| [ Total Views: 634 | Total Replies: 9 | Thread Id: 4985 ] |
|
|
 speedster356
A.k.a.: Peter Mcleod
Custom Title Time!
Plastic not Classic Racing
Posts: 1624
Threads: 256
Registered: August 25th, 2002
Member Is Offline
Location: CHRIST church NZ
Theme: UltimaBB Pro Blue ( Default )
Mood: Producing boost again in NZ
|
| posted on April 4th, 2003 at 07:45 PM |
|
|
Header lengths
Need some advice on the lengths of both the primary and secondary. Header size is 1.5" for a 1916.
Let's start the bidding at 26" primary.......why...because it was on the net!
[Edited on 4-4-2003 by speedster356]
Spyder-WISD 07-09-05 11.6s @ 125 MPH
Speedster-WISD Nats 05 14.4s @ 89 MPH
Jet cruiser-Coogee 22-09-05 900 deg C @ 110,000 rpm
Weaseling out of things is what separates us from the animals....................Except the Weasel.
|
|
|
 vw54
Super Administrator
Always Waiting 4 Friday
Posts: 16723
Threads: 378
Registered: August 26th, 2002
Member Is Offline
Location: Sunny Sydney
Theme: UltimaBB Pro Blue ( Default )
Mood: Oval resto ongoing
|
| posted on April 4th, 2003 at 08:02 PM |
|
|
R we talking about Jets in a set of Webbers ???
|
|
|
speedster356
A.k.a.: Peter Mcleod
Custom Title Time!
Plastic not Classic Racing
Posts: 1624
Threads: 256
Registered: August 25th, 2002
Member Is Offline
Location: CHRIST church NZ
Theme: UltimaBB Pro Blue ( Default )
Mood: Producing boost again in NZ
|
| posted on April 4th, 2003 at 08:29 PM |
|
|
Nope, exhaust.
primary = single pipe from head to the merg point.
secondary = merged length.
I think.......
Correct me if I'm wrong.
[Edited on 4-4-2003 by speedster356]
Spyder-WISD 07-09-05 11.6s @ 125 MPH
Speedster-WISD Nats 05 14.4s @ 89 MPH
Jet cruiser-Coogee 22-09-05 900 deg C @ 110,000 rpm
Weaseling out of things is what separates us from the animals....................Except the Weasel.
|
|
|
OvalGlen
Custom Title Time!
Posts: 1361
Threads: 46
Registered: August 27th, 2002
Member Is Offline
Location: Liverpool.
Theme: UltimaBB Pro Blue ( Default )
Mood: Change
|
| posted on April 5th, 2003 at 12:31 AM |
|
|
My feeling is that 26 " is the mid point, now I think that longer is more suited for low and mid power and shorter is for top end power.
The secondary I thought was the lenght of pipe after the merge to the outlet.
My oppinion - the shorter the better.
Or at least the least Back pressure the better.
Regards,Glenn>
|
|
|
70AutoStik
Insano Dub Head
Posts: 730
Threads: 18
Registered: August 30th, 2002
Member Is Offline
Location: Dandenong. Victoria
Theme: UltimaBB Pro Blue ( Default )
|
| posted on April 7th, 2003 at 09:00 PM |
|
|
You are looking for a simple answer to a very complex question. Tuned extractors are well nigh impossible to design on the drawing board - you are
talking about finding a tuned length of a varying velocity of a gas of varying density at varying temperatures. You'd actually be best finding
someone who has developed a tuned set of fully merged extractors for your engine combination (capacity, cam, heads, intake,) and buying it.
On a header, of course, the length of the secondary should be as short as possible - with the legth of the primary being as long as possible for
street applications, short for strip... Equal length is important in any NA setup, not so important for turbo.
|
|
|
speedster356
A.k.a.: Peter Mcleod
Custom Title Time!
Plastic not Classic Racing
Posts: 1624
Threads: 256
Registered: August 25th, 2002
Member Is Offline
Location: CHRIST church NZ
Theme: UltimaBB Pro Blue ( Default )
Mood: Producing boost again in NZ
|
| posted on April 7th, 2003 at 09:12 PM |
|
|
Yeah I understand that header/exhaust design is a very complex thing, what I'm looking for is a starting point.
An off the shelf system won't fit the bill due to my specific requirements. I'm aiming for a replica system as below.
Thanks for the input:thumb
Spyder-WISD 07-09-05 11.6s @ 125 MPH
Speedster-WISD Nats 05 14.4s @ 89 MPH
Jet cruiser-Coogee 22-09-05 900 deg C @ 110,000 rpm
Weaseling out of things is what separates us from the animals....................Except the Weasel.
|
|
|
OvalGlen
Custom Title Time!
Posts: 1361
Threads: 46
Registered: August 27th, 2002
Member Is Offline
Location: Liverpool.
Theme: UltimaBB Pro Blue ( Default )
Mood: Change
|
| posted on April 7th, 2003 at 09:23 PM |
|
|
now thats an exhaust system.
