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Flow Chart Numbers on Exhaust manifolds
#1398361
03/07/13 01:06 AM
03/07/13 01:06 AM
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Joined: Feb 2003
Posts: 16,145
Mesa, Arizona
dart4forte
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I've been listening for years on how the driver side manifold on the big block A bodies was restrictive causing a major effect on HP. Well, my buddy who owns a flowbench decided to put the argument to rest with some old fashion testing. See the attached results.
Looks like the A body driver side manifold fared pretty well
DS AQ Body 383 manifold - @ .500" of lift it flowed 157.4 CFM
PS A Body 383 manifold - @.500" of lift flowed 164.2 CFM
C Body DS magnum manifold - @ .500" of lift flowed 161.2 CFM
The second chart depicts flow numbers from the most restrictive part of each manifold
Sorry about the pics. Couldn't figure how to attach a PDF file
CHART 1
Last edited by dart4forte; 03/07/13 01:34 AM.
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Re: Flow Chart Numbers on Exhaust manifolds
[Re: dart4forte]
#1398368
03/07/13 02:16 PM
03/07/13 02:16 PM
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Joined: Jan 2003
Posts: 75,004
U.S.S.A.
JohnRR
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Quote:
I have a B body manifold but I need to get it cleaned and shot blasted. The closest thing I had at the time was a C body magnum manifold. The passenger side A manifold most likely flows the same as the B body
The A body PS side manifold is a little different in the rise just behind the # 6 outlet to clear the inner fender I assume , not sure if it is a restriction. If I ever get around to getting my 383 on the dyno I'm going to run the A body and B body manifolds on it as a comparison.
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Re: Flow Chart Numbers on Exhaust manifolds
[Re: JohnRR]
#1398369
03/07/13 04:18 PM
03/07/13 04:18 PM
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Anonymous
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From the August 1967 issue of "Hi-Performance Cars" magazine: Quote:
When we first learned that the [67 383 Barracuda] engine was only rated at 280 hp instead of 325, we immediately jumped to conclusions and pointed our fingers at the factory for cheating on the engine's rating so that the car would be shoehorned into a more desirable NHRA stock class. Plymouth's explanation was that they lost 40 to 50 hp when they had to redesign the headers to clear the chassis and shock towers on the Barracuda. This is actually nonsense as the headers do not appear to be any less restrictive than the ones on the middleweight model 383's and they would have to route them in a spiral pattern up the steering column to lose that much horsepower!
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Re: Flow Chart Numbers on Exhaust manifolds
#1398370
03/07/13 06:51 PM
03/07/13 06:51 PM
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Joined: Jan 2003
Posts: 75,004
U.S.S.A.
JohnRR
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Quote:
From the August 1967 issue of "Hi-Performance Cars" magazine:
Quote:
When we first learned that the [67 383 Barracuda] engine was only rated at 280 hp instead of 325, we immediately jumped to conclusions and pointed our fingers at the factory for cheating on the engine's rating so that the car would be shoehorned into a more desirable NHRA stock class. Plymouth's explanation was that they lost 40 to 50 hp when they had to redesign the headers to clear the chassis and shock towers on the Barracuda. This is actually nonsense as the headers do not appear to be any less restrictive than the ones on the middleweight model 383's and they would have to route them in a spiral pattern up the steering column to lose that much horsepower!
I don't know , that looks conjecture to me. 67 is a one year manifold on the drivers side , they changed the part that goes around the column for 68/69 and upped the rating , but I think 68 is only 300HP , 69 is 330hp. I don't know which cam was used in 68 but the 69 is the same engine that is in the Road Runner and Superbee rated at 335hp, same cam,a same carb number. The 383 in the 69 A bodies only differences are the exhaust manifolds and it has a dual point instead of the RR/SB engine having a single point distributor.
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Re: Flow Chart Numbers on Exhaust manifolds
[Re: JohnRR]
#1398373
03/07/13 07:36 PM
03/07/13 07:36 PM
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Anonymous
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1967 B body 383's only had 2.25 exhaust pipes, and I think the tailpipes were only 1 7/8" (but I could be wrong on that, might have been 2").
