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Discussion Starter #1
So what do y'all think about running open headers? I have heard from some that running like that would actually slow the car down and reduce HP, and I have heard some say the exact opposite. I have been looking into this QTEC thing since, and I was wondering what y'all thought. Sure can't beat the sound with the flip of a switch, though.

http://quicktimeperformance.com/QTEC/index.html
 

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rlinbatonrouge said:
So what do y'all think about running open headers? I have heard from some that running like that would actually slow the car down and reduce HP, and I have heard some say the exact opposite. I have been looking into this QTEC thing since, and I was wondering what y'all thought. Sure can't beat the sound with the flip of a switch, though.

http://quicktimeperformance.com/QTEC/index.html
I think you need to buy that things and test it, then report back! ;)
 

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Well, you aren't quite running open header, more of an open exhaust. I've seen alot of exhaust cut-outs in a lot of mags, but I don't know anyone that has personally installed one. I would think with a good flowing muffler, like a straight through design, you should have similar results. Unless you're going to put in front of the cat convertor, it's more like removing the muffler and shortening the exhaust tract. It is a neat little items though...

I have heard and read that TOO open of an exhaust, particuarly on N/A cars, can allow too much air to backflow into the system, which creates some backpressure. Goofy and someother people are runnning 3" exhaust systems though, and report no loss in power of any kind.
 

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Discussion Starter #4
Sp00ner said:
Well, you aren't quite running open header, more of an open exhaust. I've seen alot of exhaust cut-outs in a lot of mags, but I don't know anyone that has personally installed one. I would think with a good flowing muffler, like a straight through design, you should have similar results. Unless you're going to put in front of the cat convertor, it's more like removing the muffler and shortening the exhaust tract. It is a neat little items though...

I have heard and read that TOO open of an exhaust, particuarly on N/A cars, can allow too much air to backflow into the system, which creates some backpressure. Goofy and someother people are runnning 3" exhaust systems though, and report no loss in power of any kind.
This one is adjustable and goes in front of the cat so you don't have to run completly open. Even if this keeps the power the same, you can't deny the intimidation factor of hitting a switch and getting LOUD.
 

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rlinbatonrouge said:
This one is adjustable and goes in front of the cat so you don't have to run completly open. Even if this keeps the power the same, you can't deny the intimidation factor of hitting a switch and getting LOUD.
Not at all! I love the idea of a switch that turn my car into a growling monster with just a flip. I'd love to install one of the dual setups into my Vette...
 

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I've seen this done on a few trucks (some desiel some not) and my god are they loud. I don't know the people and know nothing of the power output they gain or lose because of it but I can tell you if I heard that behind me, I would look for some F1 or NASCAR car or something. Also, it sets off alarms instantly as you drive by at a contest speed. :D
 

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Discussion Starter #7
Some of my guys in the shop used to make their own like this, except they just used a cable that they would pull up on and move the valve to run the exhaust right out. I sent the company an email to get their ideas on weather or not this would help with HP. I'll let y'all know when I hear a response. One thing for sure, it will scare the living shit out of anyone next to you at a red light
 

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I like the idea.

Where would you mount it? I would think as close to the manifold as possible. It's got to yield some power if you are shortening the exhaust travel and bypassing some bends and the muffler, right?
 

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becuz your car is supercharged you might see slight loss becuz of lack of back pressure which creates a scavaging affect. a free flowing muffler and no cat should work fine.
now if you had a turbo like my srt you wouldnt have to worry about it becuz of the turbo in the exhaust path.
 

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jgb989989 said:
becuz your car is supercharged you might see slight loss becuz of lack of back pressure which creates a scavaging affect. a free flowing muffler and no cat should work fine.
now if you had a turbo like my srt you wouldnt have to worry about it becuz of the turbo in the exhaust path.

That's what people said about upping the exhaust system to 3" and a few people on here have done it with no power loss.

I thought that "back pressure" theory was just a bunch of BS anyway. :confused:
 

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jgb989989 said:
becuz your car is supercharged you might see slight loss becuz of lack of back pressure which creates a scavaging affect. a free flowing muffler and no cat should work fine.
now if you had a turbo like my srt you wouldnt have to worry about it becuz of the turbo in the exhaust path.
Incorrect, and backpressure effects turbos just as much... any backpressure will slow the exhaust gas as it leaves the turbo and will create even more turbo lag as the turbo has to overcome it. A supercharger and a turbo charger benefit from the least amount of backpressure in the exhaust. In fact, I belive it's worse for a turbo, not sure on that one. Thanks for your input, but you're missing a few facts.
 

