The 4.6L SOHC engine found in the New Edge Mustang was improved in many areas over previous years. One of these updates included the intake manifold. This article will cover the primary differences between the OEM intake and the popular aftermarket designs.
Intake Manifold | Part Number | Peak Horsepower | Peak Torque | Available In Aftermarket? |
Old FPP PI Intake Manifold | M-9424-P46 | 244.0 | 275.4 | No |
New FPP PI Intake Manifold | M-9424-P46A | 233.6 | 264.1 | Yes |
Dorman Intake Manifold | 615-178 | 222.4 | 266.2 | Yes |
On February 4, 2002, Ford issued a TSB (Technical Service Bulletin) for multiple Ford, Lincoln, and Mercury 4.6L SOHC engine models due to the plastic coolant crossover design on the intake manifold. This plastic construction would develop fatigue cracks and cause coolant seepage over time in the compromised areas. The fix was the same intake manifold but with a revised coolant crossover that was changed from plastic to cast aluminum. This redesign included a revised alternator bracket and the updated intake manifold.
We will begin with the Dorman Intake manifold. This intake fits other Ford, Lincoln, and Mercury models and the 1999 to 2004 Mustangs with the PI (which stands for Power Improved) cylinder heads. Dorman supplies an intake manifold with pre-installed individual o-ring-style gaskets, alternator bracket, self-cutting screws, thermostat, thermostat gasket, and other miscellaneous hardware depending on the model of vehicle it's being used for. Some of the fastener locations do not have threaded inserts; this is where you will use the self-cutting screws that Dorman provides in the kit.
The only factory hardware that is re-used is the intake manifold to cylinder bolts, plenum to intake manifold bolts, and alternator bracket bolts. The intake runner design is different, and the manifold chamber is significantly smaller when compared to the Ford manifold. This does change where the engine makes peak horsepower and torque numbers.
Now, we can take a look at the Ford OEM intake manifold. This intake will be the same production intake from 2002 to 2004 Mustangs. No revisions have been made, and all of the factory hardware is reused. The intake that’s branded as Ford Performance is the same intake as the original, it’s just sold under the Ford Performance brand.
You will need to purchase new intake gaskets and a thermostat gasket with this intake, as the only pre-installed gasket is the plenum gasket. This intake will not affect horsepower and torque if you’re replacing an existing Ford PI intake.
Alright, so now let’s get to the good stuff! Are there horsepower and torque differences between the two intake manifolds? Well, we are very fortunate to have the best tool in the industry to determine rear wheel horsepower and torque, which is a chassis dyno. The data we will share with you today is from our 2004 Competition Orange GT that has been featured on our channel in a full series titled Keeping Comp. During the restoration process, I put it back on the dyno with the Dorman intake manifold still in place. The car had already had a tune-up, and the check engine light was fixed from the baseline dyno. We had also switched out and added all of the parts associated with the build; that way, we would have an apples-to-apples comparison.
With the Dorman intake, the car made 222.4 HP at 5200 RPM and 266.2 lb-ft of torque at 3500 RPM. We swapped out the intakes and then made another run. With the Ford original intake manifold, the car made 241 HP at 4900 RPM and 274 lb-ft of torque at 4300 RPM. So if we take a closer look at the results between the two manifolds, peak gains were solid at 19 horsepower and 8 lb-ft. More importantly, the curve gains past 3500 RPM were 25+ horsepower and 23 lb-ft of torque. The increase in horsepower and torque is because of the runner design and the larger chamber volume on the Ford original intake. Driving the car around the street, you can feel the difference past 3500 RPM with the Ford intake. And just a friendly reminder, as we can’t stress this enough, individual results will vary!
As of August 2024, Ford Performance has released a new 4.6L 2V Intake Manifold that supersedes the original Ford Performance manifold that has been off the market for years. In the interim, the only available option was the Dorman, which was more of a replacement service part than a performance part, so 2V Mustang owners were left with choosing between a power-reducing manifold or having to find a second-hand original Ford Performance intake manifold.
With the new Ford Performance intake now available, many wanted to know what the differences were and if any previous issues had been resolved with the redesign. At first glance, the new manifold looks more like the Dorman variant than the original, leaving many to believe they would see the same power losses as they did from the Dorman intake. While performance is always going to be the first question, it is important to look at how this manifold helps to solve other issues as well.
For starters, this intake is Made In The USA and definitely shows of the quality that Ford Performance is known for. An aluminum crossover is a given as all aftermarket 4.6L 2V intake manifolds solve the previous 99-00 issue of broken plastic coolant crossovers. This intake also features individual gaskets on the runners similar to the Dorman, but a drastic change from the singular gaskets found on the original PI intake manifold. The heater hose attachment port is also made of a different material to help with longevity.
So now that we have looked at the difference between the Ford Orignal PI intake manifold vs the Dorman, it's time to see how the original stacks up against the new Ford Performance. In order for us to keep things as similar as possible, we dyno'ed the same 2004 Mustang GT with no changes in modifications. First, we ran it with the Original Ford manifold and then we installed the new Ford Performance intake manifold and ran it as well. The temperatures in the shop did not fluctuate enough to make a difference between runs and nothing else was changed between the two runs.
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