5.0L intake article update!!!! - TCCoA Forums
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post #1 of 4 (permalink) Old 10-12-2003, 07:40 PM Thread Starter
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5.0L intake article update!!!!

Neither myself nor the TCCoA are at all responsible if you screw your car up because you tried something written here and botched it up. So don’t mess about!

The most visible, and most heavily marketed, part of our engine is the intake manifold. The Ford EFI manifold has such a unique shape that it can be instantly recognized, there’s never any doubt as to what you’re packing under your hood. However, our MN-12s are poorly equipped in the intake department (to put it mildly); so why the heck not get a better one? Maybe this’ll help, read on.

General Info

An intake manifold made to fit a ’94 or ’95 Mustang 5.0L is your best bet as they are the same style manifolds used on the 91–93 MN12. They have the curved neck like the MN-12 5.0L. The Stock 5.0L manifold on the 94/95 mustang is identical to ours, so a performance intake should be sought out. An earlier style manifold may work with the addition of a throttle body adapter and some work with respect to hood clearance. Also keep in mind that the following information is given with respect to the Thunderbird. Most of what is said also applies to the 5.0L Cougars, but remember that they don’t have quite as much hood clearance. It is possible to lower the engine slightly to help compensate, but I won’t go into detail here.

As a side note, when choosing a throttle body to go with your new intake manifold; anything bigger than 65mm is usually a waste of time since the intakes can’t flow the amount of air the larger T/Bs are capable of. Thus you end up with slow throttle response and a large bog when going to WOT. This information comes straight from the horse’s mouth. This horse’s name happens to be Lonnie Doll. He has conducted a number of dyno tests and has spent way too much time working with our cars. He can be at least partially credited with where we are today with these vehicles. A lot of the information here comes either directly or indirectly from him. So shut up and listen.

Fitment and Clearance

For most of the manifolds here trimming of the hood bracing will be a requirement, although a cowl hood can be used in lieu of this. The GT-40 will require a cowl hood; just trimming the bracing isn’t adequate. It is possible to lower the engine slightly to help compensate, but I currently don’t have the details. This may allow the hood to go fit without trimming. In general to retain the stock hood, you need to keep the intake height under 10 ¼”. Keep in mind that Cougars require a little more clearance. Additionally, trimming of other components may sometimes be necessary depending on how your engine is setup, such as the wiper motor mount. Just be ready for surprises if you decide to color outside the lines.

Not all of the manifolds listed here are equipped with an ACT sensor provision. Fortunately it doesn’t take much to modify them. You can drill and tap the boss on the #5 intake runner with a 37/64 drill bit and a 3/8 NPT tap (see picture below). Or purchase an ACT Relocation Kit from Interactive Systems and Technologies for around $30 (Part number AH-8614-F either directly from Interactive Systems and Technologies or through Year One or Mustangs Unlimited). Another option is to lengthen the ACT wiring harness and use the above mentioned drill and tap on your stock airbox. This method however can only be used on naturally aspirated vehicles (no turbos or superchargers). Any manifold that isn’t already equipped with an ACT provision should be modified for one.


A simple addition to the stock intake is the addition of the Holley EFI lower (part number 300=73S. This is a direct replacement for the stock lower but has larger ports and better 1 & 5 runner configuration to improve flow to those cylinders. Edit: This part has been discontinued; they may be occasionally available on E-bay or other used parts sites.

Trick Flow Specialties

The Trick Flow Specialties Street Heat and Track Heat manifolds are a close fit, but both can usually be used with a stock hood. Trimming the rear hood reinforcement is however required. And even then the front of the manifold has been known to make contact with the hood. A throttle body adapter will need to be used with both manifolds. Your stock fuel rails wont fit either of the TFS manifolds. However '89-’93 Mustang fuel rails fit and are a simple swap. The Track Heat manifold is undoubtedly too much for most 5.0L MN-12s. The Track Heat’s runners are too short, and you will lose torque. Unless you are running a supercharger or a very wild NA engine, the Street Heat would be a much better choice. It has longer runners that foster the low torque that we need.

Ford and FRPP

The GT-40 manifold can be made to fit, but not as easily as some of your other options. A Cowl hood WILL be required. The main advantage to the GT-40 is its tubular runners. The design of the GT-40 and '93 Cobra and are very similar, they are both of the staggered port design, and essentially have the same runner design. But the GT-40's tubular runners are more consistent in their shape; keeping the flow to the cylinders slightly greater, and more consistent. And the tubular runners tend to dissipate heat more efficiently, so your air charge temperature is usually lower with a GT-40. In addition, the '93 Cobra manifold has an integral EGR provision, and because of this it interferes with the shock tower on the MN12 chassis when you add the intake elbow adapter. The '93 and earlier Cobra manifold should be avoided.

