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Author
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Topic: Header design formulas/charts?
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DutchD58
Gearhead Posts: 110
From: West Milton, OH
Registered: Jul 2000
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posted 09-09-2001 11:43 AM
   
Years ago (and I do mean years ago.....before wife v1.0) I had a number of formulas and charts that allowed an individual to design a set of headers based on displacement, RPM and exhaust valve size (primary ID/length and collector ID/length), or to determine the effectiveness of "off-the-shelf" headers for a particular application. I also know that there are a number of other factors that can come into play (valve timing, etc) in such an exercise.
Any of you folks have these formulas/charts at your fingertips that you could either post or e-mail my way?Thanks,
Kevin
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TomP
Gearhead Posts: 4780
From: Delta BC Canada
Registered: Dec 99
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posted 09-11-2001 03:49 AM
I don't believe its as exact a science as some folks would have you think. What you lose in one RPM range you gain back in another most of the time. You don't want tubes too small that restrict the ports, but an error on the too-large side isn't gonna hurt that much. Looking at relatively unlimited classes where many cars run near-identical engines, such as the 500 cubic inch NHRA ProStock, you can find Tri-Y and 4 tubes designs in sizes from 2 1/8" to 2 3/8" and a wide variety of collector designs and sizes. All are pretty similar in performance.
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Moneymaker
Administrator Posts: 19686
From: Lyons, IL, USA
Registered: May 99
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posted 09-11-2001 12:18 PM
Headers by Ed in Minn. has those formulas on line I believe. Most of the real race header manufacturers use all CAD equipment these days. Step headers make the most power and you really need a computer to determine the correct tube diameters and lengths for serious horsepower.  ------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00 & '01
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link
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DutchD58
Gearhead Posts: 110
From: West Milton, OH
Registered: Jul 2000
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posted 09-12-2001 05:17 PM
Thanks guys. My needs and concerns probably aren't that critical compared to what you gentlemen are trying to accomplish during the racing season.
Right now I have a 2V headed Cleveland and want more, so I have been spending a great deal of time lately comparing various small-block stroker packages to 460 big-blocks for my '73 Torino. Cleveland and aluminum headed Windsor based strokers (392-408 cu.inch) look appealig from a size and weight perspective, but then I'm stuck using off the shelf headers with what may be marginal primary tube size (1 5/8"-1 7/8", depending on engine family and heads). Custom headers would be an option, but would add an additional $600-$800 to my budget.
A 460 with aluminum heads, water pump and intake would be do-able, but 1 7/8" tube headers are the only option for my chassis. Just trying to be thorough before I spend a dime. Thanks, Kevin
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Clevo377
Gearhead Posts: 312
From: Blackburn, Victoria, Australia
Registered: Nov 2000
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posted 09-13-2001 06:39 AM
Kevin, I have a formula to determine peak torque RPM of a given pipe size that I got off a website a while ago. It is:
Peak torque rpm = Tube area x (88200)/(CID/8)
So for a 460 with 1 7/8 pipes (internal):
2.76 x (88200)/(460/8)= 4234 RPMFood for thought
Paul
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F551
Gearhead Posts: 172
From: Manitoba, Canada
Registered: Nov 2000
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posted 09-13-2001 09:34 PM
Hey Paul - great formula!
When we dynoed our 500 it made 651 ft/lb @ 4250 rpm with 1 7/8" headers.------------------
Fred
68 Mustang 500CID/Powerglide - "No Tubs"
86 Mustang GT Cobra
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Clevo377
Gearhead Posts: 312
From: Blackburn, Victoria, Australia
Registered: Nov 2000
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posted 09-14-2001 05:57 AM
Yeh! It seemed to work for me too. I got it from a series of online lectures given by the "Performance Professor". Was a really good site. Unfortunately it was taken over by someone else, and kinda went downhill (in my opinion). It's a paysite now  Paul
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n2oMike
Gearhead Posts: 1511
From: Spencer, WV
Registered: Jan 2001
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posted 09-14-2001 11:17 AM
As real header builders know... actual construction is full of compromises. There's a LOT of stuff in the way that needs worked around. Too bad our "dream headers" aren't too often destined for "rail" cars, where there is unlimited room!I'm sure that formula is for the INSIDE diameter of the header tube. Headers are generally sold by their OUTSIDE diameter. The thinner the tube, the larger the ID. Hooker Super Comps are generally pretty thin. You'll want to do some measuring before doing the math. Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/motorcitymustang/cmml/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
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DutchD58
Gearhead Posts: 110
From: West Milton, OH
Registered: Jul 2000
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posted 09-14-2001 01:34 PM
Thanks Paul, that's a good start for me!Kevin
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