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Re: Exhaust size
[Re: 70charger512]
#2561538
10/09/18 06:47 PM
10/09/18 06:47 PM
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Joined: Nov 2003
Posts: 5,160
Texas
dannysbee
master
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master
Joined: Nov 2003
Posts: 5,160
Texas
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For a street car I like 3" from the headers to the mufflers and 2.5 tailpipes. It will flow nearly as good as a full 3" system but will not be nearly as obnoxious.
Getting old just means you were smarter than some and luckier than others.
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Re: Exhaust size
[Re: CMcAllister]
#2561552
10/09/18 07:16 PM
10/09/18 07:16 PM
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Joined: Dec 2013
Posts: 4,687
Wichita
GY3
master
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master
Joined: Dec 2013
Posts: 4,687
Wichita
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I run 3" to the rear axle with turndowns. Walker Dynomax Ultraflow. No drone and very quiet in the car until you mash the loud pedal!
'63 Dodge 330
11.19 @ 121 mph
Pump gas, n/a, through the mufflers on street tires with 3.54's. 3,600 lbs.
10.01 @ 133mph with a 250 shot of nitrous an a splash of race gas. 1.36 60 ft. 3,700 lbs.
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Re: Exhaust size
[Re: BcudaChris]
#2561607
10/09/18 09:17 PM
10/09/18 09:17 PM
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Joined: Nov 2010
Posts: 3,696
jersey
Spaceman Spiff
master
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master
Joined: Nov 2010
Posts: 3,696
jersey
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Big block guys will correct me if I'm wrong, but conventional thinking would be 3" and think about 1 7/8" headers for max power. At your displacement/power target, I think the 2.5" would hold you back and with 1 3/4 headers you would be trading high RPM power for low end torque.
What are your goals though? Packaging, cost and weight would be the down sides of bigger tubes. Maybe noise too, depending on your goals. F.A.S.T. Class is restricted to 2 1/2in exhaust. Several of those cars are in the 9's at well over 130mph. I doubt you'd feel any difference between 2.5 and 3 inch. I know on my 526, there was no noticeable gain going to 3 inch. However, going from a 850 and an rpm intake, to a M1 and a "1000" cfm carb, picked up A LOT. Every combination is different. 3 inch WILL make it louder.
526 cubes of angry wedge, pushbutton shifted, 9 passenger killer!
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Re: Exhaust size
[Re: Spaceman Spiff]
#2561628
10/09/18 10:19 PM
10/09/18 10:19 PM
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Joined: Sep 2007
Posts: 1,893
Spahn Ranch
RMCHRGR
top fuel
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top fuel
Joined: Sep 2007
Posts: 1,893
Spahn Ranch
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F.A.S.T. Class is restricted to 2 1/2in exhaust. Several of those cars are in the 9's at well over 130mph. I doubt you'd feel any difference between 2.5 and 3 inch.
I know on my 526, there was no noticeable gain going to 3 inch.
However, going from a 850 and an rpm intake, to a M1 and a "1000" cfm carb, picked up A LOT.
Every combination is different. 3 inch WILL make it louder. Is there a point where you "need" a 3" exhaust? Like, say 600 HP - up? Would a 2.5" exhaust be enough to support that kind of power?
'71 Duster
'72 Challenger
'17 Ram 1500
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Re: Exhaust size
[Re: 70charger512]
#2561657
10/09/18 11:05 PM
10/09/18 11:05 PM
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Joined: Nov 2003
Posts: 5,160
Texas
dannysbee
master
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master
Joined: Nov 2003
Posts: 5,160
Texas
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Prosport' Duster runs mid 10's with a 500' engine and 1 3/4" headers. Tests have proven that you don't need as big pipe after the muffler as the exhaust gasses have cooled and at that point don't need the larger pipe.
Getting old just means you were smarter than some and luckier than others.
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Re: Exhaust size
[Re: dannysbee]
#2561663
10/09/18 11:17 PM
10/09/18 11:17 PM
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Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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For a street car I like 3" from the headers to the mufflers and 2.5 tailpipes. It will flow nearly as good as a full 3" system but will not be nearly as obnoxious. I ran that combination on my Challenger when it was going 11.0s. It was frequently the quieter of two cars going down the track, even when it was the faster car, too. I did upgrade to a full 3" system when the car started going about 1/2 second quicker. However, it's nowhere as subtle from a noise perspective with the bigger pipes.
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Re: Exhaust size
[Re: 70charger512]
#2561665
10/09/18 11:17 PM
10/09/18 11:17 PM
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Joined: Jan 2003
Posts: 17,876
S.E. Michigan
ZIPPY
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 17,876
S.E. Michigan
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From the other post, it seems to me the combination is undercammed, undercarbureted, and has the wrong intake manifold to make 500 real hp.
But if your heart is set on all those parts and there's no ET goal or anything like that, give it a whirl, you may end up liking it just fine and the exact number won't matter as much as feeling happy with it and knowing it's your ideas.
Ignoring all that kind of stuff, 1 7/8 with a 3" collector, 3" headpipes into mufflers/2.5" tailpipes is plenty adequate and gives a little room to grow if you decide to go with more cam and so on later, to satisfy the need for speed.
Mine went 119 with that combination minus tailpipes. And I bet the tailpipes would have just made it quieter inside.
Being a believer in making the exhaust whatever size the collector is has led me to 3.5" exhaust, which I don't actually recommend to anyone. I had fun fabricating it, though, and the car sounds really unique. But like underdrive pulleys, which I also use, I always tell everyone else not to.
Rich H.
Esse Quam Videri
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Re: Exhaust size
[Re: 70charger512]
#2561786
10/10/18 07:30 AM
10/10/18 07:30 AM
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Joined: Jan 2003
Posts: 10,011
Frostbitefalls MN (Rocky&Bullw...
gregsdart
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,011
Frostbitefalls MN (Rocky&Bullw...
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The most overlooked part of the exhaust system are mufflers. It takes 2.2 cfm of flow per hp for a no loss system, and that is part of the equation for zero loss. A 2 cfm per hp system costs you a 2 percent power loss, and the loss goes up fast from there. There is a very good chapter in David Vizards' book How to build Horsepower, new edition. To make the motor act like it has open exhaust, a termination chamber the same cubic inch as the cylinders(for a motor of 446 cubes, 223 cubic inch chamber right after each collector, no reducer, bell shaped exit) then big enough pipes and mufflers to match the power. For mufflers, to get addiquet flow you might have to use a larger entry and exit and reducers to get enough flow, like 3 inch on each end of the muffler, 2.5 inch pipes in and out.
Last edited by gregsdart; 10/10/18 07:31 AM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Exhaust size
[Re: 70charger512]
#2561843
10/10/18 11:35 AM
10/10/18 11:35 AM
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Joined: Jan 2003
Posts: 13,374
Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,374
Marion, South Carolina [><]
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Like I said on the other post, go w/ 3" exhaust and some good mufflers like Dynomax UltraFlow or Hooker Max Flow.
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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Re: Exhaust size
[Re: ZIPPY]
#2561853
10/10/18 11:47 AM
10/10/18 11:47 AM
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Joined: Sep 2018
Posts: 257
NC
70charger512
OP
#1 Thread Starter
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OP
#1 Thread Starter
Joined: Sep 2018
Posts: 257
NC
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From the other post, it seems to me the combination is undercammed, undercarbureted, and has the wrong intake manifold to make 500 real hp.
But if your heart is set on all those parts and there's no ET goal or anything like that, give it a whirl, you may end up liking it just fine and the exact number won't matter as much as feeling happy with it and knowing it's your ideas.
Ignoring all that kind of stuff, 1 7/8 with a 3" collector, 3" headpipes into mufflers/2.5" tailpipes is plenty adequate and gives a little room to grow if you decide to go with more cam and so on later, to satisfy the need for speed.
Mine went 119 with that combination minus tailpipes. And I bet the tailpipes would have just made it quieter inside.
Being a believer in making the exhaust whatever size the collector is has led me to 3.5" exhaust, which I don't actually recommend to anyone. I had fun fabricating it, though, and the car sounds really unique. But like underdrive pulleys, which I also use, I always tell everyone else not to.
500+ to the crank. I based it off a build that made 537, with a very similar cam.
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Re: Exhaust size
[Re: 70charger512]
#2561889
10/10/18 12:49 PM
10/10/18 12:49 PM
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Joined: Jan 2003
Posts: 13,374
Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,374
Marion, South Carolina [><]
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Was this 537 hp build from a magazine?
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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Re: Exhaust size
[Re: an8sec70cuda]
#2562021
10/10/18 04:59 PM
10/10/18 04:59 PM
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Joined: Jan 2003
Posts: 17,876
S.E. Michigan
ZIPPY
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 17,876
S.E. Michigan
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Here is a good example: https://www.hotrod.com/articles/how-you-can-build-a-stout-537hp-street-440/Even Steve Dulcich couldn't make a 537HP 440 without a single plane intake, larger 4150 carburetor, and significantly more aggressive camshaft than the 268/276 grind posted previously. Not saying any of this to be contradictory, in fact I am all for supporting your idea, creating your own combo and trying it....but expectations should probably be managed. I am familiar with the combo. The engine you've described will be very tame and easily able to be driven every day, there is cetainly nothing 'wrong' with it. A buddy/coworker/former team lead ran the same cam and heads + a 6 pack manifold in his challenger, he liked it. But...ol' Pizzino had a bunch more horsepower than you will have, due to his intake manifold/carb choice alone. It was a fun street engine.
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Re: Exhaust size
[Re: ZIPPY]
#2562026
10/10/18 05:06 PM
10/10/18 05:06 PM
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Joined: Jan 2003
Posts: 13,374
Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,374
Marion, South Carolina [><]
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But that was 537 HP on Westech's Dyno.  So closer to 500 hp on an accurate one. Woulda made 600+ on Koffel's.
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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Re: Exhaust size
[Re: 70charger512]
#2562269
10/11/18 01:54 AM
10/11/18 01:54 AM
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Joined: Feb 2003
Posts: 10,219
Someplace you aren't
SomeCarGuy
I Live Here
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I Live Here
Joined: Feb 2003
Posts: 10,219
Someplace you aren't
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Don’t know what that article engine had, but dulcich says to run aluminum heads ootb. Might be a limiting factor in his builds. He actually took a shot at machine shops offering services to clean up new parts.
Seems every head thread shows just a little work can wake up most any head you buy.
I want my fair share
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