Exhaust Advice...
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From: Southern California
H & X Pipes
The H-Pipe really plays very little in terms of performance- nor does it reduce backpressure in any way- it was originally introduced to equalize the pressure between the two pipes, inducing a scavenging effect, but in reality, while it did improve some things a little, all it really, the only thing it really was effective at was to reduce noise- nothing more.
An X-pipe will increase HP if it is installed at the "area of confusion"- but that area is identified by painting a small strip on the exhaust pipes about 1/2 way between the engine and the axle- the area of confusion will cause increased heat and blister/burn the paint at that location- that's where the H or X pipe would be installed- and eliminates the air flow disturbance by sending alternating pulses in that location which acts as a "vacuum" if you will to push & scavenge the remaining and incoming air out.
Muffler info.......
broaderperformance.com/muffler_flow_tests.htm (Independently tested cfm flows of the more popular mufflers, glasspacks and resonators @ 15” wc:
2 ½” diameter straight pipe 521
2 ¼” diameter straight pipe 365
2” diameter straight pipe 283
2 ¼” diameter tailpipe 268
2 ¼” round glasspack- no louvers 274
2 ¼” round glasspack- with inward punched louvers 133
2 ¼” round glasspack- inward punched louvers/installed backwards 141
2 ½” inlet/outlet Dynomax SuperTurbo 268
2 1/4” inlet/outlet Thrush CVX 260
2 ½” inlet/outlet Flowmaster 2-chamber 249
2 ¼” inlet/2 ½”outlet Cherry Bomb turbo 249
2 ¼” inlet/outlet Flowmaster 3-chamber 229
2 ¼” inlet/2 ½”outlet Maremount Super C (OEM Replacement) 149
2 ¼” inlet/2” dual outlet Maremount 183
2 ¼” inlet/outlet California Turbo 229
2 ½” inlet/outlet Hooker Aerochamber 324
2 ½” inlet/outlet Hooker MaxFlow 521
2 ¼” inlet/outlet Maremount Cherrybomb Vortex 298
2 ½” inlet center/outlet offset Borla Turbo 373
I have listed here a muffler shootout test done by CAR CRAFT:
The Mufflers
MAKE MODEL Part No. COST
SUMMIT Turbo 630125
THRUSH Magnum Glasspack 24214
THRUSH Boss Turbo 17718
HOOKER Competition 21006
DYNOMAX Super Turbo 17733
DYNOMAX Race Magnum 24215
HOOKER Super Competition 21106
SUMMIT Fully Welded 630325
FLOWTECH Afterburner 50322
MUFFLER FLOW TEST
MUFFLER Flow at 28-in H20
DynoMax Race Magnum 528.64 cfm
Thrush Magnum Glasspack 507.40 cfm
Summit Fully Welded 343.38 cfm
Flowtech Afterburner 342.20 cfm
DynoMax Super Turbo 333.94 cfm
Hooker Competition 232.46 cfm
Hooker Super Competition 320.96 cfm
Summit Turbo 331.16 cfm
Thrush Boss Turbo 297.36 cfm
MUFFLER Idle dB WOT dB
DynoMax Super Turbo 89 123
DynoMax Race Magnum 94 133
Flowtech Afterburner 92 124
Hooker Competion 92 122
Hooker Super Competion 90 125
Summit Turbo 89 124
Summit Fully Welded 92 125
Thrush Boss Turbo 90 123
Thrush Magnum Glasspack 92 128
DYNO TEST
All mufflers were dyno-tested on a 355-cube SBC with 10.0:1 compression, Air Flow Research 190 aluminum heads, a CompCams 292 hyd. a Victor Jr. intake, a Holley 750-cfm double-pumper, and 1 5/8 Headman headers.
MUFFLER HP TORQUE 2,500-6,000rpmAverage
Hooker Competition 397.4 381.1 286.8hp/351.9 lb-ft
Thrush Boss Turbo 407.1 384.9 292.1 hp/357.5 lb-ft
DynoMax Race Magnum 409.5 394.3 298.8 hp/366.9 lb-ft
Flowtech Afterburner 409.7 391.2 294.8 hp/361.7 lb-ft
Thrush Glasspack 409.5 389.8 297.7 hp/365.3 lb-ft
Summit Turbo 411.5 386.3 291.5 hp/357.4 lb-ft
DynoMax Super Turbo 412.7 387.2 292.6 hp/358.6 lb-ft
Hooker Super Comp 413.8 387.2 292.8 hp/359.0 lb-ft
Summit Fully Welded 415.4 390.7 295.6 hp/362.4 lb-ft
While there are mufflers that will out flow a glass pack design, it also depends on the design. Does the glasspack use "louvers or perforations" - Louvers reduce the flow by as much as 50% but Allied resonators (that sell for $40) each and available at any muffler shop) in independent test flowed 90%+ of a "race spec muffler". Others using other brands consistently showed similar results.
