Havent looked at cats in bit so not sure whats out there.....

Thinking of need some new cats, but need something high flow for the 421. I know they hurt hp gains, but I will be hoping they can be sleeved so I can take them off at my leasure. The hp loss isnt a huge deal since I will be putting the x pipe on to replace the reasonator, and imo will gain me 10-15rwhp/10 rwtq. I'd imagine cats will rob my combo 25rwhp.

The cam in my motor isnt too friendly even with the bigger cubes, and its getting to the point that my wife is complaining about my clothes smelling (i know).

I had a random tech cat years ago, but if my memory is correct it was very pricey. Is there something that's 2nd best sort to be speak?

Thanks Gents.

 

You got one of dem der "reasonators"? How come that didn't help ya reason out the best exhaust/cam the first time?

Sure ya ain't got one of dem der LT cars with the center reasonator, right?

Seriously...
http://www.magnaflow.com/02catalytic...versal=99659HM

In terms of flow, these is about the next best thing to RT. Might even be as good. They're on mine. Smell is not an issue for my 383. (And, I'm just some hack who did my own tune!)

 

Got your PM Black...I got the 16th best option....

Spun metallic cats, 4" body, 3" pipe. I'm going to mig on some regular 3" pipe I had expanded and cut slits into for band clamps.

My hope was to get this over to the dyno I had been running on and see what they did. I'm going to be running them post x-pipe as that is where there a slip joints for the resonator/straight pipe I already have made up. So I can quickly switch it up as much as I want. I do think they'll still get hot enough to work well and I know LG used to sell a kit that had the cats post x-pipe as well, so I'm not concerned about the position.

http://performance-curve.com/3thunde...ter415300.aspx

$65/cat

The walls of the cat are very thin. I'd say the pair weigh a lot less than my SS magnaflow resonator. They are 11" long and weigh about 2.8lbs, for reference 11" of 3" pipe is about 2.2lbs. So really not bad.

I did a lot of research, a lot of guys using them on LS1tech etc. I just happened to be helping out my brother-in-law with a SC install on his 350z and I noticed his "aftermarket high flow cats" were the exact same (made by CanAmMex) just a 2.5" version. And he said the guys using those were seeing HP gains, sooooo I hope they work. For the price, and for testing purposes... I'm happy.

This is about 3rd on my list of things I'm hoping to get a chance to work on in June.

-Rear suspension fabrication
-Permanent wiring of my wideband
-Cats
-Cut front spring pads, lower rear accordingly and re-do alignment


(In other words, dyno results probably won't be for still another couple of months...)

Camera phone photo..... sorry in advance
https://www.dropbox.com/s/ufzga019xu...2019.13.53.jpg
https://www.dropbox.com/s/3oxainm7oe...2019.14.12.jpg

Also whatever paint they used comes off on your fingers a lot, FYI.

 

That and the fact that I know I use probably 30% of the power I have when I am out DD'ing and I can throw the race exhaust on for racing, so why pollute more to have power I don't even use? Its not like it emits bunnies and unicorns out the tailpipe, we know better than that.

(And for the record, I think the CARB program is a horribly managed attempt at a solution. Give owners the right to run whatever and beat smog requirements by 10%, if we do that, who cares if the part has a certification number. Hell make us pay extra to get a non-visual test. If you pass the sniffer.... you pass. /Rant off )

 

I may go with those, but then again the one's that Chris suggested look good too and probably cheaper.

Good job on the tune. Mine hasnt really even been worked on much, and there is more left. I highly doubt anyone can make a 236/242 .620 lift cam not smell, but I am thinking that the cats will certainly help.

Chit happens when you build a performance motor.

We are on the same wave length Chris. Slip then on and off whenever needed. That is the way to go!

 

To a large extent, you get what you pay for in the converter market. The materials used to build converters aren't cheap....like platinum.

It's often been stated (including here) that the reason RT's are high is the amount of "wash" used to coat the core. Magnaflow does a good job on this too. And, yeah, they're higher by about 50%. OTOH, RTs are 4-5 times higher.

Typically, the fewer "cells per inch" c onverters use/need more wash. IIRC, the Magnaflows are 200 c/i as compared to the 300 c/i Thunderbolts. I chose the Magnaflows because they should flow better.

It may be the RTs are 100 c/i. It may be they use the most "wash" and need to charge more. I know you'll find the same level of backing for the RTs (as the best flowing converter) as AFRs in the cylinder-head community.

I decided against the Thunderbolts to get something I hoped flow more. (That's right hoped -- since none of these converter companies post CFM numbers.) You pretty much have to go on cell/inch specs. I called these places and decided (from their informal specs) that Magnaflow should be better. The RT units were priced just too high for my taste (and requirements).

For a removable unit, the thunderbolts will do the job nicely though. I used the ceramic cats from Magnaflow on my stock setup. I thought they performed very well. They're about the same price as those Thunderbolts.

