Should I cut into this manifold? Does it need porting?
 

This is Baron's DIY manifold which I just obtained. I am planning to track my vehicle and have read stories of cracked manifolds from uneven expansion. The mani looks very nicely built but to be super cautious I wonder if below make any sense. The flange is 10MM and the entire build looks very solid at room temperature.

I've seen people cut reliefs into the bolt holes, or full cuts across the flange between the ports, are either good preemptive measures? what kind of place can do this? How much should I expect it to cost? it is a 10mm flange.

Also, will I benefit from some porting? Below is one example of slight overlap between tubing and flange. (How much?)

I will be purchasing 10mm studs and iconel between mani and turbo, I will stage 8 both connections and dibond.

Images below:



https://www.miataturbo.net/attachmen...ine=1351045386

https://www.miataturbo.net/attachmen...ine=1339864181

Cut, why not.

Port, yeah it will only take 5 mins. Probably won't make any difference though.

Dann

How? Stud holes only or full cuts?

Angle grinder, exhaust shop or machine shop?

What to budget?

Angle grinder between each portseems to be the standard. I have never done it however.

Dann

I intentionally didn't grind that out anymore than it is because I was worried the weld would get thin and crack. The manifold ports are already larger than the ports in the head to begin with, so I didn't see the need. But I also built that to be a fun street and autox setup, not for the track. And if you end up removing the gasket between the turbo and manifold, the mani needs to be machine. It's flat enough for street use with a gasket and never leaked, but nowhere near close enough for track abuse.

Thanks Baron, disclaimers about application noted :). I will examine thicknesses closely and err toward not porting the flanges. I did not pay attention to much material would be left after porting. How often does someone get to have advice from the original manifold designer? This is pretty great. Thank you.

I will also find a machine shop to machine flat the exhaust surface as you also suggested by email.

What do you think about relief cuts? At first I thought it was something used on cast Iron Manis but then I realized that SS generally has a higher expansion rate than cast iron. If I cut, I will cut after machining.

I found this link about an HKS manifold:
Hks Cast Manifold Relief Cuts - Forced Induction & N/A Power Mods - MX5Nutz Forum

On the other hand, I don' t see relief cuts in Artech or AbsurdFlow flanges, nor do I see it in FM flanges though I've read in many places how corky suggests it.

Plus side: allows for thermal expansion better, less cracking

Potential negatives: mating plane will not seat as flat