Re: Open Headers versus Mufflers
[Re: GTXMEX]
#3096718
11/24/22 01:37 AM
11/24/22 01:37 AM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
master
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master
Joined: Sep 2014
Posts: 4,457
Washington
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Not if the collectors are the correct length.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: Open Headers versus Mufflers
[Re: GTXMEX]
#3096761
11/24/22 10:48 AM
11/24/22 10:48 AM
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Joined: Jan 2003
Posts: 12,301 Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,301
Benton, IL.
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Exhaust choices can have a significant impact on power. I use electric cut-outs so that I can concentrate on the tone and amount of the exhaust that I hear. Loud, quiet, X pipe, H pipe, straight through, baffled, 2 1/2", 3", 3 1/2" , brand X, brand Y, or brand Z don't have much, if any, impact on power with cut-outs. Get the right collector length with cut-outs and most of the other issues guys struggle with when it comes to the exhaust are mute. www.youtube.com/watch?v=eLceqIoTMvowww.youtube.com/watch?v=_PVXvHkr-VsThere are many, many more muffler/exhaust shoot-outs/tests on the 'tube.
Master, again and still
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Re: Open Headers versus Mufflers
[Re: Locomotion]
#3096887
11/24/22 05:58 PM
11/24/22 05:58 PM
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Joined: Sep 2003
Posts: 19,641 north of coder
moparx
"Butt Crack Bob"
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"Butt Crack Bob"
Joined: Sep 2003
Posts: 19,641
north of coder
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just now going from 3 1/2" collectors, 3" long, to a 10" extension [3 1/2"] reduced to a 3" x pipe to 3" race bullets. 446, 11 : 1 [measured compression] slightly worked RPM heads, RPM dual plane intake, big thermo-quad [? !!], 2" to 2 1/8" step TTI headers. [with the above mentioned 3 1/2" collectors] i have a vast selection of jets and metering rods for the thermo-quad, so i should be able to get a good tune on it.
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Re: Open Headers versus Mufflers
[Re: GTXMEX]
#3096904
11/24/22 07:47 PM
11/24/22 07:47 PM
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Joined: Oct 2007
Posts: 4,213 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,213
New York
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An engine with a large enough overlap triangle area* (from Vizard: OL area ~ OL Degrees^2) to benefit significantly from tuned exhaust will experience less pressure differential to the chamber with any disturbance to the exhaust return wave (diametric change, more volume, restriction).
Very mild engines may not notice any change.
* For OL area comparison using nominal valve events (IO @ BTDC + XC @ ATDC), 70 degrees is not 40% greater area than 50 degrees (70 / 50), but 70^2 / 50^2, or 96% greater (4,900 / 2,500).
Boffin Emeritus
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Re: Open Headers versus Mufflers
[Re: mgoblue9798]
#3097134
11/25/22 08:54 PM
11/25/22 08:54 PM
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Joined: Jan 2003
Posts: 12,301 Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,301
Benton, IL.
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Like the links I posted above.
Master, again and still
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Re: Open Headers versus Mufflers
[Re: GTXMEX]
#3097179
11/26/22 03:11 AM
11/26/22 03:11 AM
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Joined: May 2019
Posts: 714 Lake Villa Il
INTMD8
super stock
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super stock
Joined: May 2019
Posts: 714
Lake Villa Il
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Do these numbers and curves seem reasonable in the way mufflers are affecting power?
No. Mufflers gain 100ft/lbs 3500-4000? And then lose 80hp 60ft/lbs at 7000? Hell no. As madscientist stated, no real comparison unless you have the right collector length. Still... Said in a different way, I think you can build an exhaust system to the bumper that performs closely to open headers/optimized collector with then the only downside weight. I use pypes race flow mufflers. Despite the name they are very quiet and straight through. Made 595 rwhp @7200 through those mufflers, tailpipes (dual 3") and stock exit size tips. I think it will be 610-620rwhp after a few changes I've made. Can certainly test it but don't think there would be more than a -couple- of HP difference between the exhaust I'm running VS dropped before mufflers/tailpipes. For the wheel hp levels originally posted, dual 2.5" would efficiently cover it, and those pipes would dictate velocity. At that point, -no- muffler is picking up 100ft/lbs. And no muffler is -losing- 80hp to open headers unless total junk. So, choose exhaust pipe size to be capable of supporting max HP and pair it with a straight through/non restrictive muffler (like the race flow) and I think you've done your best.
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Open Headers versus Mufflers
[Re: INTMD8]
#3097188
11/26/22 07:34 AM
11/26/22 07:34 AM
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Joined: Oct 2015
Posts: 570 UK
rb446
mopar
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mopar
Joined: Oct 2015
Posts: 570
UK
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I don't know the exact mufflers (they are big) that are on the 589ci wedge RR I crewed on but its a full 3" system to the bumper. Has 2.1/8" TTI step hdrs with 4" collector.
Engine dyno'd@694.2hp@5500, 693@5900, same carb dyno to track, car weighs 3800@line and has been a best of 130mph on a no headwind day.
Thats 679fwhp and shows a 10.34 with a 1.44 60, cars gone 10.30@1.421 60.best. Never been run on open hdrs. Perhaps the dyno was a bit stingy?
1969 'Cuda 446ci, best 9.96@133.9 in 1990 1971 340 'Cuda, best 11.01@122.8 in 1987
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Re: Open Headers versus Mufflers
[Re: GTXMEX]
#3097195
11/26/22 08:59 AM
11/26/22 08:59 AM
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Joined: Jan 2003
Posts: 2,937 A shed in England
Tig
master
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master
Joined: Jan 2003
Posts: 2,937
A shed in England
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My 2 penneth. We have a 120db max sound level for 9.00 cars / classes and slower. They are regularly checked at race meeting but there no sound level in place at a RWYB's . I ran a true dual (no H or X) 4" system with bullet muffler to the axle with turn downs. No noticeable effect on ET or MPH, db dropped from 124.9 (open headers) to 120.4 close enough for the tech guys to pass. I later made an X pipe using the same 4" dyno max mufflers, again no noticeable effect on ET or MPH db dropped to 119.8 when tested. I've since welded V clamps to the pipes to make swapping stuff out easy, we've ran with the x pipe but no mufflers, again no noticeable effect on ET or MPH. I've yet to be tested for sound level in this configuration but to the ear it is a little louder. For the street we have a pair of old super trapps which are v clamped on to the end of the bullet mufflers in place of the turn downs. Never ran on the strip with these, I'm guessing they woukd really hurt the performance. Last time I ran with just open headers, I burnt all the candy paint off the trans crossmember
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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