Hey guys, does anybody know a trustworthy shop in South Florida that could delete the primary cat? Also, do you need an extension to replace the sensors behind the secondary?
Hey guys, does anybody know a trustworthy shop in South Florida that could delete the primary cat? Also, do you need an extension to replace the sensors behind the secondary?
when you mean delete do you mean gut it out or replace it with headers. Cause i was thinking about gutting them. It seams to take the same time as installing headers but you save the money on not having to buy them and still get the gains. but i decided to wait till the warranty is over.
let me know what you come up with.
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2006 interlagos blue silvertone interior Dyno'd 433 rwhp - scoops only
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RPi GT exhaust v2 Cat back
21" HRE 597r
when you mean delete do you mean gut it out or replace it with headers. Cause i was thinking about gutting them. It seams to take the same time as installing headers but you save the money on not having to buy them and still get the gains. but i decided to wait till the warranty is over.
let me know what you come up with.
+1 I agree, replacing just the cats with pipe or gutting them, makes the BMW OEM headers perfect, and is a lot cheaper.
Do you guys think gutting them and leaving the empty chamber wouldn't affect the air flow?
Would not recommend gutting them, as this would increase aerodynamic tumble within the exhaust flow. You would be much better off cutting the cat out and wedling in a straight pipe if you don't want to spend the money on headers. Although, the labor costs would be a bit more than just installing headers since doing this kind of job is more labor intensive. Eventhough the labor costs are higher, you will still be saving quite a bit of money over purchasing headers.
Also, you will need to do a DME re-flash for the O2 CEL.
Last edited by ASR Engineering; 23rd October 2009 at 00:09.
. i knew it would throw a CEL, but i didn't think about the aerodynamic tumble. Something to think about. There was a member in S America who did this and said it did pretty well for him but i don't remember what else he said about it or if he dynoed it afterwards.
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2006 interlagos blue silvertone interior Dyno'd 433 rwhp - scoops only
AC Schnitzer Trunk Lid Spoiler
AC Schnitzer springs
AC Schnitzer white carbon interior
RPi scoops
RPi block off plates
RPi GT exhaust v2 Cat back
21" HRE 597r
Would not recommend gutting them, as this would increase aerodynamic tumble within the exhaust flow. You would be much better off cutting the cat out and wedling in a straight pipe if you don't want to spend the money on headers. Although, the labor costs would be a bit more than just installing headers since doing this kind of job is more labor intensive. Eventhough the labor costs are higher, you will still be saving quite a bit of money over purchasing headers.
Also, you will need to do a DME re-flash for the O2 CEL.
Wouldn't the bored primary cats inner surface be smooth? What would cause aerodynamic tumble?
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Wouldn't the bored primary cats inner surface be smooth? What would cause aerodynamic tumble?
Aerodynamic tumble is basically a measure of airflow turbulance. Even if the area is smooth inside the bored out catalytic, this will still cause aerodynamic tumble since airflow turbulance is not necassarily caused by just rough exhaust path surfaces. One of the major factors of airflow turbulance in this scenario is the expansion of piping diameter right before the header collector causing a reduction of exhaust gas energy and in turn decreasing it's scavenging affect. When the cat is in place, it slows down the exhaust flow allowing it to build more exhaust gas energy to negate the fact that it is placed in a larger surface area. This is not to say that you won't make more power when the primary cat is deleted. It will make more power, but not as much as if it were done correctly.
Last edited by ASR Engineering; 23rd October 2009 at 20:50.
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I agree, replacing just the cats with pipe or gutting them, makes the BMW OEM headers perfect, and is a lot cheaper.
. i knew it would throw a CEL, but i didn't think about the aerodynamic tumble. Something to think about. There was a member in S America who did this and said it did pretty well for him but i don't remember what else he said about it or if he dynoed it afterwards.
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