Are they interchangeable?
Also heard that 2015+ have boss springs? Did the interwebs lie to me on that?
Also heard that 2015+ have boss springs? Did the interwebs lie to me on that?
2015/2016 5.0 heads fit on 2011-2014?
- Thread starter cb900f
- Start date
Yes, they fit. There is a lot more info in my build thread, these are just the highlights. Click on JPC in my wig to get to it if you are curious.
As for springs, I don't believe so. I think they are the same springs but I could be wrong.
I just want to say, sorry for all of the typos, I am writing this on my Ipad since my laptop broke last January and I don't have the money to go and get a new one just yet. The next thing I did was turn my attention to the heads. As you may know, the Boss heads were no good. They could have been repaired but I felt it was better to pursue a different path with the heads. The problem with the Boss heads is that there really isn't a lot of machining that can really be done to them compared to the GT heads. There just isn't enough meat on the heads where you can do a good head job. Outside of that the Boss heads are very good for stock heads and flow excellently and are capable of creating some very good power numbers as is. That being said, I talked to Steve over at Tasca and he hooked me up with a set of 2015 GT heads and off they went to RGR for their stage 2 head job. Sometimes it is nice to know what kind of product you are getting
The 2015 heads come bare with just valves, valve springs, and keepers so I also needed to get some roller followers along with the lash adjusters. I had the heads shipped to me and got them all ready to be put in. I have to say they are a work of art IMO. Trick Flow Valve Springs, RGR bronze valve guides Ferrea oversized valves, and a nice port work to the intake and exhaust ports along with some bowl work and a whole slew of things I am probably forgetting.
That being said, there have been people noticing that their Cobra jet Intake Manifolds intake runners were much larger in size than the intake ports are on the heads. That will cause a little bit of loss in power than if the ports were matched in size.So I took some painters tape and grabbed my x-acto knife and traced the intake ports on the manifold and transferred that over to some cardboard. Well would you look at that
Perfect fit! Don't mind me holding the piece on the head, if I had let it go, it would have fallen down the intake port and I really didn't want that to happen.
I certainly would have liked to go higher on the compression ratio but stock compression works for me for now. This way I can see what the extra cubic inches and full bolt ons will yield with a Coyote and I'm excited to see what it can do. I know that a Coyote with some big cams can make 577 HP on E85 with 318 CI and a similar setup so I am curious what my entirely different cams and stock compression will do with an extra 9 cubic inches. Plus, down the road when the engine needs to be refreshed I can go a little bit stupid and maybe get that 344ci coyote and run a 12:1 compression ratio and hurt some feelings with it MUWHAHAHAHAHA. I think I will leave this one off here for now.
Back to the fun stuff. After I turned my attention away from math and back on putting parts on the car, I put all of the ARP studs back in. I went down to the bottom of the holes because if I turned them half a turn, they were wobbly as shit and it wasn't something I was confident in. Studs went back in the engine and out came the Cometic head gaskets for a 11-14 Mustang. After lining up the head gaskets on the heads, it looks like everything lined up and is all set. So in case anyone is wondering. 2015 heads fit on the 11-14 block and with 11-14 head gaskets without issues.
Head gaskets got put on the deck and then the heads got put onto the block followed by the ARP washers and ARP nuts. As per ARP instructions I used the ARP assembly lube and put some on the threads of the studs as well as the nuts. It may have been overkill but oh well. I asked around bout the torque procedure at Tim Eichhorn over at MPR Racing Engines told me what he uses for the ARP bolts.
Follow the head stud torquing sequences below for each side
Right Hand
Left Hand
I just went ahead kept my attenion on the heads. As I said eariler, the heads come bare without followers of lash adjuters. In pricing them out, I found it cheaper to go with the newly released FRPP kits rather than buy them separately. So I went ahead and grabbed the boxes for my parts pile.
I started with the lash adjusters and put a very small amount of Comp assembly lube #103 on the lash adjuster and plopped them in their respective holes.
Next thing was to grab the followers and get those into place. They are pretty easy to install, just roll them on the lash adjusters until you hear them click. Before you put them on, always remember to clean your parts even if they are brand new. As you can see here, these are straight out of the box and they are dirty.
Followers are in now.
As for springs, I don't believe so. I think they are the same springs but I could be wrong.
Thanks for the info. Passenger head is torn up from oil starvation. So I'll prolly get a set of 2015 heada.
Is there any advantage that the 15/16 heads have over boss heads?
Price, and I think they flow about the same. Still not sure of the valvesprings.
Price is better/cheaper, They are Cast vs CNC & Material i think is also different from the 12/13 Boss heads to the 15/16 GT heads.
Correct and Unless u have a Boss or know someone with one i don't think Ford is selling the Boss heads to anyone anymore. "larger valves" is taken from my quick search for the 15/16 heads vs ALL 11-14 coyote & roadrunner heads.
Last edited:
Found this. Says "Stiffer" valve springs. Not sure what that means. I'll give the stock 2015 springs and probably 2015 cams a try and see how it goes.
We (mmr) still have plenty in stock (just received a pallet full of them from Ford) We also stock all of the components for rebuilding such as bronze guides, seals, stainless valves - you name it!
Is it true that the boss are pretty much un-portable? Could these be a better head to have ported over boss heads?
Not unportable but u have to be VERY careful for NA applications!
The Boss 302 heads are smoother from what I can tell, it's hard to find pictures of their ports. The Boss heads were CNC'd, not cast, so they are not rough like the 15 heads. When I took the headers off my late build 14 crate motor (with 15 heads) I was surprised how rough the exhaust ports were. I'm not an airflow expert, but I'm guessing smoother is better, airflow is weird though.
Users who are viewing this thread
