Let’s play the guessing game untill I dig into it shall we?
 

Let’s guess what happened lol.

risers are less than a year old

manifolds are unknown but I assume old.

engine was at 165° and still pumping water at time this happened.

was still running well just made this pop and sounded scary lol!

only thing that’s changed is rebuilt the carbs since Cig Rendezvous.

I’m thinking the discoloration of the riser is when it came off the manifold there and exhaust was shooting out it probably blowing on it?

I’ll let yall shotgun your guesses lol! And I will report back ASAP

obviously ended my weekend / poker run but luckily ended up in a new 41ft night hawk for the rest of the weekend lol.

cheers!
https://cimg5.ibsrv.net/gimg/www.off...40e479f08.jpeg

Wow! Never seen anything like that before! Stress crack or heat or a combination of all.

Motor mounts moved and/or tails are hitting on the transom cutouts?

Snapped????
woah .... never seen or heard of such thing !

Over torqued V band clamp?

Judging by the melted paint them things got hot as balls. The flanges aren`t water cooled..

Yup, for sure….and the risers are yellowed by very high temps too.

More photos
 

https://cimg4.ibsrv.net/gimg/www.off...f0820518b.jpeg
https://cimg6.ibsrv.net/gimg/www.off...86958e4e0.jpeg
https://cimg7.ibsrv.net/gimg/www.off...f08c4a563.jpeg
https://cimg8.ibsrv.net/gimg/www.off...9c023f9c6.jpeg
https://cimg9.ibsrv.net/gimg/www.off...889f43cfb.jpeg
https://cimg1.ibsrv.net/gimg/www.off...4e25f0aa4.jpeg
last 2 photos are the manifold flange it’s self.

Other side manifold is perfect in appearance wise on same engine.

That’s crazy!!

Heat.
 

As of right now ( I haven’t gotten the manifold off yet ) I see no signs of heat discoloration on my aluminum head on that side. If that means anything to anyone. When this thing blew off / broke I was 5,000 + RPMS at that particular moment for what that’s worth to?