You can make your GT run like Bob Cosby's Cobra by swapping in a Four-Valve engine from Mu
The secondary throttle plates (Intake Manifold Runner Controls) found on '96-'98 Four-Valve engines were designed to give the Cobra the best of both worlds-excellent low-end torque and top-end horsepower. The rectangular port was responsible for the low end, but at 3,200 rpm the throttle plate would open, allowing the round ports to take over and provide the top-end kick for which Four-Valve engines are known.
Of the swaps we feature in this issue, a Two-Valve to Four-Valve may just be the easiest to pull off. During the swap process, we repeatedly asked MV Performance's Tim Matherly, "Well, do you have to change this?" His answers kept coming back, "Nope!" However, even though it may be the easiest swap to do, it's far from the least expensive, with the initial engine investment the most difficult to swallow.
The first order of business will be to evict the Two-Valve from its living quarters. There
We chose Mustang Parts Specialties as the engine supplier since it's only a stone's throw from MV Performance's Statham, Georgia, headquarters. The company has Four-Valve engines from $2,900 that have been removed from '96-up Cobras. Obviously, the newer the engine, the more expensive it will be. A '99 Four-Valve will set you back roughly $4,750. These engines don't have the front accessories on them, but except for the alternator, the Two-Valve and Four-Valve share the same accessory design and components. For this swap, a corresponding computer and wiring harness will be necessary. Thankfully, MPS has these items on the shelf as well.
Before you go into shock from realizing how much this swap will cost, check out the prices for built Four-Valve engines from various Mustang shops. It can get expensive, but if ultimate modular horsepower is your goal, a Four-Valve Cobra engine is the best way to begin.
As there are few parts needed to complete this swap, we will give an overview covering the ones you don't need to change. Follow along as we show you how to inject your GT with Cobra venom.
With the two engines side by side, you can tell right away the Four-Valve is wider than th
Since the two engines share the same mounts and K-member, the Four-Valve Cobra engine can
Since each 4.6 engine differs little from any other 4.6 modular (except for the Cobra havi
You won't have to swap to a different clutch. The only change you need to make here is the
In case you were wondering why swapping in a Four-Valve Cobra engine is beneficial, take a
Since many shops have gotten into modifying the '96-'98 Four-Valve intakes by deburring, p
Even though the '99-up Cobra and GT T45 transmissions are different, if your GT already ha
In contrast, take a look at the dyno numbers of Dianna Sullivan's '98 Cobra, which was fea
This looks fun, doesn't it? Would you really want to go through this swap and not add a bl
Four-Valve in a Fox
One of the pioneers of mod motor racing, Robert Hindman swapped a Four-Valve Cobra engine into his '87 GT and commenced to clean house in both NMRA and Fun Ford modular classes in 2001. Steve Ferguson,
Lupe Davila, Joe Charles, and Gary Youngblood all had amazing success with modular powerplants under the hood of their Fox Mustangs. Robert used an Anthony Jones
K-member to drop the Four-Valve between the fenders and added a MAC exhaust, a Dynomite C4 transmission, a stock Cobra computer, a C&L 80mm mass air meter, and an MSD DIS-4 ignition. With 4.56 gears in the 8.8 out back, he ran a best time of 11.92.
However, by the time you read this, Robert will have a new '01 Mustang based on a body-in-white to take into battle. The move was necessary to comply with Fun Ford Mod Motor class rules.
When we compared an '01 Bullitt with an '01 Cobra, we also had a chance to run the two across the rollers at BBK/Brother's Performance. The results weren't surprising, as the Cobra possesses the superior power characteristics, especially in the upper-rpm range. Also not surprising was the Two-Valve showed superior numbers down low. But by 4,200 rpm, the Cobra politely waved bye-bye to the GT on the way to a peak 274 hp at 5,900 rpm. Peak torque from the Cobra arrived at 4,800, just 200 rpm lower than the Bullitt's 236hp peak.
So what's the purpose of showing this dyno comparison? If you choose the Four-Valve, you'll not only start out with more horsepower on tap, but also the results of your power-adder additions will pay excellent dividends.
|'01 Mustang GT|
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