SMOG - Running More Than One Cat
SMOG - Running More Than One Cat
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As most of you know, Mr. Wankel's design is not exactly the most environmentally friendly. Additionally, a lot of rotary owners don’t keep their car stock. After adding numerous aftermarket goodies, cats get replaced, air pumps are eliminated and problems with passing smog arise.
My car currently has a SMB metallic substrate cat with a Mangnaflow resonator and no air pump. This setup does not pass the California dyno sniffer with 1 gallon of denatured alcohol in a tank with about 5 gallons of gas. I understand that the air pump is vital in assisting the catalyst process. Rather than going through the trouble reinstalling an air pump and all stock pulleys and belts (I have a pulley kit), my goal is to pass the CA smog test without an air pump. I’m planning to install a single turbo in the future so the air pump is probably not coming back. (Has anyone with a single turbo passed the dyno smog test in California?)
Since the smog dyno test here is limited to 15mph and 25mph runs in second gear from what I recall (1700 - 3000rpms), I’m wondering if tuning my Power FC to lean out the AFRs at those speeds/rpms will help with passing smog. In the event that leaning out the AFRs is unhelpful, I’m contemplating welding on another metallic cat on my car next time I need to smog my car so there will be two cats. I have three concerns about that setup.
First and foremost, will two metallic cats substantially reduce emissions? It’s in a way like installing a larger catalytic converter because there is more substrate surface area to assist in the catalyst process since there are two cats.
Second, is the exhaust system going to get too hot with two catalytic converters?
Finally, I’m curious how much power would be lost by installing a second cat. Metallic substrate cats are compact and flow a lot more than the stock cat. If the amount of power lost is equal to simply replacing the cat with a stock catalytic converter, then it would seem pointless and expensive to run a dual metallic cat setup.
As most of you know, Mr. Wankel's design is not exactly the most environmentally friendly. Additionally, a lot of rotary owners don’t keep their car stock. After adding numerous aftermarket goodies, cats get replaced, air pumps are eliminated and problems with passing smog arise.
My car currently has a SMB metallic substrate cat with a Mangnaflow resonator and no air pump. This setup does not pass the California dyno sniffer with 1 gallon of denatured alcohol in a tank with about 5 gallons of gas. I understand that the air pump is vital in assisting the catalyst process. Rather than going through the trouble reinstalling an air pump and all stock pulleys and belts (I have a pulley kit), my goal is to pass the CA smog test without an air pump. I’m planning to install a single turbo in the future so the air pump is probably not coming back. (Has anyone with a single turbo passed the dyno smog test in California?)
Since the smog dyno test here is limited to 15mph and 25mph runs in second gear from what I recall (1700 - 3000rpms), I’m wondering if tuning my Power FC to lean out the AFRs at those speeds/rpms will help with passing smog. In the event that leaning out the AFRs is unhelpful, I’m contemplating welding on another metallic cat on my car next time I need to smog my car so there will be two cats. I have three concerns about that setup.
First and foremost, will two metallic cats substantially reduce emissions? It’s in a way like installing a larger catalytic converter because there is more substrate surface area to assist in the catalyst process since there are two cats.
Second, is the exhaust system going to get too hot with two catalytic converters?
Finally, I’m curious how much power would be lost by installing a second cat. Metallic substrate cats are compact and flow a lot more than the stock cat. If the amount of power lost is equal to simply replacing the cat with a stock catalytic converter, then it would seem pointless and expensive to run a dual metallic cat setup.
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Machupicchu
1st Generation Specific (1979-1985)
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Aug 17, 2015 08:27 PM
