headers on a 4.6 d2???

jprover2

Well-known member
Apr 8, 2017
146
10
Birmingham,Al
Why not stay with factory manifolds? Headers are hard to get sealed and a lot rust or warp, not counting clearance issues. It's a lot of headache for very little power. I say this with years of experience in a shop repairing exhaust. Not trying to knock on you, if you have a cam and heads that require more flow then by all means...

There is this guy
 

Gordo

Well-known member
Hedman makes them. I had them on a series hybrid I built and they worked and sounded well. That was with a carb set up though. Not sure it’s worth the hassle with cats and O2 sensors. The fit was fine with some minor tweaks as I recall.
 

Stocksuspension66

Well-known member
Mar 26, 2020
104
9
California
o2 sensor placement will be a hurdle. Headers won’t help due to the fact the exhaust port is so restricted. Get yourself a good muffler for noise. I running ported heads and mild cam on a 4.6 with bone stock exhaust. Big gain in midrange. The exhaust is not that restrictive on these trucks unless you bang a muffler on rock. Lol
 

gthphotography

Well-known member
Aug 27, 2008
317
3
chicago
www.greghanrahan.com
Used factory manifolds are on ebay for $50.00 each, and i'm sure tillery has a pile for a good price. Are your leaks at the exhaust ports or the y-pipe?
I recently rebuilt the engine, and things were fine again for a little bit and now it's spitting gasses at multiple points. I just don't feel that the mating surfaces are matched any longer. I have pulled them and reinstalled them with new gaskets plenty of times. With the headers, there's less surface area that comes in contact with the block and IMO less excess material to restrict the compressing of the gasket. But I could be wrong. Eh.
 

gthphotography

Well-known member
Aug 27, 2008
317
3
chicago
www.greghanrahan.com
Why not stay with factory manifolds? Headers are hard to get sealed and a lot rust or warp, not counting clearance issues. It's a lot of headache for very little power. I say this with years of experience in a shop repairing exhaust. Not trying to knock on you, if you have a cam and heads that require more flow then by all means...

There is this guy
That guy won't give out any info on what he's done to his truck except that completely bonkers hydrogen fuel setup he swears by and that Jesus will save you from the plague.
 

4Runner

Well-known member
May 24, 2007
660
110
Boise Idaho
Have you squared up your manifolds? I would before I re installed them. You could then get them ceramic coated and call it good. The manifolds are actually not a bad design. The factory Y pipe leaves a lot to be desired. The one on my 94 had so many restrictions. It really couldn’t have been worse. Not sure if they are all that way or I just got a special Monday morning version.
 

robertf

Well-known member
Jan 22, 2006
4,781
358
-
The non o2 y pipe is a much better design, but the non genuine version I got was terrible
 

gthphotography

Well-known member
Aug 27, 2008
317
3
chicago
www.greghanrahan.com
Have you squared up your manifolds? I would before I re installed them. You could then get them ceramic coated and call it good. The manifolds are actually not a bad design. The factory Y pipe leaves a lot to be desired. The one on my 94 had so many restrictions. It really couldn’t have been worse. Not sure if they are all that way or I just got a special Monday morning version.
Squared as in machined?
And I looked into ceramic coating and that's actually a good idea , thank you for reminding me.
 

robertf

Well-known member
Jan 22, 2006
4,781
358
-
Does ceramic coating do anything on cast iron? I can see it working on mild steel but cast kind of creates a ceramic barrier naturally
 

4Runner

Well-known member
May 24, 2007
660
110
Boise Idaho
Yes, like machining flat again. I would bet that if you placed a straight edge across your mating surfaces, you would find they are not all flat. I would think that the ceramic coating would make the manifolds run cooler/ not so much heat soak, but it’s certainly not necessary if you want to skip that part. I am going to try it just to see what happens.