Backpressure question

ACHEAPSHOT · Post by **ACHEAPSHOT** » Tue Jan 10, 2006 8:49 pm

I have an 05 SXT w/stock exhaust. I bought the SRT rear section from a friend of mine. I would like to put this on the car, but I want to make sure I do it right and get a muffler or something w/it. Any suggestions?

Edit- forgot to add that I was told I would need a muffler so that I would not lose any backpressure in the exhaust system.

scneonchic · Post by **scneonchic** » Tue Jan 10, 2006 9:49 pm

I believe most people get a glasspack w/ the srt exhaust to tone it down a bit, but im not 100% sure

03sxt · Post by **03sxt** » Tue Jan 10, 2006 10:09 pm

scneonchic501 wrote:I believe most people get a glasspack w/ the srt exhaust to tone it down a bit, but im not 100% sure

That's what I did. I bought the cat-back exhaust and replaced the two resonators with a glasspack muffler. It helped with the loss of backpressure issue, but there's still a hair of power loss from before.

JustANeon · Post by **JustANeon** » Tue Jan 10, 2006 10:49 pm

you dont want any backpressure

the "loss of backpressure" is actually a loss of flow because the tiny engine cant push enough air out to flow well, creating backpressure

backpressure is always a bad thing!!

refect · Post by **refect** » Tue Jan 10, 2006 10:55 pm

JustANeon wrote:you dont want any backpressure

the "loss of backpressure" is actually a loss of flow because the tiny engine cant push enough air out to flow well, creating backpressure

backpressure is always a bad thing!!

thats true on a turbo car...you want some back pressure.....too much = bad, too little can = bad too

JustANeon · Post by **JustANeon** » Tue Jan 10, 2006 11:01 pm

an engine is essentially an air pump

so no back pressure would allow you to pump more air through and therefore make more power

Baal · Post by **Baal** » Tue Jan 10, 2006 11:22 pm

refect wrote:
JustANeon wrote:you dont want any backpressure

the "loss of backpressure" is actually a loss of flow because the tiny engine cant push enough air out to flow well, creating backpressure

backpressure is always a bad thing!!
thats true on a turbo car...you want some back pressure.....too much = bad, too little can = bad too

wrong, backpressure is always a bad thing.

People think that a huge exhaust is bad because you have no backpressure, that is wrong.

a huge exhaust will create back pressure because it will generate turbulence and the gasses wont flow smoothly like they would on a smaller exhaust, and exhaust too small will ofcourse create back pressure too.

Post by **Diablo0** » Tue Jan 10, 2006 11:29 pm

Correct... The idea is to find the correct flow of gasses to keep the velocity of the air up so it flows to the end of the exhaust pipe just fine.

refect · Post by **refect** » Wed Jan 11, 2006 12:52 am

Baal wrote:
refect wrote:
JustANeon wrote:you dont want any backpressure

the "loss of backpressure" is actually a loss of flow because the tiny engine cant push enough air out to flow well, creating backpressure

backpressure is always a bad thing!!
thats true on a turbo car...you want some back pressure.....too much = bad, too little can = bad too
wrong, backpressure is always a bad thing.

People think that a huge exhaust is bad because you have no backpressure, that is wrong.

a huge exhaust will create back pressure because it will generate turbulence and the gasses wont flow smoothly like they would on a smaller exhaust, and exhaust too small will ofcourse create back pressure too.

werd i always been told you loose backpressure from a huge exhaust. but either way if you go too big or too small it wil lhurt performance?

Post by **Diablo0** » Wed Jan 11, 2006 1:01 am

You may loose backpressure but you aren't getting the gasses to the end of the exhaust pipe. It's like blwoing throw a straw. If the straw is 4 feet long and tiny it's hard to blow through, if the stray is too big like say an inch in diamter but still 4 feet long.. if you blow through it you aren't gonig to be able to blow all the gas out the other side rather a lot will puddle in the exhaust pipe and not exit out the other end. If you have a 4 foot long staw and is of normal size then blowing through it is still very easy and all the gasses are able to escape a lot faster on the other end. The only reason the piping should get bigger is if it's too small to allow the air to escape fast enough but not too much that it causes the air to not smoothly exit the other side.... make sense?

