I have the exhaust off from my car from the manifold back. I noticed that while the engine is running there is fire coming out of the end of the manifold sometimes is this normal? Is something wrong or is this just because the exhaust is off and there is no backpressure? I'd like to know because I have to buy a new converter and I don't wan't to mess up the new one if something is wrong.

 

That's normal. You may want to avoid running it too long that way. There is an old wives' tale about a chance of damaging exhaust valves on shutdown.

 

Ok thanks. I hope I haven't run it too long already.

 

When you've got open headers or manifolds you get reversion which pulls outside air into the manifold. Supposedly the cooler air hitting the hot valves damages them but I haven't seen anything to support that theory after pulling apart dozens of dragster heads that run open headers.

 

I like to offer my every time I see this topic pop up.
I believe it started in the early hot-rod days when guys would put straight pipes on a stock engine. Straight pipes and open exhaust will lean the engine a bunch. When these guys noticed they were burning exhaust valves (due to running too lean) they figured it was cold air coming in the open exhaust since it was the only thing they changed. They had no way to check the mixture. Nascar, monster trucks, tractor-pullers, dragracers all run open exhaust with no ill effects. They just adjust the mixture to compensate for the lack of backpressure.

 

Ok thanks guys.