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Old 01-31-2006, 11:45 PM   #1
Uncle Ben
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Default Hi-Flow Cat?

Is anyone running a downpipe with a hi-flow cat that passes aircare? If so what brand and where did you get it? Thinking of swapping my catless dp with a high-flow one because yanking off the dp I have now everytime I go for aircare doesn't seem like a very pleasant solution.
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Old 01-31-2006, 11:53 PM   #2
fukamoto
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Victoria has aircare?
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Old 02-01-2006, 12:33 AM   #3
tony_subaru
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Doesn't his location say Vancouver?
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Old 02-01-2006, 12:36 AM   #4
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Yeah but you're only going to be putting your stock one back in once every 2-3 years... i think its worth the effort.

Highflow cats cost more than a straight pipe and it frees up less HP..
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Old 02-01-2006, 02:22 AM   #5
fukamoto
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tony..it DID say Victoria when I posted..hehehe

I'd recommend getting a stock one. I don't know who makes a pre-fit hi-flow cat for your car, but I do know getting a universal one and welding it adds up in $$.

I just went through aircare today and its nice to know I can do whatever I want for another 2 years
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Old 02-01-2006, 03:00 AM   #6
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Um.. it hasn't said Victoria since September when I moved here

Don't a few companies make a high-flow one? I don't know if I want to relive the bloody knuckles and sprained triceps experience again, unless absolutely necessary haha.
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Old 02-01-2006, 03:24 AM   #7
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I think the Helix DP with high flow cat will do the job .... Am I right ????

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Old 02-01-2006, 04:48 AM   #8
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From reading Japanese version option magazine for quite a while, they tested a few high flow cats vs. OEM cats vs. catless on skylines. They tested the Skyline GTR on dyno and aircare thing.

High flow cat doesn't rob that many horsepower as many may have expected.

Stock w/ OEM cat = 393.7 ps
ATTKD high flow cat = 426.8 ps
ATTAIN resonator = 429.5 ps
ATTAIN straight pipe = 435.9 ps

So, horsepower gain from a straight pipe is within like 9 ps on a 400+ horsepower machine.

They also measured the noise level at idle and it all stayed within the 91 dB. At 4000 rpm. They measured all within 92.5-92.7 dB.

They also measured the aircare emission thing. The ATTKD high flow cat achieved a slightly higher CO level (0.06% vs. 0.09%) than stock, but the HG level was significantly lower than stock OEM cat (81 ppm vs. 126 ppm). I think it's good enough.

With my years of magazine digging and bench racer experience, high flow cat might pass aircare for you. But it's a bloody 48,000 yen with a Japanese brand high flow cat.

Hope this little piece of information helps.
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Old 02-01-2006, 11:46 AM   #9
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couple of things

a true high flow cat will not so much hinder the top end power but it does create increase in exhaust backpressure and temps. Catless will always win - and is cheaper. The impact of a cat vs. a non-cat is dependent on the car ! In other words, car X that runs in Y manner may be slightly impacted, while car Z may be severely impacted... A car that depends on boost more will be impacted by the cat more...

a majority of the 'generic' catted DPs out there actually do not have high cell count / high flow cats in them - even if they say they do or call themselves "high flow cats"

a car equipped with just a good DP high flow cat will pass aircare - at least if everything else is running properly. We have had countless customers with our DPs and the APSs pass - but again - as long as everything else is running properly

but to get to your main question - the reason you aircare every 2 years is that things like catalytic converters are WEAR items. A cat will get worse over time, and the speed of decay is proportional to its quality, heat, AFRs, etc. etc. So what I am trying to point out is, if you get a 'low end catted DP' to pass aircare, there is a high probability that it will only allow you to pass that one time... or at most, twice.

-Pat
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Old 02-01-2006, 12:58 PM   #10
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My friend had the same experience that Pat was talking about with his high performance car. He had a custom cat, but he had to constantly replace it in order to pass aircare, which was expensive and a drag.

personally, I think for the environment, i'll spare a couple of HP on my car which I've lovingly renamed " El Dento"
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Old 02-01-2006, 04:38 PM   #11
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Quote:
Originally Posted by patr
couple of things

a true high flow cat will not so much hinder the top end power but it does create increase in exhaust backpressure and temps. Catless will always win - and is cheaper. The impact of a cat vs. a non-cat is dependent on the car ! In other words, car X that runs in Y manner may be slightly impacted, while car Z may be severely impacted... A car that depends on boost more will be impacted by the cat more...

a majority of the 'generic' catted DPs out there actually do not have high cell count / high flow cats in them - even if they say they do or call themselves "high flow cats"

a car equipped with just a good DP high flow cat will pass aircare - at least if everything else is running properly. We have had countless customers with our DPs and the APSs pass - but again - as long as everything else is running properly

but to get to your main question - the reason you aircare every 2 years is that things like catalytic converters are WEAR items. A cat will get worse over time, and the speed of decay is proportional to its quality, heat, AFRs, etc. etc. So what I am trying to point out is, if you get a 'low end catted DP' to pass aircare, there is a high probability that it will only allow you to pass that one time... or at most, twice.

