Photos: Cats replaced with Resos

[steves]

Originally Posted by gr8titan

The two rusty "missle looking" sections ....

I'm sorry, I just can't get over the humor in using something rusty as a point of reference in photos (since I did the same thing....)

[SupraTitan]

Originally Posted by BigBlackTruck

Until he goes to pass an emissions test, and FAILS.

It will pass either a sniff test or obd II scan test no sweat.

The secondary cats make zero sense to me. If the were upstream of the primary cats it would make sense that they are there for cold start emmisions. Being that they are downstream of the primary cats makes them just about useless. All they will achieve is to retain more heat from the restriction it represents from the secondary cat to the engine, which will in turn increase underhood engine heat and shorten the life expectancy of the engine. Its amazing how much underhood heat is there from the cats alone, the cats produce more underhood heat then the engine itself. With the advent of obd II emissions this has been an increasing issue due to mounting the cat as close to the exhaust port as possible to clean up the exhaust with no regard for the engine itself. Years down the road when the engine harness becomes brittle and breaks apart in your hands as well as coolent hoses failing you can thank the good ole obd II emissions. But what can ya do hehe.

[gr8titan]

Originally Posted by steves

I'm sorry, I just can't get over the humor in using something rusty as a point of reference in photos (since I did the same thing....)

What did you do? Make the "rusty" as a point of reference (LOL) or punch out the honeycomb catalysts? If it was the later, any change in your truck's performance?

[steves]

Originally Posted by gr8titan

What did you do? Make the "rusty" as a point of reference (LOL) or punch out the honeycomb catalysts? If it was the later, any change in your truck's performance?

No, Sorry....in the pics I posted of how the hitch fits around the exhaust I had said "that rusty piece there..." and the OP used rusty to describe something in his photo.

[RockyMtnTitan]

gr8titan.....could you measure the narrowest point on the cats for me? I thought about gutting my cats (meow!), but it looks like they neck down quite a bit....to 2" or possibly narrower?? I just want to eliminate as much restriction as possible.

I'm still having trouble getting someone to install my 2.5" Dynomax race bullet resos, but I'm hopin' to have it done in the next week or so. If not, I'll probably just gut 'em and call it done!

Thanks for all the info and pics....especially of the internals of the rear cats. I'm tired of hearing over and over how these are not cats, but resos on the 4X4's!

As far as the reason for the rear cats on the 4X4's vs the 4X2's....the only explanation that makes sense to me, is that the 4X4 weighs more so the engine will work a little harder causing more exhaust emissions. I don't think it's enough to fail an emissions test. The primary cats are the same on both models.

[Clancy]

Originally Posted by RockyMtnTitan

gr8titan.....could you measure the narrowest point on the cats for me? I thought about gutting my cats (meow!), but it looks like they neck down quite a bit....to 2" or possibly narrower?? I just want to eliminate as much restriction as possible.

I'm still having trouble getting someone to install my 2.5" Dynomax race bullet resos, but I'm hopin' to have it done in the next week or so. If not, I'll probably just gut 'em and call it done!

Thanks for all the info and pics....especially of the internals of the rear cats. I'm tired of hearing over and over how these are not cats, but resos on the 4X4's!

As far as the reason for the rear cats on the 4X4's vs the 4X2's....the only explanation that makes sense to me, is that the 4X4 weighs more so the engine will work a little harder causing more exhaust emissions. I don't think it's enough to fail an emissions test. The primary cats are the same on both models.

One of those pictures makes it look like they neck down a lot, but when I thought about it it doesn't make sense. I think it's just the angle of the picture and the length of the pipe after it.

I'm temped to punch mine out... I might wait and let some others test it out first. Or perhaps I'll just have some custom bypass straight pipes fabed up when I do my system...

[RockyMtnTitan]

Originally Posted by Clancy

One of those pictures makes it look like they neck down a lot, but when I thought about it it doesn't make sense. I think it's just the angle of the picture and the length of the pipe after it.

I'm temped to punch mine out... I might wait and let some others test it out first. Or perhaps I'll just have some custom bypass straight pipes fabed up when I do my system...

I seem to remember a post at one of the sites mentioning the small pipe size at the rear cat/reso conn's......but I could be wrong about that. Since gr8titan has his out, I'm hopin' he'll do us a favor and check it out.

I say if you don't have the strick regs we have here in Colo, then have your shop fab up some test pipes for ya. I doubt it would cost you much extra to have it done while they do your new system. I'm going to use the straight-thru designed Dynomax reso's instead of straight pipes, as I don't want to add anymore noise to my Flowmaster system. M95roadster has these on his truck and likes them, also Head has the similarly designed Moroso's in place of his stock rear reso's. These should have very minimal pressure drop.

[pciley]

Originally Posted by RockyMtnTitan

I seem to remember a post at one of the sites mentioning the small pipe size at the rear cat/reso conn's......but I could be wrong about that. Since gr8titan has his out, I'm hopin' he'll do us a favor and check it out.

