Fox Body Mustang Throttle Body Selection Guide

Posted 1/20/2015 by Jeff Jimenez

FOLLOW: mustang , 79 93 mustang , fox body mustang , installation , video , throttle body , air fuel

Which Throttle Body is right for your Fox Body?

We’ve all been there. Every single one of us who own a 79-93 Mustang, you start to get that itch. You know, that one where you want to make your Fox go faster, sound meaner, handle better, or look cleaner. If you are like me, you already know that going faster is always the way to go.

The problem always seems to be choosing a part that not only stays within your budget, but ultimately gives you the most bang for your buck. For a lot of people, upgrading the Throttle Body is a budget-friendly, and easy-to-install mod for your 5.0.

What is a Throttle Body?

The Webster’s Dictionary describes the Throttle body as “A part of the air intake system of a fuel injected engine, responsible for regulating the airflow into the engine.” This description could not be more accurate. Ford equipped the 1986-1993 Mustangs with a 57 millimeter throttle body from the factory. That size of throttle body was not very friendly to the wave of performance modifications that were, and still are, available to the 302 based fox.

The reason why people swap out the throttle body is two fold. Better throttle response, and better airflow to support modifications. The latter is the biggest thing to remember, especially when considering potential head, cam and intake purchases. A throttle body by itself will not increase horsepower, but rather work in conjunction with other mods to increase horsepower.

So in short, the sole purpose of the Throttle Body is to allow air to enter the intake, in direct relation to how hard you press the gas pedal. The harder you press the gas, the more air is allowed to enter the combustion cycle, and the faster you go. Sounds pretty simple right? Not exactly.

The Science Behind the correct Throttle Body

Believe it or not, There actually is a science behind choosing the correct throttle body. Bigger is not always better when it comes to throttle bodies. I know what you may be thinking. And it all boils down to two words: Venturi Effect.

The Venturi Effect is when a fluid (air) enters a funnel the velocity of the fluid increases as the cross sectional area decreases, with the static pressure correspondingly decreasing. According to the laws governing fluid dynamics, a fluid's velocity must increase as it passes through a constriction to satisfy the principle of continuity, while its pressure must decrease to satisfy the principle of conservation of mechanical energy. Thus any gain in kinetic energy a fluid may accrue due to its increased velocity through a constriction is negated by a drop in pressure (

Basically, in layman's terms that means that the more volume of air that you can tunnel through your air intake, the higher velocity it will be as it goes into your intake manifold. This effect is easily achieved by purchasing a quality cold air intake that starts large at the inlet, and tapers down smaller into the throttle body. This is especially important when it comes to forced induction. The more air you can move, the better your engine can breathe. That means more horsepower, and more torque.

The most common problem that some people run into with their throttle bodies is the fact that they go too big for their specific application. Too big of a throttle body will actually decrease throttle response, and decrease the desired Venturi Effect you are looking to create.

So, which Throttle Body should I choose?

Just like anything else in life, there are plenty of throttle body choices to choose from. The most common throttle bodies are 65 mm, 70 mm, 75 mm, and 90 mm. All of which have a specific application that they would correspond to.

  • 65 and 70 mm throttle bodies are great choices for naturally aspirated, stock displacement engines.
  • 75 mm throttle bodies are a great choice for larger displacement engines, and forced induction applications.
  • 90 mm throttle bodies are a great choice for larger displacement engines, with high levels of boost from a forced induction application.

Once you understand the simple concept of what a throttle body is, and what it does, selecting the correct one for your car should be a walk in the park. Now that you understand that, let’s wrap our head around some of the parts that make the throttle body more effective.

EGR Spacers and Cold Air Intakes

EGR Spacers are also on the same level of misunderstanding as the throttle bodies. Anyone that has ever spent any time underneath the hood of a fox installing go-fast parts, knows about the importance of an EGR Spacer. The problem is, nobody seems to know why they are important. The purpose of an EGR Spacer, is to aid in the warming of the car in colder climates. It also helps funnel air into the throttle body. It also acts as a mounting point for your throttle linkages.

Much like the throttle body, they come in various sizes. 65, 70,and 75 mm are the main choices for the EGR Spacer. The ideal EGR Spacer will match the size of the throttle body, as anything smaller will act as a minor restriction, and anything larger will only flow what the throttle body can handle.

The Cold Air Intake plays a pretty big part in all of this airflow business too. Like I outlined earlier, a good cold air intake will always be wider at the Filter/MAF location, and taper down in size, forcing the air to essentially ram itself into the throttle body. It also helps expound the impact of your throttle body/EGR Spacer combo.

