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 Post subject: Header Primary Size
 Post Posted: Thu Feb 23, 2012 10:08 am 
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Joined: Fri Feb 17, 2012 7:47 am
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Guys,

How do you decide what size to use? My heads flow right at 305cfm intake and 205exh. I rev to 6krpm. Should I be going with 1 3/4 or 1 7/8...or full blown 2"? I am having the headers built, so how long should they be. I currently have a 1 3/4 try-y and I am going to a 5-1 as the TQ falls on it's face about 5300rpm.


I would be happy to email someone a dyno graph to post as I don't have any online hosting.


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 Post subject: Re: Header Primary Size
 Post Posted: Thu Feb 23, 2012 10:52 am 
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There's a few on here that have "Pipe Max" software so maybe one of them will chime in with numbers. If you're having headers built, then I'd also look at doing a step header.

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 Post subject: Re: Header Primary Size
 Post Posted: Thu Feb 23, 2012 11:14 am 
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I have Pipemax and could run your engine if I had the engine info. The amount of power the engine produces is what sets required pipe diameter.

Just based on your intake flow I'd say 1-3/4" or 1-7/8". I've never seen big gains with headers unless the converter doesn't stall enough and then you might help torque down low enough to help 60' with a smaller than normal header.

Rick


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 Post subject: Re: Header Primary Size
 Post Posted: Thu Feb 23, 2012 12:02 pm 
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Car made 538rwhp/570rwtq on a mustang dyno. 585/610 on a dyno jet dyno. This was with the "try-y" header. Car doesn't lack lowend....if I loose some I wouldn't miss it. For my burnout @ the strip I just rev to 2500rpm and dump the clutch.

What info do you need for pipe max?

The car is a 6sp manual.


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 Post subject: Re: Header Primary Size
 Post Posted: Thu Feb 23, 2012 3:04 pm 
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Location: Adelaide Australia
Disturbed wrote:
Car made 538rwhp/570rwtq on a mustang dyno. 585/610 on a dyno jet dyno.
Thats ridiculous. so which one is it?


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 Post subject: Re: Header Primary Size
 Post Posted: Thu Feb 23, 2012 7:44 pm 
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Here are the required inputs. Some may not be used for header sizing so if you don't know some I can make a guess.

Image

Rick


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 Post subject: Re: Header Primary Size
 Post Posted: Thu Feb 23, 2012 8:13 pm 
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shrinker wrote:
Disturbed wrote:
Car made 538rwhp/570rwtq on a mustang dyno. 585/610 on a dyno jet dyno.
Thats ridiculous. so which one is it?


Dyno's are just that numbers. Mustang always reads about 10% less than dyno jet. But it doesn't matter much, both "numbers" trap 129-130mph in the 1/4.....so...take your pick.


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 Post subject: Re: Header Primary Size
 Post Posted: Thu Feb 23, 2012 8:56 pm 
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rick360 wrote:
Here are the required inputs. Some may not be used for header sizing so if you don't know some I can make a guess.

Image

Rick


This will give away the car...making my intro thread lame. ](*,) Cam is a stock cam.

Engine Data

VE% = No clue...it's N/A so maybe 25% lol.
Bore 4.060
Stroke 4.00
Rod = U/K
Cyl = 10
Peak HP rpm = 5300-5400rpm
CR = 9.5:1 (Head was milled slightly but stock 9:1cr pistons).


Inake Data
# valves = 10
Valve Head = 2.02
Valve Stem = U/K
Lift = .320
Duration @ .050 = U/K
Intake Center line = 117*
LSA = 114* (calc)


Exhaust Data
# valves = 10
Valve Head = 1.61
Valve Stem = U/K
Lift = .320
Duration @ .050 = U/K


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 Post subject: Re: Header Primary Size
 Post Posted: Sat Feb 25, 2012 12:44 am 
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Location: Missouri
I guessed at 110%VE and pipemax recommendation for a race header w/open headers is ...

--- Single Primary Pipe Specs --- for 517.849 CID from 3400 to 5900 RPM
Diameter= 1.599 to 1.724 Length= 31.9 to 34.5 inches long
--- 2-Step Primary Pipe Specs ---
1st Dia. inches= 1.599 Length= 15.9 to 17.3
2nd Dia. inches= 1.724 Length= 15.9 to 17.3
--- 3-Step Primary Pipe Specs ---
1st Dia. inches= 1.599 Length= 15.9 to 17.3
2nd Dia. inches= 1.724 Length= 8.0 to 8.6
3rd Dia. inches= 1.849 Length= 8.0 to 8.6

--- Header Collector Specs (Conventional Straight Tube) ---
Diameter= 3.500 to 3.750 Tuned Lengths= 19.3 best and also 9.6 or 38.6

--- Header Collector Specs (Megaphone or Diffuser Cone Shape) ---
Diameter= 3.000 taper to 4.000 Megaphone/Diffuser Length= 19.3 inches

Best HP/TQ Tuned Collector Lengths= 19.3 , 38.6 , 77.2 , 154.4 inches long

Worst HP/TQ Loss Collector Lengths= 28.9 , 57.9 , 115.8 , 231.6 inches long

Note-> all Pipe Diameters are OD and based-off .0625 inch Pipe thickness

Rick


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 Post subject: Re: Header Primary Size
 Post Posted: Wed Feb 29, 2012 4:01 pm 
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rick360 wrote:
I guessed at 110%VE and pipemax recommendation for a race header w/open headers is ...

--- Single Primary Pipe Specs --- for 517.849 CID from 3400 to 5900 RPM
Diameter= 1.599 to 1.724 Length= 31.9 to 34.5 inches long
--- 2-Step Primary Pipe Specs ---
1st Dia. inches= 1.599 Length= 15.9 to 17.3
2nd Dia. inches= 1.724 Length= 15.9 to 17.3
--- 3-Step Primary Pipe Specs ---
1st Dia. inches= 1.599 Length= 15.9 to 17.3
2nd Dia. inches= 1.724 Length= 8.0 to 8.6
3rd Dia. inches= 1.849 Length= 8.0 to 8.6

--- Header Collector Specs (Conventional Straight Tube) ---
Diameter= 3.500 to 3.750 Tuned Lengths= 19.3 best and also 9.6 or 38.6

--- Header Collector Specs (Megaphone or Diffuser Cone Shape) ---
Diameter= 3.000 taper to 4.000 Megaphone/Diffuser Length= 19.3 inches

Best HP/TQ Tuned Collector Lengths= 19.3 , 38.6 , 77.2 , 154.4 inches long

Worst HP/TQ Loss Collector Lengths= 28.9 , 57.9 , 115.8 , 231.6 inches long

Note-> all Pipe Diameters are OD and based-off .0625 inch Pipe thickness

Rick



Rick thanks! I sent the info to the guy building the headers. Hope he uses it. I'd like to see if this thing will pick up 25-30rwhp with a good set of 5-1 headers over try y.


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