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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Joined: Jun 2004
Posts: 3,389 St. Charles, MO
wingman
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St. Charles, MO
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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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Posts: 36,840 South San Francisco, Californi...
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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Joined: Jun 2008
Posts: 10,847 Oakdale CT
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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Joined: Dec 2011
Posts: 892 MA
steve70
super stock
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super stock
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MA
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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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MidPenMopar
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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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Joined: Jan 2003
Posts: 727 Ottawa, ontario
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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Joined: Jan 2003
Posts: 14,513 So. Burlington, Vt.
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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Joined: Jan 2003
Posts: 15,976 Chilliwack B.C. Canada
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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