Is this right?

[Deadboy]

I just took may exhaust system apart and something looked strange.....the last pipe before the exhaust manifold has a smaller pipe in it and it does not touch manifold......i took a pic ....is this right or has the las owner of my 89 civic built it from scratch

[CivicSpoon]

From the pic, it looks like one of the gaskets that comes with DC sports headers. Try taking a small flat head and lightly pry it up to see if it pops out. DC Sports uses a ring instead of the regular flat gaskets, to connect the header to the cat.

[turtlecrxsi]

If you're going to reconnect it, then you may want to leave it alone or go get another gasket.

[Deadboy]

Amm no the gasket is new ...i was talking about the black pipe inside the main pipe. Could the inner pipe effect the car performance becouse it is deeper then the main pipe and the out going hole on the manifold is as big as the inner pipe(the main pipe is bigger so could the gases just circle around were the main pipe goes over to the smaller pipe).......sry about the crazy text ...hope u understand

If i was to put a neck inside so that the smalle pipe would connect to the manifold.....could this help the gasses get out if the system faster?

[91CRXTC]

is that the stock setup? When i took my stock header and down pipe off, the down pipe had a smaller pipe inside it like your talking, if so then.....actually i have no answer just wanted to comment.

[turtlecrxsi]

Originally Posted by 91CRXTC

is that the stock setup? When i took my stock header and down pipe off, the down pipe had a smaller pipe inside it like your talking, if so then.....actually i have no answer just wanted to comment.

That's what I originally thought. It came that way because cast iron rusts bad. My guess is that the inner piping is there as a protective inner pipe that is not dependent on the outer pipe alone. Over all, it is just heavy and de-tuned for emissions.

[91CRXTC]

although, when i sit here thinkin of the design i think they might do a dual pipe layout for low and high rpms. At low rpms you dont need alot of space for the exhaust to flow through hence the smaller pipe, but when you get more exhaust flowing through, then the pipe size would need to be greater to accept the amount of exhaust flowing through so it would use the entire inside pipe plus the outside pipe. This is only my observation of the situation which does make sence to me, which made me think about building a header that does the same but is a sleeve of somesort so that the ID grows with the pressure applied to it. or just a dual pipe exhuast all through but thats allot of pipe and wieght.

[Deadboy]

Originally Posted by 91CRXTC

although, when i sit here thinkin of the design i think they might do a dual pipe layout for low and high rpms. At low rpms you dont need alot of space for the exhaust to flow through hence the smaller pipe, but when you get more exhaust flowing through, then the pipe size would need to be greater to accept the amount of exhaust flowing through so it would use the entire inside pipe plus the outside pipe. This is only my observation of the situation which does make sence to me, which made me think about building a header that does the same but is a sleeve of somesort so that the ID grows with the pressure applied to it. or just a dual pipe exhuast all through but thats allot of pipe and wieght.

Hmm have to test the pipe out ...........if this is true could the space between the 2 pipes get clogged if u do not us high rpm? the last owner of my car was a old lady so i think she was not a racing lady .........but if i was to us a single pipe as big as the inner pipe would it be more of a problem or solution?

[91CRXTC]

Well that small pipe only goes to the cat flange, then its stock piping after that which is pretty small, probably about the same size as the inner pipe. So yeah if its a stock system its right but what was the reason for taking apart the exhaust? Are you looking to improve performance?

[Deadboy]

Originally Posted by 91CRXTC

Well that small pipe only goes to the cat flange, then its stock piping after that which is pretty small, probably about the same size as the inner pipe. So yeah if its a stock system its right but what was the reason for taking apart the exhaust? Are you looking to improve performance?

Just had to change the gasket and saw the inner pipe ........i found out that its for rust protection...the inner pipes inside the outer pipe is a about 5cm long and then gets a bit bigger.....i think its just a fast build a the factory caz if hondas where hand made they would have cut the inner pipe in the size it is ment to be ....... i removed a part of it form the exhaust manifold side and the car actualy sound nicer and seems to be just a little bit faster........the pipe has no efect on the car on low rpm but higher rpm could have problems caz the gases do not get out fast......thats what i think .....it could be wrong what i did ......i tested the car at 3000rpm and then whent to about 7000rpm seems to work fine for my car.....allso the gas i us in my car is a mixture of 95 and 98.