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Discussion Starter #104
I was suppose to have video up by now but i brought the car in to get the cat removed for more power and better flow
 

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I was suppose to have video up by now but i brought the car in to get the cat removed for more power and better flow
Removing the cat only nets 3-4 horsepower on larger modded engines. You'll probably see +1 hp...not worth it IMO.

It would be better to use a high flow cat which are proven to be 90% as effective as removing the cat. Go with an all metallic type magnaflow. They are about $70 on eBay.
 

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Removing the cat and replacing it with a header netted 5+ WHP from the guys at SFR. Yes, it's very much worth it. Moreover, in applications placing the cat BEFORE the turbo, removing the cat also eliminates the danger of metal bits 'n pieces being blown into the turbo's turbine... Under boost, the cat substrate will get much hotter and there's a good chance that eventually some bits will burn off. I've got pics of a Mitsu turbine with nicks in it from debris. That toasted the CHRA on that turbo...
 

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The catalyst in front of the turbine reduces the pulse energy quite a bit too so getting rid of it helps spool the turbine sooner.
A properly sized catalyst after the turbo will have a small effect on performance though.
 

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Removing the cat and replacing it with a header netted 5+ WHP from the guys at SFR. Yes, it's very much worth it. Moreover, in applications placing the cat BEFORE the turbo, removing the cat also eliminates the danger of metal bits 'n pieces being blown into the turbo's turbine... Under boost, the cat substrate will get much hotter and there's a good chance that eventually some bits will burn off. I've got pics of a Mitsu turbine with nicks in it from debris. That toasted the CHRA on that turbo...
Not comparing apples to apples! Removing the cat is one thing but replacing the cat with a header totally different ball game.
The oem exhaust manifold is a total disaster as far as flow goes. Hell,I seen better designs on tractor manifolds.There is power to gain just by building a better exhaust manifold from cylinder head to oem converter (naturally aspirated or turboed).
Granted I don't like the converter in front of turbo either. But, let's play by the emission laws. I love the SFR header, it's a piece of artwork. So if you replace the oem manifold and converter with a header why not incorporate a converter downsteam of turbo and maybe unit will not be for offroad use only ?:)


BARNEY O... BMS
 

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When the guys at SFR tried using a DTH header, they lost power -- and this is compared to the stock cat manifold... Nothing they tried could get the wheel HP numbers back up. They then made up their own header and they got 5+ WHP over the stock cat manifold and much more compared to what they were able to get with the DTH header. Yes -- this isn't comparing apples to apples, but inasmuch as you can't get the parts to do this, it's at least a comparison of something... In a Goldilocks sense, you've got a bowl of porridge that's cold, one that's hot and one right in the middle... I've got both the DTH and the SFR headers. I took side by side comparison pics and internal comparison pics of the collectors and O2 bungs using a video borescope. Littodevil has these pics -- I suspect he'll eventually upload them after he watermarks them.

Yes, it's entirely possible to use a cat after the turbo -- in place of a muffler... A decent cat wouldn't have much restriction and the exhaust would be cleaner (but, still not legal in many states as it's not OEM and there's no Exemption Order). The only issue would be radiant heat -- most of the X-beam suspension and the lower rear valence of the Smart have no heat shielding... I've burnt myself on a double insulated cat once long after the car was turned off and raised up on jackstands. Some of these cats get way hot and it's hard to know which brands run hot and cold with respect to radiant heat...
 

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Stop Stalling!

That is unless you are stalling the smart...

Lol. I love it.

I do 0-60 in like 16 seconds with a B.I.G Performance BIG turbo. Somebody tune me :(
If I understand your statement then your problem is the turbo.

a BIG turbo on a little car means major lag and no power...basically you downgraded yourself to 450 speeds...
 

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If I understand your statement then your problem is the turbo.

a BIG turbo on a little car means major lag and no power...basically you downgraded yourself to 450 speeds...
I have a 599cc 450, im pretty sure everyone has seen my car all over.... I have larger injectors with the BIG Performance BIG turbo/manifold. Car needs a tune but its very hard to find someone in California that can tune a 450.
 

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Removing the cat and replacing it with a header netted 5+ WHP from the guys at SFR. Yes, it's very much worth it. Moreover, in applications placing the cat BEFORE the turbo, removing the cat also eliminates the danger of metal bits 'n pieces being blown into the turbo's turbine... Under boost, the cat substrate will get much hotter and there's a good chance that eventually some bits will burn off. I've got pics of a Mitsu turbine with nicks in it from debris. That toasted the CHRA on that turbo...
That is why I said to use an ALL METALLIC cat. There is no ceramic inside to break off. It is composed of a stainless steel catalyst. They are made for high temp and turbo apps.

Do some research you'll find these high flow cats flow nearly exactly the same as no cat and you won't be breaking the law.
 

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Ahhh... Stainless has a lower melting point than ceramic... Stainless also has a high expansion coefficient -- repeated flexure leads to breaking. The bits 'n pieces of debris which toasted a Mitsu turbine (which I now use as a desk ornament, mounted on a Manfrotto tripod) were fried bits of stainless... You won't find factory turbos with cats before the turbo irrespective of flow -- it's just not a good idea. If your fuel system runs rich for some reason -- the cat and stuff downstream might get fried. In many states, any alterations to the intake, fuel or exhaust without an Exemption Order are illegal irrespective of the emission numbers. Even if you replace an existing cat, in states like Kalifornia you must show that the cat you are replacing is faulty or has over 50K miles on it. The Smart currently has such low numbers in the US that getting an E.O. isn't appealing to performance shops yet. Many people with aftermarket turbos live in hope that the performance shop which made it will eventually apply for and get an E.O. for their system. Since the E.O. process involves more than one test car with the cars tested over 40K to 50K miles -- I doubt that a performance shop would opt to register and test a turbo configuration with cats ahead of the turbo...

Anyway -- replacing the stock Smart cat with a metallic substrate cat would not achieve legality in most states (specifically in Kalifornia) and moreover would just be more prone to shed particles.
 
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