retrofit catalytic converter?
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
retrofit catalytic converter?
Ok, maybe I'm nuts, but.
I'm thinking about installing a pair of Flowmaster 2230125 catalysts on my '74 smallblock.
Reason being, I have a pair of Magnaflow mufflers on it and I think they're a bit loud and annoying. (I'm damn near 60 now and no longer have any patience with noise.)
But I enjoy the power that a free flow muffler allows, so I don't just want to install a very restrictive one. I know that installing a "cat" will attenuate the noise somewhat, probably just enough. I could bolt in a bullet muffler ahead of each Magnaflow, but by the time I do that, I may as well install a "cat" and save the planet at the same time.
What will the Rule of Unintended Consequences do here?
I'm thinking about installing a pair of Flowmaster 2230125 catalysts on my '74 smallblock.
Reason being, I have a pair of Magnaflow mufflers on it and I think they're a bit loud and annoying. (I'm damn near 60 now and no longer have any patience with noise.)
But I enjoy the power that a free flow muffler allows, so I don't just want to install a very restrictive one. I know that installing a "cat" will attenuate the noise somewhat, probably just enough. I could bolt in a bullet muffler ahead of each Magnaflow, but by the time I do that, I may as well install a "cat" and save the planet at the same time.
What will the Rule of Unintended Consequences do here?
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Forget the cats. Thats like fixing a leak with a smaller hole.
Start with an H pipe - good for near 2 db. I would say X pipe but havent seen one on a C3 close enough to the collector to be effective. Most H pipes come with a choice of a straight or curved cross over pipe and the curved pipe allows location under our trans to get the H pipe close to the collector.
U should also run the tail pipes out the back of car as exit under the car makes the car body a guitar box for noise.
D. Vizard has some great info in his "How to Max Perf sbc on a budget" book (<$20) and describes a terminator box to help with restrictive mufflers.
Good luck,
cardo0
Start with an H pipe - good for near 2 db. I would say X pipe but havent seen one on a C3 close enough to the collector to be effective. Most H pipes come with a choice of a straight or curved cross over pipe and the curved pipe allows location under our trans to get the H pipe close to the collector.
U should also run the tail pipes out the back of car as exit under the car makes the car body a guitar box for noise.
D. Vizard has some great info in his "How to Max Perf sbc on a budget" book (<$20) and describes a terminator box to help with restrictive mufflers.
Good luck,
cardo0
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
Although everyone seems to be anti Cats, it will do the job and quiet it down. I don't think you'll see much loss in power but you will be dealing with heat that may cause problems on your floor boards. I would install some type of heat barrier or shield similar to the OEM.
Pro
Joined: Jul 2010
Posts: 590
Likes: 57
From: Aurora Colorado
Adding cats to a precat car would be dangerous. The cats would overheat and cause a fire. Rich fuel mixtures will cause the cat to overheat.
That is what happened to Zora Duntov when he drove ,in 1974, a 1975 C3 prototype down Pikes Peak with the engine ignition off---and in gear. It caused the cat to overheat and the C3 burned to the ground. Very embarrassing to Zora.He was low on fuel and wanted to save enough fuel to get down from the mountain by coasting down and using engine compression to slow the decent.
That is what happened to Zora Duntov when he drove ,in 1974, a 1975 C3 prototype down Pikes Peak with the engine ignition off---and in gear. It caused the cat to overheat and the C3 burned to the ground. Very embarrassing to Zora.He was low on fuel and wanted to save enough fuel to get down from the mountain by coasting down and using engine compression to slow the decent.
Last edited by phoneman91; May 12, 2014 at 05:44 PM.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Adding cats to a precat car would be dangerous. The cats would overheat and cause a fire. Rich fuel mixtures will cause the cat to overheat.
That is what happened to Zora Duntov when he drove ,in 1974, a 1975 C3 prototype down Pikes Peak with the engine ignition off---and in gear. It caused the cat to overheat and the C3 burned to the ground. Very embarrassing to Zora.He was low on fuel and wanted to save enough fuel to get down from the mountain by coasting down and using engine compression to slow the decent.
That is what happened to Zora Duntov when he drove ,in 1974, a 1975 C3 prototype down Pikes Peak with the engine ignition off---and in gear. It caused the cat to overheat and the C3 burned to the ground. Very embarrassing to Zora.He was low on fuel and wanted to save enough fuel to get down from the mountain by coasting down and using engine compression to slow the decent.
Prior to the introduction of cats, the cars weren't designed to run so much richer that it would clog a cat. Zora's car burnt down because with the engine off, the car was still sucking fuel through the carburetor(the mechanical pump is still spinning, the pistons are moving; fuel is going to get into the motor, even if it's only on the idle circuit). This filled the catalytic converter full of raw fuel and plugged it up - which made it run hot enough to lit the car up after he parked it. This cat got MUCH hotter than any typical cat would run.
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Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
U could try some exh "tips" extensions to see if moving the exit farther back does the job.
What is explained in that book i mentioned is terminator boxes allow a quieter/more restrictive muffler but has less restriction because the exh "pulses" are eliminated. Eliminator box is a gutted muffler case but some dimensions are required - u would need the book. So with the eliminator box u can use a quieter muffler w/o the backpressure/restriction.
cardo0
What is explained in that book i mentioned is terminator boxes allow a quieter/more restrictive muffler but has less restriction because the exh "pulses" are eliminated. Eliminator box is a gutted muffler case but some dimensions are required - u would need the book. So with the eliminator box u can use a quieter muffler w/o the backpressure/restriction.
cardo0