Simple Question for the Experts...

Psycho Mythic

Psycho Mythic

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Im shopping for a couple high flow cats, and i can see the difference in the design of them as compared to stockers, but the ones i have researched so far look exactly the same inside. The "honeycomb" seems to be just as restrictive.
Is the honeycomb designed to flow more or is it just the design of the casing? (or am i just looking at cheap high flows)?

Thanks for any feedback on this guys :D
 
Well, if you were on some of the Ford/GM sites, you would find that in some of the aftermarket "H-Flow" cat shootouts, they didn't work as well (flow) as the o.e.m. units. The o.e.m. cats have come a LONG way, especially the ones used on the factory performance vehicles.

With our trucks, getting rid of the FOUR o.e.m. cats in favour of TWO "Hi-Flow" cats is generally a good move toward better performance. I run two B&B Hi-Flow cats and noticed a nice difference coming from the 4 factory cats..pipe diameter and mandrel bends with a complete performance exhaust system, also helps in the big picture.

I would have gone catless but I don't like the stink...I had more than enough of that with the old muscle cars.

..if any of this helps answer your question(s)...

Ronnie
 
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Basically all aftermarket cats have a ceramic substrate (the guts) that during manufacturing is coated with a solution of platinum, palladium and rhodium. This coating is what causes the catalyst reaction once the converter reaches a certain temperature supplied by the vehicles exhaust gasses. These substrates are made like a beehive honeycomb and are comprised of 400 cells per square inch across their surface. In theory, an aftermarket cat is higher flow than it's O.E. counterpart because the O.E. converter has a substrate made up of 700 cells per square inch, so the exhaust flow with and aftermarket converter is a little free:D
 
rottenronnie said:
Well, if you were on some of the Ford/GM sites, you would find that in some of the aftermarket "H-Flow" cat shootouts, they didn't work as well (flow) as the o.e.m. units. The o.e.m. cats have come a LONG way, especially the ones used on the factory performance vehicles.

With our trucks, getting rid of the FOUR o.e.m. cats in favour of TWO "Hi-Flow" cats is generally a good move toward better performance. I run two B&B Hi-Flow cats and noticed a nice difference coming from the 4 factory cats..pipe diameter and mandrel bends with a complete performance exhaust system, also helps in the big picture.

I would have gone catless but I don't like the stink...I had more than enough of that with the old muscle cars.

..if any of this helps answer your question(s)...

Ronnie
Click to expand...

How much were your B&B high flows and where could i get some from?
Also, if anyone has any pics of their high flow cats that would be awesome!!
Thanks
 
Stinker said:
Basically all aftermarket cats have a ceramic substrate (the guts) that during manufacturing is coated with a solution of platinum, palladium and rhodium. This coating is what causes the catalyst reaction once the converter reaches a certain temperature supplied by the vehicles exhaust gasses. These substrates are made like a beehive honeycomb and are comprised of 400 cells per square inch across their surface. In theory, an aftermarket cat is higher flow than it's O.E. counterpart because the O.E. converter has a substrate made up of 700 cells per square inch, so the exhaust flow with and aftermarket converter is a little free:D
Click to expand...

Oh yeah, thanks Tony!
Why didn't you just give them a technical answer while you were at it...:D
 
I don't know all the differences but in a Viper the cats are under the door sill and changing the OEM's to aftermarket makes a huge difference in how hot the door sills get to the touch. May have to do with the extra material per sq/in in the OEM's.
 
Ya don't have to be an expert to answer this question.....:

Delete your cats...PERIOD.. Save 'em in a box and replace them with straight pipe, 02 sensor bungs and sims if ya wanna go all the way....

Cats are bullshit....... delete 'em and get at least an extra 15rwhp....

D
 
Psycho Mythic said:
How much were your B&B high flows and where could i get some from?
Also, if anyone has any pics of their high flow cats that would be awesome!!
Thanks
Click to expand...

I don't remember now for just the Hi-Flows, but in Canada, the whole system was around $3800 without headers.
Check with B&B or some of the vendors on this site as to getting some.
 
Django said:
Ya don't have to be an expert to answer this question.....:

Delete your cats...PERIOD.. Save 'em in a box and replace them with straight pipe, 02 sensor bungs and sims if ya wanna go all the way....

Cats are bullshit....... delete 'em and get at least an extra 15rwhp....

D
Click to expand...

This is nice and true to some extent, but unfortunatly some of the elders in certain neighborhoods dont cope well with over 500hp free flowing at 5:30 in the morning. Catless is loud...very loud...and even lounder in a garage :eek:
 
Django said:
Ya don't have to be an expert to answer this question.....:

Delete your cats...PERIOD.. Save 'em in a box and replace them with straight pipe, 02 sensor bungs and sims if ya wanna go all the way....

Cats are bullshit....... delete 'em and get at least an extra 15rwhp....

D
Click to expand...
this is very true:rock:

even going with a hi flow cat you want gain any hp over a oem cat, if so maybe 2-4 hp at most I would think,

any cat is restrictive to a certain degree, no cats gain a ton, but you get the smell and the noise, aftermarket cats are basically all close to the same.

i seem to tend to go with maggies for the simple reason of there price, there are alot out there, but the ones that are super cheap seem to fail frequently.
but once you get to a normal area of pricing, the quality is about the same from a $100 cat to a $200 cat.
 
Ive got super high flow stainless metallic substrate, 200 cel per inch cats for $290 a pair. Weve dyno'd a ~450whp viper before and after with these cats and it made less than 5whp difference from catless.
Justin
 
DUDE! Get cats, and than e-cutouts between the headers and cats, you have LOUD and STINKY when you want (thats what she said), and quiet when you want!
 
Here are my hi-flows welded in. Got them from Stinker. Different sound than stock but I did not notice any real increase in power. Cody you heard mine, and it does not sound anything like your catless mids with magnaflow catback.

58.jpg



img_0057.jpg



img_0051.jpg
 
JMB Justin said:
Ive got super high flow stainless metallic substrate, 200 cel per inch cats for $290 a pair. Weve dyno'd a ~450whp viper before and after with these cats and it made less than 5whp difference from catless.
Justin
Click to expand...

Thanks Justin,
I've always heard that good Hi-Flows are very close to going catless, but without the smell.. :)
 
The stock mids not only have 4 cats (not truly 4 but more or less) but also has excessive bends and the ID if I remember is around 2 5/8". I picked up a set of B&B mids w/HF cats for around $500. They were at least a 1/4" larger ID and had significantly less bends (better flow).

My truck produced 19rwhp and 30ftlbs more with the B&B's (I had to dyno tune a little to get that max gain)
 
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