 

For the record here, I'm not advocating one way or another. Rick PM'd me and asked me to comment, so I did. I'm not looking for a debate, just sharing the info on what I am trying in the future.

FWIW, the other factors in my decision process were that I wanted to stay away from ceramics (brick melt/blowout) and I had read that the difference in RT's 100 cell and 300 cell metallics is 40cfm. Some site also did flow tests on the 2" thunderbolt when I was looking and it flowed sufficiently enough it didn't concern me. (Internet folklore has people saying 500cfms for the 3" thunderbolts, no mention of how it was measured or a link to a test, but that is what people say. I doubt it, but would be pleasantly surprised if I was wrong.) (EDIT: And I was looking to actually have it kill some volume too so my wife will go on longer trips with me... )

Again, I had hoped to dyno these to get an idea but like I said, who knows when that will happen.

Until then, you have cell/in but that doesn't factor in wall thickness which can decrease flow in a 200cell/in over a 300cell/in cat. Plus you also have to pay attention to OD of the substrate section. These are a 4" OD, RT has cats that are 5" I think. This drastically changes the flow area and may allow for equal surface contact area with less restriction.

The moral of the story is unless you want to pay for a flow session, nobody knows. I wish the manufacturers would provide this.

Gregg, do you have pics of the inside of your cats?

Also, could you share a link for the Maggies at that price. They might be a good option for round 2, if these go belly up in a year. Which they definitely may... TIA

 

LS1Tech had quite a few posts on this topic:

Random Tech Cat-327CFM
Carsound/Magnaflow-400CFM
Catco-365CFM
Stock-220CFM
Random Tech Metallic-535CFM

I bought the metallics...even though I didn't know the flow rates at the time. My engine builder told me if I insisted on CATS, that was hands down the best flowing catalytic converter. I've never been disappointed with ANY of his recommendations...

And is it ever fun to have it on the trailer, start it up and see heads turn. Then they look under the car and see CATS installed...

And I kick their butt around the course all day long.

Then go to get the inspection done and they look under it and see the CATS and sign off...

ALL without ever needing to touch the exhaust system.

 

I take it you went with the 5" OD 3"inlet/outlet 100 cell RT's? Do you have a PN?

I doubt anyone would disagree with you, those are the best possible for flow. Once I see what the HP drop is, maybe I'll buck up and buy those...

The problem with all the posts like that one linked is they lack so much info, for instance, I think those flow numbers are all for ceramics which I thought flowed less than metallics generally, and then the RT metallic it isn't specified which one it is. (They have 3 different metallic 3" inlet/out cats alone.) I actually believe that one is for their 7000 series 4" body, 300 cell metallic but who knows. Just pointing this out so others don't make assumptions.

 

Their part numbers have changed, but I think they were the 141-30000...

Universal fit 3" Inlet/Outlet ones...

 

Rick,

This is the thread I had bookmarked on the old computer. It has part numbers but is a little outdated.

Hope you can make some sense out of all of this.


http://ls1tech.com/forums/generation...cats-best.html

 

Say thanks. That 300 does pretty well.

 

Magnaflow 99659HM might be a good choice. Just over $100 ea. That's about what I paid.

There's another model where the model# sounds more familiar 59559 but they actually cost more @ $160ish.

Both might flow near the graph above...check on cell density before purchase.

The test graph above doesn't look too bad for the Mag 3" 300 c/i cats. Pretty much the same flow at Random (depending on how they did there test). Just over 600cfm (in a 1000cfm system).

The 400 c/i cats would be your ceramic hi-flow cheapies.

GREAT LINK USAsONLYway!!!

 

http://www.zr1specialist.com/HAT%20W...kpressurea.jpg

Would not worry about cat power loss

 

This is why I keep telling people to install cats for sound control...and avoid going catless with performance mufflers. It's worse for the environment and their goal(s).

Catalytic converters can provide just as much sound control as a sport muffler.

 

Dont see you needing more than 600cfm/pipe probably less. Power loss shouldnt even be a consideration meaning taking off/on.Just run em.

 

Any clearance issues with autos? Seems 6 speeds have a little more room within the tunnel area. Or can you put the cats before an X Pipe where the resonator would go?

 

Don't know on an auto equipped car...

This is what my ZF6 looks like...

 

Yeah, I didn't realize stock can be 600cells/in

Great link. Did you do this?

I'd be curious to see if dP(cat) changed after the muffler was replaced.

This is my hope, but if all goes well I'll have a dyno to back it up and share with all of you.

Of course mine won't be on par with the race 100 RTs.

My plan is:
LT's -> x-pipe -> (resonator, straight pipe or cats) -> mufflers

I think the only custom work that will be needed is some heat shielding. I'm going to try to either fab something up like the stock 4+3 main cat shield or line the tunnel.

 

Nice. If I had LTs, x pipe then cats I need to ensure that the floor boards dont get hot from the cats. And I need to ensure they can get hot enough to work.