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Re: Building a hand made tunnel for a hemi
[Re: 500dart]
#2742785
02/14/20 10:41 AM
02/14/20 10:41 AM
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Joined: Aug 2013
Posts: 369 Indy
496 A-body
enthusiast
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enthusiast
Joined: Aug 2013
Posts: 369
Indy
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I am currently working on one for a modern hemi, I used 6061-T6 alloy as I did not do any forming, 3003 would be a better choice if you are going to form your runners. I found the Tech info on Swartz website very helpful: http://www.swartzracingmanifolds.com/tech/index.htm
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Re: Building a hand made tunnel for a hemi
[Re: 496 A-body]
#2742958
02/14/20 07:58 PM
02/14/20 07:58 PM
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Joined: Oct 2007
Posts: 4,205 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,205
New York
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How far apart are the runner angles from the port downdraft angles? Any pictures of the final runner entry shape into the plenum?
Boffin Emeritus
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Re: Building a hand made tunnel for a hemi
[Re: 500dart]
#2743302
02/15/20 07:45 PM
02/15/20 07:45 PM
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Joined: Oct 2007
Posts: 4,205 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,205
New York
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A tall rectangular plenum runner entry is more difficult to improve with a radius, bell mouth etc. (which should extend above the floor for maximum CFM). There is also a theory that the plenum cross-sectional area just inside the TB air entry should be considerably larger than the area after the last cylinders (linear taper or exponential? IDK), and the plenum should extend significantly beyond them (at least 1 entry diameter). It appears from the pictures that your runner angle is more horizontal than your port centerline. IIRC unless you know better, closer alignment is preferred, but that may require a "horseshoe" runner (as seen in cross section across the valley) with curved legs.
Boffin Emeritus
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Re: Building a hand made tunnel for a hemi
[Re: polyspheric]
#2743324
02/15/20 08:56 PM
02/15/20 08:56 PM
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Joined: Jan 2005
Posts: 2,540 Milwaukee WI
TRENDZ
master
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master
Joined: Jan 2005
Posts: 2,540
Milwaukee WI
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Agree with all of the above.
I realize the gen 3 pics are not from the OP, but the above info should all be applied to the gen2 from the OP. A cross section of a gen 3 head shows the port entry angle. The pics (from the angle taken) look like the port entrance angle may be less than ideal.
"use it 'till it breaks, replace as needed"
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