-Pat


Pa pow!!

Get a catless DP and learn to swap it out.


OR


Get some great tuning from Rocket Rally with a catless downpipe, then pay every 2 years to get the stock DP re-installed and car detuned just for aircare. Small price to pay for a lot of good fun.
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Old 02-01-2006, 04:56 PM   #12
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Just curious, how much do the auto shops charge you to reinstall the stock DP? Then they charge you to install the DP again??
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Old 02-01-2006, 04:59 PM   #13
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Quote:
Originally Posted by terror7
Just curious, how much do the auto shops charge you to reinstall the stock DP? Then they charge you to install the DP again??

DIY



but if you have tuning that is *critical* of you running w/o cat's... get the mech's to do it.
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Old 02-01-2006, 06:52 PM   #14
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I'm with Happy_Days.
The dp is easy to re&re once it's been done already. Getting all those damn heatshields and backets off are the hardest part.

I reinstall my stock exhaust every 2 years for aircare, then go back to catless shortly after. There are some negatives in running catless though. Both sound and smell tend to be changed. The sound gets louder, but also more raspy with a bit of a tinny sound. As for the smell, well it's kind of like sulpher, except not as painful to the respiratory system.



bwco, that's some cool info on peak power losses.
The question now becomes, is it worth the additional 5-10hp?

Patr, also some great info regarding EGTs.
Another question you have to ask, how important are the 50-100 deg.f EGT that you lose due to better flow?
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Old 02-01-2006, 08:23 PM   #15
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Find a friend in Hope and insure your car at thier place no air care
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Old 02-01-2006, 08:32 PM   #16
Happy_Days
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Quote:
Originally Posted by hypa
I'm with Happy_Days.
The dp is easy to re&re once it's been done already. Getting all those damn heatshields and backets off are the hardest part.

I reinstall my stock exhaust every 2 years for aircare, then go back to catless shortly after. There are some negatives in running catless though. Both sound and smell tend to be changed. The sound gets louder, but also more raspy with a bit of a tinny sound. As for the smell, well it's kind of like sulpher, except not as painful to the respiratory system.



bwco, that's some cool info on peak power losses.
The question now becomes, is it worth the additional 5-10hp?

Patr, also some great info regarding EGTs.
Another question you have to ask, how important are the 50-100 deg.f EGT that you lose due to better flow?

After gaining more experience in installing different types of turboback systems... I noticed how nice of a difference having a big 'ol muffler in the axel end of the exhaust made for the sound.. much more civilized than the "can" type of axel back housing.
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Old 02-01-2006, 11:16 PM   #17
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All my numbers came straight from the magazine. I really believe in the results of the Japanese products. However, Patr really gave a good point in how the cat will deteriorate over time. I never know that it may went bad in the long run.

I've tons of japanese magazine and best motoring and hot versions, so it's really easy for me to post up numbers from these things.

Everyday is a learning day ! Glad i'm in the subaru forum, it's hilarious in the Mercedes forum and reading how they think about the BOV on the Mercedes. I just got this fight with a guy arguing how "fast" his C230 compared with a Honda Prelude. I got a good laugh !
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Old 02-02-2006, 12:59 AM   #18
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I'd just stick the stock DP back on for aircare. If you do that, do it a few days before aircare so your car settles down with it's cats back in, and get them nice and warm before taking it in. Also a ethanol blend gas helps to raise EGT's getting the cats up to speed, Mokawk/Husky 10% 94 for Aircare reducing your CO.

Last edited by Gethin; 02-02-2006 at 05:49 PM.
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Old 02-02-2006, 04:23 AM   #19
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So will a DP with a high flow cat pass Aircare ????

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Old 02-02-2006, 04:29 PM   #20
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if the cat is still functional and of proper function, if the car is running right (as per specs, not as per butt dyno), if the car has a proper tune for its mods (if any), it should

but all of the above is... hard to tell if you drive it every day.
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Old 02-03-2006, 12:14 AM   #21
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YeS.SiR did with a cobb catted DP

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