Re: Headers vs stock exhaust manifolds. Opinions?
[Re: MidPenMopar]
#2317347
06/06/17 10:04 PM
06/06/17 10:04 PM
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wingman
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There are a lot of good reasons to run manifolds, but to say they flow "almost as good" as your TTIs is simply not true.
Last edited by wingman; 06/06/17 10:05 PM.
1969 Dodge Coronet Super Bee 383 A4 1970 Plymouth Road Runner 440 FC7 (sold)
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: wingman]
#2317354
06/06/17 10:10 PM
06/06/17 10:10 PM
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MidPenMopar
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There are a lot of good reasons to run manifolds, but to say they flow "almost as good" as your TTIs is simply not true. That was my impression as well that they flow way better then stock, so much so it's worth the small hassles.
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: wingman]
#2317513
06/07/17 07:28 AM
06/07/17 07:28 AM
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gdonovan
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There are a lot of good reasons to run manifolds, but to say they flow "almost as good" as your TTIs is simply not true. The mechanic is wrong. I went from manifolds to Dougs headers on my small block and picked up 70+ hp. Car went from a best of 14.2 to 13.0
"I think its got a hemi"
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: MidPenMopar]
#2317530
06/07/17 09:24 AM
06/07/17 09:24 AM
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steve70
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I had a great local shop build a 340 stroker motor for me but I wanted stock carb and manifolds as it's going in an OE restoration. He broke the engine in using his favorite Holley carb and headers. After break-in the final numbers were 397 HP-465 TQ. After he swapped over to stock exhaust manifolds and thermoquad the final numbers were 395HP-443 TQ
Last edited by steve70; 06/07/17 09:25 AM.
1970 Challenger T/A 4 speed
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: DaytonaTurbo]
#2317573
06/07/17 11:38 AM
06/07/17 11:38 AM
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I mean, you have them already so I wouldn't change them because coated TTI headers aren't exactly the same as the summit cheapo junkies, so yeah. Yea, i am keeping the TTIs but was just wondering about how much the gain in HP is worth the hassles of headers after we started discussing it. In fact thinking back I can't remember a car i owned that didn't have headers on it except for a daily driver. Stu
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: steve70]
#2317617
06/07/17 01:12 PM
06/07/17 01:12 PM
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dd340
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I had a great local shop build a 340 stroker motor for me but I wanted stock carb and manifolds as it's going in an OE restoration. He broke the engine in using his favorite Holley carb and headers. After break-in the final numbers were 397 HP-465 TQ. After he swapped over to stock exhaust manifolds and thermoquad the final numbers were 395HP-443 TQ I am willing to bet that you were using stock heads on this build and the reason your hp didn't change is because your heads are the biggest cork in engine. if you swapped heads to Edelbrocks or something similar and the redo the test you would see a very large difference between headers and manifolds. Stroker motors can push a lot of air at a lower RPM but you quickly find the limit of flow in the heads.
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: MidPenMopar]
#2317625
06/07/17 01:23 PM
06/07/17 01:23 PM
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fast68plymouth
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On a mild 383 with a fairly small cam, the difference is probably only like 20hp.
I've dyno tested several stroker FAST builds, and I can tell you the volumetric efficiency of those motors is really quite low, especially for the level of effort involved with the builds.
I'd say that most of the ones I tested would have easily made 100hp more with headers, and maybe a cam swap........ But probably 50-70hp from the headers alone.
How much difference you'd see depends on what you're testing.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: FurryStump]
#2317651
06/07/17 02:38 PM
06/07/17 02:38 PM
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RUNCHARGER
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On a stock 383 with a good exhaust system I would guess 20HP gain with the headers as well. I have swapped headers onto stock engines and not felt much gain. On a built 440 with street ported heads and camshaft you would see more of a gain. IMHO.
Sheldon
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: IMGTX]
#2317676
06/07/17 03:22 PM
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Kevin Kowalski
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Headers all the way.
There is something about the sound of headers that is just right for a musclecar. Stock Cast iron manifolds don't cut it and sound kinda boring and anemic.
I would argue that the rest of the exhaust system has more to do with the exhaust note than the minor difference between headers or cast iron manifolds. Usually most if not all of the exhaust system is changed when making a swap from exhaust manifolds to headers or vice versa so there's no apples to apples comparison. The SuperCar and FAST cars running stock manifolds with free flowing exhaust systems sound anything but boring and anemic.
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: Supercuda]
#2317773
06/07/17 07:16 PM
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gdonovan
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I went by an article on a 360 with headers and... it was utter garbage. My mild 5.9 in my Duster with NO OTHER changes went from 14.2 to 13.49 out of the box and with jetting changes dropped to 13.0. Manifolds vs headers - headers beat manifolds like a rented car.
"I think its got a hemi"
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: MidPenMopar]
#2317786
06/07/17 08:00 PM
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71rm23
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: gdonovan]
#2317891
06/08/17 12:00 AM
06/08/17 12:00 AM
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Supercuda
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I went by an article on a 360 with headers and... it was utter garbage. My mild 5.9 in my Duster with NO OTHER changes went from 14.2 to 13.49 out of the box and with jetting changes dropped to 13.0. Manifolds vs headers - headers beat manifolds like a rented car. Did you read the article? It basically says the same thing, but with dyno numbers
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: Supercuda]
#2317960
06/08/17 06:43 AM
06/08/17 06:43 AM
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gdonovan
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Did you read the article?
It basically says the same thing, but with dyno numbers
Yup and the numbers are fairly low, I found the spread to be much wider.
"I think its got a hemi"
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Re: Headers vs stock exhaust manifolds. Opinions?
[Re: 73DAD]
#2318157
06/08/17 06:03 PM
06/08/17 06:03 PM
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Streetwize
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I'll bet on a mild 383 you'll gain almost as much just by using 2 1/2" 440 head pipes (instead of 2 1/4" 383 pipes) as you would going to headers. 440's had H pipes which helped a bit too, you'll need to section an RB head pipe set to narrow it to use on a B motor.
Factory motors all had wide 114-ish lobe spreads which reduces overlap, generally the narrower the lobe separation (tighter, ie 106-110) angle the more headers help you. headers are also somewhat limited by the rest of the exhaust system too.
I had a basically stock 69 440 out of a Newport with ported closed chamber 67 "915 heads and a 484 purple shaft in a 73 duster with narrowed factory "Newport" logs on both sides. I realized on the Pass side I could fit a 68-71 Magnum Ram horn manifold so I did, The car picked up about 1 1/2 tenths (IN THE 1/8TH!) so maybe 2 1/2 in the 1/4? So it does help, but I'll bet if I ran the wider LSA 528 the gains would not have been as significant.
I've read that on small blocks a set of ported Magnums are about as good as Shorties and better than ported 340 manifolds
Last edited by Streetwize; 06/08/17 06:04 PM.
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