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How To Upgrade Your Foxbody's Intake Manifold

Written By: Connor MC

Shop Foxbody Intakes

There are a variety of intake manifolds to choose from depending on your build and horsepower end goals. Also consider the under hood appeal if you're looking to build a show fox.

Shop Intake Manifolds

Use the links below to find out everything you need to know about the GT40, Cobra and Explorer intake manifold. All 3 are a very popular upgrade for Fox body Mustang owners, and a beneficial one at that!

American Muscle

How do I Identify My Intake Manifold

There are a lot of terms floating around the internet regarding Ford intake manifolds, and perhaps is the reason why many find it a very confusing topic. In essence, there are 3 manifolds out there. There is the Cobra intake, which was the intake manifold installed on Mustang Cobras (real Cobras, 1993 only), the Explorer manifold (available on 95 Ford Explorers) and the third, the GT40 tubular intake manifold. Perhaps some of the confusion stems from the fact that both Ford Explorer and Ford Mustang Cobra engines are interchangeably called GT40 engines, due to their GT40 cylinder heads. In reality, the official 'GT40' intake was of a tubular design (AKA, very pretty), and was offered by Ford Racing via their aftermarket catalog. The GT40 intake did not come stock on any Mustang or Explorer, but it did come on 93-95 Lightnings. Still confused? Here is a summary below. Clicking the name of each manifold will open up a picture.

1) Cobra Intake, 1993 Mustang Cobra

  • Part #F3ZZ-9424-C

2) Early Explorer Intake, 1995-97 Ford Explorer, Mountaineer

  • Casting #RF-F87E-9K461-BA

3) Late Explorer Intake, mid-1997 Ford Explorer, Mountaineer

  • Casting # RF-F87E-9K461-BB

4) GT40 Intake, FRPP Catalog OR 1993-95 Ford Lightning
FRPP Part #M-6001-A50, lower casting #RF-F87E, #RF-F3TE (lightning lower)
Tubular GT40 intakes from Ford Lightnings had a different plenum cover bolt pattern. Thereby, a cover from an FRPP GT40 will not fit on a Lightning, and vice versa. Furthermore, a Lightning lower will not fit on a Mustang 302 V8, as the Lightning lower is for a 351W V8.

More pictures

OK, that is where we can source the different intake manifolds. Now let's move on to actually describing each intake manifold in further detail, EGR and ACT provisions for the lower portions. Be forewarned, all Explorer engines used an EXTERNAL EGR setup, BUT, early-model Explorer intake manifolds have provisions for internal EGR.

Ford Lower Intake Manifolds

Lower Cobra Intake Manifold: As mentioned, the Cobra intake manifold only came on the 1993 Mustang Cobra. The Cobra lower has the standard EGR (center hole and return line) and ACT provisions, no drilling or tapping required. Should be a direct swap.

Early Lower Explorer Intake Manifold, 1995-early 1997): Early model Explorer intakes have the center EGR hole drilled, but no return line. If you wish to run the full EGR setup, you will have to drill through the boss at the back of the intake so that you can run the regular EGR setup. Furthermore, there is a boss for the ACT sensor located on runner #5, but it is not drilled. In order to install the ACT sensor in the stock location, you will have to drill and tap this boss (3/8" NPT). Otherwise, you can relocate the ACT elsewhere (but will still require drilling anyway, so might as well use the provided boss for this)

1997 Lower Explorer Intake Manifold: Unlike the early model lowers, from February 1997 and onward, Explorer intakes came solely as external EGR manifolds. Meaning, there are zero provisions for internal EGR. In this case, most people using this intake just bypass the EGR system. It is possible to drill the lines for the EGR coolant spacer, but be careful, as these later model intakes have thinner walls. Furthermore, there is no boss for the ACT sensor. You can drill and tap runner #5 for this, but again, becareful as the later model Explorer intakes have less material. An alternative is to relocate the ACT sensor upstream, to the air inlet tube.

GT40 Lower Intake Manifold: The last to look at is the GT40 tubular intake. As mentioned, the only Ford vehicle to feature this style of intake was the Ford Lightning. Please note: using a lower from a Lightning will not work (i.e: original GT40 lower) as it is for a 351W engine, not a 302, and will not fit.

Interestingly enough, however, is that all GT40 intakes ordered through FRPP came with the lower that was used for 95-97 Explorers (the early version). Thereby, if you have a proper, matching GT40 tubular upper and lower, it should have the internal EGR provisions somewhat set up, like the early model lower Explorer intake.

