Header size ?

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Header size ?

Post  whitefield on September 30th 2012, 9:19 pm

Is there such a thing as header size to big ? say 2" versus 2 1/2 " ?
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Re: Header size ?

Post  richter69 on September 30th 2012, 10:49 pm

depends what its on
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Re: Header size ?

Post  whitefield on September 30th 2012, 10:52 pm

richter69 wrote:depends what its on
466
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Re: Header size ?

Post  richter69 on September 30th 2012, 11:06 pm

i cant see where it would need a 2.5
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Re: Header size ?

Post  whitefield on September 30th 2012, 11:20 pm

richter69 wrote:i cant see where it would need a 2.5

I don't think it would need them either, but was wanting to know if it would hurt power and torque to run a larger primary tube header ?
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Re: Header size ?

Post  bbf-falcon on September 30th 2012, 11:36 pm

I would think 2.5" exh. would hurt torque down low on a 4.390 bore 466. confused

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Re: Header size ?

Post  cool40 on September 30th 2012, 11:37 pm

on a n/a setup i'd think too big would hurt torque but how big is too big? study i was looking at 2 3/8 for the 605 but 2 3/8 to 2 1/2 was what i got. dynatec was one place i looked for info......... Smile
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Re: Header size ?

Post  c.evans on October 1st 2012, 12:37 am

whitefield wrote:Is there such a thing as header size to big ? say 2" versus 2 1/2 " ?

Yes there is. It's been proven countless times on dynos everywhere. Chapters in books have been devoted to the subject.

Charlie

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Re: Header size ?

Post  whitefield on October 1st 2012, 8:42 am

c.evans wrote:
whitefield wrote:Is there such a thing as header size to big ? say 2" versus 2 1/2 " ?

Yes there is. It's been proven countless times on dynos everywhere. Chapters in books have been devoted to the subject.


Charlie

Thanks for the info.
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Re: Header size ?

Post  IDT-572 on October 1st 2012, 12:46 pm

You will lose exhaust velocity which will hurt during the overlap period when your starting your intake charge. (which hurts torque)

Unless it's a over the top 466, 2 inch is all that will be necessary.
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Re: Header size ?

Post  whitefield on October 1st 2012, 1:07 pm

IDT-572 wrote:You will lose exhaust velocity which will hurt during the overlap period when your starting your intake charge. (which hurts torque)

Unless it's a over the top 466, 2 inch is all that will be necessary.


I got to thinking what if you are running a 390 to 427 cubic inch engine would going from 1 3/4" to 2" primary headers be to large ?
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Re: Header size ?

Post  richter69 on October 1st 2012, 1:28 pm

fwiw we run a 1 7/8 on our 306
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Re: Header size ?

Post  IDT-572 on October 1st 2012, 2:36 pm

richter69 wrote:fwiw we run a 1 7/8 on our 306

Again, its about application. 6000 converter on a 306 sure, not a problem, but I would be willing to bet it would be just as fast with short tube 1.750 primary's on it.
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Re: Header size ?

Post  IDT-572 on October 1st 2012, 2:39 pm

whitefield wrote:
IDT-572 wrote:You will lose exhaust velocity which will hurt during the overlap period when your starting your intake charge. (which hurts torque)

Unless it's a over the top 466, 2 inch is all that will be necessary.


I got to thinking what if you are running a 390 to 427 cubic inch engine would going from 1 3/4" to 2" primary headers be to large ?

If it's a full out race engine, no 2 inch will work. That's what I ran on the 414 Windsor with c-302 B's 6200 rpm converter. Shifting at 7200
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Re: Header size ?

Post  whitefield on October 1st 2012, 3:04 pm

IDT-572 wrote:
whitefield wrote:
IDT-572 wrote:You will lose exhaust velocity which will hurt during the overlap period when your starting your intake charge. (which hurts torque)

Unless it's a over the top 466, 2 inch is all that will be necessary.


I got to thinking what if you are running a 390 to 427 cubic inch engine would going from 1 3/4" to 2" primary headers be to large ?

If it's a full out race engine, no 2 inch will work. That's what I ran on the 414 Windsor with c-302 B's 6200 rpm converter. Shifting at 7200

Thanks, I think I am understanding this header deal better! Embarassed study scratch
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