Basically i would like to know if a closed cutout would change the sound of an exhaust system and if it would reduce hp.

I have an electric cutout placed in the i-pipe on my stock catback. Im going to be installing a new catback soon and i just want to know if i should bother with installing the cutout. I probably will anyway just because its cool.

Be yeah it you think about it, a closed cutout will create turbulence from the exhaust gases flowing down the cutout but haveing nowhere to go, so it has to come back and exit through the catback. Will this change the sound or reduce hp in any way. Even if its tenths of a hp, I would like to know.

This has just been on my mind for a while and i would like to know if anybody has an answer.

 

i don't have a answer in terms of dyno proven numbers....but i've had a cut out on my car for 2 years and i know that the car isn't as fast w/the cut out closed..of course if the exhaust can take a shorter route that will provide the most HP...i don't believe the "turbulence" from the cut-out being closed would cause any loss in HP...it should be the same as if a cut-out wasn't there

 

A closed cutout gives you your backpressure back. increasing torque if anything.

Also in a closed cutout, it's not going to flow any better than a strait pipe. But of you have a nice exhaust system with out any bottlenecks or restrictions a lil "turbulence" is not going to hurt anything.

 

I don't believe it's anything you would notice. A tenth of a hp? Are you really concerned about it if it is that minimal? I don't think it's possible to get readings accurate enough to be able to say "well...there goes 1/10 of my power..."

As for there being any turbulence - I'm not a aeronautical engineer (electrical rather....in THAT case there would be zero air entering the cutout at all if it's closed entirely), so hopefully someone who is (or close to one) can answer that.

 

Old wive's tale. Backpressure does not add torque.

 

Dyno results usually show that an open cutout does yield gains. As for sound, I purposely run mine open all the time because it sounds alot better and louder then my Magnaflow catback.

 

He's not asking if an open cutout shows HP gains.... he's asking if having the "Y" shaped element in the exhaust path when the cutout is closed causes any disruption of exhaust gas flow, resulting in a loss of HP compared to having a smooth pipe in its place. The cutout is bound to increase turbulence as the exhaust gas resonates in the closed branch of the "Y", but I doubt you could measure the effects.

Don't worry about it.

 

Yeah im not worried about it at all. I was just wondering.

 

From a physics perspective, Bernoulli's priciple may play a part. The high velocity air moving down the pipe would be at lower pressure than the stagnent air in the cutout chamber, thus creating a dome of high pressure causing a restriction..and more back pressure withou adding torque? Curious question, I might have to consult another engineer...

 

Actually, the Bernoulli principal would show that the fast moving gas in the pipe causes a REDUCTION in pressure in the direction perpendicular to flow, and would cause a slight reduction in pressure in the stagnent chamber.

Repeat - don't worry about it.

 

Injuneer, sorry I wasn't clear. What I meant was that the stagnent air in the "dead leg" of the flow would cause turblence resulting in a high pressure zone. Although it would be about as significant as a mosquito farting in a hurricane...
Thinking about putting cut-outs in my other car though....

 

Apply that to my car. My car is slower than ***** with the cutout open.