Ok, I like to pretend I know alot about cars when im with my friends, but in reality, I DONT! lol. anywho, I do have one friend that is fairly knowledgeable about cars and my one friend has a manifold leak, and my one friend is always like, " hes gettin more power on the top end cuz the exhaust is getting out quicker, but hes burning up his valves." The first time i heard this, I just went along with it, but now as I start to actually think about it, im realizing that it was fairly wrong, or so I think. And what does he mean by burning up the valves, or is he just talking out of his you know what.

 

In that particular case, he's probably loosing power because there's oxygen getting into the exhaust gases and throwing off the O2 reading. I think your friend is trying to impress you with his

 

by burning his valves...he means exactly that. Correct me if i am wrong guys, but from what i understand if you run too lean you will cause your engine to detinate more then normal and the excess heat will literally BURN your valves...when you tear the head off and apart the valves are white and the valves rods (don't know the propper name, but it is the shaft connected to the valve) are chared black.

I might be mistaken about how it happens, but that is what a burnt valves is.

 

Basically, burnt valves are caused by an incorrect fuel mixture or timing. What happens is the temperature inside the cylinder goes beyond what the valves are rated to handle which can cause the valve to actually begin to burn (exhaust valves are more commonly burned because there is no cool fuel mixture being sprayed against them). It can also burn the pistons, the intake valves, and crack the heads. On a carbed car with no computer controls, an exhaust manifold leak wouldn't really affect anything, it will just produce a very annoying ticking sound. On a computer controlled car, if the leak is big enough, it will throw off the reading from the O2 sensor and make the computer think the car is running lean (which is isn't) and the computer will add fuel to compensate which will make the car run rich.