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Cooling System - Headers vs Manifolds |
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madams
AMC Addicted Joined: Jun/26/2017 Location: Duncan OK Status: Offline Points: 603 |
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Posted: Aug/14/2022 at 7:41am |
Do headers increase/decrease the heat load on the cooling system? Seems like not having to cool a big chunk of iron bolted to the head would reduce the heat dumped into the radiator.
Conventional wisdom is that headers raise the under-hood temperature which suggests that the heat is dissipated by the headers rather than making it to the radiator. Interested in some definitive info on both heat load and under-hood temps
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68 AMX 390 4SP
67 RS Camaro 327 Auto |
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Boris Badanov
AMC Addicted Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
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Headers DO increase under hood tempratures.
Headers can make for vapor lock on a hot day. Headers DO cause performance issues on a hot day. Headers CAN cause a over heated intake heat (choke) stove at any speed especially idle. So, the anwser is a bit clouded. Having run into all the above I say YES, heat loading is greater with headers. Eliminating the choke heat stove crossover eliminates most of the heat issue and helps make for a cooler running engine anyway. I block the heat crossover every time. |
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Gremlin Dreams
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Mopar_guy
Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4826 |
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While I agree with Boris on his observations, I don't think it adds to the cooling system load. I may be wrong but I don't see how it would unless the car is standing still for long periods, or in stop and go traffic where you could get some heat soak but there's still the fan to help push that out of the engine compartment.
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"Hemilina" My 1973, 5.7 Hemi swapped Javelin |
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73hornut
AMC Addicted Joined: Jul/03/2007 Location: Southern Oregon Status: Offline Points: 3130 |
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Reduce internal friction by running highest pressure rated oil.
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71 Javelin
74 Gremlin 79 Spirit AMX Rogue Valley Rumblers Like Us on FB https://www.facebook.com/groups/1602825606650796 |
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Red Devil
AMC Addicted Joined: Jul/10/2007 Location: Canada Status: Offline Points: 1743 |
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Depends on the conditions where you are measuring. If headers
reduce the fuel consumed at the test point to yeild same power, by
increasing efficiency, they should have a net decrease on cooling system
heat load. If they increase fuel consumed, i.e. worse efficiency
under the test condition, a net increase. So it depends. Effect
on ability of cooling system to reject heat is another consideration.
Headers generally have much more surface area than manifolds and
radiate more heat. If the average underhood temperature increases,
the deta-T across the radiator likely decreases making the cooling
system less efficient - especially at lower speeds, idling, stop-and-go
traffic. If average underhood temperature
increases, it may also affect intake air temperaure and AFR. The
standard "upgrade" to headers and an open element air cleaner ingesting
underhood air isn't ideal. So lots to consider ;)
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devildog80
AMC Apprentice Joined: Jul/29/2022 Location: Apache Junction Status: Offline Points: 143 |
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Just a thought
I was taught the reason OEM manifold were cast, and not thin steel like a header, was the cast will transfer heat away from the engine best, thereby keeping the engine cooler by simple transference?
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'81 CJ5 Base, 258 I6, MC2100, T176 4 spd, 300 TC, D30 Front NT, 3.31, 2-Piece AMC 20 rear NT, 3.31
'84 Grand Wagoneer, 401 V8 (.030 over), MC2150, 727, ST NP229, AMC 20 Rear - D44 Front - WT 3.31 |
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BBO UK
AMC Nut Joined: Feb/17/2020 Location: UK Status: Offline Points: 288 |
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Modern ceramic coated headers, together with a "wrap" reduce the heat transference under the hood a fair bit from bare metal so some modern technology may come to the rescue for people installing new headers. Heat transfer from the manifold may also be reduced with an insulating gasket. I doubt either setup has much effect on overall cooling load, but I`ve no facts to back that up with.
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