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Building a hand made tunnel for a hemi #2742689
02/13/20 10:42 PM
02/13/20 10:42 PM
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edmonton alberta canada
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500dart Offline OP
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edmonton alberta canada
I,m am building a hand made tunnel for a 572 hemi . I am trying to maximize it , plenum volume , runner taper ,round runner vs square runners . What is the best aluminium alloy to build it from. I have 3100 lbs dart . I red line it at 7500 rpm. The convertor flashes to about 5700 rpm . I am currently running a indy tunnel ram with 2 850 cfm quick fuel carbs .

Re: Building a hand made tunnel for a hemi [Re: 500dart] #2742746
02/14/20 08:54 AM
02/14/20 08:54 AM
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Posts: 2,794
Shelby Twp. Mi
HardcoreB Offline
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3003 aluminium. I have a buddy building his own right now and he is having the runners done by Swartz out of Kansas.

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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496 A-body Online content
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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



G3_intake.jpgG3_intake2.jpg
Re: Building a hand made tunnel for a hemi [Re: 500dart] #2742952
02/14/20 07:43 PM
02/14/20 07:43 PM
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fredericksburg,va
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cudaman1969 Offline
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Look at the SS Cudas and Darts basically tunnel rams and they work. Incorporate lid spacers to tune for size of engine. But realistically it’ll be like throwing rocks at a moving train blindfolded. You might hit it eventually.

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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New York
polyspheric Offline
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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?


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Re: Building a hand made tunnel for a hemi [Re: polyspheric] #2742966
02/14/20 08:20 PM
02/14/20 08:20 PM
Joined: Oct 2011
Posts: 13
edmonton alberta canada
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500dart Offline OP
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edmonton alberta canada
I have not started on the build yet only in planning stages but debating on round runners vs square runners and taper rate.

Re: Building a hand made tunnel for a hemi [Re: 500dart] #2743282
02/15/20 06:55 PM
02/15/20 06:55 PM
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AndyF Offline
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Start with a copy of PipeMax

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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New York
polyspheric Offline
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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.


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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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Milwaukee WI
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TRENDZ Online content
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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.

A0177529-0BE6-4A35-812C-596FE89DD275.jpeg

"use it 'till it breaks, replace as needed"
Re: Building a hand made tunnel for a hemi [Re: AndyF] #2743826
02/17/20 03:00 AM
02/17/20 03:00 AM
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Posts: 5,747
Melbourne , Australia
LA360 Offline
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Originally Posted by AndyF
Start with a copy of PipeMax


This is great advice

http://www.maxracesoftware.com/PIPE395.htm


Alan Jones






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