V6 Mustang headers (Page 1/1)
longjonsilver DEC 21, 07:08 AM
i am putting a 3800SC from a 2002 GTP into my 84. i have read about using the 95 Mustang 3.8 V6 headers to eliminate the crossover. This would make my exhaust more free flowing and reduce heat near the air throttle body, plus free up the transmission linkages so they can be left stock. i either modify the transmission linkage connections or i modify the exhaust. i got the idea from here, third post down:

http://www.fiero.nl/forum/A...120111-2-088852.html

There is also these discussions:

http://www.fiero.nl/forum/A...060206-2-067914.html

http://www.fiero.nl/forum/A...090907-2-092163.html

So i got some questions for y'all.

Can the flanges from the 3800SC manifolds be cut off and welded to the Mustang headers, rather than rotating the center Mustang flange? Is it hard to weld to the 3800SC exhaust manifolds, or does it flow real well with stick and 6011 rod? Where should i weld in an O2 sensor or do like Dan does and use the 3800 rear manifold with its O2 sensor and block off the crossover?

Thanks
jon
Dennis LaGrua DEC 21, 08:07 AM
Hello and Merry Christmas in Nova Scotia. Its a beautiful province.
Just a few thoughts. I have never tried this install but based upon what you have mentioned, there are some issues with your plan. The manifold that ends up near the firewall in a 3800 swap is cast iron. The Mustang headers are steel. IMO, it would be nearly impossible to cut the cast iron 3800 flanges off and weld them to tube steel headers. You could modify the Mustang headers to fit but why do it?
My recommendation is to scrap this plan and buy the powerlog manifold from ZZ Performance. Its non restrictive and the fit is easy and the flow is far better. The firewall manifold (lft side) is the restrictive part of the OEM system and the powerlog eliminates that. Why try to reinvent the wheel when a bolt in solution is available?

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

longjonsilver DEC 21, 08:52 AM

quote
Originally posted by Dennis LaGrua:
My recommendation is to scrap this plan and buy the powerlog manifold from ZZ Performance. Its non restrictive and the fit is easy and the flow is far better. The firewall manifold (lft side) is the restrictive part of the OEM system and the powerlog eliminates that. Why try to reinvent the wheel when a bolt in solution is available?



Well, cuz the powerlog is 149US - $200C - plus shipping, taxes and handling charges (i had to pay it from ZZP for my gaskets) - translate better part of $300C to my door, when the Mustang V6 headers are available locally for $70 each tax included - i might just buy the one for the front of the 3800SC - and use of the crossover still makes me build a solution to the tranny linkages.

Nother question: i would need the RIGHT side of the Mustang headers, no? So that the exhaust is towards the Right side of the Fiero? In other words, i put them on backwards. Or is there something i am missing here?

jon

------------------
Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.

Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.

I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun!

Raydar DEC 21, 10:15 AM
While not exactly what you asked, "Johns 4.9" is in the process of developing a complete "true dual" header/exhaust system for the 3800.
It'll be complete from the heads to the elbows at the rear. You'll need to supply your own tips.
The trunk will not need to be cut.
Obviously, it will be more spendy than the ebay or Mustang headers, but how much were you budgeting for the rest of your exhaust?

[This message has been edited by Raydar (edited 12-21-2020).]

longjonsilver DEC 21, 11:43 AM

quote
Originally posted by Raydar:
Obviously, it will be more spendy than the ebay or Mustang headers, but how much were you budgeting for the rest of your exhaust?



But yeah, thats great to know, and like everything in my life i want to spend as little as possible, and still do good work, i am not looking for the most power possible. i am leaning towards using the rear 3800 manifold as is, blocking off the crossover (i am assuming that it is steel and can be welded). That gives me the O2 sensor in stock position, takes the heat away from the intake, and eliminates the need to build around the shifter linkages. i have heard several places (and Dennis) that the restrictive exhaust manifold is the front one, so that solves that. What i don't know is if i need to modify the cradle this way or if i can still use a full sized muffler. More questions....

------------------
Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.

Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.

I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun!

Dennis LaGrua DEC 22, 12:35 PM
Just a point of clarification. The rear manifold on a 3800 is the one that is on the front when in the Grand Prix and other FWD car applications that have used it. So it is confusing when you refer to front and rear. The best way to describe is left (driver side) and right (passenger side). If you wish to replace the cast iron manifold on the 3800SC with a Mustang header the process is to re-orient the flanges and do some mig welding. On the installs that I have read about , it seems that some use the header sides interchangeably depending on where you want the exhaust feed. The question that often comes up is : do the Mustang headers actually give you that much more horsepower?

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 12-22-2020).]

longjonsilver DEC 22, 02:25 PM

quote
Originally posted by Dennis LaGrua:
The question that often comes up is : do the Mustang headers actually give you that much more horsepower?



Yes, it is confusing. i often call it the rear, cuz that is how i see it from my position at the back of the Fiero. Actually it is in front of the engine and on the drivers side when installed in a normal front engine rear wheel drive configuration like the Mustang.

i am not looking for more power but not modifying my 4 speed transmission linkages and getting heat away from the intake. Power is secondary.

jon

------------------
Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.

Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.

I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun!