Justin_Sane420

"Pretty good for a 1st post... Welcome aboard!!! "

thanks a lot

and the part about ceramic. very true, ceramic is very good. but stainless doesnt need the add on because it has a much lower thermal conductivity than mild steel has in the first place. and grade 321 stainless is much better than the sufficient 304 stainless for racing turbo headers.

but whichever one is cheaper or more convienient. ceramic does its job very well too

b16_destroyer

A cast iron manifold will outlast any Stainless Steel mani any day simply because of its design and metal properties. Castiron has good vibrational resistance and good thermal stress resistance. The high carbon content in the cast iron forms graphite inside the metal which acts as deadner to vibrations. Cast manifolds are also much thicker and usually shorter. Less surface for the turbo to cause residual stresses and stresses from its own weight.

The popular 304 stainless steel mani's are very pretty but are also very misleading. They flow great but the welds rust. You would need 304L stainless which stands for low carbon content or use 321 stainless for it contains more alloying elements that help in heat fatigue and subsequent cracking.

The welds rust and/or crack because when 304 stainless steel is welded, the metal is heated well above its martensitic stage and looses its corrosion resistance properties. Another reason why the welds crack is because they are cast. And the final best reason why these mani's are ---- is because they are 16 gauge which is almost looseleaf thin.

Go with a good flowing cast mani and be done with it.

BLACKSI

hum my stainless manifolds have never cracked so i dont think that all stainless manifolds crack infact stainless is way stronger than mild or most other materials so the chances of it cracking is very small maybe the manifolds they make are made from mild steel then chrome plated?


Beau

typert

Stainless steel, before it has been treated in any way, is much stronger than mild steel. However, it does not have the same quality as mild steel to expand and contract under heat and stress. When it is treated and bent, Like U-bends, it becomes more brittle. The cracking comes from improper welding or points of high stress. Like hanging a 20lb turbo a manifold that is not braced

Bracing the manifold to itself is better than nothing, but you are better off if you can find a threaded hole on the block and supporting the weight of the turbo with a brace from the block to the turbo.

Johnyquest

I just want to let everyone know, I looked into this a little bit and the SSAUTOCHROME manifolds on ebay are NOT OBX manifolds. They are two totally different peices. If you go to the www.obxracingsports.com website you can see for yourself, but i'll make it obvious for everyone. Yes they are similar, but you can't judge the OBX by looks. Here's how I KNOW they are different:



here's the SS autochrome above. Look at it closely.


and here's the OBX. Notice how the wastegate is on the OTHER SIDE!? They are NOT the same peice. I bought OBX headers when I first got my car, as well as did a friend of mine. We both ran them for almost two years, great fitment, nice looks, SS, and no cracks. OBX products are GOOD for the money! Lastly, notice how the OBX manifold ***** the turbo the other way (COUNTER-clockwise, from the top) as opposed to clockwise, like the SSautochrome.

Justin_Sane420

"A cast iron manifold will outlast any Stainless Steel mani any day simply because of its design and metal properties. Castiron has good vibrational resistance and good thermal stress resistance. The high carbon content in the cast iron forms graphite inside the metal which acts as deadner to vibrations. Cast manifolds are also much thicker and usually shorter. Less surface for the turbo to cause residual stresses and stresses from its own weight.

The popular 304 stainless steel mani's are very pretty but are also very misleading. They flow great but the welds rust. You would need 304L stainless which stands for low carbon content or use 321 stainless for it contains more alloying elements that help in heat fatigue and subsequent cracking."

Yes bust cast iron being thicker and with a much higher level of thermal conductivity, loses a lot of the energy in the exhaust gases through heat transfer. thats another problem, it conducts massive amounts of heat compared to stainless. this is also not good. overheating problems are more likely. cast manifolds are also much heavier than stainless.

"The welds rust and/or crack because when 304 stainless steel is welded, the metal is heated well above its martensitic stage and looses its corrosion resistance properties."

not if they are welded properly with the proper filler and are back purged with argon gas.

"And the final best reason why these mani's are ---- is because they are 16 gauge which is almost looseleaf thin."

get thicker metal then.

RENR

woow. that was along *** post. your guys are nerds . keep up the good work.

Semnos

:P

ProjectZC

I dont know where you're getting this information from but OBX and spark racing are not the same company..

miss-piggy

literacy rate is very low in this country...hes saying that the manifolds are sold under different names but they are all the same quality. Personally i wouldnt buy a manifold from any of those companies. brace away....thin steel is the problem with those products. If they used the right kind of steel they wouldnt be able to sell the product for that inexpensive. If the problem with them was only that the turbo was too heavy and needed bracing...dont you think everyone would buy them and just spend $40 and have them braced? I think the problem lies within the product they use, not the welds.