catalic converter

[r33freely]

A freind of mine tells me i need a high flow catr to make more power, i have a complete 3" systyme and a standard 3" cat.

Does the high flow make that much difference, what about dropping the standard one and slightly damaging it...lol, would this have a better effect on performance?

what you guys &gals reckon?

[2BNVS]

a 3" hi flow cat would be a good upgrade to finish off the exhaust, and create a lot less restriction, if u start damaging ur cat like gutting it, ur gonna get constant pblack smoke comin out and its bloody annoying, could pick up a cat for round 300 if not look for a 2nd hand gtr one they are quite good

[lukew105]

Generally "dropping" and breaking the standard cat you have atm is much better flow and generally much better power, however it ****s up your back pressure. Im not an expert but im going thru the same thing atm.

[always_me]

not suppose to be constant black smoke out of the exhaust if you gut it. back pressure is a bitch but some sacrafises are made for more power

[R31Nismoid]

Generally "dropping" and breaking the standard cat you have atm is much better flow and generally much better power, however it ****s up your back pressure. Im not an expert but im going thru the same thing atm.

why on earth would you want backpressure on a turbo motor?

gutting the cat reduces this and thats what you need to aim for for performance gains.

a hi-flo cat isnt bad, a hollow one is better

[Slide]

hamer + screwdriver = killawatts

[R33S2]

back pressure is created by turbo and gases passing out of turbo need to get away quick so as not to slow it, a high flow cat is best and from what what ive read in other posts gutting cat works but dont get caught as they retard the release of carciogenics into atmosphere and is whole reason its there. ( supposedly better than releasing lead into air)

[PlasticStan]

How do you get lead in your exhaust emmisions by removing the cat? Here in the UK the first thing anyone does is remove the cat, helps turbo spool up much quicker and makes more bhp at higher revs. You may lose a bit of power at low revs when the turbo isn't spinning because of the loss of back pressure, but it will be minimal. I couldn't feel any loss in power when I removed my cat.

[Gamatron]

I have "hiflowed" my cat too, runs great, fcuk spending $300 on a 5L cat when you can sit in your garage with a hammer n flat head screwdriver n bash tha shit out of it. just shoots flames alot more, just dont flog it round cops, they love fireballs

[someonestolecc]

The cat is there for a reason.

Carbon monoxide is dangerous. Dangerous to you, and anyone following you.. Sure you don't care because you're in the cabin but it's also bad for the planet.. (you know, the one you live on, with the polar ice caps melting and the ozone layer hole and stuff).

Also, the difference on a dyno for most cars is sweet **** all.

Now if those 2 logical reasons didn't get you - how about the bullshit fine that's probably half the price of your car that the EPA will bend you over with, and YES believe it or not they do run around with mobile testing stations and even the good ol' broom stick to see if you're gutted it.

So to answer the thread starter - yes a hi flow is the way to go, however stay away from a 4" for example because that may create turbulance. Just stick with your 3" now and if it's gonna die or you have some extra cash, put a high flow in. I'm assuming you have stock turbo/dumppipe/frontpipe. If you upgrade any of those get a high flow too.

Good luck.

[lukew105]

Agreed!

[Panikin]

Sydneykid said he used a 4" hi flow cat on a 3 or 3.25" exhaust with no power loss.

As for not having a cat in your exh. it's no good for your bank balance "if" you get busted and does greenhouse effect mean anything to you enviro-rapists??

[Sydneykid]

Sydneykid said he used a 4" hi flow cat on a 3 or 3.25" exhaust with no power loss.

I have been quoted again, at least someone reads them. :headspin:

A quick clarification, same car 3" hi flow cat, made 245 rwkw. Replace with gutted 3" compliance cat, made 252 rwkw. There is turbulance there because of the much larger step up and down in diameter through the gutted cat. You can see the heat differential with a laser heat gun. Replace cat with straight through 3" pipe, 262 rwkw. Fitted Magic 4" cat, 260 rwkw. No tuning changes (fuel or ignition timing ) were made, however the boost does move a little bit as the restriction changes. So I consider it a "real world" test.

Test number 2, put 4" Magic cat on the SupaFlow bench and compared to the "compliance" 3" cat, it flows almost 3 times as much. Over the years we have tested a number of so called "hi flow" 3" cats and none of them gets anywhere near the 4" Magic cat. It is almost as good as a straight though 3" piece of pipe at very high exhaust flows.

So if you don't mind being illegal and an enviro terrorist, a straight though piece of 3" pipe is much better than a gutted cat. Otherwise the 4" Magic cat is a good piece of gear and you can feel safe in the knowledge that your are running legally, making good power and not killing penguins in the antarctic.

PS; we paid for the Magic cat, it wasn't a freebee and there aren't any kick backs. We were doing some testing, as there is ongoing talk of going to cat's for circuit racing (they do it in Germany already).

[caminperth]

Searched the net for a "Magic" catalytic converter and couldn't find a supplier. Where can we get these Hi-flo cat's from SK?

[Beer Baron]

their contact details are in this forum. seach for the word magic and no doubt the thread will apear.

[Beer Baron]

http://www.skylinesaustralia.com/forums/sh...highlight=magic

that was not so hard.

[Panikin]

Thanks for clarifying that SK. I was sure your eagle eye would catch that and correct me if need be and inform us of your experience with hi flo cats

[600hp]

I've seen a car with a 3'' high flow cat at CRD get the 4'' magig cat installed and power went from 200 at the wheels to 220 with nothing else changed.

[INASNT]

Still no test as to how the magic cat flows on a big hp car after a few 1000km's of hard driving.

[Sydneykid]

Still no test as to how the magic cat flows on a big hp car after a few 1000km's of hard driving.

If 265 rwkw is "big hp", then our previous experience with cats (eg; the R34GTT has a hi flow 3.25") has shown that properly tuned (not rich as) means no deterioration for 25,000k's so far. Obviously it only runs on premium unleaded (Optimax mostly), no octane boosters or Avgas. It still makes the same power and it's been a bit over 2 years. I see no reason why the Magic 4" would be any different.

On poorly tuned (especially rich) cars I have seen deterioration in the cat performance after as litttle as 10,000k's of city driving. I have that found a long hard run (5 hours or more) seems to cleans up the cat, as it burns off some of the over rich contaminents. This doesn't work for Avgas (or other leaded fuels) of course, the lead doesn't burn off.

PS; I will come back to this thread when the car with the Magic 4" has done a few more k's.