I was always told that the damage was done after you shut the vehicle down.
It'll be fine so long as you a running around, but as soon as you shut the engine off, you no longer have fresh, cooled coolant coming from the rad, nor do you have any air from 4 cylinders being pushed out. The air in the manifold quickly cools down, moreso than it would with a couple feet of pipe in it, and warps the exhaust valves, which are extremely hot from the engine running.
And yes, there is an ignition source to burn any unburnt fuel that may be coming out of the engine. Ever run an engine without the manifolds? Every single port shoots out a flame a good 3 feet long after the piston fires, and pushes the exhaust out. There is plenty of fire left in an open manifold to burn any un-burnt fuel. But, that happens with the pipes on anyways, just that it is muffled by the mufflers. In my opinion, those little explosions are mostly what you are muffling in the first place, cause when the valves are closed, and the engine fires, the sound should be mostly contained to the cylinder, it shouldn't make as much noise as an engine does, lol
It'll be fine so long as you a running around, but as soon as you shut the engine off, you no longer have fresh, cooled coolant coming from the rad, nor do you have any air from 4 cylinders being pushed out. The air in the manifold quickly cools down, moreso than it would with a couple feet of pipe in it, and warps the exhaust valves, which are extremely hot from the engine running.
And yes, there is an ignition source to burn any unburnt fuel that may be coming out of the engine. Ever run an engine without the manifolds? Every single port shoots out a flame a good 3 feet long after the piston fires, and pushes the exhaust out. There is plenty of fire left in an open manifold to burn any un-burnt fuel. But, that happens with the pipes on anyways, just that it is muffled by the mufflers. In my opinion, those little explosions are mostly what you are muffling in the first place, cause when the valves are closed, and the engine fires, the sound should be mostly contained to the cylinder, it shouldn't make as much noise as an engine does, lol
