Open headers?
Race Director
Joined: Jun 2009
Posts: 10,428
Likes: 9
From: Southside of Western Norte Americano State of Confusion, ColoFornia
St. Jude '13
Many many engines are run continuously with open headers and short exhaust stacks.. there are probably 10,000 inline sixes and old Smallblock chevys that have been run for months at a time on wells in nebraska for 10 years with the headers cut off 12" from the exhaust ports. ( these are older carbed engines and I think its where all the 327 chevys live now)
They use those engines to power the well pumps, they run at or near 4500 rpm for 10-12 hours at a time. and no burned or warped valves or problems related to no headers or exhaust system.
The right way to set up an exhaust for drag racing is to have a short length of pipe after the header collector, draw a line on this pipe lengthwise using a crayon or heat sensitive chalk.. where the line is gone, cut the pipe, that is usually close to the most efficient length for scavenging. (ok thats the right way for us old farts.. there may be something new out there now.)
They use those engines to power the well pumps, they run at or near 4500 rpm for 10-12 hours at a time. and no burned or warped valves or problems related to no headers or exhaust system.
The right way to set up an exhaust for drag racing is to have a short length of pipe after the header collector, draw a line on this pipe lengthwise using a crayon or heat sensitive chalk.. where the line is gone, cut the pipe, that is usually close to the most efficient length for scavenging. (ok thats the right way for us old farts.. there may be something new out there now.)
Thread Starter
Instructor
Joined: Dec 2009
Posts: 236
Likes: 0
From: Houston Texas
I can see how you could ruin your valves from the cold air getting sucked back into the engine "cooling" your valves too fast and "warping" them (or ruining them) but im kinda sceptical that even that could happen because even if true the headers would be plenty of length for the air to warm back up as it flows back into the engine, when not running of course, But as far as runining your heads Im am not sure. Maybe someone can explain the heads part?
Thread Starter
Instructor
Joined: Dec 2009
Posts: 236
Likes: 0
From: Houston Texas
Many many engines are run continuously with open headers and short exhaust stacks.. there are probably 10,000 inline sixes and old Smallblock chevys that have been run for months at a time on wells in nebraska for 10 years with the headers cut off 12" from the exhaust ports. ( these are older carbed engines and I think its where all the 327 chevys live now)
They use those engines to power the well pumps, they run at or near 4500 rpm for 10-12 hours at a time. and no burned or warped valves or problems related to no headers or exhaust system.
The right way to set up an exhaust for drag racing is to have a short length of pipe after the header collector, draw a line on this pipe lengthwise using a crayon or heat sensitive chalk.. where the line is gone, cut the pipe, that is usually close to the most efficient length for scavenging. (ok thats the right way for us old farts.. there may be something new out there now.)
They use those engines to power the well pumps, they run at or near 4500 rpm for 10-12 hours at a time. and no burned or warped valves or problems related to no headers or exhaust system.
The right way to set up an exhaust for drag racing is to have a short length of pipe after the header collector, draw a line on this pipe lengthwise using a crayon or heat sensitive chalk.. where the line is gone, cut the pipe, that is usually close to the most efficient length for scavenging. (ok thats the right way for us old farts.. there may be something new out there now.)
Team Owner
Joined: Dec 2007
Posts: 20,974
Likes: 261
I was always told you need some back pressure to keep valves good for driving, now racing for 9-15 seconds on a track,or 3 minutes of run time is not going to matter.
If you look at hot rods, jet boats, drag boats they run for long periods of time on just headers, so the choice is yours, but I think the size of off the shelf long tube headers, and the bends that are in them are probably creating some back pressure. ( I am not talking about zoomies, or customs that are almost straight though)
If you look at hot rods, jet boats, drag boats they run for long periods of time on just headers, so the choice is yours, but I think the size of off the shelf long tube headers, and the bends that are in them are probably creating some back pressure. ( I am not talking about zoomies, or customs that are almost straight though)
Last edited by pologreen1; Jul 11, 2010 at 12:50 AM.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Nothing of the sort.Do a Google search
Most of the burned valve myths come from motorcycle guys that did exh mods and didn't retune engine to suit.
With the stock fueling the engine ran lean because of the better flow through chamber and the valves got burnt
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Melting Slicks
Joined: Mar 2002
Posts: 3,108
Likes: 126
From: S.L.C. UT
I can see how you could ruin your valves from the cold air getting sucked back into the engine "cooling" your valves too fast and "warping" them (or ruining them) but im kinda sceptical that even that could happen because even if true the headers would be plenty of length for the air to warm back up as it flows back into the engine, when not running of course, But as far as runining your heads Im am not sure. Maybe someone can explain the heads part?
Running open headers won't warp valves. That is a old wives tale.
Last edited by tpi 421 vette; Jul 11, 2010 at 01:24 AM.
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
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