3 1/2" collector/x pipe ?
#2694941
09/06/19 11:36 AM
09/06/19 11:36 AM
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Joined: Sep 2003
Posts: 19,307
north of coder
moparx
OP
"Butt Crack Bob"
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OP
"Butt Crack Bob"
Joined: Sep 2003
Posts: 19,307
north of coder
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bracket engine header question. 2"-2 1/8" step TTI's, going into a 3 1/2" collector approximately 3" long. should the collectors be stepped down to 3" and go to the X pipe, or should the pipes stay at 3 1/2" to the X, then step down to 3" and through the mufflers. torque is the quest here. .030 over 440, aluminum RPM heads, 6K shift point, 3.91 gear, tires to be determined. i know this is a question with lots of "it depends on" ???????, but using up stuff that is laying around is what is going on here, so these pipes will be used regardless if they are correct for the combination or not. TIA as always !  
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Re: 3 1/2" collector/x pipe ?
[Re: moparx]
#2694942
09/06/19 11:43 AM
09/06/19 11:43 AM
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Joined: Jan 2003
Posts: 3,830
N.E. Ohio
6bblFLASH
master
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master
Joined: Jan 2003
Posts: 3,830
N.E. Ohio
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On mine it is 3-1/2" to 3" reducer- 3" "X" ,reduced again to 2-1/2" mufflers. Have actually tested exhaust pressure at WOT- less than 1/2 lb. Small blower on a 440,moves quite a bit of volume about 550hp. I doubt you would see much either way,I would pick the smaller of the 2 choices. Torq. is more important than peak HP. unless steep geared screamer...............  I trap at 4,800rpm @ 120 MPH
Last edited by 6bblFLASH; 09/06/19 11:46 AM.
70` Cuda`,440 6BBL Jerico,Dana 4.56 Still on 93 Pump Gas
9.87 @ 136/1.31-60ft.`09 Mopar Nationals PASSON PERFORMANCE "Stick-Shift" Champ!
2013 StickShift Challenge Winner@ Mopar Nationals!
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Re: 3 1/2" collector/x pipe ?
[Re: AndyF]
#2695061
09/06/19 08:18 PM
09/06/19 08:18 PM
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Joined: Oct 2006
Posts: 1,264
New York, USA
Chargerfan68
pro stock
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pro stock
Joined: Oct 2006
Posts: 1,264
New York, USA
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I agree with Andy. I put the 1-7/8” headers with 3” collector dia into 2-1/2” exhaust with an h pipe bcause i drive this car semi- daily and wanted it a little quieter. I ran it at the track with full exhaust, and then dropped the exhaust and bolted on an 18” collector 3” dia. It was .15 sec et difference and 1 mph difference. This is 609 hp and 630 lb/ft tq engine.
I thought the exhaust was gonna rob more power , but it didn’t.
11.70 @ 114.4. Full exhaust
11.55 @ 115.4. Open header
Last edited by Chargerfan68; 09/06/19 08:25 PM.
1.50 60Ft. , 10.75@ 127MPH Hauling 3900 LBS.
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Re: 3 1/2" collector/x pipe ?
[Re: AndyF]
#2695097
09/07/19 12:09 AM
09/07/19 12:09 AM
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Joined: May 2003
Posts: 409
Texas
mprhound
mopar
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mopar
Joined: May 2003
Posts: 409
Texas
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Your headers are way too big for your engine but if that is what you have then use them. You could've used 1 3/4 inch headers on that engine and been fine. You don't even need a 3 inch exhaust with that engine, 2 1/2 will work just fine, even 2 inch would've worked just fine. If you have the room and the parts on hand then go ahead and build whatever fits and works but it is going to be a lot bigger, heavier and louder than what it could've been. I'm in the process of ripping the 3 inch exhaust out of my '65 Coronet and replacing it with 2 1/2 inch since I'm tired of all the extra weight, space and noise. My engine is 600 hp and it doesn't need a full 3 inch exhaust system. Bigger isn't always better......... Andy What formula do you use to determine exhaust size? Or is it a rule of thumb for horsepower and/or cubic inch? For example my motor Dynoed 864 hp? 547 cubic inch I have tti 2 to 2 1/8 step headers 3 1/2 inch collectors and 3 inch h pipe exhaust, I do drag week so et is more important to me, I was considering going to a 3 1/2 inch with x pipe, not worth it?
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Re: 3 1/2" collector/x pipe ?
[Re: AndyF]
#2695185
09/07/19 11:32 AM
09/07/19 11:32 AM
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Joined: Sep 2003
Posts: 19,307
north of coder
moparx
OP
"Butt Crack Bob"
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OP
"Butt Crack Bob"
Joined: Sep 2003
Posts: 19,307
north of coder
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you have a TON more experience than i will ever have on this stuff andy. [i bought ALL your books and have read them several times.  ] this effort is to use up stuff laying around to ease the clutter here. i already know it won't be optimal weight and horsepower wise, but just wondering what will happen torque wise, going with 3" vs 3 1/2" from the collector to the X. THANKS for the responses guys !
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