Catalytic Convert Replacement

Aug 14, 2008 9 Replies

Somebody cut out one of my catalytic converters on my 99 4wd Suburban (also on my Toyota PU). My concern is that an aftermarket (affordable) replacement might have a significantly different resistance (backpressure) than the OEM that they didn't get and cause vibration due to uneven backpressure. How significant is this with 2 different catalytic converters?



Mike D.


Don't you have a cross over connect pipe on the exhaust?

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The 2 catalytic converters go into the muffler so the muffler acts as a crossover.

Kindergarten science? One bank with one measure of resistance and another with a different measure of resistance causes uneven running. The qwuestion is will it be enough to have a significant effect? Years ago Bell Aerospace experimented with a partially ducted fan aircraft. The vibration tore the engine apart due to unbalanced resistance.

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Yes it will. One bank with significant resistance followed by another bank with little resistance will cause vibration. With no cat there will definitely be vibration. With mismatched cats there will be vibration. That is simple fluid dynamics. The question is will the difference in styles and sizes of cats make enough of a vibration to significantly affect long term engine wear. Since you reject basic science your answer is totally invalid. Go back to science class and study basic fluid dynamics. Racers understand this and that is why they go to great lengths to balance flow in intakes and exhaust, especially in those high revving grand prix racers.

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Well now, you have answered your own question haven't you?

Nope. I still do not have an answer about the significance of the imbalance. The fact is any imbalance will affect longevity. The question is will it cause a significant decrease to the life of the engine. And now it is a mote question. I could not run around with the converter missing. I had to get one to use the truck. Good thing I did as the 35 mpg pickup was stolen. Now the suburban is both people hauler and construction vehicle.

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