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ok, from what i have learnt, the point of an after market exhaust system is to provide less restriction on the outwards flow of the exhaust gases by supplying less backpressure in the tubes, so can this be done by adding a suction pump into the tubes which sucks the air out of the exhaust tube, providing a vacume effect i.e. as minimal back pressure as possible.

 
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Are you serious?

Engines run with a small amount of vacuum in the combustion chamber, but adding vacuum to the exhuast is just silly. You want the gasses to make their own way out as easily as possible. . .not force them out.

 
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i am sorry, i am just slowly learning new stuff about engines so bear with me, can u please explain what is wrong with forcing the gases out?

 
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That would create too much vacuum during the exhaust port stage of the combustion process. The ECU wouldn't be able to compensate for that, and the engine would simply run worse. The gases need to be pushed out by the combustion process to ensure a smooth flow of gasses. Besides. . . all engines (less the full-on race motors) require some form of back pressure in order to run properly. The trick is tuning it just right for the most desired results.

 
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Bows to Yukon. . oh wise one.

 
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correct me if i am wrong, but doesn't the back pressure creates torque? You will need some sort of back press or else why not just get a straight pipe and no muffler

 
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THe car is most powerful without an exhaust system. NO BACKPRESSURE. Cars have exhaust in order to reduce pollution and noise.

 
Rep Power: 307

I think only at low RPMs backpressure is a good thing. Keeps the engine running in a balanced fashion or some crap like that. (I really should study this stuff in a technical sense a bit more) At higher RPMs the engine's just running ***** to the wall, anyway. . . . in that case, less backpressure is a good thing.

 
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backpressure does create torque at lower RPM, but makes the engine force the exhaust out at higher RPM. If you can find the balance between backpressure and free flowing exhaust, then you will be extremely happy. Because you will have power no matter the RPM.

 
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How many race cars do you see running at low RPMs? You dont, thats why you get pulled over for having an aftermarket exhuast. Most companies have disclosures stating their exhaust is intended for race use only. Not just exhuast, but everything else too.

 
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what if one had a variable pressured exhaust. something that controlled backpressure based on rpm...

 
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Im sure it has been tried, but it is hard to do.

There is a certain turbo called a "Variable Vein Turbo" which would actually make the area of the turbine blade smaller or larger as the demand for more exhaust gas increassed or decreased. They were a great idea, but were not very reliable.

 
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