Yo

Just use headers pipes all the back as the exhaust?

 

Yes it's possible. It would be extremely loud and probably very raspy. It would attract cops, and their ticket books, like a magnet.

 

not to mention SES lights, fuel problems, and lack of backpressure costing you horsepower.

 

Throw some O2 sims on to take care of the ses light.
Why would you have fuel problems?
And if a free flowing exhaust costs horsepower why do you have a cutout?

 

your one to talk..... that car made me drool!

 

If you run open headers you will run rich. I've got a couple friends who tried this, and they ran really rich. (ie the fuel problems....)

a cutout is very different than running open headers. I have stock manifolds, y-pipe, cats,.... and then a cutout. There is enough backpressure. To achieve the most horsepower, you want to get very low backpressure. However if you have almost zero backpressure, you will lose horsepower.

 

My biggest problem with this forum is the conflicting opinions. I'm knew to the horsepower game and I never know who to believe.

Check out this thread over in the dragracing forum http://web.camaross.com/forums/showt...hreadid=216444

I know if you run straight out of the head, without manifolds or headers, you lose power because you lose the scavenging affect. However, if he's running headers and pipes to the back of the car, which is the way I understood his question, I dont see how you loose power. I've seen lots of people at dirt track races that run open headers.

 

Good information is always difficult to find because board members vary widely in actual experience and knowlege. All mean well but their answers will vary greatly. I'm sure no expert but through the years I have learned a few things, mostly by screwing things up a time or two learning to do it right. In a race car using open headers the only concern is maximum power at wide open throttle. So they want zero back pressure. On the street we don't drive at full throttle all the time. We have to make compromises. Our exhaust must be quieter and we need a LITTLE bit of back pressure for low end torque. From the factory our exhausts must be tucked up out of sight and be quiet. We hot rodders want more sound and more horsepower so we put on headers with less restrictive mufflers and use larger diameter exhaust tubing to keep the flow higher. A result of this is a louder exhaust. Usually the louder the exhaust the less restriction to it and the more power it lets the engine make. The system you propose will be extremely loud. You may like it but your neighbors will hate you. It will have very little back pressure so at low and mid rpms it will make LESS horsepower and you will be able to feel it. At high rpms back pressure ceases to be a necessity and it will produce MORE horsepower. By adding a small bullet muffler to each pipe you will increase back pressure slightly and pickup some of the power you lost on the low end without hurting your power on top end. If you add an X pipe between the two pipes the gases flowing through each pipe will help scavenge the gases flowing through the other pipe and you will GAIN horsepower. A properly designed set of dual pipes which utilize an x pipe and small efficient mufflers will actually make more horsepower than open headers. My own exhaust system comes off the headers into 3" pipes then goes into a Dr Gas tandem junction (x-pipe) and then tucks up along the driveshaft into two 12" twister mufflers then dumps in front of the rear axle. Is it loud? Oh yes! I would lose horsepower by going to open headers.
Try this site to see what truely efficient exhausts look like. http://laneswheels.com/ The black painted set is the set I have on my car.

 

It's not the open header per se that is causing you to run rich. It's the fact that the O2 sensor sits in the collector.

When you run open headers the sensor becomes exposed to outside air. Causing the PCM to believe the car is running lean, therefore compensating by richening up the mixture.

Simply extend the the collector and the problem is solved.

And back pressure any back pressure does not make horsepower, it robs it plain and simple. Anything that impedes the scavanging of the cylinders will cause a loss of power ...

 

......what he said. That's what I meant. I was just tired and didn't want to give a detailed explanation. You nailed it right on the head man!

[QUOTE]Originally posted by V6toZ28

And back pressure any back pressure does not make horsepower, it robs it plain and simple. Anything that impedes the scavanging of the cylinders will cause a loss of power ...

read the last part of Gold Z's post.

 

[QUOTE]Originally posted by GoFast908Z
......what he said. That's what I meant. I was just tired and didn't want to give a detailed explanation. You nailed it right on the head man!

Quote:

Originally posted by V6toZ28

And back pressure any back pressure does not make horsepower, it robs it plain and simple. Anything that impedes the scavanging of the cylinders will cause a loss of power ...

read the last part of Gold Z's post.

Scavaging and back pressure are not the same thing ...

 

scavenging- literally sucking air out of the other side

back pressure- restriction in flow

 

I know that, but if there is zero backpressure, you will lose hp unless your car is tuned to run like that at WOT at the track. Thats all i'm saying. Read what Gold Z said about it. I agree with him. Don't want to start an argument here. I'm not very good with words, maybe someone (possibly me, or others) misunderstood. Hey it's all in good fun right.

 

Until he can say how back pressure creates HP, he's wrong ...

 

backpressure can slightly shift the tq curve down the rpm range.. but I don't think it makes a too much of a difference with a stock engine.

If you had an unlimited budget, you could reduce exhuast backpressure, and the readjust your cam and timing to make the tq curve a hair wider, so you gain power everywhere again.