Cat. Convertor questions.
Retired Moderator - RIP
Joined: May 2008
Posts: 18,729
Likes: 17
From: NH
You need to fix the lower intake now. As that's pretty much why the cat went bad. Do a search on here for "plenum gasket" and you'll learn all about it. Welcome to DF btw.
Record Breaker
Joined: Aug 2008
Posts: 1,354
Likes: 1
From: stationed in nc
Wrong, Wrong, Wrong. Backpressure is always bad. Scavenging is always good. No one seems to understand this. Scavenging is the exhaust causing vacuum on the back of the exhaust valves so that the exhaust gases get sucked out rather than pushed out. To get good scavenging at low RPM's you need small pipes because there isn' much flow so to create the vacuum you can't have to much cross sectional area. What I think people get confused about is that if you have small pipes causing good scavenging at low RPM's when the RPM's go up and more flow is created so the small pipes restrict the flow and backpressure is created. Exhaust systems are tuned for an RPM range. Bigger pipes scavenge at high RPM and high flow, small pipes scavenge at low RPM and low flow.
Sorry for the rant, its nothing personal. It just REALLY p*sses me off when I see people talking about exhaust when they don't understand. Scavenging and backpressure are one of the least understood topics Ive ever seen.
Sorry for the rant, its nothing personal. It just REALLY p*sses me off when I see people talking about exhaust when they don't understand. Scavenging and backpressure are one of the least understood topics Ive ever seen.
but now that i found a guy who is so good with it... how do i get good mid range power? thats where i always am... low to mid range...
Record Breaker
Joined: Jan 2010
Posts: 1,048
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From: Wisconsin
i will admit, i am wrong, i know little about exhaust, but i do know about all this stuff and shouldnt have posted this... i am more of a suspention guy...
but now that i found a guy who is so good with it... how do i get good mid range power? thats where i always am... low to mid range...
but now that i found a guy who is so good with it... how do i get good mid range power? thats where i always am... low to mid range...
I have Pacesetter shorties, a homemade Y-pipe with 2" primaries into a 2.5" collector, then a 3" in/out magnnflow cat, then 3" pipe to a flowmaster 40. I have dual 2.5's out to the back which are a little big (I bought years ago when I didn't have a clue). When they rust out I am going to a single 3".
Record Breaker
Joined: Aug 2008
Posts: 1,354
Likes: 1
From: stationed in nc
ok so i have the pacesetter shorties, magnaflow hiflow y and cat ( stock setup but hiflow) and then a glass pack... to a dump...
would i be better off keeping the glass pack or adding a peice of 3" pipe in place of it and still dumping it?
would i be better off keeping the glass pack or adding a peice of 3" pipe in place of it and still dumping it?
Record Breaker
Joined: Jan 2010
Posts: 1,048
Likes: 1
From: Wisconsin
The glasspack won't restrict flow so I would leave it. You said before that you wanted it loud. You could get a cutout so it would be loud but you could close it for work.
Record Breaker
Joined: Aug 2008
Posts: 1,354
Likes: 1
From: stationed in nc
well like i said, i love being one of the senior guys here, and i do what i want, so i want it louder now, and it was, but i dont know if it was ok for it.. i just had the cat, to a turn down... like a foot later... would that hurt anything..
and sorry for the thread jack...
and sorry for the thread jack...
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Professional
Joined: Nov 2008
Posts: 181
Likes: 0
From: Michigan
so if I can get the cat cut out. go ahead and do it? or put a new in. I really dont ahve the money for a new cat right now... so im leaning towards a diff. y-pipe and calling it good.
and for the record the 02sim is in the post cat sensor.
What i dont understand is why the motor ran fine for 448 miles all the way up there, and then acted up on the way home??
and for the record the 02sim is in the post cat sensor.
What i dont understand is why the motor ran fine for 448 miles all the way up there, and then acted up on the way home??
Record Breaker
Joined: Aug 2008
Posts: 1,354
Likes: 1
From: stationed in nc
ok, for now, until you can save money for a good cat, cut yours out, take some rebar, and punch it out, and weld it back in... it will do the same thing...
why get a new ypipe? there shouldnt be anything wrong with yours...
and they tend to go in a hurry, there is ussually no warning.. and after that long, the cat just got hot and gave out... its not to uncommon
why get a new ypipe? there shouldnt be anything wrong with yours...
and they tend to go in a hurry, there is ussually no warning.. and after that long, the cat just got hot and gave out... its not to uncommon
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Professional
Joined: Nov 2008
Posts: 181
Likes: 0
From: Michigan
I think i got my money out of this cat. It is the original cat. never been replace and shes got 165,000 on the clock. decent if you ask me. Cat outlasted the trany. Trany went at 161,000
thanks for all the input
thanks for all the input
Veteran
Joined: Mar 2007
Posts: 419
Likes: 1
So if my truck runs bad I can go home and punch my cat and get 15 more horsepower? Poor kitty.lol