DP & Headers

Jake LXer

Jake LXer

Jaykwabee and the R18
497
310
New York
Vehicle Model
civic
Body Style
sedan
i'm in the market for a downpipe and i was wondering....

does the downpipe connect right to the block where the exhaust runners end or does it connect after the cat?

I'm seeing downpipes for sale as well as the 1 port 4-1 "headers"

btw i have a 14 civic LX, R18
 
It's a single port on the r18 off the head.

HeaderTBS030.jpg


stock on the left -

HeaderTBS039.jpg


note the cat that is almost right up at the flange which connects to the head of the engine. Aftermarket downpipe on the right ^

here is the downpipe removed from the head below

HeaderTBS042.jpg
 
On the R18 when you open the hood you will be looking at a large semi round silver/gray heat shield. That is your catalytic convertor. Its bolted right to the "exhaust manifold" port on the block. The exhaust manifold is cast into the block and just has one large (relatively) opening. From the catalytic convertor there is a small "down pipe" if you can call it that. That short section connects the cat to the mid pipe of the exhaust. The mid pipe runs basically the full length of the car back to the muffler.

On these cars there really isn't a header. People call it that for ease of terminology. Replacing the cat is where you would put a "header" but most of them are just a "test pipe" as they call it. That will bolt in place of the cat and connect to the "down pipe." I know there are companies that offer that short section and call it a down pipe buts its really not a DP in the sense of the ones you see for the Si.

In this diagram you see the cat which is bolted to the block: The big round cylinder. The E-10-10 tag is where it bolts to the block and you see the single opening. At the bottom notice the B-2 tag.

9eec81637ea03a9409da0b7a2abfedea.gif




This is the rest of the exhaust setup: Notice on the left front of the image the small kinked pipe with the E-4 tag. That is your "down pipe" which bolts to the B-2 on the above image. Then the long mid pipe and finally follow the zig-zag to the muffler. This part is referred to as the axle-back section. So if you see an axle back for sale its just that last piece. A catback system will replace everything from the mid pipe back. Usually those exhausts do not replace that small "down pipe" section.

ef9f2a3cc517a44436fae45d3053641c.gif



Hopefully that helps you understand what each piece should be and might be called when shopping.
 
Hey question for you. It looks like there is a second cat in line as well? If I get the high flow cat that bolts to the motor should I get custom straight pipes back to a new muffler ? If I do it the second cat out what kind of damage will that do to the mpg? Thanks for the help
 
Dee Swayzee said:
Hey question for you. It looks like there is a second cat in line as well? If I get the high flow cat that bolts to the motor should I get custom straight pipes back to a new muffler ? If I do it the second cat out what kind of damage will that do to the mpg? Thanks for the help
Click to expand...
since this thread came out, rv6 made a downpipe for the r18 engine.

https://rv6-p.com/9c18hfpc.html?category_id=61

you really need hondata flashpro or ktuner to be able to tune the car for this downpipe
 
If you rid the second cat, without flashpro you will have a CEL..it will basically hide the light but the code is still there you will not pass emissions
 
webby said:
since this thread came out, rv6 made a downpipe for the r18 engine.

https://rv6-p.com/9c18hfpc.html?category_id=61

you really need hondata flashpro or ktuner to be able to tune the car for this downpipe
Click to expand...

Awesome yea rv6 catted is what I was looking at then doing custom pipes from downpipe to axle back. Where my next question comes in. I've seen come exhaust cat back that say fit 2012_2015 then I've seen some that are up to 15.. The tsudo catalog says doesn't fit 15. Any idea why that would be?
 
prob just haven't updated things. The 14 sedan non-si is the same as the 15 sedan non-si
 
webby said:
prob just haven't updated things. The 14 sedan non-si is the same as the 15 sedan non-si
Click to expand...
I have a coupe so any 9th gen coupe exhaust should fit? Also hear that so 8th gen will too axle back only. I've noticed some midpipes are 2 piece didn't know if that changed things
 
non-si coupe exhaust from 14 will work on the non-si 15 coupes. 8th gen si axleback exhaust bolts up to the 9th gen non-si.
 
Any idea why this says it won't fit 2015? Thanks again for all the help
 

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