some one that i was talking to said that if you dont have a muffler on then it doesnt create enough back pressure and your rings need that but another person said it doesnt really matter so what do you think

 

Backpressure is bad anyway you look at it. You never want it. You cannot damage your rings with just an exhaust change. You can however bend valves if you run open headers that are very short. That rarely happens though.

 

here is the way all that was explained to me. Running open headers on a race car does not damage anything in the motor while it is running. It is after the car is shut down that creates the problem. The short amount of pipe from the motor to the end of the header can cause a very rapid cooling of hot engine heads because fresh cool air can blow right up in there. This extremely rapid cooldown with the rest of the engine hot is what damages things causes stuff to warp. As long as you plug the headers after a drive or race everythig should be ok. Once again that is the way a really smart dude explained it to me. It made a lot of since beacause the shorter the exhaust the more heat should be able to escape the motor while the car is on.

P.S. Straight pipes are the loudest most annoying thing I have ever done to my car. I am only 21 years old and I already feel like Im too old for that noise.

 

Yup you got it. You were told right.

 

So wait a second, I'm confused. This situation you're talking about, is this only when your exhaust dumps directly after the headers??? You said you should plug it up after usage, like with a towel or something? So if i have a cutout right after my headers I should close it before I turn off the car I guess huh?

 

If you have a sinlge cut out I would not worry about it to much. I would close my cutout anyways to keep anything from crawling up there.

 

I agree. It is always a good idea to close the cutout. that thing I said earlier is only a possibility its not to say every car with open headers or cutout/dumps will have damaged exhaust valves. It is just a precautionary measure if you have very short exhaust like just headers and nothing else. Rapid cooling of one part of the engine when the rest is still hot is just never a good Idea. Also normal driving with a cutout is different than a 10 sec pass with open headers right before shutting down.
Hope I didnt scare anyone.

P.S. I have no idea what to plug a hot header with. Perhaps a shop towel. ha ha

 

Thanks for the clarification

 

I ran my car with only a y pipe and nothing attached after it for a few months with no ill effects.

 

other than yelling "WHAT?" whenever someone talks to you

 

I know this debate went for about 3 pages once, but I think the message got lost in the bickering. You must have backpressure to run a n/a car, IF you want to make top end power . Without backpressure, the lack of exhaust flow will kill low end torque.

A turbo car on the other hand, needs none at all. The more you uncap it, the more power you make throughout the rpms.

By this I'm talking about open headers, not a mufflerless exhaust.

 

Wrong. Back pressure is bad any way you look at it. You are confusing this with scavaging. Scavaging is what you want. You ultimately vary that with pipe size based on power out put. If scavaging is poor then you lose low end power because the exhaust gases do not have enough veloctiy at low rpm. The exhust on a turbo car is no different than a NA car except a portion of it is re-routed to drive the turbo/s. The reason why some have lag (besides displacment reasons) is because the pipe size is too large and the gases are going to slow to spool the turbos. As rpm's and exhaust volume increase you use that larger pipe effectively.

 

wrong.

its a veloctiy vs pipe size thing.... NOT backpressure.



and if you have headers on a car, that is MORE then long enough to make up for any "cooling warping" of the head/valves.. even shorty headers.... or manifolds... or blockhuggers...