4.6 heads

I'm looking for a set of performance heads for the 95 ford thunderbird with the 4.6 at any price the best that can be found I hope, I am willing to wait and save up.:confused: I've looked and none of the heads I've seen seem to work for the standard 4.6. And also any other bolt on parts for the 95 4.6 that add decent horsepower. Thanks

How about the 'Stang Cobra DOHC heads? Does anyone know if those are an easy bolt on?

That would be sweet...

The Cobra DOHC heads will not fit if you're running SOHC. It would require an entire engine swap.

I think the GT-40 heads will fit, but require serious modifications or you risk cracking the block. The 4.6 is just a 289 core, so it is possible that heads/intake can be adapted with other SBF parts, but I have yet to see it done.

I'd look at a Summit catalog and see what's available, and you can also call their 800 number for product support/questions.

OK, update: I was told by a friend that using SBF 289 parts will not work on a 4.6 (damn shame too, lol). Although i do believe that the 99-up GT 4.6 mustang heads are a direct swap.

HOWEVER, I was told that it is possible to adapt the heads of a 5.4L triton motor with some new gaskets/runners and that's it. don't know if it'll really be that easy, but its worth a look if your looking for extra HP. i think someone on cardomain.com might already have a similar set up.

Just a thought.

Thanks for the help, I will try and see if I can find a good set. Would jegs have a set of heads that would offer some power.

Ok, let's set the record straight as there is more urban myth in this thread than facts.

1) The 4.6L was introduced in 1991 in the Lincoln TC. It is NOT in ANY WAY a derivitive of a prior Ford engine, not the SBF, BBF, FE etc, NONE. NO parts from a pushrod enigne can be used on these "modular" OHC eninges.

2) You cannot just bolt on 4V heads.

3) There is NO difference between 4.6L and 5.4L heads of the same design... they are completely interchangeable.

4) There are two basic 2V heads. The newer "Performance Improved" (PI) heads with rectangular intake ports and slightly larger exhaust valves, and the Non-"PI" or NPI heads.

5) There are EXACTLY TWO 2V cam profiles. One for the "NPI" heads ('91-'98 all, some thru '00), and another for the "PI" heads. If you have a '96 or newer modular engine, you CAN use the "PI" cams in it w/o modification, but you CANNOT use them on '95 and older engines... NO WAY.

6) The combustion chamber on the "PI" head are SMALLER than on the "NPI" head. Therefore, if you replace a NPI head with a PI head you will increase your Compression ratio from about 9.4:1 to nearly 10.3:1.. which is a good thing if you want more power and better economy. The catch is you will NEED to run premium fuels.

7) If you are mechanically inclined, you can install the newer "PI" cams, and replace your intake with one for an engine with "PI" heads, and those two things alone will gain you close to 20 RWHP. Add some full length headers and better exhaust and you could be nearing 200 RWHP (about 165 RWHP is stock).

ModMech: I have a 94 4.6, and am wondering about a new cam/internals upgrades. Is there an aftermarket cam made for the pre-96 4.6 or similar swap? Summit has a cam kit for 221-302 SBF, would that fit/work with my engine or are we basically S.O.L.?

I know a new cam will change my valvetrain geometry and possibly require new pushrods, seats, etc, so what are our options? The last thing I want to do is throw a rod through my hood as one older thread indicated.

Raven,

The 4.6L is a MODULAR engine, they are ALL Overhead Cam. There are no push-tubes, or lifters. One cam in each head.

There are also 4.6L DOHC and 5.4L DOHC engines, but none in a factory 'Bird (Mustang Cobra, Naviagator, Lightning, Ford GT, Maruader).

With a '94, you NEED different heads to install a different cams, or you could pull your heads and have them re-machined.

About the only way you toss a rod with a 4.6/5.4/6.8 is to either: Run really thick oil and spin the bearings, knock HARD, or over-rev it (6200 RPM). Then they'll break for sure. The stock 2V rods are only "good" for about 6200 RPM, after that they begin to streatch, and at about 6350 they no longer snap back, they just snap.

ModMech is this the same for a 95?? Thanks for the help.

"the same", as in not being able to get better cams? Unfortuneately, yes. Ford changed the valve train in '96, well actually very late in '95 but I do not know what the part number chenged from/to.

I do not know of anyone who has been able to install "PI" (or any other cams) in '95 or earlier heads. The problem is the amount that you can compress the valve before the spring coils bind. As far as I know, there are not even aftermarket springs that will solve this for the '95 and earlier heads, it's that short.

thunderbird muscle: the 94+95 4.6L block is the same and still applies (for tbirds, cougars, and mark VIIs). The 96-2004 4.6L are all the same as well (mustangs, tbirds, cougars, explorers,), but differ from the 94/5 "production prototype" years. Ours are not as refined/debugged as the newer ones.