Plus the 67 B body 383's didn't have hi-po exhaust manifolds; they had the ones below, under my 69 A body manifolds. No way the A body manifolds cost 45 hp.
One more thing: Because the 67 driver's side manifold is different than the 68-9, and the 67's hp rating was the lowest, everyone assumes the 67 driver's side manifold is more restrictive than the 68-9. I've seen both, and I don't see the 67 being more restrictive. The 68 A body 383's got better heads, intake manifold and carb, and the 69 got a better cam; that's where the increased hp ratings in 68-9 came from. IMHO.
OK, still one more thing: A 2-barrel 383 with a dinky 252 degree cam and single exhaust was rated at 305 hp in 1964. There's no way it really had more hp than a 67 A body 383 4-barrel with dual exhausts. I don't know why Chrysler dropped the hp rating for A body 383's compared to B body 383's, but I think it's pretty obvious they did.
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Re: Flow Chart Numbers on Exhaust manifolds
#1398374
03/07/13 07:49 PM
03/07/13 07:49 PM
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Anonymous
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Okay, one more thing. Most road tests of the 67 383 Barracuda have it running 15.2 to 15.4 in the quarter mile. Hi-Performance Cars magazine got theirs into the high 14's. Super Stock and Drag Illustrated (April 1967) got the bright idea to shift the automatic trans manually and got theirs down to 14.53, which was only two tenths slower than a 67 Coronet R/T they had tested three months earlier.
R/T's five best runs:
14.35 @99.00
14.37 @100.11
14.46 @99.88
14.49 @100.11
14.52 @99.88
First run for the 383 Barracuda, left in drive: 15.37 @92.59
Shifting the torqueflite manually:
14.91
14.80
14.79
14.68
14.56
14.53
Trap speed was 97.
The R/T ran best in Drive. The 383 Barracuda ran much better shifting manually.
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Re: Flow Chart Numbers on Exhaust manifolds
[Re: moper]
#1398376
03/07/13 11:15 PM
03/07/13 11:15 PM
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Joined: Feb 2003
Posts: 16,145
Mesa, Arizona
dart4forte
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OP
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Posts: 16,145
Mesa, Arizona
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Quote:
How was this tested?
On a flow bench
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Re: Flow Chart Numbers on Exhaust manifolds
[Re: dart4forte]
#1398377
03/11/13 07:35 PM
03/11/13 07:35 PM
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Joined: Jan 2005
Posts: 4,406
Michigan
MarkZ
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Michigan
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Mopar Muscle did a similar comparison of SB manifolds on a 300HP 360 crate. The results were just same as the BB manifold comparison posted up top; there was really no discernible difference in the entire lot. So called high performance manifolds seem to really be overrated for the BB and SB alike. http://www.moparmusclemagazine.com/techa...st/viewall.html
1987 Fifth Avenue - 512/518/D60
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Re: Flow Chart Numbers on Exhaust manifolds
[Re: MarkZ]
#1398379
03/12/13 06:50 PM
03/12/13 06:50 PM
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Joined: Aug 2010
Posts: 343
S.E.Mich
drew72
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S.E.Mich
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Quote:
Mopar Muscle did a similar comparison of SB manifolds on a 300HP 360 crate. The results were just same as the BB manifold comparison posted up top; there was really no discernible difference in the entire lot. So called high performance manifolds seem to really be overrated for the BB and SB alike.
http://www.moparmusclemagazine.com/techa...st/viewall.html
I guess I'm confused. I took from this that there wasn't a discernable difference between manifolds and headers. What didn't I understand?
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Re: Flow Chart Numbers on Exhaust manifolds
[Re: drew72]
#1398380
03/12/13 06:57 PM
03/12/13 06:57 PM
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Joined: Jan 2003
Posts: 4,587
St. John's Newfoundland
440newport
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St. John's Newfoundland
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Quote:
I guess I'm confused. I took from this that there wasn't a discernable difference between manifolds and headers. What didn't I understand?
At that power level (300hp) there isn't much difference. As power goes up and with more aggressive cam timing, the HP difference between each exhaust type will be larger.
Similar to Hot Rod's 383 intake test a while back. In the mild state of tune there wasn't much more than a 10hp difference between best and worst, but at 450 hp or so, the spread was more like 40hp.
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