BossRacing71

Ok, I've just about got everything together to do the PI swap I've been threatening to do for close to a year. My last few questions revolve around the intake. I'm upgrading to 85mm mass and 24# injectors. The 70 mm TB from a 5.4 would also be an upgrade on my 4.6, yes? Are the plenums from the 4.6 and the 5.4 the same, or should I be using the 5.4's plenum as well? I thank y'all in advance for Ur time and input.

P.S. I've been given a pair of shorty headers. I know the consensus is that shorties are no great advantage over stock, but FREE is cheaper than tracking down some PI manifolds. Thoughts?

Captain C

I'm fairly new to the Triton motors, but it seems I read that the block deck height is different on the 4.6 and the 5.4. That would mean you need a 4.6 plenum on a 4.6 motor and a 5.4 plenum on a 5.4.

I think you would lose a lot of low end and mid range with the 85MM throttle body based on my experience with that size motor of another manufacturer. Go for the 70MM TB, leave the injectors alone, and get a programmer.

If you are going to all the trouble to do the head work, might as well add a 5.4 shortblock to those heads.......

BossRacing71

Thanx for the input, Captain. The Mass Air is/was to be 85mm. That along with the 24# injectors were just some parts I had laying around from some previous Mustang projects. I'm not planning on going above 70mm on the TB for no more mods than I have going into this, at this time. After speaking at length to a few of my Mustang buddies who have also modded their Ford trucks, the consensus seems to be that the trucks don't respond as much or as well to some of the mods that we've done on our Mustangs. So the current plan will be to add the bolt-ons in stages, and see what does or doesn't help. Stage 1 will be the heads/cams, Gotts Mod, Silencer Mod, and 70 mm TB.

Started teardown today (Friday). So far I've found 2 minor oil leaks, and one leaky heater hose. I would've never found these if not for the teardown. Of course, I had already bought ALL the necessary hoses so everything will be new anyway. I guess I should have bought stock in Mean Green Degreaser. I'll be using it quite a bit. Anyway, I'm pretty much down to the intake, valve covers, timing cover, then the heads. Has anyone come up with an ingenious way to remount or relocate the power steering reservoir? Just something I was pondering during teardown, ways to unclutter the motor somewhat.

If anyone would be interested in pics along with this write-up, please speak up.

Captain C

The main issues I have gleaned from my research are as follows:
1. The heads can't flow enough air to support a 5.4 at "reasonably" high horsepower levels without a blower/Turbo.
2. The intake manifolds on a 5.4 won't flow what a set of PI heads will flow, much less the TrickFlow heads.

The only options that seem to be available are:
1. Mild, torque related camshafts
2. Valves with back-cut stems for more air flow.
3. Port matching the heads with perhaps a bowl job. (I need to see pictures of the bowl first)
4. Use a 4.6 performance type intake (Shorter, larger diameter runners) with adapters to fit the 5.4 block (about $270 for the adapters)
5. Performance exhaust setup containing:
- Headers
- High flow Cats
- Mandrel bent cat back exhaust
6. A Programmer to make use of these mods. You will also need to find software to connect to your OBD II port so you can see what the changes have done to your fuel curves. You will need to check your Base Line Measurement (BLM) and Integer (INT) for each RPM band your vehicles computer allows) You will want those both to be as close to 128 as possible. But that was on a OBD I computer, I don't know what all an OBD II computer contains yet (But I will!!)

Also, I now have the head gasket related oil leak so pictures would be helpful to me!!!!