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no its not bs
ask anyone the backpressure causing a scavaging affect which removes exhaust faster. they mite not notice any power loss but there is probably a low end torque decrease.
but ya it would sound mean as shit
 

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jgb989989 said:
no its not bs
ask anyone the backpressure causing a scavaging affect which removes exhaust faster. they mite not notice any power loss but there is probably a low end torque decrease.
but ya it would sound mean as shit
A LACK of backpressure will help remove exhaust gas from the cyls faster than pressure pushing back into the cyls...
 

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Sp00ner said:
A LACK of backpressure will help remove exhaust gas from the cyls faster than pressure pushing back into the cyls...

Exactly. I always thought that the faster the engine can move air through, from intake to out of the exhaust system, the better.
 

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Since I can already tell he's not going to belive us, here's what Sport Compact Car (Yes, I know they suck, but this is hard numbers and facts, not their ability to drive), tested on their SRT project. I would assume you'd be familiar with this:

Exhaust backpressure is the enemy of the internal combustion engine. Reducing it makes it easier for exhaust gases to exit the combustion chamber, which reduces the amount of work the engine has to do to shove it out (pumping losses if you're an engineer). Less backpressure also means less leftover exhaust diluting the next intake charge, which means more gas, more oxygen and less heat. All of this means more power.

Reducing backpressure in most boosted engines has the additional benefit of better turbine efficiency, which results in better boost response and more boost. However, the SRT-4's active feedback boost control will cancel this benefit with more aggressive wastegate operation so the only gains would theoretically come from increases in pumping efficiency. Realistically, this means reducing backpressure on the SRT-4 engine should yield similar gains as it would on a normally aspirated engine--not nearly as great as on other boosted engines.
 

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Wasn't that all due to the leaded gasoline, and with no backpressure, there was no chance for the lead to lubricate the valve train the gas just excaped too soon, and ended up burning the valves???
 

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Discussion Starter #17
Just got another response from the company making the valve. Here it is:


It will be a gain on the cobalt. We are very popular with supercharged grand prix crowd. They gain alot with the qtec. No exhaust is the best exhaust for a force induction.
Sales Team
www.QuickTimePerformance.com
201-444-0998

Sounds like I may get this.
 

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Jesus...I come from helping a nation of idiots at my job only to find this. 1) We have a supercharger to scavage the cylinders. 2) Back pressure, as Spooner already stated, would only hinder that effect. Since we're boosted, the more open the exhaust, the better. I posted the following in regards to this back in Jan. on this thread http://www.redlineforums.com/forums/showthread.php?p=8674#post8674 : "...The rules are different when dealing with forced induction. For example, you don't even need the exhaust pipes routed to a collector (see top fuel engines). Besides consolidating all of the pipes to one to be able to attach a muffler, the main reason they're tied together is to create a "scavaging effect" in which the pressure from one pipe flowing by another creates a vacuum which helps pull the air/fuel mixture into the cylinders & pull the exhaust out". Sorry if I'm rude but I can't tolerate ppl with no common sense.
 

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So, where would be the best place to attach this thing? I am thinking as close to the manifold as possible, but I'm not really sure.

If I end up getting a refund for the SCDyne header, I'm gonna use the cash to do this.

K&N CAI + Supercharger + Open Exhaust = HELL YEAH!!!!!

Even if a car beats me, I'll scare the hell out of them when I rev before we run. :D
 

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I would think you'd want it pretty close to the exhaust manifold, but one question, are you just going to vent the exhaust right out into the air from there? If so, you might want to get it a little lower or something. Otherwise I think you're going to be pouring exhaust fumes right into the passenger compartment of the car, I'm not sure where it draws air in, but I know when you have an exhaust leak in that part of the exhaust, it POURS into the cabin. I have near fatal experience with this, my girlfriend almost died, ok maybe not died, but she was throwing up all over, couldn't maintain a wakeful state, and we almost had to take her to the hospital. This was interstate driving too, not slowly around town. So PLEASE think about that fact when you're putting it in. Not to mention having that exhaust all the way up there, might funnel alot of heat and exhaust right into the engine bay too. Maybe right in front of the cat would be better?
 
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