I say if you don't have the strick regs we have here in Colo, then have your shop fab up some test pipes for ya. I doubt it would cost you much extra to have it done while they do your new system. I'm going to use the straight-thru designed Dynomax reso's instead of straight pipes, as I don't want to add anymore noise to my Flowmaster system. M95roadster has these on his truck and likes them, also Head has the similarly designed Moroso's in place of his stock rear reso's. These should have very minimal pressure drop.

That post was probably me:
3" Straight Pipes Installed

Read post 2, you will see the pic of the horrible bottleneck on the stock reso's.

I don't know why you would replace your rear cats with resonators for that much $$$. Just have a cheap set of $40 straight pipes made (once you have the flanges). You will STILL pass emissions. Your primary cats are still the same up front and here in CA the emissions are very strict and I know I won't have any problems. The Resonators are mostly for noise reduction and not to help with emissions.

BY THE WAY!! Smogging isn't an issue with whatever you do to the secondary cats or resonators. They are BOLT ON. If you are going to get smogged, bolt the stockers back on and you won't even have to worry (although it won't affect the emissions). The swap takes maybe 20 minutes with hand tools, less time with air tools obviously.

[gr8titan]

Originally Posted by RockyMtnTitan

I seem to remember a post at one of the sites mentioning the small pipe size at the rear cat/reso conn's......but I could be wrong about that. Since gr8titan has his out, I'm hopin' he'll do us a favor and check it out.

I measured them and took pics BUT I dropped the camera and screwed it up and wouldn't upload photos to my computer.

Anyway, the "outlet" diameter of the catalytic converter casing is 2 1/2 inches while the "inlet" of the long tube is only 2 inches. I replaced my cats with 2 1/2 inch tube all the way with the resonator (3 1/2 in) somewhere after the O2 sensor.

I took a 150 mile highway drive today and noticed that there is a mild drone that developed at 1800-2000 RPM. Not bad because the wife and I still carried out a conversation. The accelaration rumble is louder and downshifting to 4th gear exhaust tone is very evident.

I'll try to fix my camera and hopefull will be able to post those unretrieved photos. 'Good day!!

[RockyMtnTitan]

Originally Posted by pciley

That post was probably me:
3" Straight Pipes Installed

Read post 2, you will see the pic of the horrible bottleneck on the stock reso's.

I don't know why you would replace your rear cats with resonators for that much $$$. Just have a cheap set of $40 straight pipes made (once you have the flanges). You will STILL pass emissions. Your primary cats are still the same up front and here in CA the emissions are very strict and I know I won't have any problems. The Resonators are mostly for noise reduction and not to help with emissions.

BY THE WAY!! Smogging isn't an issue with whatever you do to the secondary cats or resonators. They are BOLT ON. If you are going to get smogged, bolt the stockers back on and you won't even have to worry (although it won't affect the emissions). The swap takes maybe 20 minutes with hand tools, less time with air tools obviously.

Yeah, I'm guessin' this will only cost me around $100. I already have the Dynomax reso's and they're only $30 ea, and O2 bungs were only $5 ea. So pretty inexpensive. gr8titan's were expensive, but he went with all mandrel bent 304 SS, so that's understandable.

[RockyMtnTitan]

Originally Posted by gr8titan

I measured them and took pics BUT I dropped the camera and screwed it up and wouldn't upload photos to my computer.

Anyway, the "outlet" diameter of the catalytic converter casing is 2 1/2 inches while the "inlet" of the long tube is only 2 inches. I replaced my cats with 2 1/2 inch tube all the way with the resonator (3 1/2 in) somewhere after the O2 sensor.

I took a 150 mile highway drive today and noticed that there is a mild drone that developed at 1800-2000 RPM. Not bad because the wife and I still carried out a conversation. The accelaration rumble is louder and downshifting to 4th gear exhaust tone is very evident.

I'll try to fix my camera and hopefull will be able to post those unretrieved photos. 'Good day!!

Thanks, gr8titan.....You Rock, man! I may go ahead and do a bef/aft back pressure test to see how much it is reduced with high flow reso's vs cats.

[black04titan]

I think i'm going to replace those cats and not for performance or anything, but seeing how flat out UGLY!! those cats are, I just can't drive my truck for very much longer knowing that they is somthing like that attached to it...

[joone]

I don't mean to highjack this thread. But what Gr8t is doing is somewhat fixing the global warming problem, according to the links.

While following the links to "How stuff works" and learned about catalytic converters, I found this:

http://auto.howstuffworks.com/framed...s2/catalyt.htm

I guess for those environmentalist, this mod is a must!!

[HavockWK]

Originally Posted by joone

I don't mean to highjack this thread. But what Gr8t is doing is somewhat fixing the global warming problem, according to the links.

While following the links to "How stuff works" and learned about catalytic converters, I found this:

http://auto.howstuffworks.com/framed...s2/catalyt.htm

I guess for those environmentalist, this mod is a must!!

Wow! Take that tree huggers!

That info was a very interesting read. Thanks!

[RockyMtnTitan]

Now, see....that's what I'm talkin' about! I'm not selfishly thinking of myself, and how this mod is gonna make my truck go faster, sound better, etc, etc. I'm doin' it for good ol' Ma Nature...lol! Thanks, for the link....interesting stuff.