance? It does look cool.

Get it Jet-Hot coated inside and out and never look back. 

i was thinking of getting some wrap. but then felix/dfl showed me that he had all these shiny fibres coming into the engine compartment.
now i'm thinking of just getting some VHT 2000F Flameproof.

how about aluminizing, wasn't that done back in the day too? or is it a little outdated now?

a friend and I were chatting with Tiger from A-1 .....we were talking about coatings and he recommended that could use a coat of high temp paint over the coating  this way if you get a oil stain you could scotch brite it and touch up as needed..! and never see any rust ..!

Black HPC. Jet Hot is too bloody expensive...

We did the wrap on our V4 engine and never had any problems with them cracking. Our headers were not painted or coated, and yes they rusted under the wrap. But the up side is no one ever burned them self on the tubes. So yes they can be a good idea. The biggest thing for us was allways running the engine after washing the car, getting it up to temp so they will dry completly.

My header is currently already coated.  I was just looking for some way to keep temps down around the heads and engine.  I was not really doing it for performance considerations or looks.  I will kick it around as I am finishing up all my tin work.

I appreciate all the good feedback. The common sense idea of allowing the motor to run for a few minutes to help dry it off (if needed) made good sense.  I have never heard of the metal getting too brittle but then again, if the the temps are too high, the material can get affected.  Some good input.

Rick M

I have wrapped a couple header sets and had the brittle crystallizing problem.  They were not painted but don't now if it would have mattered.  Will never again wrap. I had all my headers ceramic coated.  Dave Rhoads

Yes that is true. First I thought that this derbish comes from the generator. After the first runs at DDD8 there were very small glasfibres all over the engine compartment...
No the fibres are gone/sucked in by the motor  ::)
The wrap is original Thermo tec and I even rolled it up complete and went over some times with an towell.

Inn future I will cermanic coat the header and lose the wrap.

One other thing to mention.
I saw many times that the wrap was wraped around the header up to the head- exhaustflange. In my opinion that is not such a good idea. I always stop for about 5-10 cm before the exhaust/head flange.
Otherwise your heads will even run hotter cause header even gives away some heat from the heads...

my heat wrap also covered my engine in loads of little shiney fibres.

iv now brought a speedshop stainless header and wont be wrapping that

it is a bonus tho when workig on the engine when its hot

stef

Hi All,

Have opinions changed on wrapping? I have a berg 1" 7/8 ceramic coated header and I am about to wrap it. The main reason is to help reduce engine bay temps.

At the moment here the ambient temps are in the low 40's (Celsius) so all the heat I can take out of the engine area is a bonus! It probably rains 5 times a year here so getting the header wet when driving is not a concern.

Has anyone just wrapped the J-tubes under the heads and left the rest of the header bare or is it advisable to do it all or nothing?

Cheers

Tom

I wrapped a system once and that's all it took for me. I believe the metal couldn't breath, became very hot and crystallized. Tubes literally fell apart. Worst than if it rusted. This was on a daily driver street car with a 2110. 8 1/2 compression. 1 5/8 header. If engine compartment is sealed good you shouldn't have any problem with the heat from the exhaust unless you sit in one spot and have the engine running without air moving across the exhaust to cool and move heat away from the car.

Gday.
Temps here are the same as over there really.
I have wrapped the J-tubes in the past, but only the stainless ones, and only just the straight sections, and it made a slight difference.
What made the biggest difference to my engine bay temps though was a combination of coating the underside of the engine tin surrounds (to stop heating up the tin itself which then re-radiates), and plumbing in extra cooling air through the back plate (fan side).

Hi Dave, hope all is well that side of the pond.

Thanks for the detail, problem on my car is the firewall open to above the gearbox so in traffic I will suffer from heat rise. I have added top decklid standoffs but haven't been out again for a run since as I am doing some other mods, Dakota head temp gauge etc..

I don't really want to be buying a new header every few years! :)  

Tom

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Hi modnrod, thanks for the info. What coating did you use on the engine tin? Also as you are in a warm climate like myself what oil temps do you see on a 43c day when leaning on your motor? I don't trust oil temps as 100% confirmation if an engine is running hot or cold so that's why I am just about to fit a Dakota head temp gauge. I guess armed with that and an LM2 I should be able to really understand if I am just being paranoid and actually everything is ok.

Tom :)

i would rather trust a oil pressure gauge to a temp gauge, if you run your engine without pushing it, you would get reading X on your meter (really doesn't matter, some read low, some high, but you just need to know it is OK and get to know YOUR gauge) if you drive it on hotter days with more spirited driving it should stay the same, certainly not drop too much below reading X. i know it is certainly not scientific or 'correct', but it has worked for me in my engines as i have found the pressure that i read is lower then what it really is.
as for wrapping a header, i have found there are benefits when driving, but when the car is parked, the heat comes through the wrapping longer and will heat up the engine bay anyway.

They do recommend spraying the wrap to seal & protect it.

http://www.thermotec.com/products/12001-hi-heat-coating.html

  I am relaying my personal experiances so if yours are differant  do not take offense to this.  I wrapped my Berg headers many years ago because I burned myself and it worked perfectly . The headers were recently sold ( my friend John Toomey has them )  and the new owner unwrapped them to repaint and rewrap them, still usable after 25 years so the crystalizing  and cracking does not always happen. When I had Dave Kawell build my first turbo system I had them JETHOT ceramic coated inside and out , they looked beautiful for awhile , here is a pic.

