Well i have a after market exhaust. Came with the truck when i bought it, i think its just been change from muffler back. Not to sure gotta get under and take a look. Is it worth putting a high flow cat in? Will it be any better over stock one? Wat about putting a pipe instead like a straight pipe? Would ethier of these make my truck lowder or any differnt over stock? Maybe even a power gain?


Thanks

 

It is hard to find honest flow tests of catalytic converters that claim to be 'High Flow'. Notice that most practice deceptive advertising like having you look through it, instead of having an independent lab flow test it against its competitors.

Here's an old post from Aug 2000 that has the only published independent flow testing of catalytic converters. Perhaps the student volunteers at the School of Automotive Machinists in Texas have done additional testing by now too:
=====

The newest issue of Hot Rod magazine has an article about the Houston Texas branch of the School of Automotive Machinists (SAM) student project of mods to a drag racing '99 Camaro with a LS1 engine.

Inside the article is a small table where S.A.M. students flow tested some
catalytic converters looking for a less restrictive one. It is rare to see an
independent test of cats, especially at the standard flow bench pressure of
1.5 inches of Hg (Mercury, which is equivalent ot 20.4 inches of water).

Most times the cat manufacturers like to list the cfm @ 24 or 28 inches of
water. This gives a higher number and sounds better for 'hype' advertising.

The highest flowing cat listed was out of a '98 Chevy Tahoe Vortec 350 V8 with 459 cfm at 1.5 inches of Hg pressure.

The lowest flowing was out of a Dodge Viper 273 cfm @ 1.5"Hg
{but doesn't a Viper has two of these catalytic converters ?}.

The '99 Camaro factory cat was 304 cfm at 1.5"Hg.

In between were aftermarket cats from Car Sounds, Random Technologies, MAC and Dynomax. Part numbers are listed along with cfm's. I didn't have pen or paper to write the numbers down. Maybe someone who gets Hot Rod magazine can post them?

What does the factory catalytic converter on a Dodge Ram flow ?

I don't know, I haven't read of a flow test.
But on the Dakota list there have been dyno reports that the factory cat
causes a restriction of 1 psi at max horsepower. This was equal to a 6 Hp
loss.

Bolstering these dyno tests, the Dodge Ram Field Service Manual chapter on
diagnostics says that a good, unclogged factory Ram truck cat should have less than 2 psi backpressure at full throttle.

The Engine Analyser 3.0 software 'guess' is that the exhaust flow of a 1995
5.9 Magnum V8 is about 410 cfm at 4000 rpm and 245 Hp.

1 psi is about the same as 2 inches of Mercury (abbreviation Hg) pressure.

To convert cfm flows at different pressures you take the square root of the
ratio of pressures and multiply by cfm.

So SQUARE ROOT( 1.5/2.0) times 410
= 355 cfm @ 1.5 inches Hg.

Remember, that is just a guess - could be off +/- 50 cfm easy.

355 cfm at 1.5 inches Hg (20.4 inches water) is the same as:
385 cfm at 24 inches of water,
or 416 cfm at 28 inches of water,
- in case you are looking at aftermarket catalytic converter catalogs using
those pressures.

 

umm.... in other words...yes if you get a good one but you can get screwed if not careful. I'd just punch out the old one if i were you. I have a hi flo on mine it works pretty good i'd rather have it punched though

 

Shhhh.......

$5,000.00 fine if EPA hears you....

 

Wat you mean by punching in out? putting holes in it? Or taking it out completly? I know my buddy took out his cat in is car, and has a pipe to replace it and sounds way more beefer. Im thinking ill just do that since its like maybe 100 somthing compard to 200 somthing for a nice high flow cat. Wonder if i will get worse gas mileage? maybe better? wat about power gain?

 

I bought my magnaflow high flow cat for $75

 

step 1 cut cat off
step 2 Ram steel rod through cat long ways over and over tearing out the guts so it is hollow
step 3 weld "cat" back in place

 

Will it make my truck any louder? Cuz thats all really care, its loud now but i want to send more meaner!! lol Well here up in Canada, well BC we have aircare and you gotta take your vechile every 2 years to see if it passes. So i would just take out the cat keep for when i gotta aircare my truck and then leave in the straight pipe(or watever you wanna call it) the rest of the time.

 

That's what we did down here in Florida when we used to have inspections. We would have a dump pipe, just a straight pipe with flanges welded to it and run that until inspection, then just pop the cat back on and take it off after inspection. but we did away with inspections in Florida so that's not an issue now.

 

Ya, is that the actually name dump pipe? Did it make any more of a difference then the cat, like more of meaner sound or power since the better flow??