Hey everyone,
I purchased a 2000 Impreza 2 door 2.5RS last year from a friend (as a winter car and rallycross car).
The exhaust pieces were all falling apart at the flanges (where they rust away to nothing eventually), so decided to have a little fun and get the Borla unequal length headers, a cheap-ish high-flow cat-pipe (it's a CNT Racing / ERZ brand, I think it was under $200), and the rest of the exhaust is basically OEM.
My problem is that the high flow cat is round (whereas the OEM ones were more flat), and it hits against the bottom of the car near the passenger footwell. I'm not immediately worried about anything getting hot enough to cause problems (like a fire), but it rattles a bit and that part is an annoyance.
The pipe does have a bracket where it bolts up to the transmission case (as do a few different Subaru models), and I have tried with and without that bolt in place. Either way, the cat rattles against the bottom of the car.
I'm not sure that I would be able to slightly bash in the bottom of the car where it's touching, to give it a half inch of clearance..... but, if there was a good material that I could wedge in there, that won't catch fire, and maybe absorb some vibration, that might be ideal.
I think that the outside of the cat hits temperatures between 300 and 400 degrees F (according to my infrared cheapo laser thermometer...but I might need to double check that reading).
I was wondering if anyone knows of a good material that I could easily find in a store, or on the internet, that I could wedge between the cat and underside of the car to insulate it, and stop the rattling ? like a high-temp rubber, silicone, other flame-proof material ?
I had considered a few layers of exhaust header wrap, except that when I wrapped the downpipe on one of my other cars, it soaked up the road salt and caused the pipe to rust out eventually (lots of road salt here in Buffalo), even when I attempted to seal it with the high temp silicone spray.
I don't have tools to safely bend piping with, to try to move it lower and out of the way, but just wanted to see if anyone has any other clever, simple or cheap ideas ?
thanks ! :)
The perfect tool for the job:
Yeah there's nothing you can pad it with, you need to move or make clearance on something, or stiffen the exhaust-to-chassis mounting so the exhaust can't move enough to hit the underside of the car.
i had a similar problem with my landcruiser, exhaust pipe hitting the frame, i took it to an exhaust shop and they cut a section, then put a slight angle on one pipe and welded it back together, the angle pushed the pipe up enough to clear the frame.
i'd just take it to an exhaust shop and have them look at it and see what some more permanent options would be
okay, thanks all, I'll consider the pry bar if it doesn't look like anything will be stressed or broken (it's always a good day when I get to use it on something)
and I'll consider the exhaust shop as probably the best option.
Ceramic fiber insulation? Not sure how it would stand up to water but it can take the heat and not transmit it to the car floor. It would also probably ware out as it would become the ware material between the floor and the cat. Used on the space shuttle in brick form it is also available as wood stove insulation.
that's an interesting idea too. I had originally thought that ideally maybe there was some type of high temperature rubber or silicone material, that I could use a square piece of, maybe 1/4" thick or so (that's probably about as thick of a material as I could jam in between the floorpan and the catalytic converter). it would absorb some vibration and insulate the two from direct heat transfer.
Anything you stick in there that will work will also pick up salt water and lead to corrosion. How are the motor and trans mounts? Agreed on notching and welding if everything else is in order.
I think the transmission mount is okay, I recall that when I first got the car, I thought that mount was broken, I removed it (and then actually broke it while removing it), so it's been replaced. I think the engine mounts are okay (had those unbolted when I replaced the heads last winter).
Some people with catless versions resorted to flattening their resonators slightly with a hammer, but since this has a catalyst inside, I would be afraid of damaging or causing bits inside to break apart and come loose.
Double check the torque/dogbone/antirotation/whatever funny name Subaru has for it mount.
oh right, yes, that thing. I'll make sure it is still in place. I know my GD chassis WRX has one, but haven't poked around this coupe enough times to see if all those parts are mostly the same and in the same places.
