Re: Whats the defference between cast exh manifold and HP
[Re: BSB67]
#1684799
10/12/14 03:02 PM
10/12/14 03:02 PM
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Joined: Jan 2013
Posts: 103 M.A.
Fern
OP
member
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OP
member
Joined: Jan 2013
Posts: 103
M.A.
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Quote:
As compared to what?
AS compared to the non HP stock manifolds. Sorry.
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Re: Whats the defference between cast exh manifold and HP
[Re: Fern]
#1684805
10/12/14 05:37 PM
10/12/14 05:37 PM
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Joined: Dec 2004
Posts: 10,555 Rittman Ohio
fourgearsavoy
I Live Here
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I Live Here
Joined: Dec 2004
Posts: 10,555
Rittman Ohio
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All you really need to do is look at them side by side and you can easily see which exhaust would flow better Are you actually looking for dyno numbers? AndyF has done some real world testing on HP manifolds and had some surprising horsepower figures but also noted that some custom ground cams would be required to optimize the cast iron HP manifolds. You can use the custom Google search at the top of the page for more info. Gus
64 Plymouth Savoy 493 Indy EZ's by Nick at Compu-Flow 5-Speed Richmond faceplate Liberty box Dana 60
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Re: Whats the defference between cast exh manifold and HP
[Re: Kern Dog]
#1684809
10/16/14 07:11 AM
10/16/14 07:11 AM
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Joined: Jan 2005
Posts: 4,862 the frozen wastes...
Pale_Roader
Swears too much
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Swears too much
Joined: Jan 2005
Posts: 4,862
the frozen wastes...
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Quote:
Not a direct comparison, BUT... The TNT 440 in the 67 Chrysler 300 was essentially a 440 Magnum. It used the same style "Magnum" manifolds with dual exhaust, the same intake, carburetor and camshaft. It also had a windage tray. The 440 "Magnum/Super Commando/TNT" was rated at 375 HP. The base 440 in the 67 Chrysler and other models used a log type exhaust manifold, a Y pipe into a single exhaust pipe and a milder cam. It was rated at 350 HP. The 25 HP difference is attributed to the cam, exhaust and windage tray. Its safe to figure that 8-10 HP could be from the exhaust system.
While its nice and fun to bench race like this... with Mopar you cannot even begin to use factory ratings for comparisons. Not even in the vicinity ov 'close'. The TNT never made that 375 and the stock 440 never even came close to 350. I would agree though that from most ov my reading (thats a lot), the HP iron would probably make about that difference, give or take... but also vastly dependent on the build too. The numbers some guys (F.A.S.T.) are getting from HP manifolds is utterly obscene, but there is a LOT ov voodoo going on there obviously...
I will say from experience that on big block Mopars, the difference between a log and an HP manifold is a lot closer than the difference between the HP and even a cheap 'bad' header. I've wanted to go back to manifolds forever too... but thats just too big a hit for me to take. NOTHING wakes a Mopar big block up like headers... that should tell you something. Some makes you can add headers and its just not worth the hassle at all.
Maybe just head down to the local Pick a Part and score some Max Wedge manifolds...
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Re: Whats the defference between cast exh manifold and HP
[Re: Pale_Roader]
#1684810
10/16/14 07:15 AM
10/16/14 07:15 AM
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Joined: Jan 2005
Posts: 4,862 the frozen wastes...
Pale_Roader
Swears too much
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Swears too much
Joined: Jan 2005
Posts: 4,862
the frozen wastes...
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Is there a specific reason why you dont want headers? If its the usual header BS, then how about Schumacher engine swap headers? Maybe not the best performing, but still WAY better than iron, and no install hassles, no leak hassles, no header sound and no clearance hassles. VERY nice quality looking pieces too. Unless its about visuals, like staying OEM, or maybe building a sleeper, the Schumachers cover a LOT ov bases.
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Re: Whats the defference between cast exh manifold and HP
[Re: Pale_Roader]
#1684811
10/16/14 08:23 AM
10/16/14 08:23 AM
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Joined: Jan 2003
Posts: 10,748 North Dakota
6PakBee
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,748
North Dakota
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Looking at the Dulcich article I found it interesting that the HP difference at 3000 was about 16 and at 5800 was about 75. If the test had been done with a 383 with the lower exhaust flow, would there have been any difference at all?
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: Whats the defference between cast exh manifold and HP
[Re: Fern]
#1684812
10/16/14 11:41 AM
10/16/14 11:41 AM
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Joined: Oct 2011
Posts: 559 Idaho
LaRoy Engines
mopar
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mopar
Joined: Oct 2011
Posts: 559
Idaho
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I personally tested the log manifold vs the HP manifold on a 300 horsepower 440. We gained a whole 4 horsepower when we installed the HP manifolds.
Last edited by LaRoy Engines; 10/16/14 11:43 AM.
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Re: Whats the defference between cast exh manifold and HP
[Re: LaRoy Engines]
#1684813
10/16/14 11:59 AM
10/16/14 11:59 AM
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Joined: Jan 2003
Posts: 75,080 U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,080
U.S.S.A.
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Quote:
I personally tested the log manifold vs the HP manifold on a 300 horsepower 440. We gained a whole 4 horsepower when we installed the HP manifolds.
What size headpipes did you use with each set of manifolds? One of the main differences is the outlet on the HP manifold is almost 2.5" , the log is I am pretty sure 2".
the question the OP needs to ask himself is the extra money to switch to the HP manifolds , in both the cost of the manifolds and the cost of the exhaust system change worth it to him ?
Some people just don't want to deal with the headaches involved with headers on a car that may only see the track , for fun and little else , maybe once or twice , a year ... or ever ...
But the OP never said what car he has ...
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Re: Whats the defference between cast exh manifold and HP
[Re: 6PakBee]
#1684814
10/16/14 08:07 PM
10/16/14 08:07 PM
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Joined: Feb 2005
Posts: 4,318 Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,318
Prospect, PA
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Quote:
Looking at the Dulcich article I found it interesting that the HP difference at 3000 was about 16 and at 5800 was about 75. If the test had been done with a 383 with the lower exhaust flow, would there have been any difference at all?
I think the manifold portion of the article is worthless. The manifolds were open.
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