Open Headers?
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Fleet Mechanic
Joined: Jun 2011
Posts: 1,804
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From: Southern California
Open Headers?
[SIZE=3][FONT=Calibri]So today I decided to take the exhaust off and see what open headers sound like. Mine sound sick! I have a friend who runs open headers during the summer months due to the warmer air. He was telling me if I do open headers, every time I turn the engine off, I need to stuff a rag or towel or something to block cold air from going up into the block. Is this true? What would happen if cold air goes up the headers after I have been driving?
Posting Guru
Joined: Dec 2009
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From: Mississippi
You can crack a valve or so I have heard. They are red hot when running, you shut it down and the cold air rushs in and they crack but I dont think this will happen with headers, only a really short system, such as exhaust manifold only. This is what I've heard, if true, I doubt you could get the rags in quick enough anyway.
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Fleet Mechanic
Joined: Jun 2011
Posts: 1,804
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From: Southern California
Ok not getting the rags in fast enough is what i was thinking. So its almost pointless to try and most likely burn yourself. What i was thinking though is putting short 12" drop off. So have about a foot of 3" pipe come off the collecters and then nose down so the exaust is straight down towards the ground. Kinda harder to let air in. Idk. I really want that super cool deep throaty sound mine make when they are open but dont need to mess up my engine
Posting Guru
Joined: Dec 2009
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From: Mississippi
Its not going to do it with headers I feel sure. When I was in high school guys used to uncap their headers all the time. We used to run 12'' straight pipes on 180 lycoming aircraft engines on airboats as well. The headers should be plenty long enough to heat the air coming in until the valves cool just a bit. FWIW open headers should only be run on really bad *** trucks IMO, like someone said in the LOWD thread, if its gonna be loud as hell, it better be fast....
Post Fiend
Joined: Apr 2008
Posts: 8,261
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From: Big Sky Country
Old wive's tale that just refuses to die, scenario... you park your truck outside overnight and the ambient temperature is below zero, the valves, ports, block, heads, etc. and air inside the engine are all at or below zero, you start the engine and it fires up and the first thing that happens as the gas ignites is 900 degree combustion temperatures hit the cold exhaust valves, do the valves warp? No, do people who live in cold country have to do valve jobs every year? No.
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Fleet Mechanic
Joined: Jun 2011
Posts: 1,804
Likes: 5
From: Southern California
Its not going to do it with headers I feel sure. When I was in high school guys used to uncap their headers all the time. We used to run 12'' straight pipes on 180 lycoming aircraft engines on airboats as well. The headers should be plenty long enough to heat the air coming in until the valves cool just a bit. FWIW open headers should only be run on really bad *** trucks IMO, like someone said in the LOWD thread, if its gonna be loud as hell, it better be fast....
And when you say "uncap", what do you mean?
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Posting Guru
Joined: Dec 2009
Posts: 2,134
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From: Mississippi
Old wive's tale that just refuses to die, scenario... you park your truck outside overnight and the ambient temperature is below zero, the valves, ports, block, heads, etc. and air inside the engine are all at or below zero, you start the engine and it fires up and the first thing that happens as the gas ignites is 900 degree combustion temperatures hit the cold exhaust valves, do the valves warp? No, do people who live in cold country have to do valve jobs every year? No.
Fleet Mechanic
Joined: Mar 2004
Posts: 1,398
Likes: 17
From: Hesperia, CA
Old wive's tale that just refuses to die, scenario... you park your truck outside overnight and the ambient temperature is below zero, the valves, ports, block, heads, etc. and air inside the engine are all at or below zero, you start the engine and it fires up and the first thing that happens as the gas ignites is 900 degree combustion temperatures hit the cold exhaust valves, do the valves warp? No, do people who live in cold country have to do valve jobs every year? No.
Tuned
Joined: Dec 2008
Posts: 269
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From: Paradise, CA
I use to uncap my mustang when I was younger. I loved the way it sounded when I first started it up but I grew tired of the loudness and reverb along with the loss of torque. If you want loud and are concerned about the valve issue why not just remove the mufflers from the system. It will still be quite loud, but behind you, won't loose as much torque, and being that we're in California, more likely "Ponch" won't pull you over.
Post Fiend
Joined: Apr 2008
Posts: 8,261
Likes: 15
From: Big Sky Country
Agreed! WWII aircraft piston engines ran with 10" short pipes with air temperatures at altitude of -20 degrees or lower and never had trouble with warped valves.
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