refect · Post by **refect** » Wed Jan 11, 2006 1:21 am

werd well explained as always jason

makes perfect sense

Baal · Post by **Baal** » Wed Jan 11, 2006 2:25 am

Diablo0 wrote:You may loose backpressure but you aren't getting the gasses to the end of the exhaust pipe. It's like blwoing throw a straw. If the straw is 4 feet long and tiny it's hard to blow through, if the stray is too big like say an inch in diamter but still 4 feet long.. if you blow through it you aren't gonig to be able to blow all the gas out the other side rather a lot will puddle in the exhaust pipe and not exit out the other end. If you have a 4 foot long staw and is of normal size then blowing through it is still very easy and all the gasses are able to escape a lot faster on the other end. The only reason the piping should get bigger is if it's too small to allow the air to escape fast enough but not too much that it causes the air to not smoothly exit the other side.... make sense?

Actually as far as i know you dont loose backpressure at all, it takes more effort for the engine to push the gasses, since the exhaust is too big and the air doesnt gain enough velocity to exit properly it end up in the middle of the exhaust, causing the gas "behind" it backpressure.

03sxt · Post by **03sxt** » Wed Jan 11, 2006 7:34 am

Okay... I guess my point was that I lost a bit of low end performance... Some part of the exhaust I put on caused that.

Post by **Diablo0** » Wed Jan 11, 2006 8:08 am

Yes b/c at low RPMs which is your low end area there isn't enough air moving through the pipping at a high enough rate to keep the flow going... so it's like we explained above... too big of pipping and it'll sorta puddle in the tubing and the engine will have to work harder to push it out then. At high RPMs the flow will be much greater and the air flows just fine b/c then it can actually utilize the large pipping.

ACHEAPSHOT · Post by **ACHEAPSHOT** » Wed Jan 11, 2006 11:23 am

Ok, so I just need to keep the 2.25" piping, and throw on a resonator?

Rapley · Post by **Rapley** » Wed Jan 11, 2006 3:31 pm

you could just get the stock midsection from an SRT-4....it has 2 resonators, and will bolt right up.

JustANeon · Post by **JustANeon** » Wed Jan 11, 2006 3:46 pm

be better off getting the SRT rear section than midsection i think

03sxt · Post by **03sxt** » Wed Jan 11, 2006 3:49 pm

JustANeon wrote:be better off getting the SRT rear section than midsection i think

The resonators are way less restrictive than the stock muffler and a lot louder.

rice_eater · Post by **rice_eater** » Wed Jan 11, 2006 4:12 pm

if you're gonna get an srt exhaust, you might aswell save shipping and get just the rear pretzel... your stock piping is hte same size as the srt, so just have a glasspack put on your stock piping, unbolt muttler and replace with pretzel on your own and you're done

ACHEAPSHOT · Post by **ACHEAPSHOT** » Wed Jan 11, 2006 4:47 pm

Thanks, I will go w/the glasspack and SRT pretzel.

Baal · Post by **Baal** » Wed Jan 11, 2006 6:41 pm

mmm pretzels

Smoke · Post by **Smoke** » Wed Jan 11, 2006 7:21 pm

as far as the glasspack goes

I looked all over town and could not find one of any length to make it worth changing the resonators out, so I went to PepBoys and bought a Magnaflow round muffler. they list at $60 from Summit, but i got it through PepBoys for $15, and it works just fine.

Post by **Canada** » Wed Jan 11, 2006 8:11 pm

Smoke, how quiet is it? Did you try putting on just the rear with nothing, and then the muffler? I want to use the SRT rear, but was looking for a round MUFFLER, not a glasspack, cause they don't quiet it enough, and they wear out...

ACHEAPSHOT · Post by **ACHEAPSHOT** » Wed Jan 11, 2006 9:09 pm

Smoke,
I talked to the local muffler shop (Ripley's in North Houston) and they said a glasspack won't make it much quieter, and suggested a round (chambered) muffler like you have on yours. I have a question for you: Did you cut the bumper to accomodate the tips, or just hang them below the bumper?

