Cat delete power loss??

fmagz91 · 12-13-2011, 02:13 PM

A month ago i installed ar catless dps which was a pain in the ass.. but worth the power gains.. yesterday i got bored and went to my local welder and took the 2 remaining cats out assuming better flow=more power.. i still got the stock muffler and resi... So bottom line i almost feel like i lost power by deleting the last 2 cats. is this possible or am i just crazy?

MDORPHN · 12-13-2011, 02:20 PM

Quote:

Originally Posted by fmagz91

A month ago i installed ar catless dps which was a pain in the ass.. but worth the power gains.. yesterday i got bored and went to my local welder and took the 2 remaining cats out assuming better flow=more power.. i still got the stock muffler and resi... So bottom line i almost feel like i lost power by deleting the last 2 cats. is this possible or am i just crazy?

You're crazy. You do not lose power from reducing backpressure in a turbocharged system.

Neil

Dackelone · 12-13-2011, 02:48 PM

Did the muffler shop use the same OE size dia pipes? Or maybe smaler ones? It might be better to just get a N55 mid pipe. ?

ESC OFF · 12-13-2011, 02:55 PM

Neil is correct ^^^ I was wondering the same until I did some research, Downstream of the turbine you want the least backpressure possible. The general rule of larger is better of turboback exhausts is true. If you minimize the pressure downstream of the turbine you will make the most effective use of the pressure that is being generated upstream of the turbine.

1SerieStud · 12-13-2011, 03:55 PM

Quote:

Originally Posted by MDORPHN

You're crazy. You do not lose power from reducing backpressure in a turbocharged system.

Neil

+1

fmagz91 · 12-13-2011, 04:10 PM

guys, im not soo much of a noob, know how it works which is why i mentioned "assumed" in the post.. if i could run open dps i would! but i was asking this for people who know more than me about the n54 exhaust sys.. they are the same size pipes i was watching him weld.. my theory was that since theres so much flow the stock muffler cant handle it on a high map and it backs it up resulting in a power loss.. i noticed good gains on the stock map vs with the cats on the stock map but when i switched it up to high boost i was almost dissapointed.. im going to do some more runs soon and doube check.. my car likes to choose the days she wants to perform so.. and using the n55 dp would be interesting, id like to look into the sizes and such.. but thanks for the feedback guys

fmagz91 · 12-13-2011, 04:11 PM

midpipe**

NihonX · 12-14-2011, 02:46 AM

You might 'feel' a loss of low-end torque, but the high-end horsepower will sure be there.

Dackelone · 12-14-2011, 07:27 AM

Quote:

Originally Posted by fmagz91

... my car likes to choose the days she wants to perform so.. and using the n55 dp would be interesting, id like to look into the sizes and such.. but thanks for the feedback guys

I just measured my N55 mid pipes. The O.D. is 58mm to 60mm depending on where you measure. Maybe you can measure your custom mids.

fmagz91 · 12-15-2011, 01:53 AM

ahh, i did some more runs today.. its just not the same.. its deff slower on higher boost levels. i'm just gunna get rid of that muffler

Papethova · 12-15-2011, 12:57 PM

I definitely gained power by deleting the 2ary cats and the resonator from the mid pipe. Disclaimer... it was on the 135, the M mods are still pending

fmagz91 · 12-19-2011, 08:52 PM

Quote:

Originally Posted by Papethova

I definitely gained power by deleting the 2ary cats and the resonator from the mid pipe. Disclaimer... it was on the 135, the M mods are still pending

yea, you might have gained some power but i did it the wrong way.. wen i first did the dps with cat deletes and the rest stock it was perfect.. i got bored and took the mid pipe cats out and it was too much flow for the stock muffler which robbed me of power on higher boost levels.. now i fixed the solution= straight pipes with a resi.. sounds ridiculously loud when cold but its not so bad once its warm.. and the gains are crazy..

RaihaX · 12-19-2011, 09:07 PM

i swap my midpipes with resonated midpipes and my butt dyno says it has gain power.

fmagz91 · 12-24-2011, 06:42 PM

Quote:

Originally Posted by RaihaX

i swap my midpipes with resonated midpipes and my butt dyno says it has gain power.

nice car btw, and your stock mids, were they catted and resonated to begin with?