(http://i91.photobucket.com/albums/k300/dragvw2180/IM000130.jpg) (http://s91.photobucket.com/user/dragvw2180/media/IM000130.jpg.html)

  If the coating worked as well as it looked I would have loved them but they do not , the coating burns off the inside plus dulls out to a grey on the outside along with it bubling near the flanges  .My brand new Kawell  headers are wrapped because I want the heat to go out the tail pipe rather than being sucked back into my engine through the fan  plus with my turbo it makes the turbo work better . I also added a turbo cover made to contain the turbo exhaust housing heat .
    The point of all this is that all the systems you have been talking about have their places but all have their problems. Paint burns off.  Ceramic coatings look good but do not last forever . Wrap looks good to me when I paint it with the ceramic paint made for it and provides the benifit of reducing heat in the engine compartment .

Thinking about it now the header was not painted.  The wrap was put on the bare metal.  If painted that might have insulated it and not cracked or crystallized.  Not sure but a thought. Thanks for reminding me that it was unpainted. It was many years ago.

Gday Tom.

I used the ceramic exhaust coating, the stuff they use on the inside of the pipes. My local company did it, but there would be plenty of other company options out there.
I also tried layering the underside with the foil insulation used in roofing (without the batt fluffy stuff), but it didn't seem to get the same results.

With a 1641/mild cam/centre 1BBL/good 041 heads, at about 46*C and 10% humidity, into a 10-20kph headwind, up and down rolling hilly country, the oil temp would get up to 120*C after 1/2 hour when "leaning" on it..........which is too hot. With the benefit of more years and experience, especially in tuning, I rekn I could do much better, but these conditions are certainly not aircooled friendly.

Assuming your tuning is good, there are still other tricks out there that I'll be using on this new motor for these conditions (if I ever get the damn thing ever started one day  ::)  *sigh*  ) while still making it look stock inside the engine bay, but mostly trying to avoid heat soak at all costs to begin with seems to have worked best in the past. Other things (like a water mist sprayer into the fan from a windscreen washer kit every few minutes.........) are really just band-aids, although effective.

 I at the least would wrap the header below the head , by doing this alone I believe you would see a noticable  lowering of cylinder head temps. Mike McCarthy

Here's mine. So far, so good. Looks cool with the old school mummified turbo. No particles anywhere.
http://img.photobucket.com/albums/v415/mschilling/IMG_2994.jpg
http://img.photobucket.com/albums/v415/mschilling/IMG_2991.jpg

FWIW    When you use wrap,  soak it in water untill it is saturated and pull it tight when you install it and like leather it will tighten up when it dries. It will smoke when first started but is no big deal . When I have done this it is very tight and smooth.  :)

When I was younger and stupider I made the mistake of wrapping a pair of headers on my old V8 Morris, without wetting the wrap down first!!!  It was a baking hot day and I did it bare chested to boot!

Talk about itchy.  :D Won't be doing that again in a hurry...

LOL , been there and done that too. Mike McCarthy

Isn't this the big point, keep the heat in the exhaust as long as possible, at least until its outside the engine compartment.

Yes it is, there are some different experiences shared on this thread but I have decided to take the plunge and will use some DEI Titanium wrap when it arrives on it's long journey from Jeg's. Thanks everyone for their thoughts and opinions, when done I will report back with my experience.

Happiness is driving your Hot VW which has cool heads. :) :)


Thanks Mike! Great info. :)


Nice real life experiences there with heat! It's definitely cooking here at the mo and everything I can do to keep her cool seems like a win win situation. The last time I was out it was 43c and the oil peaked up at 225f and I backed her off. I'm running the motor fat in the 12- 12.5 AFR range as I don't think the Middle East fuel is good compared to back in the UK but I want to lean on it more and not drop some valve seats! I am armed with a head temp gauge too now so I should be a little more confident.. :) as you say not really Aircooled friendly weather for a bug especially a black one like mine!

 
Health and Safety noted! :) :)


Thanks Nicolas, oil pressure at idle when warm is stable at around 10psi and no oil light flicker to date. :)

 
Dave, what's on the TV now in the workshop? :)
Thanks Martin, hope it all stays that way. :)

I recall a couple of years ago or more there was an article in Hot VW's about making heat shieds out of thin sheet metal / aluminum cans for pipes under and around the engine. They were supposed to work and I think had some data to back it up. There were even patterns to use to make the shields. I'll look at my old Hot VW's mags.......

That article was written by Howard Washington.  He did have data to support it. 

Sounds like some great info to share Jeff!

Cheers

Tom :)

The only downside I can see to wrapping an exhaust would be the potential corrosion issue. In a dry environment like Arizona, that reservation goes away.

I never wrapped my header when the car was NA. With the turbo, I wrapped it for a couple reasons. Due to it's proximity to some fuel system components, I wanted to have a heat barrier there. Not only did I wrap the header, I also put hi temp sleeving over the fuel lines it is close to. The other was to keep it from hurting the paint on the deck lid. So far, so good. I used the DEI titanium wrap. It's not easy to use. It's much stiffer than other kinds, but I wanted max protection, and that was the one that got the best reviews.

Hi, there was a long discussion regarding this in the group b car club a few years ago. What we found is that because of the wrap, the headers could not cool properly witch lead to heat sink in the heads and in extreme cases warp the valve guides.  Stainless heat shields over the headers worked better than anything else and allowed them to cool naturally and divert the heat out of the bay. Some had a thermostatic switched fans that would draw hot air out of the engine bay when the car was stopped .  Some nice stainless sheet that would fit between the headers and rear valance and direct the hot air away would be the thing. It's a pity I'm not talented enough to make one :D
Cheers Paul.