The downfalls of extractor wrap

[SYKOV6]

yep procoat is good got the headers on the corty done cost $240 for both so a 4cyl turb manifold prolly around $160-180

[isnowi]

i am curios about the comments of steam pipe rusting from the inside out, i beleive being steam pipe that it is in fact often used to transport steam, also known as superheated gaseous H2O. Now correct me if i am wrong, but as i understand it, water causes rust. Also steam is far more corrosive than water, and is also the sole byproduct of perfect combustion, now i know that the internal combustion engine cannot produce perfect combustion, but i'll lay dollars to donuts even a really rough motor produces a pretty reasonable amount of steam as part of its exhaust gas.

Sorry for being a smart ass /\ sometimes i can't help myself.

As for the heat wrapping debate, i vaguely recall a specialised coating (sprayed from a can) that goes onto the pipe before the wrap and possibly over the wrap itself that is meant to drastically reduce rust. Its a silicon rich coating i think, IIRC its availabkle through pioneer auto parts, but i can't remember who makes it.

[v3k]

You can keep being a smart ass.... Rust needs 3 things

Water (yes can be in steam form),

Oxygen,

Carbon (in the steel, not on it).

Water and oxygen obvious (I dont know how much oxygen is in exhaust gas).

The carbon is needed, but doesnt have to at the site of the rust... But it usually is, most steel has carbon used as hardening.

BUT! I think the reason steam pipes dont rust from the inside out is the lack of oxygen inside, so I think your theory falls apart.

Anyway - random addition to the topic that doesnt really add anything, I'll go now..

[isnowi]

H2O = water = 2 parts hydrogen, 1 part oxygen.

Point is steam is known to be exceptionally corrosive.

[v3k]

H2O = water = 2 parts ATOMIC hydrogen, 1 part ATOMIC oxygen.

Point is steam is known to be exceptionally corrosive.

Diatomic oxygen (O2) is the stuff that is needed for corrosion. The energy from the steam is what makes it particularly corrosive as well.

Im not arguing, I was trying to present a reason why steam pipes might not be good for manifolds...

After all, theory should never be used over true experience, and my knowledge is only theory.

[Burntrubber]

After all, theory should never be used over true experience, and my knowledge is only theory.

I was about to say the same thing. I have a steam pipe manifold that I used everyday for six months. The inside of the runners are blue the way steel goes when its heated not even a hint of rust.

The issue with flaking on the inside of the manifold is heat related thats why I wouldnt wrap a mild steel turbo manifold.

[Random]

think the answer is this

2Fe + 3H2O = Fe2O3 + 3H2

this reaction happens at high temperature of both Iron and water (steam)

Fe2O3 + 3H2 = 2Fe +3H2O

It also happens in reverse.

Eventually it will corrode through (nothing last forever) but its not going to do it in 5 minutes either.

HPC coating is very good at keeping the heat into the the exhaust air, therefore keeping it hot and flowing fast. when exhaust cools it becomes denser and harder to move, so the longer it can stay hot the easyer it is to move, less horsepower loss trying to push exhaust air out the exaust pipe some 3-5 meters long (its why diameter goes up the further away from the engine, to suport the heavyer, slower moving air)

With turbos, this puts tremendous amounts of heat being put into the turbo. i have heard alot of turbo berring falure due to heat. weather or not they where cheap berrings it would be enough for consern. it might also be that the engines were not let to "run down". i think many beleive that leaving a turbo to idle for a few minutes is to let the tubo slow down. i dont think this is true. the engine is left running to let the heat in the turbo to disapate through the engine oil and air, and let the manifold to cool down as well. Turning a hot turbo off immediately will result in the turbo super heating and since the engine head is cooler will draw the heat from the turbo through the manifold back to the head. since the intake side of the head will cool faster than the exhaust it can result in a cracked head, cracked manifold. also, if an engine like this has been left to cool, the oil is cool (say 20-30 degrees C) but the ceramic berrings are still hot (over 100 degrees C) on contact the berrings may crack resulting in berring falure. (its what can happen in ceramic tap washers with single lever taps - they crack and leak)

Its something to consider. It makes sense, but it dosent mean it right.

just my controbution.

[Gaz]

^^^ turbo timer theory is correct. Its not so the turbo can wind down

[2DR73XA]

underhood engine fires!, had some header wrap on, unbeknownist to me, i had an oil leak which pooled and collected on the header wrap...... went for a drive, headers got hot, and the header wrap and the oil caught fire!!!........ thank F@#K for the $29 i spent on a lil fire extinguisher!

[v3k]

think the answer is this

2Fe + 3H2O = Fe2O3 + 3H2

this reaction happens at high temperature of both Iron and water (steam)

Fe2O3 + 3H2 = 2Fe +3H2O

It also happens in reverse.

You do need oxygen to be present

http://en.wikipedia.org/wiki/Rust

However the by-products of combustion are CO2 and H2O and these combined (in a pool particularly) form carbonic acid which starts pitting the metal and starting the rusting process (this is why you middle and end mufflers rust out first in your exhaust system, water pools in them).

ANYWAY - lovely thread pulled back from the dead.

Lets be honest, if you dont plan on keeping your car for more than 2 years, it shouldnt really matter because if exhaust wrap is a problem, it wont be yours. If you do plan on keeping the car for ages, HPC coat it for that underhood porn.

[isnowi]

Doh' i hate when a conversation leaves me behind, i got lost at the talk of diatomic particles, not my chosen area of expertise....

oh well i still enjoy this sort of conversation, much to be gleaned from others knowledge pool.

I think the general consensus is that steam pipe manifolds ( like all manifolds really) will corrode over time, although not as quickly as other materials perhaps.

How about stainless? i know it probably doesn't corrode as such, but stainless manifolds are known for becoming weak and brittle, is this due purely to the different rates of ezpansion and contraction between the manifold/head/turbo? or is it perhaps to do with poor welding practice changing the metals characteristics near the weld?

Or maybe it does corrode in some way/shape/or form? i know that the 316 sheet that we use as panelling does corrode over time, usually in the middle of a panel strangely enough. I have seen some that has badly corroded (to the point were the rust is no longer just surface bound) in a matter of only 18 months, admittedly it is in constant contact with sea spray, but i thought 316 was one of the most corrosion resistant alloys?