Have you guys ever realized how frustrating the search function is on this site? Just sayin'... anyway:

I've got to the last project which is out of my hands and in the shops, but it's up to me to make sure I'm asking him to do it right...

Exhaust on a CALI emissions 5.9L-

what has to happen to go true duals? what are the sensor issues? It already has two cats before the Y, and I split it again to dual mufflers after... I'm going with Magna High Flow cats, and likely either magna muffler, or another set of flowmaster 44's.. any thoughts on this? I've heard the 44's restrict flow, true or false?

and a silly question: seafoam before the overhaul or after? I'm thinking before, right? - - - (stupid question of the month, but I want to be sure)

I'm pulling the trigger tomorrow, any help would be appreciated greatly..

 

seafoam before so you get all your crud through the engine before your tune up or overhaul... as far as exhaust not really sure i run a stock setup and like it no problems at all

 

good luck getting highflow cats in cali they wont ship to cali for the emmisions they have

 

I'm in north carolina, truck is cali emissions.. long story..

 

If your gonna put high flow cats on a cali emissions truck, the CEL will be on. I don't know if it'll effect the performance...I think it might though.

 

and this is why I'm a little concerned.. I just helped a buddy in the spring put a v8 in a YJ.. he got it complete, and cheap... he spec'd everything out before he went to work, including exhaust and wiring harness.. he had no idea the engine was cali emissions.. and he went through three harnesses before he found out.. the dang things are different in the craziest of places.. exhaust being one of the obvious places.. I don't want to see that CEL, though I'm sure the state would love to see it on my next inspection..

 

if you have a post and pre o2 i would just get 1 highflow cat and bring it to a y and put the cat after and do a si/do or si.so muffler

 

effin' cali emissions...

so, the exhaust guy won't help me do what I want to do, because of legal issues (I can't blame him), and has no clue if it will benefit or hurt my situation.. here it is, please - if you can inject anything or direct me to a place to learn about this please do..

I have two 'monitored' catalytic converters mounted directly behind the collector flange... the typical o2 sensors downwind, and o2 sensors inside the cat's themselves.. total of four of those rascals (2 upwind, 2 downwind)..

they 'Y', and then a 2.5" pipe runs to ANOTHER catalytic converter- this one unmonitored (no sensors).. It IS NOT a resonator, it's a dang Cat for sure..

Since it isn't monitored, my notion was to just remove it and run true duals... but he has legal questions about doing that which are understandable.. Now, if I cut it out, and bring it back to him w/o, he CAN do true duals for me.. but I have pause about this, and have a question to field here:

By eliminating the third cat, and running true duals, I am in effect DOUBLING my exhaust flow- since the Y will be eliminated and the two headers will no longer share a 2.5" pipe to the third cat, and then muffler.. How much will this hurt my low end?

I'm not one bit concerned about a CEL, because this type of rig will only be eliminating the unmonitored cat... but I AM worried about being TOO open and not getting enough scavenging to allow good bottom end.. If I had to choose between low end or top end, it would be low end every time...

bear in mind also now, that I upgraded to H&S 1.7's, and went with 4.56:1 gears- which I mention because of two things- the intake is gulping more fuel/air, and the RPM's in the usable range have climbed- which means opening the exhaust to a degree will be beneficial, but at what point will the engines necessary scavenging start to wain?

Please help a brutha out!

 

this is a good link to better information about this by the way, but it can't possibly answer my question...

..here..

if the link doesn't work I'll copy and paste, but it's a heckuva long winded commentary..

 

alright... this is just to close this out, because I hate it when folks don't return to do so and it makes researching similar issues on forums impossible to know the conclusion..

that 'third cat' is most definitely NOT at catalytic converter, but IS a resonator.. resonators aren't legally required.. that rascal is going to join Hoffa..

I'm going to 2.5" pipes from collector to cali catalytic converter to si/so flowmaster 40's or 44's (which is going to be dependent on what he has in stock).. the cat's (both of them) will remain.. which is what I wanted in the first place..

I AM concerned about this rig opening the exhaust up too much and losing the heat related scavenging (which most refer to as required back-pressure, but it's not the same).. all I can say is, if it is a problem I will go back an experiment with smaller diameter tubes (2.25" as opposed to 2.5") to retain the scavenging vacuum effect...

here is the absolute gem of all of this, and you guys running with cali rigs should appreciate this- having two cats and four o2 sensors actually makes the conversion to true duals easier I'm thinking.. there is no need for an X or an H pipe w/ center bung on them.. The question remains, though, if this will be TOO open at 2.5" per four cylinder.. I'll report back when I have a Levi's Dyno for you..