I was talking to one of my good buddies about ym rx7 build. I advised me to go with a cast iron exhaist manifold, his reasoning is the following. Stainless steel eshaist manifold will crack under extreme heat?? is this true? Im not looking for exessive power (250 ish). Thanks

 

WHEN DONE RIGHT, the SS tube manifold will not crack.
The problem with "doing it right" is that you use quality materials with adequate thickness with GOOD welds.
Usually, the SS material is poor (the price should give you a clue), and the flanges are not thick enough (i.e. will eventually warp).
Welding SS is not easy, and you basically need a certified weldor (the guy who does the welding) to do this right.

The cast manifold will usually be more robust and better at resisting warping.

Remember, the turbo is sitting on the turbo exhaust manifold, and the cast manifold is better at handling the turbo weight, especially under high heat.
A tube (not necessarily SS) turbo manifold will sag due to the turbo weight and heat - this is how substandard welds will mostly crack.


-Ted

 

if the ss manifold/header has ANY strait pieces in it dont buy it.. all custom headers/manifoldd should be completly curved and be equal lenght.. otherwise strait pieces will be the weakest and snap of or crack

Dave

equal lenght good kind
http://www.stikiller.com/productimages/t_16697.jpg

BAD design look at the strait piece
http://bobswelding.tripod.com/DSCN0808small.jpg

 

you get what you pay for but yeah everything has been covered.

 

^ your second pic doesnt work.


1revvin7 on this forum makes the best manifolds for our cars that ive ever seen but you gotta pay to play. i think for your application a greddy or hks cast manifold will do fine but we need to know what turbo you are using. these manifolds arent for the stock turbo. if you are using the stock turbo then your best bet would probably be the stock manifold.

 

honestly im not a fan of the 90 degree wall the front rotor exhaust has to hit but when it comes down to cost...

 

Cast for reliability, SS for looks. Id say Cast myself, I like the look of cast as much as stainless, and no worries of cracks. Plus cheaper

 

agreed! i love how there design pulls it up towards the rad.!