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Exhaust down pipe question...Dent?

D

Deadman 94 xj

NAXJA Forum User
Location
Pittsburgh, PA
This is my second xj and they both have had a nice size dent (crimp) in the down pipe just below where it connects to the header, above the O2 sensor. It's almost like it was dented with a BFH.
I can't for the life of me figure out why it would be there seeing as how it restricts so much air flow.

Is this normal (stock)? Or have I just had 2 beat up down pipes?

It's a 96
 
Yeah looks that way. Good call on the drive shaft, I didn't think of that.
I just looked down inside of it today and it sure as hell blocks a lot of air flow.

Thanks for the replies.
 
wolfpackjeeper said:
you can have one made without the dent, but if you have little or no lift you will just dent that one
Click to expand...

I hate that you can't buy a mandrel bent pipe from a parts store. When I had the 94 I looked everywhere for one and ended up going with one of those $35 deals from advanceauto. It was ugly but I'd bet it flowed better than this one.

IIRC the dealer wanted upwards of $300 for a stock replacement :shocked:
 
thats is unbelievable - 300?! i had mine done at a local shop - mandrel bent and buzzed it into place for about 40... it helps some but i honestly cant say how much - i have a k and n intake, tb spacer, bored tb, hi flow cat, flowmaster muffler and banks header so it was a complimentary upgrade
 
housemaster0630 said:
i replaced mine with a downpipe from a 1st gen grand cherokee and it works great

best $2 upgrade i have ever done
Click to expand...

Really? I never would have thought. What's different about it? No dent?
 
thats the only difference i found

it took a hacksaw to egt it off of the gc
and a couple hours with a dye cutter and a grinder to get it clean so it would fit nicely

and welding it is not the easiest thing to do because its fairly close to the body

but when its done its beautiful


and i compared the old pipe with the gc pipe
they are the same except for the dent

i actually didnt think that the dent was intentional

the previous owner of my xj said that once his driveshaft broke and flew up and hit somthing

so i assumed that that is what dented it
 
housemaster0630 said:
thats the only difference i found

it took a hacksaw to egt it off of the gc
and a couple hours with a dye cutter and a grinder to get it clean so it would fit nicely

and welding it is not the easiest thing to do because its fairly close to the body

but when its done its beautiful


and i compared the old pipe with the gc pipe
they are the same except for the dent

i actually didnt think that the dent was intentional

the previous owner of my xj said that once his driveshaft broke and flew up and hit somthing

so i assumed that that is what dented it
Click to expand...

Nice, I'll look into it.

It sucks doing all these intake mods just to bolt it all up to that big pinched pipe.
Honestly I can't really say how much it restricts it. What I've done has helped performance but I'd guess at least a third is blocked.
 
beaudrya said:
so no one makes an aftermarket downpipe to bolt to the factory manifold?
Click to expand...

Not unless you go with a header that includes a down pipe. Pacesetter does this, although I've heard negitive things about it's quality.

Otherwise you can get one from advanced but if you've never seen one they're not pretty. It has all kinds of kinks in the bends. I forget what they call that.


Bending, denting, the pipe for DS clearence seems pretty strange to me for some reason. You'd thing that the engineers would have come up with something else rather than compromising another part.
I'm wondering if they didn't do it for low end torque or something.
I've read stuff about smaller diameter tube being better for torque due to the back pressure (something like that)

Any thoughts?
 
housemaster0630 said:
there is back pressure and then there is restriction

the grand cherokee 4.0l has the exact same pipe but without the dent
Click to expand...

The Gand Cherokee also have a low pinion D30. That should help to keep the drive shaft further away from the exhaust.
 
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