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Re: 340 exhaust worth the extra $$$$?
[Re: migsBIG]
#141784
10/26/08 07:19 PM
10/26/08 07:19 PM
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Joined: Jan 2003
Posts: 152
Worcester, Mass
68goldfish
member
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member
Joined: Jan 2003
Posts: 152
Worcester, Mass
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Yes, spend the money. One thing people tend to forget is the massive amount of heat that headers give off for a small gain in HP. Cast iron will help control noise and heat under the hood.The 68-70 cast iron flow close to what a header will give.
Last edited by 68goldfish; 10/26/08 07:27 PM.
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Re: 340 exhaust worth the extra $$$$?
[Re: 68goldfish]
#141787
10/27/08 11:14 PM
10/27/08 11:14 PM
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Joined: Apr 2008
Posts: 1,195
Snowing in the north!
Dart 340
moparts member
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moparts member
Joined: Apr 2008
Posts: 1,195
Snowing in the north!
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Quote:
Yes, spend the money. One thing people tend to forget is the massive amount of heat that headers give off for a small gain in HP. Cast iron will help control noise and heat under the hood.The 68-70 cast iron flow close to what a header will give.
Wrap the headers and you will take care of the heat.
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Re: 340 exhaust worth the extra $$$$?
[Re: Dart 340]
#141789
10/28/08 07:44 AM
10/28/08 07:44 AM
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Joined: Jan 2003
Posts: 7,978
Bethel Ct
AdamR
master
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master
Joined: Jan 2003
Posts: 7,978
Bethel Ct
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Quote:
Quote:
Yes, spend the money. One thing people tend to forget is the massive amount of heat that headers give off for a small gain in HP. Cast iron will help control noise and heat under the hood.The 68-70 cast iron flow close to what a header will give.
Wrap the headers and you will take care of the heat.
The wrap will hold moisture and rot the pipes though. Having the headers coated in and out is a better idea.
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Re: 340 exhaust worth the extra $$$$?
[Re: AdamR]
#141790
10/28/08 07:50 AM
10/28/08 07:50 AM
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Anonymous
Unregistered
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Anonymous
Unregistered
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the higher the hp potential of the motor, the bigger the gains you'll see going to the headers
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Re: 340 exhaust worth the extra $$$$?
[Re: Get-X]
#141792
10/28/08 11:36 AM
10/28/08 11:36 AM
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Anonymous
Unregistered
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Anonymous
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Quote:
Quote:
This should help.
on a 300hp 360 magnum there was 4hp and 6ftlbs of torque difference between the 318 manifolds and the early 340 manifolds.
There was 11hp and 16ftlbs difference between the 340 manifolds and a set of TTIs.
Thats with a very mild cam that I believe has a wide lsa.
The more power the motor makes the igger the difference you will see between the hp manifolds and headers.
That said Im still considering running manifolds on my next motor.
Which 318 manifolds? The good magnums or a set off of a 72 318 2bbl motor? The early magnum manifolds are very good and are comparable to the early 340s where as the non-magnum 318 manifolds are no where close.
They were 1969 318 manifolds. They also tested 1977 360 manifolds.
http://www.moparmusclemagazine.com/techarticles/155_0307_mopar_crate_engine_exhaust/photo_17.html
The difference between the 69 318 manifolds and the good 340 manifolds was only 4 hp at peak, but the 340 manifolds were 7 hp stronger at 4000 rpm, 5 hp stronger at 5000, and 8 hp stronger at 5400 - despite the motor being almost 1000 rpms above its 4500 rpm power peak.
Draw your own conclusions about how well the old 318 manifolds would work on a higher revving engine . . . .
(That said, the 77 360 manifolds looked pretty good.)
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Re: 340 exhaust worth the extra $$$$?
#141793
10/28/08 11:42 AM
10/28/08 11:42 AM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
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Quote:
Quote:
Quote:
This should help.
on a 300hp 360 magnum there was 4hp and 6ftlbs of torque difference between the 318 manifolds and the early 340 manifolds.
There was 11hp and 16ftlbs difference between the 340 manifolds and a set of TTIs.
Thats with a very mild cam that I believe has a wide lsa.
The more power the motor makes the igger the difference you will see between the hp manifolds and headers.
That said Im still considering running manifolds on my next motor.
Which 318 manifolds? The good magnums or a set off of a 72 318 2bbl motor? The early magnum manifolds are very good and are comparable to the early 340s where as the non-magnum 318 manifolds are no where close.