Upper Explorer Intake: At the back of a stock HO intake manifold, there are 3 vacuum ports (fuel pressure regulator, EGR, vacuum tree). Both early and late model Explorer intakes, there are only usually 2 ports. In order to hook everything up like it was with the stock manifold, grab a plastic vacuum T fitting and split one of the ports. Fuel pressure regulator, emissions system and a line back to the vacuum tree are what need to be connected from the back of the upper Explorer intake.

Explorer, GT40, Cobra Intake Horsepower Gains: This is the question most probably everyone wants to know. What are the horsepower gains like from any of these intakes? Typical gains are from 15-20 horsepower on a stock motor (meaning only the intake is switched.) What is super interesting, however, is that no matter which intake you pick, all 3 are very nearly identical in performance. Super Ford did a comparison a while back, and their results show that the intakes are always within 4 HP of each other. Click here to view the Super Ford results. In my opinion, 15-20 HP is a great gain, but not everyone thinks this. In fact, many consider the Explorer/GT40/Cobra intake family to be 'junk', and not worth putting on at all. Many will recommend to put on a different aftermarket intake (Edelbrock, Holley, TrickFlow etc). Are these intakes better than the humble Ford variety? Yes and no. Most name brand aftermarket intakes will outflow a GT40/Explorer/Cobra intake, but that does NOT mean an aftermarket brand is better. In my opinion, I think the Ford family of intakes are actually one of the best intakes out there for street driven Fox body Mustangs. Sure, they may not flow a zillion CFM, but they produce respectable power and torque across the band, which is an essential ingredient to make a good street car! Furthermore, show the lowers some love with a dremel, and these intakes will respond very well! Read the next section for more on porting.

Porting the lower, is it beneficial: Definitely! If you're looking to squeeze some more ponies out of any of these intakes, port, or have someone port, the lower intake. The major restriction with these intakes is actually within the lower unit, not the upper. A good port job on the lower can net another 10 HP, and should be able to support a set of cylinder heads flowing around 250 CFM (which is what most aftermarket 302 heads flow, anyway.) Again, these intakes are superb for moderate street/strip combos. For more info on porting the lower, check out the website of Tmoss, a veritable head/intake pro at

Where can I find them? What do they cost? Like their GT40/GT40P cylinder head counterparts, these intakes are relatively easy to find - well, at least the Explorer is. Explorer intakes can be found all over. Local scrap yards, eBay, classified sections, any and all of these methods should yield intakes aplenty (since the Explorer/Mountaineer was a mass produced vehicle, there should be plenty available). Since there are so many of these available, they are the cheapest. Scrap yard prices all vary, but a typical range is from $50-$100 at a scrapyard, $150-$200 from a Fox body enthusiast board.

Concerning Cobra intakes, these require more searching (and more $$), but are out there in strong enough numbers that it shouldn't be too difficult to find one. Areas to check for the Cobra are online classifieds, swap meets and eBay. You can check local junk yards too, but what are the chances there is a 1993 Cobra in there? Due to their lesser numbers, the usually sell for upwards of $250 via online classifieds, sometimes even more on eBay.

The GT40 tubular design is by far the hardest to find. It is the prettiest of the three, which makes it highly coveted, but also produced in lesser numbers. Recall, the GT40 intake only came from 93-95 Ford Lightnings, or ordered via the FRPP catalog when it was available (I don't believe it is anymore). For these reasons, the GT40 tubular intake is also the most expensive. Expect to pay around $400-$500 for one of these off of an online classified section (typically on Mustang enthusiast sites). If you're lucky, you might find one on a scrapped Lightning, but again, these are very few and far between.

Summary of prices (purchasing used via scrapyard, used classified):

  • Explorer: $50-$200
  • Cobra: $250-$300
  • GT40 tubular: $400-$500

Which Intake to Choose?

Ah, the million dollar question... which intake to choose... well, if you read the whole page, you'll know that the differences between each manifold are pretty small. In terms of power, there is hardly a difference. Also, all three will fit under the stock hood without any problems, so size isn't a concern either. So, if power and size are practically the same, what factors are left? Style and cost. Really, it depends how much you want to spend. There isn't really a 'better' intake (out of these 3), just some that are more expensive. However, in the case of the GT40 intake, it is the most expensive, but also the prettiest. Having said that, is there one in particular I would choose over the others myself? The answer is no, there isn't. I would take whichever one I could score the best deal on, and ideally get the matching lower ported.

If you want to know more about upgrading your Fox body Mustang, check out the accompanying GT40/GT40P cylinder head guide. GT40 & GT40P style heads work absolutely great with an Explorer, Cobra or GT40 intake, and are a superb budget upgrade.