Love the look of that ceramic coating
Regards,Glenn>
|
|
|
70AutoStik
Insano Dub Head
Posts: 730
Threads: 18
Registered: August 30th, 2002
Member Is Offline
Location: Dandenong. Victoria
Theme: UltimaBB Pro Blue ( Default )
|
| posted on April 7th, 2003 at 09:39 PM |
|
|
Yep, that's a header! 
You'd have a bugger of a time trying to get away with it on the street, however. The exhaust is not supposed to protude past the body of the
vehicle...
|
|
|
OvalGlen
Custom Title Time!
Posts: 1361
Threads: 46
Registered: August 27th, 2002
Member Is Offline
Location: Liverpool.
Theme: UltimaBB Pro Blue ( Default )
Mood: Change
|
| posted on April 7th, 2003 at 10:02 PM |
|
|
of course a mid engined 356 would be different story.
Regards,Glenn>
|
|
|
speedster356
A.k.a.: Peter Mcleod
Custom Title Time!
Plastic not Classic Racing
Posts: 1624
Threads: 256
Registered: August 25th, 2002
Member Is Offline
Location: CHRIST church NZ
Theme: UltimaBB Pro Blue ( Default )
Mood: Producing boost again in NZ
|
| posted on April 8th, 2003 at 06:20 PM |
|
|
Looks like I'll have an overhang out the back but what the hell........
Spyder-WISD 07-09-05 11.6s @ 125 MPH
Speedster-WISD Nats 05 14.4s @ 89 MPH
Jet cruiser-Coogee 22-09-05 900 deg C @ 110,000 rpm
Weaseling out of things is what separates us from the animals....................Except the Weasel.
|
|
|
Baja Wes
Bishop of Volkswagenism
V6 Baja Pioneer
Posts: 3119
Threads: 94
Registered: August 26th, 2002
Member Is Offline
Location: Brisbane
Theme: UltimaBB Pro Blue ( Default )
Mood: Content
|
| posted on April 11th, 2003 at 07:56 AM |
|
|
I was originally keeping quiet on this subject, in a hope someone smarter would enlighten us all. Since this post has hit the 2nd page I guess that
ain't going to happen. I am also interested in info since I will be building extractors soon.
in a 4-1 system, the 4 is the primary's, and there are no secondary's.
in a 4-2-1 system, the 4 is the primary, and the 2 is the secondary.
The only equation that I could find (so far) gives you the length to the final merge (the start of the 1).
L = (850 x ED)/RPM - 3
Where L is the pipe length is inches
ED is 180 plus the number of degrees the exhaust valve opens before TDC
RPM is, well rpm.
That formula is a rough guide given in Graham Bell's book, "performance tuning in theory and practice".
They is apparently a computer program called "engine analyser" that is good for designing headers, and requires heaps of info like exhaust
port size and length...
|
|
|
Baja Wes
Bishop of Volkswagenism
V6 Baja Pioneer
Posts: 3119
Threads: 94
Registered: August 26th, 2002
Member Is Offline
Location: Brisbane
Theme: UltimaBB Pro Blue ( Default )
Mood: Content
|
| posted on April 11th, 2003 at 09:41 PM |
|
|
You might also wanna check this out
http://www.bgsoflex.com/auto.html
go to "best header" in the menu on the left. Seems very simplied but might be another check on the length your after.
oh, and here's some useful conversions
1inch = 25.4mm
1mm = 0.03936996 inch
1 cc = 0.06102374 cu.in
1 cu.in = 16.38706 cc
I reckon it's out of what though. The lengths it estimates are out of whack. They seem too short.
[Edited on 11-4-2003 by Baja Wes]
[Edited on 11-4-2003 by Baja Wes]
|
|
|
speedster356
A.k.a.: Peter Mcleod
Custom Title Time!
Plastic not Classic Racing
Posts: 1624
Threads: 256
Registered: August 25th, 2002
Member Is Offline
Location: CHRIST church NZ
Theme: UltimaBB Pro Blue ( Default )
Mood: Producing boost again in NZ
|
| posted on April 11th, 2003 at 11:23 PM |
|
|
ur right wes, they do seem a bit short on it......14"? hmmmm:o
Spyder-WISD 07-09-05 11.6s @ 125 MPH
Speedster-WISD Nats 05 14.4s @ 89 MPH
Jet cruiser-Coogee 22-09-05 900 deg C @ 110,000 rpm
Weaseling out of things is what separates us from the animals....................Except the Weasel.
|
|
|
Baja Wes
Bishop of Volkswagenism
V6 Baja Pioneer
Posts: 3119
Threads: 94
Registered: August 26th, 2002
Member Is Offline
Location: Brisbane
Theme: UltimaBB Pro Blue ( Default )
Mood: Content
|
| posted on April 11th, 2003 at 11:42 PM |
|
|
you can download a demo version of the "engine analyser V3.0" here
http://www.performancetrends.com/download.htm
|
|
|
