4.0L SOHC V6 performance heads?

I'm starting to investigate the availability of performance heads for my 4.0L SOHC V6.

Morana Racing with a $300 core charge (for a pair) offers three options:

Stage 1 for $700 includes rebuild, 3 angle valve job, match ported & lightly polished around the intake/exhaust ports.

Stage 2 for $980 appears to include Stage 1 plus porting & bowl work

Stage 3 for $2300 appears to include Stage 1 & 2 plus best street porting, larger intake & exhaust valves, heavy duty springs

I didn't find any performance results for the above on their website and I haven't found any posts on the internet for Mustangs, Rangers or Explorers using their heads.

Super Six Motorsports (SSM) with a $300 core charge (for a pair) offers two options:

Eco Heads for $1150 includes gasket matched exhaust ports, blended intake & exhaust bowls, unshrouded valves, standard valve job, new seals & springs w/shims, surfaced and assembled, 220 CFM/168 CFM exhaust, use with stock or regrind cams

Stage 3 for $1900 includes fully ported & polished intake & exhaust ports & bowls, unshrouded & polished chambers, 1.86/1.56 swirl polished stainless steel valves, new valve springs w/shims, 236 CFM intake/176 CFM exhaust, use with stock or regrind cams

Their website has a dyno graph for a stock Mustang with Stage 2+ (equivalent to Eco?) heads with a 25 increase of max rwhp and larger increases at lower engine speeds. They did not post the performance increase for the Stage 3 heads. I found a thread on a Mustang forum for a build using the Stage 2+ heads, stock cams, Manley rods and pistons, 63 gph injectors, a MP1900 TVS blower (14 psi) and a custom tune. The engine produced a max 342 rwhp and 347 rwtq and has provided reliable transportation to date for more than 40K miles.

I've read that there are no significant idle issues running the Stage 3 heads with the SSM reground camshafts but that fuel economy suffers. I would like to find out what the performance increase (and disadvantages) would be running the Stage 3 heads with stock camshafts. Larger valves seems desirable but may have little effect without larger lift cams. Also, the gains may be insignificant at low to mid engine speeds.

 

[Dono]

This might help on valve sizing.

I've researched larger valves (unshrouded also) on the v8 gt40p heads. The results are huge flow increases in low and mid, but no appreciable gain on high lift. I'd expect results to be similar on the sohc valves. Following these results, is a higher lift cam really going to make a huge difference?
I'm really thinking of sticking with a low lift cam and larger valves sometime down the road. Another huge bonus is the lower stress on the springs and related assembly.

 

[2000StreetRod]

new valve springs

I suspect that the new valve springs in SSM's Stage 3 heads are stiffer than stock to support the higher lift cam. I'd rather not increase valve train stress. Larger diameter valves with the stock lift may require even more valve unshrouding than the Eco heads to get the same flow.

SSM states in their tech article that the stock valves are poor quality with visible porosity.

For street driving the additional cost of Stage 3 ($750) vs Eco probably isn't worth it. If I could get 25 more rwhp with Eco heads ($1150), new gaskets, and a head stud kit ($475) that should meet my $100/rwhp increase and I wouldn't have to pull the engine.

 

[jd4242]

Why not have a local shop do the work?? Im sure you could build the stage 3 for about half of what they are charging. .you then could have them built for your application, forced induction. .

Man I haven't seen the sohc heads in awile, those valves are crammed in there

 

[2000StreetRod]

local shop

Using a local shop would be my preference since I like to get involved in any modifications performed on/for my Sport. I would like to find a shop that has experience with the SOHC V6 heads. Unfortunately, most Mustang V6 owners don't perform significant performance improvements on their engines. Instead they upgrade to the V8s. Greenville, SC only has a drag strip in the area and I don't want to drive to Charlotte, NC or Atlanta, GA. for machine work. I've been watching for a "bargain" engine to purchase for experimentation. I'm still trying to find out what the casting changes were and when they occurred. That will determine if I purchase an Explorer, Ranger or Mustang engine and what year. When I get one I'll start visiting the local shops asking about their capabilities and experience.

 

[jd4242]

Using a local shop would be my preference since I like to get involved in any modifications performed on/for my Sport. I would like to find a shop that has experience with the SOHC V6 heads. Unfortunately, most Mustang V6 owners don't perform significant performance improvements on their engines. Instead they upgrade to the V8s. Greenville, SC only has a drag strip in the area and I don't want to drive to Charlotte, NC or Atlanta, GA. for machine work. I've been watching for a "bargain" engine to purchase for experimentation. I'm still trying to find out what the casting changes were and when they occurred. That will determine if I purchase an Explorer, Ranger or Mustang engine and what year. When I get one I'll start visiting the local shops asking about their capabilities and experience.

My buddy probably has a couple sets laying around if you want me to ask..

 

[2000StreetRod]

long block

I plan to purchase a long block. But it would be helpful to know if the head casting changed or the block casting. On some year of the 3rd generation and later the opening for the front cassette in the head does not align with the opening in the block. That makes it difficult to extract and install the guide assembly because the pivot bushing will not clear the opening.

Ford eventually replaced the pressed bushing with a circlip bushing allowing the guide to be disassembled for removal/installation with the head in place.

If the change was in the block casting then maybe the cylinder wall thickness also changed. I'm wondering if Ford strengthened the block in 2004 in anticipation of using it in the Mustangs.