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The Underappreciated Catalytic Converter?

Community Manager

Check out this video and note that a new Hellcat makes 707hp (SAE net, not SAE gross) on catalytic converters.  I think when you see how far cats have evolved, what benefit they give, it's real easy to love them even if you are a performance junkie.  

 

I always go back to the Hellcat's 707hp when people with not-racing cars talk about removing their cats, because odds are they will never make enough power for cats to be a restriction.  My last such argument was the most obvious: with a guy with a 150hp Lincoln Town Car, and I had to apologize for laughing when he said he was gonna remove the cats so it will go faster. (owner is a nice guy, just unaware of other issues like a 50mm throttle body, 14 lb/hr injectors, and terrible heads/cam that make his plan impossible.) 

 

And if you have an older vehicle with 2-way or early 3-way cats, just upgrading to an off-the-shelf modern cat will outflow your engine for years to come.    Tell me what you think of this! 

 

 

https://www.youtube.com/watch?v=Jj-ufVglr6M

 

 

20 REPLIES 20
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Re: The Underappreciated Catalytic Converter?

Detailer

I personally find this really interesting. At times I have faced "the environmental comments" when driving an older vehicle to school or work. A bit of performance loss is situational... it wouldn't matter a bit (if I put cats on) in some of the rides I have had because they just cruise (I'm not racing). I would enjoy being able to use the rebuttal of "yeah it's a 66 inline six but has a 2017 cat system and blows cleaner than your 2011 Honda". Maybe that isn't a realistic goal.

 

But a how-to article/video that showed how to properly apply a modern cat and such to older configurations would be interesting.

 

-something 50s or earlier (pre pcv valve and limp factory performance)

-60s carb keeping the carb

-old engine with modern efi

-maybe even early efi gen1 cat era

 

Besides, there may come a time that this might become a compliance piece to drive old cars in some places. Some DIY as an option than having to do a compliant engine swap makes sense to me.

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Re: The Underappreciated Catalytic Converter?

Intermediate Driver

Admittedly, I am guilty of removing the cat on a few older vehicles I have owned in the past. Mainly as a cost savings move for dealing with a plugged bead type unit. Here in Michigan there's no emissions testing, so there's no enforced penalty for removing it. That said, I agree that there is little to no real benefit for removing it, I think for anyone worried about a restrictive exhaust, changing the muffler will allow for better results, however I think that exhaust technology in general is quite good these days. The only reason to swap a muffler on a new vehicle is for sound purposes.

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Re: The Underappreciated Catalytic Converter?

Community Manager

Great feedback @Greg_I @Pepperalls as I think many opinions would change if information on 1) "upgrading" a pre-emissions car to a modern cat (might be harder than expected) and 2) dyno testing an all original malaise-era car with a modern cat to see how much power it picks up, and if it gets any cleaner.

 

Of course with the malaise era cars you will also need to upgrade the cam/heads/pistons (many had deep dishes for low compression) to take full advantage of the better tech. And pre-emissions vehicles might need some modifications to keep a cat from melting...who knows. 

 

 

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Re: The Underappreciated Catalytic Converter?

New Driver

I had a 1989 Town Car, with the same 150 hp 302 you described. At 180,000 miles, I removed it and installed a Mustang 225 hp 302. Was it a race car? No, but it was noticeably quicker. One of the best cars I have owned! 

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Re: The Underappreciated Catalytic Converter?

Pit Crew
I don't think that installing a catalyst on an older vehicle is realistic. The catalyst requires very tight fuel control that just does not exist on pre emissions vehicles. I expect my 53 Mercury flathead would plug up a modern catalyst in short order. A modern feedback fuel injection system would be required, at a minimum. Upgrading an early catalyst to a modern catalyst is much more realistic.
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Re: The Underappreciated Catalytic Converter?

New Driver

I had a Ford Fiesta in the early 80's and replaced the catalytic with a straight 'tester' pipe. That made that little car run much better and it would still pass emission tests. The only problem was that if would backfire under certain circumstances and it sounded like a rifle shot going off. I don't really know about the performance of the newer cars  and the effect of the catalytic, but you don't see them on race cars.

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Re: The Underappreciated Catalytic Converter?

New Driver
The only problem have with the (mandatory) cats here in Calif is the price! but as the saying goes--how much horsepower can you afford~~~
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Re: The Underappreciated Catalytic Converter?

Community Manager

Go test drive a 400-700hp car sometime, they are amazing. And they have cats. 

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Re: The Underappreciated Catalytic Converter?

Pit Crew
FYI, in Europe, many race cars are required to have catalysts.