open headers

bad@ss mike · 04-02-2006, 07:50 PM

hey guys, i just put headers on my car but my exhaust system is on back order. is it bad for the engine or will it mess anything up if i ran it with open headers?

**redline** · 04-02-2006, 09:05 PM

you will burn up the exhaust valves. just try to stay out of the rpms til you get pipes

**hammertime** · 04-03-2006, 09:26 AM

Open headers won't burn the exhaust valves. You'll probably get some backfires and such when the rich mixtures reach the atmospere, but no flame can travel all the way back up to the valves.

But you won't be able to run much rpms, cause it's going to be way loud.

Open headers aren't that great for performance though. Racers usually run a 18 - 24" collector extention to help scavenging.

**redline** · 04-03-2006, 07:42 PM

im sorry he made a huge mistake in his reply (RUNNING OPEN HEADERS AT HIGH RPMS FOR A PROLONGED AMOUNT OF TIME CAN BRING EXHAUST TEMPS DANGEROUSLY HIGH ON THE EXHAUST SIDE OF THE HEAD)

**hammertime** · 04-04-2006, 06:38 AM

Originally Posted by redline

im sorry he made a huge mistake in his reply (RUNNING OPEN HEADERS AT HIGH RPMS FOR A PROLONGED AMOUNT OF TIME CAN BRING EXHAUST TEMPS DANGEROUSLY HIGH ON THE EXHAUST SIDE OF THE HEAD)

well, you seem to know something I don't - can you enlighten us as to why?

**redline** · 04-04-2006, 08:51 AM

i just said why

**hammertime** · 04-04-2006, 06:11 PM

You said why not to run open headers. I'm asking why "RUNNING OPEN HEADERS AT HIGH RPMS FOR A PROLONGED AMOUNT OF TIME CAN BRING EXHAUST TEMPS DANGEROUSLY HIGH ON THE EXHAUST SIDE OF THE HEAD"

Why would the temperature on the exhaust side of the head be any higher with open headers than it would be with a full exhaust system behind the headers?

**blue02Z** · 04-04-2006, 07:30 PM

I don't know about the LS1 but i've run open headers on my old camaros and my pickup, no problems yet

**oneBADDz** · 04-04-2006, 07:34 PM

open headers won't hurt it, no headers or anything would, but open headers won't

**redline** · 04-05-2006, 04:55 PM

i dont know ive always been told that running with no back pressure that far up the exhaust can cause damage. the thing is i always see these guys at the track running them open. I always figured they had enough (mechanical mods) on the upper end to compensate for the lack of at the bottom end. The kicker is a lot of buddies from high school would always run open headers on there little 4 bangers to sound cool then they would come to me with a running problem such as knocking or and eratic idle. Typicly i always thought it was a timing belt, well that never fixed a damn thing so one day i got a hair in my ass and decided to take a bore scope to one, come to find out #1 cylinder ehxaust valvle had a hairline crack in it. Rebuilt the heads an it ran like a champ. Since then ive seen a few other cars do it but never a ls1 so i always assumed it was the lack of back pressure. So i did a little research and came up with a few things to shed some light on the situation. fact- ( it is possible when running open headers to recieve a backdraft of cool air upon deseleration that will reach a hot valve and cause it to fracture) not a fact-( full exhaust allows hot air to escape away from head so as not to over heat a head) Now it may be ok to run a full length header open but not so shore about a shorty. Personaly i have ran open headers and had no problems but ended up putting pipes on not only because i noticed a loss of power but because it makes a daily driver a daily annoyance.

**hammertime** · 04-06-2006, 06:41 AM

A well tuned combination should have the correct air/fuel mixture and therefore, should not be prone to backfiring. If I had to guess, your buddy with the 4 banger probably ripped of his old exhaust and never bothered to recalibrate the A/F ratio for it.

And I agree, open exhaust on the street is not only a nuisance to the driver, but asking for trouble from the law. Also, just dumping the exhaust right out of the collector does not yield the most effective scavenging of exhaust. A lot of racers will experiment with collector lengths to maximise their 60' time (more torque) or gain mph (more HP) in the quarter.

**oneBADDz** · 04-06-2006, 09:34 AM

there is no way that a backdraft of cool air running up those smokin exhaust pipes is any cooler than the air that's running in through the intake. If anything the air through the intake is substantially cooler. It's only running through the TB and intake to get there which a substantially cooler and a shorter ride than through the exhaust which is triple the temperature of the intake, so it's impossible that cooler air would reach the valves through the exhaust than what is already hitting them through the intake