5.4 is Bigger Than 4.6

5.4 Fit and Finish

Mustangs have always seemed to have a smaller cubic inch motor than its competition.  Late model Mustangs are no exception.  The 302 from Ford seems to be put up against Chevy 350s all the time. Turns out in 1996 Ford dumped the 5.0 motor in the Mustangs and went a whole new direction.  The modular 4.6 was now placed in between the Mustangs struts.  We went even smaller, and guess what, our competition got even more powerful, they came out with one of the best motors of all time, the LS1.  With just heads, cam, and intake the LS1 will push out over 450 RWHP when built correctly. Try that with a 4.6, we are lucky to get 350 RWHP.  Now just imagine a Ford Factory Production Mustang GT with a 5.4(330).  They have the same heads and cams, all they would have had to do was develop an intake for it.  The closest we ever came was a 5.4 in the 2000 Cobra R, not a common street car.  But now easier than ever, you can put a 5.4 in your modular based Mustang GT and have it look factory and feel factory.

One of the major problems with swapping a 5.4 for our 4.6 initially was an intake that would fit. Being that the 5.4 deck height is 10.079” versus the 8.937” from a 4.6, a normal 4.6 Mustang PI intake would not be wide enough.  The 5.4 was built to be put in trucks anyway, and had an intake design built for low end torque.  The truck intake is also very tall compared to a Mustang PI intake. You had to either run a very tall cowl hood or just cut a hole in your hood and put a scoop to make it work, and you would still have a truck intake not capable of making power above 4000 RPM.  HPS came out with adapter plates, they allowed the use of a PI intake of off a Mustang to be used on a 5.4. Problem with these plates were that they also were thick and required the use of a cowl hood.  The plates also caused turbulence issues with the airflow and limited the revs on the motors.

Adapter Plates

Now new to the game is HPS’s new 5.4 intake build and designed specifically for the 5.4 Mustang Swaps.  This intake has been in the making for quite a while now but is now shipping.  The intake itself is made of aluminum meaning it will hold a small nitrous backfire without cracking and can be ported and polished.  The intake does not limit the revs of the motor like the adapter plates did.  In fact the intake manifold flows very similarly to the Stock PI plastic Intake.  The HPS 5.4 intake was designed with the help of a few guys that have done the 5.4 swap, so the fit and finish of the intake is great.  While in development one of the requirements was for the intake to fit underneath a stock hood.  The intake is a very nice piece of work.

Bare 5.4 Intkae HPS

Another issue for a 5.4 swap was the header clearance issue.  The stock manifolds would work just fine.  No clearance issues what so ever although the H pipe connecting to it would need to be modified to reach up to the manifold flanges.  So since the 5.4 2V heads are the same as the 4.6 2V heads, why don’t you just mount up your nice 4.6 long tubes?  Well being the heads are up higher in the engine bay, the header then tucks too high to the firewall and floorboards.  The actual header tubes are not long enough.  This cause you to either run a shorty manifold, or chop up and weld up a set of long tubes to hope they would work.  Now a set of Longtube Headers have been developed with the help of r3dn3ck (Colin Burns).  This allows the extra air in the bigger cubic inch motor to exhale easier.

Now with an easy inhaling and exhaling motor, the car can be setup to make really decent power. Not only that, but the motor will look completely factory stock, but will have around 100 more foot pounds of torque and nearly 50 extra horsepower in stock form.  So when you line up against that bolt on 4.6 GT you can just say you have the driver mod… Or bring the envious to the dark side, and tell him the secret of the 5.4.