The GT-40 flows well, a bit better than the Cobra manifold. But for as good an intake as the GT-40 is, it isn’t perfect. There is a crimp near the throttle body; and because the tubular runners aren’t perfectly identical to each other airflow to each cylinder isn’t necessarily exactly equal. However if you are building a serious (supercharged, or wild NA) motor, the GT-40 might be the way to go. For the rest of us, we are probably better off with the Cobra.

Overall the 94/95 Cobra intake manifold is perhaps our best bet, unless your car is heavily modified (I mean HEAVILY). Its long runners help build good low end torque, but top end breathing is still much improved over stock. And with trimming it will clear the stock hood in most cases. However the 94/95 Cobra manifolds does not always have an ACT sensor provision.

If you use an intake off a 94/95 Cobra (as opposed to the Ford MotorSports intake) you can instead use the lower intake from a ‘96 Explorer 5.0L. This lower intake is essentially the same as a Cobra lower but with better port configuration in the #1 and #5 runners. The Ford MotorSports intake already has the higher flowing lower half. The Ford MotorSports intake manifold is identical to the Cobra, except for the Plaque and the aforementioned lower intake (additionally it may also have the ACT bung prepared).

The ‘93 Cobra intake manifold is actually at the limit of fitting under the stock hood. Sometimes it fits with the removal of the hood structures and then sometimes it doesn’t. This manifold does flow slightly better then the 94/95 Cobra but you have to come up with your own induction tube between the filter and throttle body, as it does not have the intake elbow.

The Intake from a ’96 and newer 5.0L Explorer can be used as well. Its dimensions are similar to the GT-40, but the upper intake is cast instead of tubular. Airflow is not as high as the GT-40 (or the Cobra for that matter), and air charge temperatures tend to be a bit higher compared to the GT-40 due to the cast upper (instead of tubular). Fitment problems are similar. It requires an adapter elbow and a possibly a cowl hood, along with any other modifications listed above. Also keep in mind that the ’96 Explorer intake was the only Explorer intake equipped with an EGR provision. So if emissions compliance is needed, make sure to stick to the ’96. It is possible to convert a later intake, but only with a lot of not-so-cheap machining.

The upper GT-40 manifold from a ’93-’95 Lightning mated with a Cobra lower is a good combination as well. Airflow is comparable the GT-40 and probably a lot cheaper (depending on where you get your parts). You still need to overcome the fitment issues associated with the GT-40 manifold however. If the Cobra lower you use does not have an ACT provision, you can either modify it as outlined above, or you can extend the ACT harness and use the boss for the vacuum T-fitting employed on the Lightning. The threads are the same.

Final thoughts

As a good rule of thumb when choosing a new intake for your MN-12, DO NOT expect the intake that you saw in a magazine to perform the same on your MN-12 as it did in a Mustang. Our cars are heavier and geared differently. We need that low end torque badly.

Here is a link to an article regarding 5.0L intake manifolds: Intake Overload. The article has a lot of good theory, and at the end there is a table with a listing of flow numbers by individual runner.

math > pasta

Last edited by StupidFly; 12-01-2007 at 03:27 PM.
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post #2 of 4 (permalink) Old 10-12-2003, 07:40 PM Thread Starter
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I cannot take credit for any of the technical information, testing, or data above. The greater portion of this article was gleaned from the TCCoA forums and a slew of other intelligent folks. Thanks to everyone who contributed. Especially Lonnie Doll, Mike McGrew, 88grandmarq, John Stroede, and Mark McCormack (for the picture and Cougar perspective).

Nigel Fullerton

math > pasta
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post #3 of 4 (permalink) Old 10-12-2003, 07:46 PM Thread Starter
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Once again, please pour over this and point out any spelling and grammar mistakes. This is alot of cut and paste from the last one, so if something seems out of order or just in the wrong place point that out too. Also some of the facts are getting a little fuzzy in my head, so try to keep me honest.

and anyone with info you think should be added please speak up. Especially info on manifolds that arent mentioned.

thanks guys

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post #4 of 4 (permalink) Old 04-13-2006, 08:37 AM
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I'm using the '99 Explorer intake. The lower flows exactly like a gt-40. What the upper flows is debatable. Fitment after trimming the brace is excellent. With an elbow it would fit just like a gt-40. EGR doesn't matter if using an elbow, since the exhaust comes from the header and goes to the elbow. '96/'97 has a boss you can drill for the act sensor and have egr drilled, later lowers don't.

Mine has an Explorer 65mm tb without a spacer or elbow. The Explorer tps will barely touch the hood. A fox tps would clear just fine.

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