You would always want to consider purchasing the EGR Spacer Plate when you purchase a throttle body to maximize the performance gains that the increased airflow has to offer. Especially if you are considering going with an aftermarket heads, cam, and intake combo.

Considering all of the science, and everything that I’ve laid out for you, a Throttle Body/EGR Spacer combo is a fun, easy, and budget friendly way to bolt on some additional performance to your 1986-1993 5.0 Mustang!

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About the Video

Mustang Throttle Body Installation - SVE (86-93 5.0L Fox Body)

Check out our YouTube channel for even more tech tips, installation videos, how-tos, and more. The best place to go for anything Mustang related!

Published on 2013-10-21
Upgrade your puny factory throttle body with a SVE 70mm throttle body kit that includes the TB, correct EGR spacer and all needed gaskets. Not only will it give you a boost in performance but it will also improve the under hood appearance with its polished finish. Watch the video as Jmac shows you how to install a new performance throttle body on your Fox Body Mustang.

Part Number# SVE-TB1501K
Fits: Ford Mustang 5.0L GT LX
Fits the following years: 1986 (86) - 1987 (87) - 1988 (88) - 1989 (89) - 1990 (90) - 1991 (91) - 1992 (92) - 1993 (93)

SVE Throttle Body & EGR Spacer Kit
This 1986-1993 Mustang SVE 70mm throttle body and spacer kit is perfect for adding horsepower and torque to your 5.0L motor. By increasing the size of your throttle body and EGR spacer, you get more air flowing into your motor which gives you increased performance! Pick up this kit today and get your Foxbody outrunning the competition.

SVE 70mm Throttle Body
This 1986-1993 Mustang SVE throttle body is a great way to bring in more air for more power on your 5.0L motor. This throttle body has an opening of 70mm, a huge increase from the 55mm that came stock on these motors. This allows you to bring in as much air as possible to help maximize your performance. Pair it up with a cold air intake and a new intake manifold for serious horsepower gains!

SVE 70mm EGR Spacer
This is an SVE 70MM EGR spacer for your 1986-1993 Mustang 5.0L. This spacer is needed when replacing your throttle body to ensure proper flow through the throttle body to the intake manifold. It also has coolant line provisions that help in heating your air charge temperature. Includes the EGR gasket and spacer-to-intake gasket.
If you're looking to add some performance to your '86 to '93 five liter Fox Mustang, look no further than our SVE throttle body and EGR spacer.

Unplug the mass airflow sensor, if equipped. Loosen the clamps and remove your air inlet tube. Pry the throttle position sensor connector free from the throttle cable bracket and unplug. Disconnect the EGR vacuum line and unplug the electrical connector. Unplug the idle air control valve connector. Disconnect the valve cover hose from the throttle body. Remove the two idle air control bolts and remove the IAC. Remove the two throttle cable bracket bolts and unclip the throttle cable from the throttle body. Disconnect the EGR spacer coolant hoses. Be sure to lay down a towel or some rags to catch the coolant mess. Remove the four throttle body retaining nuts. A couple of sharp hits to the throttle body may be needed to knock it loose. Then you can remove the throttle body. Remove the EGR spacer.

If your studs are corroded or broken like ours, remove them from the intake, clean the threads, go ahead and remove them from the intake, and replace with new. Clean the intake mating surface. Install your new studs.

Remove the EGR valve from the old EGR spacer. Clean the EGR valve mating surface. Put your new EGR gasket on the new EGR spacer, and install the EGR valve using the supplied hardware. Put your EGR spacer to intake gasket onto they intake. Slide on the EGR spacer, followed by the throttle body to EGR spacer gasket, and finally the throttle body.

Install the four throttle body retaining nuts. Clip your throttle cable back on to the throttle body. Reinstall the two throttle cable bracket bolts. Plug-in the EGR connector and reconnect the EGR vacuum line. Hook up the EGR spacer coolant hoses. Reinstall the idle air control motor and plug in the connector. Reconnect the valve cover hose.

Remove the throttle position sensor from the old throttle body, and install it on the new throttle body. Reconnect the throttle position sensor connector. Reinstall your air inlet tube and tighten the clamps. And plug in your mass airflow meter.

And with that, your installation is done. Be sure to reset your idle and your throttle position sensor voltage. To see how to do that along with more Fox Mustang tech, be sure to check out