They were 1969 318 manifolds. They also tested 1977 360 manifolds.
http://www.moparmusclemagazine.com/techarticles/155_0307_mopar_crate_engine_exhaust/photo_17.html
The difference between the 69 318 manifolds and the good 340 manifolds was only 4 hp at peak, but the 340 manifolds were 7 hp stronger at 4000 rpm, 5 hp stronger at 5000, and 8 hp stronger at 5400 - despite the motor being almost 1000 rpms above its 4500 rpm power peak.
Draw your own conclusions about how well the old 318 manifolds would work on a higher revving engine . . . .
(That said, the 77 360 manifolds looked pretty good.)
Better check out your dyno if you got those small port, small log manifold to flow up that close to the early 340 manifolds because they sure don't show it in the real world. Another reason I don't put much faith in dyno testing.
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Re: 340 exhaust worth the extra $$$$?
[Re: MoparforLife]
#141794
10/28/08 11:54 AM
10/28/08 11:54 AM
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Anonymous
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Anonymous
Unregistered
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Better check out your dyno if you got those small port, small log manifold to flow up that close to the early 340 manifolds because they sure don't show it in the real world. Another reason I don't put much faith in dyno testing.
Hey - it ain't my dyno, and I've posted a number of times that I don't have much faith in this particular test, as I've said just about every time it has been cited (and it's come up again and again).
Just pointing out factors to consider even if you accept the validity of one test of one motor. 
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Re: 340 exhaust worth the extra $$$$?
#141795
10/28/08 12:02 PM
10/28/08 12:02 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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I knew of a SB abody that was in the 12's with them(68-70 HP manifolds). They are pricey. visually comparing them to the 318 logs they gotta be quite a bit better .
live every 24 hour block of time like it's your last day on earth
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Re: 340 exhaust worth the extra $$$$?
[Re: RapidRobert]
#141796
10/28/08 03:12 PM
10/28/08 03:12 PM
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Joined: Feb 2003
Posts: 4,204
Fort Worth, TX
Clair_Davis
master
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master
Joined: Feb 2003
Posts: 4,204
Fort Worth, TX
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I'd be willing to bet someone else's money that the pinch on the DS 340 manifold is smaller than the outlet on the 318 turd manifolds, so regardless of how nice they look, they're really no better than any other log. I wish MM, MA, or some other magazine would run a drag test as well, and maybe plug in a WBO2 sensor to get some additional data. Personally, I think the MM test is a very good indicator of the way things work, regardless of whether it's EXACTLY right or not.
A concern I have is how the various manifolds affected the mixture on the test engine. I don't know if the mix was optimized for each change, which is how anybody really tuning a combo would do things. How many times have we heard about folks bolting on headers and slowing down? Most likely it's due to the new better flowing combo running leaner than the old restrictive combo.
It's also a good point to see the whole power curve, not just peak numbers. A combo that puts more power under the curve will be faster than one with a higher peak but less under the curve.
Clair
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Re: 340 exhaust worth the extra $$$$?
[Re: Clair_Davis]
#141797
10/28/08 03:53 PM
10/28/08 03:53 PM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
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Quote:
I'd be willing to bet someone else's money that the pinch on the DS 340 manifold is smaller than the outlet on the 318 turd manifolds, so regardless of how nice they look, they're really no better than any other log. I wish MM, MA, or some other magazine would run a drag test as well, and maybe plug in a WBO2 sensor to get some additional data. Personally, I think the MM test is a very good indicator of the way things work, regardless of whether it's EXACTLY right or not.
A concern I have is how the various manifolds affected the mixture on the test engine. I don't know if the mix was optimized for each change, which is how anybody really tuning a combo would do things. How many times have we heard about folks bolting on headers and slowing down? Most likely it's due to the new better flowing combo running leaner than the old restrictive combo.
It's also a good point to see the whole power curve, not just peak numbers. A combo that puts more power under the curve will be faster than one with a higher peak but less under the curve.
Clair
Evidently never rally looked at or compared them in a real world application. Are they worth it at teh price collectors are willing to pay for them? IMO - no not when you can get a new style magnum manifold that will perform just short of as well for a lot less $$$.
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Re: 340 exhaust worth the extra $$$$?
[Re: RapidRobert]
#141799
10/28/08 08:54 PM
10/28/08 08:54 PM
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Joined: Jan 2003
Posts: 7,978
Bethel Ct
AdamR
master
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master
Joined: Jan 2003
Posts: 7,978
Bethel Ct
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Quote:
I knew of a SB abody that was in the 12's with them(68-70 HP manifolds). They are pricey. visually comparing them to the 318 logs they gotta be quite a bit better .
Theres guys running the FAST series in the 11s with the 71 style 340 manifolds (center dump passenger side)that doesnt mean they wouldnt pick up a bunch of power switching to headers.
Take a look at a set of 71 340 manifolds and then a set of early 318 manifolds.
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but that's up to you 