OB · Post by OB » Wed Jan 11, 2006 9:47 pm

Diablo0 wrote:You may loose backpressure but you aren't getting the gasses to the end of the exhaust pipe. It's like blwoing throw a straw. If the straw is 4 feet long and tiny it's hard to blow through, if the stray is too big like say an inch in diamter but still 4 feet long.. if you blow through it you aren't gonig to be able to blow all the gas out the other side rather a lot will puddle in the exhaust pipe and not exit out the other end. If you have a 4 foot long staw and is of normal size then blowing through it is still very easy and all the gasses are able to escape a lot faster on the other end. The only reason the piping should get bigger is if it's too small to allow the air to escape fast enough but not too much that it causes the air to not smoothly exit the other side.... make sense?

I have my apexi n1 catback on the way as we speak. piping is 60mm and the muffler is a straight thru n1 style w/ 115mm tip. since the piping is very close to stock (2.3"), wont my backpressure/lack of bp be in balance still, even tho my muffler is straight thru? I know this exhuast is good shit, apexi is known for having some of the best products period. Plus its actually made for the neon, not an srt (turbo) exhaust. designed and tuned for the 2gn. im pretty damn excited

JustANeon · Post by **JustANeon** » Wed Jan 11, 2006 10:19 pm

orangeblastsxt wrote:
Diablo0 wrote:You may loose backpressure but you aren't getting the gasses to the end of the exhaust pipe. It's like blwoing throw a straw. If the straw is 4 feet long and tiny it's hard to blow through, if the stray is too big like say an inch in diamter but still 4 feet long.. if you blow through it you aren't gonig to be able to blow all the gas out the other side rather a lot will puddle in the exhaust pipe and not exit out the other end. If you have a 4 foot long staw and is of normal size then blowing through it is still very easy and all the gasses are able to escape a lot faster on the other end. The only reason the piping should get bigger is if it's too small to allow the air to escape fast enough but not too much that it causes the air to not smoothly exit the other side.... make sense?
I have my apexi n1 catback on the way as we speak. piping is 60mm and the muffler is a straight thru n1 style w/ 115mm tip. since the piping is very close to stock (2.3"), wont my backpressure/lack of bp be in balance still, even tho my muffler is straight thru? I know this exhuast is good shit, apexi is known for having some of the best products period. Plus its actually made for the neon, not an srt (turbo) exhaust. designed and tuned for the 2gn. im pretty damn excited

sounds like a good exhaust system!

ACHEAPSHOT · Post by **ACHEAPSHOT** » Thu Jan 12, 2006 9:10 am

I am getting the exhaust installed as I type this. $117.02 w/purchase of a resonator. Not too bad IMO. Thanks for all the info guys. This really is the better .org!

01rtgurl · Post by **01rtgurl** » Thu Jan 12, 2006 10:41 pm

Diablo0 wrote:Yes b/c at low RPMs which is your low end area there isn't enough air moving through the pipping at a high enough rate to keep the flow going... so it's like we explained above... too big of pipping and it'll sorta puddle in the tubing and the engine will have to work harder to push it out then. At high RPMs the flow will be much greater and the air flows just fine b/c then it can actually utilize the large pipping.

I understand exactly what you are saying (you explained it very well with the straw analogy) but on my dyno graph, the torque was WAY up in the low end, way more than the horsepower. I KNOW I lost low end, however, because it's extremely difficult to take off fast from a dead stop, way worse than before my 3" exhaust. But then the top end trailed off, both hp AND tq! Shouldn't I theoretically have gained there?!

nght18 · Post by **nght18** » Mon Feb 06, 2006 12:00 am

hey whats guys...Cheapshot. I had a SRT-4 exhaust on my 05 sxt and it touch the bumper and burn lil slots for the pipes. Not very big or anything to notice. i saw it when my car was up on the lift. And about the glass pack with srt exhaust i dont know much about that. All i know is that had on a srt cat back and it was loud and my car felt slower. I took Jason advise and order a magnaflow exhaust from trubendz..ups should be dropping it off tomorrow (2/6/06) i cant wait..

black sleeper · Post by **black sleeper** » Mon Feb 06, 2006 6:23 pm

I run a fast fabs long tube with the srt exhaust but i cut out one of the resignators and had a 4 inch round muffler put in and it seems to give me enough back presure.