RaihaX · 12-24-2011, 10:04 PM

Quote:

Originally Posted by fmagz91

nice car btw, and your stock mids, were they catted and resonated to begin with?

Yeah they are, n54 midpipes have cats and resonator.

12-13-2011, 02:13 PM	#1
fmagz91 New Member 2 Rep 9 Posts Drives: 2010 135i, 2005 325ci Join Date: May 2010 Location: New York iTrader: (0)	Cat delete power loss?? A month ago i installed ar catless dps which was a pain in the ass.. but worth the power gains.. yesterday i got bored and went to my local welder and took the 2 remaining cats out assuming better flow=more power.. i still got the stock muffler and resi... So bottom line i almost feel like i lost power by deleting the last 2 cats. is this possible or am i just crazy?
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12-13-2011, 02:48 PM	#3
Dackelone European Editor 10528 Rep 22,992 Posts Drives: N54 e82 Join Date: Feb 2010 Location: Bayern, Germany iTrader: (1)	Did the muffler shop use the same OE size dia pipes? Or maybe smaler ones? It might be better to just get a N55 mid pipe. ?
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12-13-2011, 02:55 PM	#4
ESC OFF Major 40 Rep 1,058 Posts Drives: 1M, CaymanS, 914, 500 Abarth Join Date: Oct 2009 Location: Chicago iTrader: (0)	Neil is correct ^^^ I was wondering the same until I did some research, Downstream of the turbine you want the least backpressure possible. The general rule of larger is better of turboback exhausts is true. If you minimize the pressure downstream of the turbine you will make the most effective use of the pressure that is being generated upstream of the turbine. __________________ The faster you go, the better it feels
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12-13-2011, 04:10 PM	#6
fmagz91 New Member 2 Rep 9 Posts Drives: 2010 135i, 2005 325ci Join Date: May 2010 Location: New York iTrader: (0)	guys, im not soo much of a noob, know how it works which is why i mentioned "assumed" in the post.. if i could run open dps i would! but i was asking this for people who know more than me about the n54 exhaust sys.. they are the same size pipes i was watching him weld.. my theory was that since theres so much flow the stock muffler cant handle it on a high map and it backs it up resulting in a power loss.. i noticed good gains on the stock map vs with the cats on the stock map but when i switched it up to high boost i was almost dissapointed.. im going to do some more runs soon and doube check.. my car likes to choose the days she wants to perform so.. and using the n55 dp would be interesting, id like to look into the sizes and such.. but thanks for the feedback guys
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12-13-2011, 04:11 PM	#7
fmagz91 New Member 2 Rep 9 Posts Drives: 2010 135i, 2005 325ci Join Date: May 2010 Location: New York iTrader: (0)	midpipe**
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12-14-2011, 02:46 AM	#8
NihonX Captain 63 Rep 901 Posts Drives: 2011 VO 1M Join Date: Sep 2008 Location: Antioch iTrader: (8)	You might 'feel' a loss of low-end torque, but the high-end horsepower will sure be there. __________________ 2011 VO 1M
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12-15-2011, 01:53 AM	#10
fmagz91 New Member 2 Rep 9 Posts Drives: 2010 135i, 2005 325ci Join Date: May 2010 Location: New York iTrader: (0)	ahh, i did some more runs today.. its just not the same.. its deff slower on higher boost levels. i'm just gunna get rid of that muffler
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12-15-2011, 12:57 PM	#11
Papethova Banned 224 Rep 3,094 Posts Drives: '08 135/ '11 1M Join Date: Oct 2007 Location: at Death Valley 127 iTrader: (1)	I definitely gained power by deleting the 2ary cats and the resonator from the mid pipe. Disclaimer... it was on the 135, the M mods are still pending
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12-19-2011, 09:07 PM	#13
RaihaX Major General 156 Rep 4,995 Posts Drives: 08' 135i Join Date: Aug 2008 Location: Australia, Perth iTrader: (2)	i swap my midpipes with resonated midpipes and my butt dyno says it has gain power.
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