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Flow Chart Numbers on Exhaust manifolds

Posted By: dart4forte

Flow Chart Numbers on Exhaust manifolds - 03/07/13 05:06 AM

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

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Posted By: dart4forte

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 05:35 AM

CHART 1 Data

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Posted By: dart4forte

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 05:36 AM

CHART 2

Attached picture 7616435-Chart2.JPG
Posted By: dart4forte

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 05:36 AM

CHART 2 Data

Attached picture 7616437-Chart2Data.JPG
Posted By: Jim_Lusk

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 06:07 AM

It would be interesting to get the data on a B-body HP manifold as that is supposed to flow better.
Posted By: dart4forte

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 06:22 AM

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
Posted By: moper

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 05:57 PM

How was this tested?
Posted By: JohnRR

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 06:16 PM

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.
Posted By: Anonymous

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 08:18 PM

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!

Posted By: JohnRR

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 10:51 PM

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.
Posted By: topside

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 11:18 PM

I don't doubt that Chrysler may have played with the ratings to fit the car into an NHRA class; oftentimes ratings were published at a lower RPM than what may have provided bigger #s.
That said, I recall a set of A-body 440 headers (race Hookers) on a Stock Eliminator '69 Cuda that gave almost 40 HP less on the dyno than a set that wouldn't fit that chassis.
Another consideration is how that manifold measurement relates to what the head is trying to push through it; for example, if each port is trying to push 200CFM, what will the manifold flow? Seems like you'd have to rig it on a flow bench so that firing order was duplicated & factored in.
Posted By: JohnRR

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 11:24 PM

I just remembered also the A body has a cork for an 3xhaust system , 2.25 headpipes and 2" tailpipes .

I guess they are right baout the lower HP rating , what class would the 67 BB dart have run . The Magnum engine wasn't out yet so 33oHP was the top engine in 67 , I assumed the dart got the 300 hp engine as a base ?
Posted By: Anonymous

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 11:36 PM

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.

Attached picture 7617307-DSCF0077.jpg
Posted By: Anonymous

Re: Flow Chart Numbers on Exhaust manifolds - 03/07/13 11:49 PM

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.
Posted By: dart4forte

Re: Flow Chart Numbers on Exhaust manifolds - 03/08/13 03:14 AM

If you look at the numbers you'll see there's little difference between the manifolds that would suggest a significant HP difference relating to exhaust flow. With that said I would lean more toward the fact that manipulation of information from Ma Mopar in terms of the HP ratings was the norm. I haven't found anything to suggest that this type of test was conducted by the factory in terms of the manifolds.
Posted By: dart4forte

Re: Flow Chart Numbers on Exhaust manifolds - 03/08/13 03:15 AM

Quote:

How was this tested?



On a flow bench
Posted By: MarkZ

Re: Flow Chart Numbers on Exhaust manifolds - 03/11/13 11:35 PM

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
Posted By: dart1962_440

Re: Flow Chart Numbers on Exhaust manifolds - 03/12/13 10:28 PM

It'd be interesting to see how the 67 (which I think are 62-66) manifolds that 413 coronet shows in the picture flow. That's what early b bodies use and it would show if its really worth going to HP b body ones from later years.
Posted By: drew72

Re: Flow Chart Numbers on Exhaust manifolds - 03/12/13 10:50 PM

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?
Posted By: 440newport

Re: Flow Chart Numbers on Exhaust manifolds - 03/12/13 10:57 PM

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.
Posted By: dogdays

Re: Flow Chart Numbers on Exhaust manifolds - 03/13/13 12:21 AM

BUT there is a difference. There is a misconception that the header benefit comes exclusively from lack of flow restriction. That isn't necessarily so. The separation of pulses by the long tube header is very important and contributes to the long tube header's superiority below the torque peak. This was pointed out a few years ago by the tests referred to above. Look at the torque progression at low speeds. The longer the separation between ports, the greater the benefit, is how I categorize the results. of course, the word "longer" is within reason, I'm not pushing 120" long primaries!

R.

PS: This article and test was done by Steve Dulcich, a board member. Reading his article again, I find I'm restating much of what he said. Thanks, Steve!
Posted By: imfixinmopars426

Re: Flow Chart Numbers on Exhaust manifolds - 03/13/13 12:30 AM

back when i first bought my 69/383 dart,i threw out the rusty headers,and used a C body on the left,and a 68-69 "900" on the right. my exhaust guy in town used a 2" to hook the lh to the 2.25 pipe,and worked great. he bent it around the t-bar,and missed all the 4spd stuff. that was in 1984,and the car still has all the exhaust on it still...the correct manifolds were unabtainable in my stupid little town,lol
Posted By: BSB67

Re: Flow Chart Numbers on Exhaust manifolds - 03/13/13 02:03 AM

I'm not really sure the value of these results at such low flows. And the Dp will increase exponentially with the flow.
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