morris

iTrader: (2)

Tomorrow we are suposed to gut my cats, I wanted to know what is the difference between gutting the cats or replaceing them with a test pipe?

Basically does it matter which way we go.

SprtDesign

iTrader: (21)

Maybe for asethics(looks) when you do emissions every year?

morris

iTrader: (2)

Yea I was told that if we gutted them it would still look legit for emissions inspections. But then my son told me that the large expansion area and then shrinking the exhaust path back down could be bad.

LB Lex

Maybe you could gut it and then put/force a 2 1/2 piping (or whatever the size of the stock exhaust is) inside to stop the large expansion.

mikeyboy

well the cat would silence the sound more definitly, acts as a resonator in a way. test pipe will definitly make your car louder and cause less back pressure to the engine

sniper

iTrader: (4)

Id say if you had the time and money, get some test pipes made up that you can bolt right in. That way, when you need to smog the car, you can bolt the stock cats back into place. And test pipes are going to flow better anyways

morris

iTrader: (2)

I'm short on cash right now and I'm getting it done for free, so beggars cant be choosers on top of that I'm trying to solve what we think is a backpressure problem that is effecting the supercharger. So it is all experimental at this point, sort of see what happens type of thing.

I just was trying to see if there were any serious negative aspects of the gutting process.

mikeyboy

morris im not too familiar w/ FI but i am w/ cars. Guttin the cat will release back pressure. Do you need more back pressure or less. On my car i did a 3" piping cat back exhaust and i dont have enough back pressure only because im doing FI in the near future, so backpressure is good, at times, and at times bad. I can assume u need less back pressure so yea that would do the job. So would bigger exhaust piping. u should just remove all piping from the cat to the muffler and see if the car is any faster, that can tell you if its back pressure or what.

P.S: MAKE SURE WHOEVER GUTS THE CAT WEARS A MASK!!!

morris

iTrader: (2)

Basically it appears that my Supercharger stops spinning freely as we get up in rpm's we are hoping that the cause is excess back pressure caused by the cats. See this link post 13 for details https://www.clublexus.com/forums/sho...2&page=1&pp=15

The theory is that hte exhaust back pressure is backing up into the intake side and creating resistance to the blower.

A few times one of teh cats was throwing codes.

mikeyboy

i think i understand, so basically the RPMs freeze or slowly increase at certain points. Yea definitly back pressure in one way or another. It might be too much back pressure due to a clogged cat. over 200k miles think its too much back pressure.

morris

iTrader: (2)

Well the way it is manifesting it self is that the blower pulley stops spinning as the boost increases this causes the belt to start slipping and the coggs get ripped off the belt. We are hopoing that the backpressure is making it hard for the impeller to turn.

JBrady

Flow restriction (backpressure) will increase boost readings. The stock exhaust manifolds cause more "backpressure" than the cats.

The stock cats are VERY expensive. Gutting them is not easy and will not give you the results you are looking for. The car will be louder and will loose low RPM reponse and torque. The noise increase will be tinny and booming. This is NOT recommended.

Obviously headers and 2.25" pipes with a racing Y or X pipe is the correct solution. Getting the cats gutted for "free" will end up being one of the more expensive options you could choose and the results will not be what you hoped.

Have some test pipes made or better yet pull the cats off the car and have dual 2.25" pipes with a quality X or Y pipe installed.

morris

iTrader: (2)

Thanks for the information, maybe we can just pull the cats and see if we have the problem still or maybe I can get them too make the pipe.

morris

iTrader: (2)

Well let me ask you this does it sound like pulling the cats or replacing them with pipes will help with the actual problem of the supercharger not wanting to spin?

mikeyboy

Well if you're trying to get rid of backpressure, then it should help. Depending how clogged the cat is in the first place, depends how much back pressure its sending. I agree on the headers, talk to LXOGOOD he just picked up OBX headers for like $300