40 replies to this topic

[jpelle]

OK, there doesn't seem to be too many 'out-of-the-box' choices for aftermarket exhausts for '87 CRX DXs...  So did all of you get custom pipes made?  Do you have to weld all the parts together or is there some other form of connecting two pipe ends?

What about these flexible bits 'o pipe that I've seen around -- they any good?  (In case you haven't seen them, they're this kind of woven metal tubing meant for exhaust repairs.)

[Davidov]

DO NOT, I repeat, please do not use "Flex-tubing", or exhaust repair pipes.
For one, they are supposed to be tempoary, two, they restrict flow due to the uneven inside surface.

I considered constructing a custom exhaust route using mandrel bent tubing(piping bent at a smoother angle than most stock exhaust pipe), but I recommend not using this method.

Here is what you should do [since the only company that makes cat-back exhausts for our model cars is Pacesetter(crappy, rusts and falls apart fast)]

1)Find a good exhaust shop, see if they use mandrel bent piping, if not that should do if you aren't too picky.

2)Purchase a universal muffler, I can give you referall sites if you want them.

3)Take your car to the shop, and have them make custom catalytic converter back  2" or 2.25" is good, no larger.

4)Have them weld it all in, don't pay too much though, over $300 is a little iffy.

Hope this helped

[jpelle]

do not use "Flex-tubing", or exhaust repair pipes

*Sigh*  I kinda figured.

OK, so let me see if I understand this stuff correctly.  I can get exhaust headers.  I can't get a cat-back system (except from Pacesetter, which is apparently bad).  I can get a good muffler and good pipes.  So, do I get a good header, pipes to the cat, pipes from the cat to the muffler, and a good muffler?  All about 2" in diameter?  Would the cat be a bottleneck (but a necessary one)?  Is this what everyone with a 1st gen has to do?!  (Good thing this is a future mod! )

[jpelle]

see if they use mandrel bent piping, if not that should do if you aren't too picky

So what's mandrel bent piping?

[rpr]

It's pretty obvious when you see them side by side. Mandrel bending is visible by the fact that the bend is smooth all through the bend, whereas a non-mandrel bend, also called a 'crush' bend,  has wrinkles on the inside of the bend. I believe mandrel bending uses heat, but I'm not sure.

[solo2crx]

the crush bending does not always have the wrinkles as you mentioned although that is the most common way it is seen. Some curves just have a very slight compression of the tubbing in the radius of the curve. It can be seen with the naked eye but can really be felt if you run your hand along it. Both types for crush bending can really reduce the inside diameter of the pipe. If you have to go crush bent go with 2.25" for the tubing. I saw on Honda at the local autocross that had 2.25" straight tubing but eveywhere there was a crush bend he went to 2.5" tubing to compensate for the reduced diameter. It seemed to work great for him and the system looked pretty good.

Mandrel bending is, as the name implies, bent with a mandrel or die in the inside of the tube. The tubing is supported while bending on both the inside and outside by mandrels to prevent any change in diameter. No heat is used from what I have seen although there might be some processes that use heat.

There is also the lost art of sand bending. It was used in years past to make custom headers and exhausts. The tubing is packed with sand and sealed at either end. The tubing is then held in a vise while the bend area is heated with a oxy/accetylene or MAP gas torch and slowly bent. The sand acts as the Mandrel and prevents crushing of the tube. It is a slow process and as I said an art form sort of lost but it can make some fancy parts.

Later,
Jaosn F.

[rpr]

Hey, thanks for the info. It never ceases to amaze me to realize how little I really know.

[jpelle]

Can anybody describe the cdm DX exhaust manifold?  Or better yet, does anyone have pics?  The manifold on my car looks...different.  At least different than my manual (which, sucks, I know, but it's all I've got at this moment).

[rpr]

The manifold on my DX was wacky. It went from the exhaust ports, all the way down underneath almost under the oilpan, if I remember correctly. It was all one piece, cast iron as far as I could tell. Big clunky lookin thing. I'm pretty sure all the CDM DX's I have seen were like that as well.

[jpelle]

Mine looks like it's 2 pieces (1&2 together, 3&4 together), joins into one (but this is hard to tell right now, cause it's hidden under the exhaust shroud), but goes back to two pipes under the oil pan where it again joins.  It must be two pipes under the shroud but it looks like one piece.  I'll see it better when I pull off the head (whenever that might be).

[Gasoline Fumes]

Is this the Canadian manifold?
http://www.luk-korbm...de/Autos/ew.jpg

[jpelle]

Is this the Canadian manifold?

Hard to say 'cause of the shroud.  I'd like to see the piece that goes under the block.

Oh, and that engine is not a 87 CRX DX -- it's FI.  'Course, I never specified '87 CRX, did I?  ???

[rpr]

Well, that engine sure looks like an SI, but that exhaust manifold is what was on my DX, as far as I remember. If the garage door opener wasn't so loud, I'd go and take a pic of the DX in the garage and put this one to bed once and for all! I'll try and remember to do it tomorrow morning.

Chris, my wife is the same...