|
Author
|
Topic: What size headers for my combo? .... Having them custom made
|
89_coupe
Gearhead Posts: 248
From: Ontario (Upstate), NY
Registered: Mar 2001
|
posted 03-01-2005 11:59 AM
   
I am having another set and hopefully the last set of headers made for my car this month at the chassis shop. This time I want to make sure the headers have the right size primary diameters and length. It's a 392 stroker (3.85" stroke & 4.04" bore) with a shift point of about 7200-7500RPM with a new cam (depending what Ed Curtis comes up with for a grind) and I have a 5000 stall. I was thinking 1 7/8" about 32" long and 3.5" collectors but should I go to 2" primaries or longer/shorter primaries? I have a full 3.5" exhaust already and will keep the exhaust system and just modify it to fit the new headers. Maybe step headers from 1 7/8-2"? Any knowlegable people out there or anybody know of a website with calculators for calculating correct header dimensions per application? I need to make the decision soon so I can order the flanges and J bends.------------------
Kent '68 Falcon wagon stock 289
'65 Fairlane 500 wagon 10.5:1 351W
'78 Fairmont wagon 10.5:1 302
'76 Pinto wagon 392 stroke
'01 Focus SE DOHC 2.0L
'04 Explorer XLT 4.6 3.73 trac lock What is this FE fixation for which there seems to be no real cure? Something about wanting to spend twice as much money to go half as fast for one third the number of passes between explosions and not being able to find parts to fix it when it does explode. Pinto 392W 15:1, Iron Pro Topline 64/215s ported to 237cc, angle milled .115" to 52.5cc chambers with 2.08/1.6 valves, ported Super Victor, 1.72 rockers, Isky solid roller (290/300 adv, 256/266 at .050", .650" net lift, 108LSA/108 ICL), Crane Pro Series solid roller lifters, 9375 1050 Dominator, Victor water pump, billet 9 key timing set, custom 1 7/8"-2" step headers, 3.5" H-pipe and Hooker Aero Chamber mufflers, C4 w/9" 5000 stall, 4.30 gears, 28/10.5/15 MT ET Drags, 3200#s w/o driver.
IP: Logged |
Rustang
Gearhead Posts: 805
From: Clarion PA
Registered: Nov 2000
|
posted 03-01-2005 12:05 PM
I just went thru this a month ago for my 347. For your cubes and rpm I'd say your on the money with length and 2" dia.I'll post some links when I get a sec
 ------------------
'68 mustang 351 clevor- 10.92@124
'67 Stang, 351W -11.18@118
'69 351C Torino-14.90@100
'78 Pickup 351W-15.56@88
'79 Pickup 460 ET=??
IP: Logged |
Rustang
Gearhead Posts: 805
From: Clarion PA
Registered: Nov 2000
|
posted 03-01-2005 01:13 PM
Here's a calculator
http://www.slowgt.com/Calc2.htm#HeaderLooks pretty close to 2"dia and 4" collector. There's some other ones out there but this one seemed more in tune with what some of the header mfg's were telling me.
IP: Logged |
n2oMike
Gearhead Posts: 2680
From: Spencer, WV
Registered: Jan 2001
|
posted 03-01-2005 03:36 PM
I vote for stepped headers.Speaking of headers, I saw the factories have started doing something I've been waiting for the aftermarket to do. They are HYDROFORMING tubular exhaust headers. (GM I believe) This allows for a shape other than round. As most of us know, a 'D' shape with the flat floor flows best around a curve... as it allows the gas along the wider floor flow at a slower velocity, and make its tighter radius turn. I've been looking for this (for the tighter turns) for some time now. I'm surprised NASCAR and others haven't started doing it yet. It's like continuing port technology on into the header. Makes sense to me, anyway. Probably expensive to pull off though. It should definitely be worth something on mustangs, etc, where that first turn out of the head is VERY tight. Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
IP: Logged |
kid vishus
Gearhead Posts: 6395
From: middle of NC
Registered: Oct 2000
|
posted 03-01-2005 09:58 PM
Considering the way my 1 7/8" primary Super Comps choked the power on my 402" motor, I would definately suggest a bigger primary for yours. The previous owners had 2" stepped to 2 1/8" primary headers on it, with a 4" collector. Between the bigger headers and the bigger carb they were using, they made over 50 hp more to the wheels than I am. And we could see on the dyno sheet where there was a restriction in my system. [This message has been edited by kid vishus (edited 03-02-2005).]
IP: Logged |
TomP
Gearhead Posts: 6000
From: Delta BC Canada
Registered: Dec 99
|
posted 03-01-2005 10:08 PM
I'd go with 1 7/8" to 2" stepped with a 3 1/2" collector or a merge collector. I wouldn't use a 4" collector on 2" tubes and prefer a 3 1/2" one even for 2 1/8" tubes.
IP: Logged |
n2oMike
Gearhead Posts: 2680
From: Spencer, WV
Registered: Jan 2001
|
posted 03-02-2005 07:26 AM
In case you didn't know... TomP builds custom headers.------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
IP: Logged |
89_coupe
Gearhead Posts: 248
From: Ontario (Upstate), NY
Registered: Mar 2001
|
posted 03-02-2005 05:05 PM
Thanks for the replies. I will try to get 2" primaries made if I can find the Dart 3" bolt spread flanges. I found the 1 7/8" flanges from Stahl but no 2" yet. I've read about those new primaries with the "D" shape. Supposedly like a short turn radius on a port floor into a valve bowl. I want to go with 2" primaries because I plan on a larger stroker with more RPMs in the future like a 418-427 at 7800 RPM (7200-7500 HP peak) or maybe a little nitrous with the current 392. If Tom wasn't so far away, I would have hecked with him about having a set made. Thanks guys for helping me to decide on how to have them built ------------------
Kent '68 Falcon wagon stock 289
'65 Fairlane 500 wagon 10.5:1 351W
'78 Fairmont wagon 10.5:1 302
'76 Pinto wagon 392 stroke
'01 Focus SE DOHC 2.0L
'04 Explorer XLT 4.6 3.73 trac lock What is this FE fixation for which there seems to be no real cure? Something about wanting to spend twice as much money to go half as fast for one third the number of passes between explosions and not being able to find parts to fix it when it does explode. Pinto 392W 15:1, Iron Pro Topline 64/215s ported to 237cc, angle milled .115" to 52.5cc chambers with 2.08/1.6 valves, ported Super Victor, 1.72 rockers, Isky solid roller (290/300 adv, 256/266 at .050", .650" net lift, 108LSA/108 ICL), Crane Pro Series solid roller lifters, 9375 1050 Dominator, Victor water pump, billet 9 key timing set, custom 1 7/8"-2" step headers, 3.5" H-pipe and Hooker Aero Chamber mufflers, C4 w/9" 5000 stall, 4.30 gears, 28/10.5/15 MT ET Drags, 3200#s w/o driver.
IP: Logged |
Mustangsandmore Forums
