Does porting an exhaust manifold increase the chances of cracking?

[Captain D]

I have a 1G exhaust manifold that has numerous cracks. I want to replace it with a 2G manifold. My goal is to have an exhaust manifold that will last as long as possible without cracking. Does porting a manifold increase the chances that it will crack?

 

[kris_stewart10]

not really it does nothing i would just keep it like it is you arent going to get anymore boost or exhaust out i mean do what you want but i would def. replace the cracked one i have an aftermarket tubular manifold and i get significant results from it and in my honest opinion i would wait and get a high flow aftermarket from DSMparts.com

its like 130 and it is better than the 2g and the cracked one

 

[DGajre777]

What is your budget? FP makes an awesome exhaust manifold!

 

[Captain D]

The FP manifold seems a bit steep in price. Is there a big difference in performance and quality between the FP manifold and a GT manifold? Does anyone have any knowledge of a FP or GT manifold cracking?

 

[kris_stewart10]

i still say go with the maifold from dsmparts.com i checked the price and its 175 including shipping (give or take some) but its a high flow stock manifold

i have heard its good but its whatever you want to do buddy

 

[xsboost]

I've ported every factory manifold that I've had and never had a problem with them cracking any worse than they already have. The problem is that cast iron doesn't take heating-cooling-heating-cooling . . . over and over again. FP makes a good one out of something called d5s material for about $300 and GTheaders makes a good one out of nickel/iron alloy that's super strong. There's a few more that make em out of stainless. Wish I could send you a link but I can't for the life of me find any right now. I had a GTheaders manifold that I got from turbochargers.com with a kit and never had any problems. you used to be able to find them on ebay. The runners and outlet are bigger than a ported evo manifold, they have an egt bung and the stock heat shield bolts right up.

 

[4g63Powered]

In theory, yes, it does increase the chances of it cracking. You're removing material, therefore increasing the stress.

Now, the amount that you're likely to take out would only be negligible, therefore only increasing stress by a small amoutn. So cracking isn't going to be a huge issue.

 

[4G63 Power]

couldn't you port the 2G and it would hold up or it is better to buy a new one

 

[xsboost]

^I guess that depends on your cash flow situation. If you have the money to blow on a new one go for it. But the ported oem ones always held up for me.

 

[scoby41]

Sorry to thread jack, but if I'm going with a "stockish" manifold... would a ported 1g or 2g work better? I already have the ported 1g manifold/o2, just not installed.

 

[xsboost]

2g directs exhaust gases more directly into the turbo for better spool. If you put a 1g and 2g manifold side by side you'll notice that the runners on the 2g are slightly raised before entering the turbo. Just check out the difference in the amount of material around the turbo bolt holes. Plus the 2g runners are bigger. Also any manifold is better than a stock 1g auto.