Floored Fab Long Tubes: INSTALLED
10-11-2011, 08:19 PM
#26
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E55, CTS-V Wagon, Duc 1098R
Chiromikey - Sounds like you have tried it. Where did you see the torque loss and did you gain it back later in the power band? I'm ok with loosing some down low to get it back up high. I would absolutely get a tune to match as well.
don't remove the cats unless you have a tune to go with it. it's the only way to bring back enough hp to mitigate the more prominent tq loss.
btw, even with all cats removed, the sound is still quite tame going into e55 mufflers. remove some matting from the mufflers and it sounds really good...but even with that, you'll feel the tq loss!
btw, even with all cats removed, the sound is still quite tame going into e55 mufflers. remove some matting from the mufflers and it sounds really good...but even with that, you'll feel the tq loss!
10-11-2011, 08:49 PM
#27
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the tq loss is quite noticeable, even on fully modded cars. the loss is through the bottom and mid range and you will not gain enough top end hp through a 1/4mile run to justify the missing tq without a tune. with a tune i was able to gain a little overall top end hp and return most of the tq so at that point it became worth it.
10-11-2011, 09:17 PM
#28
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Wow, thanks for sharing! I'm interested in power under the curve between shift points. Sounds like you ultimately saw gains. Would you mind sharing how much?
THANKS AGAIN!
THANKS AGAIN!
yep, tried it all with dyno runs and track time to back up my own impressions.
the tq loss is quite noticeable, even on fully modded cars. the loss is through the bottom and mid range and you will not gain enough top end hp through a 1/4mile run to justify the missing tq without a tune. with a tune i was able to gain a little overall top end hp and return most of the tq so at that point it became worth it.
the tq loss is quite noticeable, even on fully modded cars. the loss is through the bottom and mid range and you will not gain enough top end hp through a 1/4mile run to justify the missing tq without a tune. with a tune i was able to gain a little overall top end hp and return most of the tq so at that point it became worth it.
10-11-2011, 09:57 PM
#29
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after tuning i got back all but about 5rwtq throughout the curve and gained about 12-15rwhp up top.
i haven't been to the track or dyno since i partially gutted my mufflers but judging by those impressions i'd say i'm down 15rwtq without a tune. been thinking about putting in a small restrictor until i can get on the dyno...
Last edited by chiromikey; 10-11-2011 at 10:00 PM.
10-11-2011, 11:06 PM
#30
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Thanks again for the info. I didn't expect it to see that much of a decline and happy to see an improvement in the end.
this was a while ago but iirc, after removing 200cell cats (i have no primary cats and no resonator) initially i lost about .1+ in the 1/4 with zero gain in mph. took it to the dyno and found out i was down about 25rwtq throughout most of the curve and peak hp was relatively unchanged.
after tuning i got back all but about 5rwtq throughout the curve and gained about 12-15rwhp up top.
i haven't been to the track or dyno since i partially gutted my mufflers but judging by those impressions i'd say i'm down 15rwtq without a tune. been thinking about putting in a small restrictor until i can get on the dyno...
after tuning i got back all but about 5rwtq throughout the curve and gained about 12-15rwhp up top.
i haven't been to the track or dyno since i partially gutted my mufflers but judging by those impressions i'd say i'm down 15rwtq without a tune. been thinking about putting in a small restrictor until i can get on the dyno...
10-12-2011, 12:19 PM
#31
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After reading this thread im a bit confused. I have a set of EC longtubes coming and was planning on having my exhaust shop fab a some 3 inch straight midpipes deleting the 2nd cats. Should I keep my secondary cats in place and just have a the midpipe to the 2nd cats? I dont have emissions testing but I would like to keep the car civilized and avoid the gasy smell that sometimes comes with catless cars.
10-12-2011, 12:27 PM
#32
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2nd cats are no problem. Your plans sounds like a good system but remember that the collector on the headers is 2.5" so I'm not sure how advantageous a 3" mid pipe would be. I was talking about the 200 cell primary cats that come with the full system and bolt after the x-pipe.
10-12-2011, 12:38 PM
#33
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The loss of back pressure will lose some TRQ (and boost), but with a proper tune, you can get most back, and pick up a good amout of HP. Catless is (IMO) the way to go if you live in a non-emmisions state. Tune is the key
ALSO- Collector size can reduce the loss of torque which is why the FF have a 2.5". EC are 3". As Chiromikey mentioned, a reducer can also be used. Goal is to provide positive pressure back to the exhaust ports to maintain the torque. I would prefer to emiminate as much back pressure as is realistic, and tune the car for that set up.
ALSO- Collector size can reduce the loss of torque which is why the FF have a 2.5". EC are 3". As Chiromikey mentioned, a reducer can also be used. Goal is to provide positive pressure back to the exhaust ports to maintain the torque. I would prefer to emiminate as much back pressure as is realistic, and tune the car for that set up.
