i heard this from a friend. i was just wondering if it is true/false.

 

Worst it does it just run rich.

 

the conserns I heard about it before was that cold air could easily run into your engine and cause it to cool too rapidly, causing dameage, a full exhaust makes sure that cold air dosent make it in. but I'm not sure how much of that I belive...

 

the only thing ive ever heard ( and i dont know if its true) is that running an open header ( or like a 3" straight pipe) is bad for the valves. never thought too much into it, though. im sure if you only do it at the track, it wont hurt anything. ( hopefully you wouldnt run that setup all the time, so i dont know why i said the track thing) oh well

 

I don't see why it would damage anything. I don't believe air could get sucked in there....it's the exhaust, after all.

And besides, cold air gets easily into the engine through a cold-air intake anyways.


[Modified by Lsos, 3:34 AM 12/12/2002]

 

Don't think it hurts your motor, but it sure decreases power in a stock motor. I would know. I'm the only idiot that likes the excessive noise and lack thereof power.

 

Since when does cold air rise?

 

yeah i heard (keyword:heard) it can burn out yer valves easier, but i think thats just far fetched, i wouldnt really pay any mind to it, besides, im sure yer not gonan run open header for extensive amounts of tiem, good luck!

 

thanks for the info guys. i feel better now. you see i put a race header on my 97 lude and b/c it's longer there's no room for the cat. i'm in the process of having a pipe made, but the shop i'm going to is real busy right now. currently rolling in my gf's car--just in case.

 

My car was a couple tenghts faster with open header. 89 crx dx w/ b16

 

I didn't mean while the engine was running, but as soon as you turn it off all of the air circulates. The hot air in the exhaust moves up and out and is replaced by cooler air surrounding. good point on cool air coming into the engine on me.

 

People tend to confuse running open head and open header when relaying information. Running open head is ridiculously bad your your engine. Open header is just fine.

 

I always heard it was the back pressure story. You know, not enough back pressure and its bad for the valves. I've been told thats mostly and old wifes tale with the old school domestic guys.

 

Knocked a couple tenths off my time

 

yeah thats what people are sayin but i doubt it would really damage anything

 

it has nothing to do with backpressure,,,,,back presure is bad

 

More backpressure is good for bottom end torque, smaller amounts better for top end power, No backpressure is bad.

 

Lots of bad information going around. Running an open header can (notice I did not say will) make you run LEAN at high rpm. This is because of higher flow rates and loss of pulse wave scavenging. I doubt you could damage it running that setup if it's a stock motor hooked to a stock ecu, but you can always try...

 

Backpressure is always a bad thing, it means resistance to airflow. Being that an engine is primarily an air pump, resistance to airflow is not going to help anything, ever. The term you're looking for is delta pressure, which is a good thing as it describes velocity gain from the port to exhaust primary. Not enough velocity promotes reversion, and reversion is always a bad thing too (in terms of power output at least).

 

open header offers minimal gains. those quick 8 all motor guys run OPEN HEADER because their engines have been built to suck in as much air and scavange it out as fast as possible. a built head with the right valve train would benefit from open header. common bolt ons on a fairly stock engine, its not gonna do anything except sound louder. cold air going through the engine is good because its entering the engine and travel through the tb,then the intake manifold, which then the INTAKE valves open up. on the COMPRESSION stroke both intake and exhaust valves are closed. during the POWER stroke both intake and exhaust valves are closed. on the EXHAUST stroke intake valves close exhaust valves open which in turn comes out the exhaust system. if you run open headers and for some reason you car backfires say at high rpms, then cold air will be allowed to enter through the header contacting the HOT EXHAUST VALVES which will result in warpage.

 

Like I said, I was a couple tenths faster with open headers (on many, many occasions), going from upgraded exhaust. I was about .4 sec faster going from stock DX exhaust to the upgraded exhaust, which gives a total of over half a second and around 4mph difference going from stock dx to open headers.

So, it depends on what kind of exhaust and engine you have. Crappy exhaust and great engine gives huge gains, good exhaust with crappy engine will offer minimal gains.

 

I've also heard that it's bad for the valves.

A friend of mine had to run open header to meineke, and he said his car was DIRT slow.

Goldfingiz

 

every car ive seen running open header has ran a faster quarter mile than with an exaust on. i went from a 14.6 to a 14.3. a freind of mine went from a 14.7 with his stock exaust, to a 14.2 with open header. then we ran it with slicks and eventually got it down to a 13.9. both were in i/h/e b16a crx's

 

i went from a 13.9 to 13.7.

 

i think the only thing it will hurt is your ears