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Whats the defference between cast exh manifold and HP

Posted By: Fern

Whats the defference between cast exh manifold and HP - 10/12/14 06:16 PM

Not looking to go with headers, will HP manifolds make a big difference in performance. Its a 440.
And what is different about them?
Thanks
Posted By: BSB67

Re: Whats the defference between cast exh manifold and HP - 10/12/14 06:59 PM

As compared to what?
Posted By: Fern

Re: Whats the defference between cast exh manifold and HP - 10/12/14 07:02 PM

Quote:

As compared to what?



AS compared to the non HP stock manifolds.
Sorry.
Posted By: CR8CRSHR

Re: Whats the defference between cast exh manifold and HP - 10/12/14 07:51 PM

Both types of manifolds are "Cast" pieces. The "stock logs" are not as performance oriented compared to the HP Manifold. Better flow out of the HP. I prefer the HP over Headers on a mostly street driven car. Back in the day they were really quite acceptable in those MOPAR Muscle Cars. Yet to the first thing yanked after the purchase of one of them was to replace them with Headers. Still I like the HP's...
Posted By: Fern

Re: Whats the defference between cast exh manifold and HP - 10/12/14 09:16 PM

What Im trying to find out is, how much better flow do you get from the HP manifolds as compared to the non HP. Or what is the horse power increase? if any.

Did lots of searching but could only find comparisons from HP manifolds to headers, which I dont want.

Thanks
Posted By: RSNOMO

Re: Whats the defference between cast exh manifold and HP - 10/12/14 09:22 PM

You want to maximize your cast-iron HP manifolds, get 'em extrude-honed...
Posted By: Stewpar

Re: Whats the defference between cast exh manifold and HP - 10/12/14 09:26 PM

Quote:

You want to maximize your cast-iron HP manifolds, get 'em extrude-honed...



That is A LOT of money for maybe 5-10 HP.......

Stock HP manifolds are just fine.
Posted By: 6bblgt

Re: Whats the defference between cast exh manifold and HP - 10/12/14 09:33 PM

& the real question appears to be: How much do I need to spend?

A) $50 pair of "log" manifolds
B) $350 pair of dual exhaust/HP manifolds
C) $500+ pair of quality headers

& what are the horsepower consequences?

as always more information is needed: What kind of vehicle & what's in your 440 build? What are your intended uses with said vehicle?
Posted By: fourgearsavoy

Re: Whats the defference between cast exh manifold and HP - 10/12/14 09:37 PM

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

Attached picture 8298232-rearviewsavoy.jpg
Posted By: BigBlockMopar

Re: Whats the defference between cast exh manifold and HP - 10/12/14 09:57 PM

I recall one of the magazines had done some testing on the manifolds and the outcome was that there were just minor differences between the HP's and the stockers.
The manifold exit diameter was the most telling how well a manifold performed I recall but the didn't come close to a simple shorty header.
I think I have it bookmarked somewhere.
Posted By: BigBlockMopar

Re: Whats the defference between cast exh manifold and HP - 10/12/14 10:17 PM

Here's an article of Steve Dulcich;
http://www.moparmusclemagazine.com/techarticles/mopp_0106_manifolds_vs_headers/

Here's one from Panic on how to modify manifolds;
http://victorylibrary.com/mopar/ci-man-tech-c.htm
Posted By: Kern Dog

Re: Whats the defference between cast exh manifold and HP - 10/13/14 12:12 AM

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.
Posted By: Pale_Roader

Re: Whats the defference between cast exh manifold and HP - 10/16/14 11:11 AM

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...
Posted By: Pale_Roader

Re: Whats the defference between cast exh manifold and HP - 10/16/14 11:15 AM


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.
Posted By: 6PakBee

Re: Whats the defference between cast exh manifold and HP - 10/16/14 12:23 PM

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?
Posted By: LaRoy Engines

Re: Whats the defference between cast exh manifold and HP - 10/16/14 03:41 PM

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.
Posted By: JohnRR

Re: Whats the defference between cast exh manifold and HP - 10/16/14 03:59 PM

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 ...
Posted By: BSB67

Re: Whats the defference between cast exh manifold and HP - 10/17/14 12:07 AM

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.
Posted By: Pynzo

Re: Whats the defference between cast exh manifold and HP - 10/17/14 01:53 AM

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?



With the right exhaust-yes. Going from ('70 383 Magnum) headers and 2-1/2" exhaust, turbo mufflers, to stock HP manifolds and new TTI 2-1/2 exhaust- same performance without the burnt ignition wires, clearance for everything hassle of headers. I love the sound of a stock Mopar starter. Newer headers I looked at required mini starters.
Edit-
No Dyno No Computer tests
It's what I feel in my gas pedal foot and by the way my head snaps back when I mash down the gas pedal-
Posted By: Pynzo

Re: Whats the defference between cast exh manifold and HP - 10/17/14 02:45 AM

Quote:

Here's an article of Steve Dulcich;
http://www.moparmusclemagazine.com/techarticles/mopp_0106_manifolds_vs_headers/

Here's one from Panic on how to modify manifolds;
http://victorylibrary.com/mopar/ci-man-tech-c.htm



If you read this article and want custom carbide burrs- I have been making them for almost 30 years. Any shape, cut, or shank(solid or flex) length. I also repair used broken burrs. Just Sayin.
Posted By: GTX MATT

Re: Whats the defference between cast exh manifold and HP - 10/17/14 03:16 AM

Not much, they both suck. HP manifolds look much better though.
Posted By: Fern

Re: Whats the defference between cast exh manifold and HP - 10/20/14 01:48 AM

Quote:


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.



I have a 70 Challenger with fast ratio steering and getting headers to fit is near impossible. I'm also not a fan of the heat they throw off.
Posted By: Fern

Re: Whats the defference between cast exh manifold and HP - 10/20/14 01:51 AM

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.



Thats, yea for 4 HP its not worth the time and effort to swap out the logs.

Thanks!
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