how prone are stainless manifolds for cracking?

[23redblock]

hi all
just got my stainless steal exhaust manifold yesterday from kl racing and looks ok just been hearing a lot of people saying they are prone to cracking and its got me paranoid. what are everyone's opinions on this? the manifold in question is this one http://shop.klracing.se/sv/artiklar/vol ... em-t3.html . also in description its says that joints are expanded then inserted and welded but mine is not does anyone do why this is? ive emailed kl racing and am waiting for a reply.

cheers guys

[23redblock]

any one?

[hauge]

how long is a thread ??

Yes stainless is more prone to cracking than mild steel. Some stainless qualities are not suited for high temperature applications..especially those with alloyed with molybdenium ("acidproof stainless"). Normally you would use a chromuim steel above 12% chrome, which is per definition stainless, perhaps with some high temperature stabilisation elements which works ok in such an application.
What I´m trying to say is that it is unlikely that the manifold will crack but the risk is higher than with mild steel.

Regarding the expanding of joints, I assume it is practical, since you cannot cut or bend each part exactly right. There is always some adjustment, and the expanded joint leaves some room for fine adjustment of the parts for a good fit without having to cut/grind the parts individually for a perfect fit. Without the expanded joints, the price would probably rise substantially.

Edit: some obvious misspellings corrected

[Kadett4wd]

I´ve seen many manifold in stainless cracked.
BUT!! when developing the manifold with my late friend PeterG we came to a couple of conclusions that really prolongued life.
equal length pipes.
Try to have the least amount of welds on the pipes as you can acheive.
Do NOT restrain the turbo, let it have some room to move.
(If restraining, than you have to use some sliding couplings like they did on Audi´s back in the years.)
About the same lengt as manifold downwards on the downpipe, that´s the first place to begin to think about a really rigid mounting on the engine/gearbox.
Then a flexpipe after that coupled the rest of exhaust.

Maybe sound odd,, but it worked.
After using this solution no manifolds at all cracked.
We designed the manifolds in "321" if i remember correctly.


But! using a big heavy industriturbo, well you have to restrain the turbo.
And i can´t recomend stainless at all in that setup.

Last, Chinamade junk in stainless almost always cracks

[Jens Gustavsson]

Hej jag tror de grenrören inte är speciellt benägna att spricka de är bra svetsade och i mycket tjockare rör än många andra rör. sen de är inte tillverkade i kina.

tyvärr är de inte puls splittade i kolektorn det får man fixa själv men det kommer nog framöver?

liknade rör jag körde 673 hk i min test B230 med små trimmad 8v topp. http://forum.savarturbo.se/viewtopic.php?f=46&t=79039

mvh jens

[Kadett4wd]

inte tillverkade i Kina?
var är de tillverkade då?

Med det där priset så blir svårt att ha en hög kvalité om det skulle vara tillverkat i Europa exempelvis.
Även kineserna har bekymmer med kvalité, men vi är så dumma och köper skiten ändå.

[Jens Gustavsson]

mins inte men de är tillvärkade i europa vad jag mins. riktigt fina svetsar och rören är pressade över varandra i skarvarna så det finns inge svets fog inne i rören samt det blir nog en starkare skarv. bara synd de inte är pulsplittade men som sagt det kommer nog men det är jobbigare att bygga så det blir nog lite dyrare??

hadde ett sådant grenrör till 240 i rostfritt i dynon förra veckan med omsvetsad kolektor och super HX35 och det fungerade bra man måste dock flytta till 740 generator fästen.

mvh jens

[23redblock]

jens in picture they have expanded joints but but when my arrived it hasent :/ which sucked a bit so emailed kl racing to here what they say. all pipes are near enough same length welds arnt bad. i would of got a mild steel one but didnt know they done them with a t3 flange till after i brought it

[23redblock]

ahhhh man i thought £400 was quite a bit lol as they do some for £200 lol

[Jens Gustavsson]

jag föredrar järn rör men jag tror de fungerar de i rostfritt med och som sakt det är rätt fin kvalite men lite jobb för att få dem exakt som man vill ha dem om man ska ha puls splitt. ajden gör fina rör också som man kan få lite mer custom men de kostar lite också men värda varända krona om man frågar mig som byggt några rör i mina dagar (det tar grymt med tid ca 50 timmar om man är noga)

mvh jens