Why is there water in ehaust manifolds?

[Darkhorse1201]

This may be a stupid question, but why does water go into exhaust manifolds on I/Os? I know that the engine draws its cooling supply from the body of water the boat suts upon, but why does it need to be vent out through the exhaust manifolds or more specifically why does it need to be vented into the manifold so close to the engine? I see that many people on here have many problems with water being sucked back into the engine. Why cant you just provide a place for the water to enter the exhaust system further down the line? Cars run with headers and while I realize that they would put off a lot of heat but that cant be the only reason for the design of the manifolds. Perhaps one of the engineering types on the board can enlighten me. Thanks!

 

[tommays]

Re: Why is there water in ehaust manifolds?

It all has to due with FIRE saftey<br /><br />Gas will burn at about 850 degrees on contact<br /><br /> If you dont water cool them they will easely get well above 850 and any spilled fuel would burn ASAP along with you and the boat which would be no fun at all<br /><br />tommays

 

[bruceb58]

Re: Why is there water in ehaust manifolds?

It would be way to hot in an enclosed environmnet to be able to get the heat out with just circulating air.

 

[Buttanic]

Re: Why is there water in ehaust manifolds?

Plus rubber exhaust hose is not rated for much over 250 degrees

 

[Darkhorse1201]

Re: Why is there water in ehaust manifolds?

Okay, that answers my question!