There are 2 problems with trying to modify the 5.4 2V. First off, there are no good flowing intake manifolds for it, so all the cam and head work in the world is going to get choked off by the intake, and second the motor has a small bore and long stroke, so when you start trying to run higher rpms for more power, you run into issues with not being able to fill the cylinders enough. Really the easiest way for more power out of the 5.4 2V is going to be a lightning supercharger swap. If you kept the stock lightning blower and had a conservative tune, you could get away with leaving the stock bottom end alone. Obviously a turbo setup will also work, but that will involve more custom fabrication. Another option that might be a cheaper way out would be to swap the engine for a Lincoln Navigator 5.4 4V engine. That engine will bolt right in place of your existing one, makes 40hp more than your existing motor in stock form, and responds much better to mods than the 5.4 2V does.

 

Mikey, have to disagree with you about the intakes. Granted that when it comes to off the shelf intakes the choices are limited but there are some. Trick Flow has their Street Burner intakes along with Fox Lake. Both open up at 5k RPM and are to 7 and 8k respectively with stock heads. Beyond these there are a number of speed shops that build proven intake designs to order. SHM also will take a stock 4V intake and cut the bottom off and fabricate straight runner intakes to customer designs that offers massive power improvements. EFI Hardware also makes an intake that pumps enough air that it is also designed to run the brake booster off of it because of the vacuum it creates. It does require a custom PCM though. Of course much more cash is involved compared to the off the shelf products but there are some swap options for those interested in track performance or in just doing something different. There's also the reality that there are a lot fewer people building for profit compared to those that do it because they have to.

You are absolutely right though about what a 4V swap can offer for a whole lot less of an impact on the wallet.

 

My Buddy just put a 4V Navi motor in his F150, and is running it off 2V electronics.

 

That's interesting. I would have thought the AFR would be out of specs. Apparently not which opens up a lot of options. IIRC, wasn't it was said the 4.6 and 5.4 use the same electronics?

 

The fox lake and trick flow intakes are for the 4.6 2v. The 5.4 has a taller deck height, and so it needs a wider intake manifold, and nobody makes a good performance intake manifold for the 5.4 2v. You can buy manifolds for the 4.6 2v, the 4.6 4v, and the 5.4 4v, and you can build impressive power with any of those motors, but the 5.4 2v is completely ignored by the aftermarket.

 

He's also a dealer for SCT, so I am sure he's done something with the A/F ratio.

And yes, you can run a 5.4 off of 4.6 electronics.

 

I wonder why that is? Is it simply a lack of support or are there specific reasons for not supporting the engine? There is still the option of places like Hogan's that will build you whatever you want. It may be a bad choice with better options but they will still build it for you.

 

All the 4.6 2V support exists because of the millions of Mustang GTs that came with that motor. The 5.4 2V only ever came in trucks, and most truck owners are looking for low rpm torque over horsepower, so there really isn't much of a market for truck owners wanting short runner intake manifolds. Since 4.6 and 5.4 2Vs generally make the same horsepower and just different torque numbers, there also aren't too many Mustang owners going through all the work of an engine swap, and since the intake is physically wider, you would need a whole separate casting, and there simply aren't enough buyers to justify the cost of doing all that.

 

So anybody that wants to should go check out this guy "auto detour" on youtube. He's been driving around in a 5.4 2v with a 4.6 2v turbo system that he modified to work on a 5.4. Now he went with 8 lbs of boost and was making 500+ tq at the wheels, and yeah I get what everyone has said, and I agree, but dang he has been driving around like that for almost 2 years, just started forging the internals so he can make more power. I'm somewhat curious if someone could run the same setup at about 6lbs and make in the 400tq range, would this be a fun and reliable truck or is that still too much for it?
I still feel like I'm not getting any clear answers though, I get the long stroke small bore issue, but what exactly is the weak point in these engines? Are the rods brittle? Is the crank made of cast silly putty? does it have asthma and just cant breathe enough?
@River1 I will need to look into that book. I'd love to learn how to port the heads for the torque gains I want. I wonder how much info they have about short tube vs long tubes? I plan to use this truck to pull my jeep to the trails and vette to the track, so I'll be looking at all low end gain modifications all day. High end hp is boring in a truck without the proper grunt.


DISCLAIMER: I am doubtful I'll ever build the truck for lots of power, but dang it looks cool, and if I had the cash....I would.

 

The weak point of the internals is the rods and the pistons. The rods are powdered metal, which means they take a bunch of fine metal powder, and compress it with heat to form the rod. It is a cheap and effective way to make rods, but when they fail, they don't bend, they shatter into a million pieces. The pistons have a very narrow top ring land. That is great for efficiency and reduced engine wear, but if you get detonation, especially under boost, it can break a ring land off the piston. That being said, 400ft-lbs or even 500ft-lbs is not out of the question on a stock bottom end. I have a MarkVIII with a Procharger on it, running 9psi, and it dyno'd at 450ft-lbs on a stock bottom end, but the tune is very conservative. A buddy of mine also has a 4.6 with the SVO blower on top of a 200K mile NPI bottom end with PI heads on it, so that is about 10psi on top of 10.8:1 compression, and the stock bottom end has held up fine for years. Turbos and centrifugal superchargers are easier on the bottom end than a roots blower is too, so keeping 6-8psi from a turbo, with a conservative tune, you would likely be fine. Of course every engine is different, so don't come blaming me if it grenades, but if it were my truck, I would try everything out on a stock bottom end first. If it survives, great, but if it blows, then you can either swap in another stock engine and dial it back a bit, or build a full forged bottom end for it.

As for headers, long-tubes, or nothing! Shorty headers only add power due to less restriction, which means they will only add power in the higher rpm range, and since the manifolds on the 4.6/5.4 actually flow a decent amount, shorty headers likely won't even gain you that. Long-tubes can sometimes add 30ft-lbs of torque in the midrange! Long-tubes are the only way you are going to get any scavenging effect, which will benefit power production all through the rpm band. If you aren't going to run longtubes, just leave the stock manifolds, or port the manifolds, but either way, manifolds take a long time to rust out, are quieter, and don't need periodic re-torquing to make sure they aren't coming loose. Shorty headers give you all of the headaches of headers, with little or none of the gain.