The H-Pipe really plays very little in terms of performance- nor does it reduce backpressure in any way- it was originally introduced to equalize the pressure between the two pipes, inducing a scavenging effect, but in reality, while it did improve some things a little, all it really, the only thing it really was effective at was to reduce noise- nothing more.
An X-pipe will increase HP if it is installed at the "area of confusion"- but that area is identified by painting a small strip on the exhaust pipes about 1/2 way between the engine and the axle- the area of confusion will cause increased heat and blister/burn the paint at that location- that's where the H or X pipe would be installed- and eliminates the air flow disturbance by sending alternating pulses in that location which acts as a "vacuum" if you will to push & scavenge the remaining and incoming air out.
Muffler info.......
broaderperformance.com/muffler_flow_tests.htm (Independently tested cfm flows of the more popular mufflers, glasspacks and resonators @ 15” wc:
2 ½” diameter straight pipe 521
2 ¼” diameter straight pipe 365
2” diameter straight pipe 283
2 ¼” diameter tailpipe 268
2 ¼” round glasspack- no louvers 274
2 ¼” round glasspack- with inward punched louvers 133
2 ¼” round glasspack- inward punched louvers/installed backwards 141
2 ½” inlet/outlet Dynomax SuperTurbo 268
2 1/4” inlet/outlet Thrush CVX 260
2 ½” inlet/outlet Flowmaster 2-chamber 249
2 ¼” inlet/2 ½”outlet Cherry Bomb turbo 249
2 ¼” inlet/outlet Flowmaster 3-chamber 229
2 ¼” inlet/2 ½”outlet Maremount Super C (OEM Replacement) 149
2 ¼” inlet/2” dual outlet Maremount 183
2 ¼” inlet/outlet California Turbo 229
2 ½” inlet/outlet Hooker Aerochamber 324
2 ½” inlet/outlet Hooker MaxFlow 521
2 ¼” inlet/outlet Maremount Cherrybomb Vortex 298
2 ½” inlet center/outlet offset Borla Turbo 373
I have listed here a muffler shootout test done by CAR CRAFT:
The Mufflers
MAKE MODEL Part No. COST
SUMMIT Turbo 630125
THRUSH Magnum Glasspack 24214
THRUSH Boss Turbo 17718
HOOKER Competition 21006
DYNOMAX Super Turbo 17733
DYNOMAX Race Magnum 24215
HOOKER Super Competition 21106
SUMMIT Fully Welded 630325
FLOWTECH Afterburner 50322
MUFFLER FLOW TEST
MUFFLER Flow at 28-in H20
DynoMax Race Magnum 528.64 cfm
Thrush Magnum Glasspack 507.40 cfm
Summit Fully Welded 343.38 cfm
Flowtech Afterburner 342.20 cfm
DynoMax Super Turbo 333.94 cfm
Hooker Competition 232.46 cfm
Hooker Super Competition 320.96 cfm
Summit Turbo 331.16 cfm
Thrush Boss Turbo 297.36 cfm
MUFFLER Idle dB WOT dB
DynoMax Super Turbo 89 123
DynoMax Race Magnum 94 133
Flowtech Afterburner 92 124
Hooker Competion 92 122
Hooker Super Competion 90 125
Summit Turbo 89 124
Summit Fully Welded 92 125
Thrush Boss Turbo 90 123
Thrush Magnum Glasspack 92 128
DYNO TEST
All mufflers were dyno-tested on a 355-cube SBC with 10.0:1 compression, Air Flow Research 190 aluminum heads, a CompCams 292 hyd. a Victor Jr. intake, a Holley 750-cfm double-pumper, and 1 5/8 Headman headers.
MUFFLER HP TORQUE 2,500-6,000rpmAverage
Hooker Competition 397.4 381.1 286.8hp/351.9 lb-ft
Thrush Boss Turbo 407.1 384.9 292.1 hp/357.5 lb-ft
DynoMax Race Magnum 409.5 394.3 298.8 hp/366.9 lb-ft
Flowtech Afterburner 409.7 391.2 294.8 hp/361.7 lb-ft
Thrush Glasspack 409.5 389.8 297.7 hp/365.3 lb-ft
Summit Turbo 411.5 386.3 291.5 hp/357.4 lb-ft
DynoMax Super Turbo 412.7 387.2 292.6 hp/358.6 lb-ft
Hooker Super Comp 413.8 387.2 292.8 hp/359.0 lb-ft
Summit Fully Welded 415.4 390.7 295.6 hp/362.4 lb-ft
While there are mufflers that will out flow a glass pack design, it also depends on the design. Does the glasspack use "louvers or perforations" - Louvers reduce the flow by as much as 50% but Allied resonators (that sell for $40) each and available at any muffler shop) in independent test flowed 90%+ of a "race spec muffler". Others using other brands consistently showed similar results.
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