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lipsticktracer t1_iw43xhy wrote

Reply to comment by Jerry_Williams69 in Catalytic converter by Zestyclose_Ad3489

Not accurate. You can fuck things up by putting on way too small of a cat so you’re actually creating excess back pressure, but there’s no such thing as too little back pressure and unless you’re totally choking the exhaust, the computer will adjust and you won’t notice any difference.

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Zane42v2 t1_iw48xfz wrote

Yes, there is absolutely such thing as too little back pressure.

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Jerry_Williams69 t1_iw45uzj wrote

Of course you can over-restrict the exhaust. Engines are designed to operate in a back pressure range. Too high or too low, and they don't work right. Especially if the engine has an EGR system. You are flat out wrong about not noticing a difference.

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lipsticktracer t1_iw4cd8v wrote

I'm saying you can overrestrict, but you can't underrestrict. And if you buy a normal-sized aftermarket cat, you aren't in danger of overrestricting. These things are not that picky.

FWIW, I spent a decade fucking around with the exhausts of seven different POS lemons racecars. I've fucked around with every possible cat-delete configuration on a bunch of japanese and american cars. Modern emissions systems are really really tolerant and have enough map range to accommodate almost anything an amateur mechanic can throw at it. These are not high-strung race cars operating at the edge of their envelope. They're grocery-getters built to keep running fine under all kinds of environmental and maintenance conditions. Chill.

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Jerry_Williams69 t1_iw4e0qd wrote

Cool story bro. I've designed engines for CAT and Cummins. I know a thing or two about emissions systems and engine back pressure. You just don't realize that your "tuned"/deleted engines aren't running the best they could. You also aren't giving enough credit to the Prius's power train. It is pretty advanced for a mass produced auto product.

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