Exhaust Back Pressure

[laborsmith]

This links to what I consider to be a good summary of issues relating to designing/selecting a car exhaust system: Exhaust back pressure - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums - Camaro5.com

Laborsmith

 

[SSpeckerwood]

that is a great article.

so would it be safe to say that keeping the stock exhaust diameter but removing cat's and muffler would be the better performer than putting a larger pipe on?

 

[el_guapo]

that is a great article.

so would it be safe to say that keeping the stock exhaust diameter but removing cat's and muffler would be the better performer than putting a larger pipe on?

That would not be the same as getting an aftermarket exhaust, which would be a much better idea since the exhaust flow will be impeded when it enters the larger catalytic chambers then has to squeeze through the exhaust pipe again. Just an assumption, I may be wrong though, but it has to enter a chamber where the "pulses" might lose velocity and dampen the flow leading to loss of gas flow speed.

 

[SSpeckerwood]

that is a great article.

so would it be safe to say that keeping the stock exhaust diameter but removing cat's and muffler would be the better performer than putting a larger pipe on?

That would not be the same as getting an aftermarket exhaust, which would be a much better idea since the exhaust flow will be impeded when it enters the larger catalytic chambers then has to squeeze through the exhaust pipe again. Just an assumption, I may be wrong though, but it has to enter a chamber where the "pulses" might lose velocity and dampen the flow leading to loss of gas flow speed.

It wouldn't be entering any catallytic converters..

 

[el_guapo]

It wouldn't be entering any catallytic converters..

it wouldn't enter the chamber of the gutted cats? I was assuming the cats would be gutted since there is no catless off-road pipe that is selling yet. Unless i haven't seen it.

 

[SSpeckerwood]

in my county we have 0 emission requirements. i would remove the cat's completely and put the down-pipe and another piece of pipe in the 2nd cat's place.

 

[el_guapo]

0 emissions? that's awesome. well let us know how it turns out.

 

[el_guapo]

can the trifecta tune also run catless exhaust?

 

[SSpeckerwood]

it'll be a few months. still rebuilding my harley from the wreck last year.


but my question wasn't answered;

so would it be safe to say that keeping the stock exhaust diameter but removing cat's and muffler would be the better performer than putting a larger pipe on?

 

[keto06]

it wouldn't enter the chamber of the gutted cats? I was assuming the cats would be gutted since there is no catless off-road pipe that is selling yet. Unless i haven't seen it.

BNR or ZZP. And exhaust diameter varies GREATLY between turbo and NA cars.

 

[laborsmith]

SSpeckwood, it would depend on what one wants in their exhaust, quiet OR performance. But if moving to a larger diameter, which is often done when seeking to improve performance, care needs to be taken to get the right size and not get a size that will impair performance. Now we get an idea why changing for the sake of change does not always work.

Tuning will also make a difference in how the drive train will respond.

If one is satisfied with the exhaust sound, then Chevy engineers will have provided the optimum for sound and performance. If one desires an increase in performance or a change in sound, then the article gives the cautions to be considered when making a change.

Laborsmith

 

[SSpeckerwood]

i'd like your advice laborsmith.

i'll be looking for performance.. plan to do a catless down pipe and remove the other cat. probably going to put a shorter style noise reducing muffler in.

go up in diameter or leave it how it is?

 

[Opticon]

Turbo cars do not benefit from exhaust tuning. Engine backpressure is created by the turbine. And backpressure between the turbine and the tailpipe is just slowing your spool time.

Turbo cars benefit from the lowest restriction exhaust possible.

 

[laborsmith]

Opticon, could you explain the seeming contradiction between your first sentence and your last sentence.

Laborsmith

 

[Eric Smit]

i believe he is referring to finding the perfect exhaust diameter to create the perfect amount of back pressure.


-Eric Smit

 

[laborsmith]

Eric, that could be what he meant, it is most definitely not what he wrote.

Laborsmith

 

[CoHPhasor]

Opticon is correct.

Basically the only place you want high pressure in the exhaust is at the turbo exhaust housing.
The exhaust needs to be hot and pushing hard at that point.

From every point after the exhaust housing you want absolutely as little pressure as possible.
(High pressure in front of the turbine and low behind it encourages the exhaust to move quickly passed the turbine quickening spool)

Other car communities have argued this like crazy about this, but once they made properly flowing divorced downpipes the benefit is blatant.

 

[Eric Smit]

I think he meant that as tuning, and tuning is not necessary, because you should just get the biggest monster of a pipe you can, which I'm sure we both disagree with.


-Eric Smit

 

[laborsmith]

Eric, I do not disagree in general, understanding that there is a decibel factor some of us have to consider. I live in a condo complex and the lady who is most often the president of the association will borrow the decibel counter from Center Line to measure the decibel of the residents motor vehicles. Therefore going to 2.25 from 1.75 (w/o muffler) is more likely to stay within limits than going to 2.5. Clearly the system you describe would be better for performance; just not very good for the ears of anyone at hand, including the driver.

Laborsmith

 

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