ModM: thanks for the info, though i've had this car a while, i'm not familiar with the modular engine internal specifics; i got my feet wet on a 390 FE and other 289s. I ask cause i've already located a pair of 5.4 heads in perfect condition from a local auto dismantler and was curious about the possibilities, what cam options are there for a 4.6 with a 5.4 head swap?

Raven, what are the intake port shapes of your "5.4L" heads? If they are tear-drop, then you have NPI heads... basically the same as all other '92-'98 4.6L heads. If they are squareish, then your in luck..you have the newer "PI" heads.

In any event, since the 5.4Ls are ALL '97 up, you can install "PI" cams without any problems at all. If you have PI heads, the cams should have come with them. If not, they will set you back about $250/pr.

Many different cams have been tried, so far, I've not seen anything better overall then the factory PI cams for a normally aspirated engine. If you have a turbo or blower, then definately, there are better cams for that.

I'm really just looking for a set of heads that are made just for the 4.6 less risk.

ModMech: so what is the net difference in performance between PI and NPI 5.4L heads installed on a 4.6 (HP, TRQ, etc.) besides dispalacement?

Also, while I'm at it should I also try and snag the 5.4 intake manifold as well or reuse stock one (is there a PI 5.4)? Would the 4.6 PI intake in a 99+ GT be interchangeable with the 5.4 heads or no dice? I'm looking for the best combo.

Will my 4.6 headers bolt up easily with the new 5.4 heads as well? Thanks in advance.

will any year 4.6 heads and from any make (except for the DOHC and supercharged ones) work with a 95 4.6 If not what years and what makes will Thanks for all the help!!!!!

Ok,

1) ALL, and I do mean ALL 4.6/5.4 heads ARE THE SAME, there is NO difference. One head will bolt onto the other block and no one will know.

2) There are THREE "2Valve" head designs (except the motorsport "SVO" heads). a) '91-'95: NPI, large chamber, teardrop intake ports, small valve guide/short lift capacity; b) '96-'00 "NPI": large chamber, teardrop intake port, high lift capacity, large valve guide; c) '99-up "PI": squarish intake ports, high lift capacity, small chamber.

3) When installing "PI" heads with smaller chambers to replace "NPI" heads you will GAIN about 0.9 CR points (go from 9.4:1 to about 10.3:1). This is good, but requires premimum fuels.

4) The intakes go with the ENGINE displacement, however the "PI" intakes flow much better than the NPI ones (aluminum or plastic).

5) There is NO NEED to swap heads on a '96 up engine to get more power. All you need is a set of "PI" cams and a "PI" intake to make the SAME power as someone who did the "full" headswap. You will be close, but not exactly the same because you will have the stock CR of about 9.4, while a headswap will yeild 10.3, so it will make slightly more power.

Petis051 Are they performance?

Does anyone know ways to increase horspower by doing things my self ex. Air intake. the only one I know how to do really is the only one really talked about. Thanks for the Help!!!!!!!!!!!!!!!!!!!!!!

If I can help in any way just ask.............

Petis051 Are they performance?

Does anyone know ways to increase horspower by doing things my self ex. Air intake. the only one I know how to do really is the only one really talked about. Thanks for the Help!!!!!!!!!!!!!!!!!!!!!!

If I can help in any way just ask.............


There's tons of stuff you can do yourself.... intake/air silencer removal, underdrive pulleys, throttle body/or tb spacer, MAFs, coil packs, plugs/wires, B&M electronic shift kit, headers, and on and on. The only restriction really is time and $$$$.

check the other threads, I answered this same question for you a while back - peace :2cents:

Thanks

I quess I did forget to add cheap.
I already did the air intake, I'm taking off the silencer this saturday

Where can I find the best tb spacer at a decent price at what size should I get

Also does anyone know how to build an airbox for a ram air hood???

Thanks for all the help!!!!!!!!!!!

No there not performance heads. there off a 95 t-bird 4.6 with twin cams. I was looking though for anyone who knew the best way to change motors in a 95 t-bird, 4.6. any tips would be helpfull. I'll keep an ear out tho for any performance parts for a 4.6 tho. Thanks

What kind of motor do you want to change to a 5.0?

there is a kit to convert a 4.6 to 5.0 over at www.modularperformance.com.

This will give all you need to know. Modular mix and match. Part 1
see it at: www.musclemustangfastfords.com/tech/MixedMatch If you
read all of it twice. Boom, you got your answere. caddy :smokin: