Open Headers??

[W68Firebird97]

Is it ok to run open headers on our cars without the Y pipe? or will there not be enough back pressure.
Thanks
Brandon

[Shirl]

definately not enough back pressure, unless of course you add forced induction or nitrous, but even then.. needs backpressure. James (12secv6) did a couple of dyno runs.. one with open exhaust and one with closed exhaust. The run with closed exhaust made substantially more hp (sorry I don't remember the exact #). I heard the V6 sounds like crap with an open exhaust also. If you are thinking about upgrading your exhaust, you could see what it sounds like when the stock exhaust is off and maybe even run it on the street before hand to see for yourself.

[Magnus]

I wouldn't run open headers because of where the headers end, there are too many thigns too close that would get too hot.

I would run Open Y-Pipe. In fact I do.

I ran 12.3 with open y-pipe.

I ran 14.2 NA with open Y-Pipe.

With my setup, NA... I did some testing. 3" cat + muffler I ran 14.8@87... 2.5" off-road pipe + muffler I ran 14.7@88... with open y-pipe I ran 14.5@90.

I ran 3 passes with each, then I went back again and did a pass with each once more to do some more testing.. 60's were almost identical.

From now on I will be running open y-pipe at the track.

I don't believe a stock convertered A4 or a M5 would see gains like mine. A high stall A4 might see similar gains though.

[bluecmaro96]

ok i would like others opinions on this since you see what magnus gained from having no back pressure. i was thinking of running true duals off the headers one on each side. not the whole way back though, just maybe 4 ft and out the sides of the car. do you think i would have about equal gains from this as an open y ipe since technically ill have open headers?

[Voodoo410]

I ran open headers on my '87 Corvette and it ran better times than with closed and sounded a LOT better too...but as for a V6, it sounds really bad with open headers and it doesn't gain anything horsepower wise I don't think.

[Ramair90]

im sorry but this is pissing me off...BACKPRESSURE is BAD! You are talking about velocity. they are 2 completely different things. :rolleyes:

[Backfire]

<blockquote>quote:</font><hr>im sorry but this is pissing me off...BACKPRESSURE is BAD! You are talking about velocity. they are 2 completely different things. <hr></blockquote>Would you care to elaborate on your reasoning?

It was my understanding that any motor needs adequete back pressure to develop maximum power. The need for it has to do with exhaust gas scavenging. With the back pressure too low, unburned air and fuel is drawn into the exhaust before the valve closes, reducing the potential power. It can also reduces the cylinder pressure which reduces torque. The loss in torque is seen by some even when just changing to a free flowing full exhaust system. There are some other things like elevated exhaust temperature becsuse the combustion continues in the headers. This does nothing for your power/torque output and is simply wasted energy.

There are ways to compensate for this, such as cam changes, but that is probably beyond what W68Firebird97 is looking to do.

[Damien214]

My car sucked major *** when I was running with an open Y pipe. I even lose major power when running without a muffler, so I'm gonna say [img]graemlins/thumbsdown.gif[/img] to the open headers idea.

[v6maro]

you need SOME kind of backpressure, it lets the O2's get hot and get better readings, a y-pipe for the track will be fine since it is a strait strip and it'll work great, but for the streets, keep it all hooked up.
-Steve