Twin Turbo Kit Installation FAQ

Kit Manufacture: Incon Systems
Vehicle: Ford Mustang (86-93)
Type Of Power Adder: Intercooled Twin Turbo kit

Things You May Ask Before You Buy:

Q: Will I have to remove my engine to install the twin turbo kit?

A: No, the instructions were written for installation into your fox body car with the motor in the car.

Do you have to remove the motor for head gasket changes and normal maintenance?

A: No, you can still perform normal maintenance such as oil changes, plug changes with the motor still in the car. It may, however be necessary to jack up the motor to get enough clearance to cut/weld/install the turbos and clearance plate. The kit can be installed with the motor out, and may prove to be less time consuming. Unfortunately this necessitates an engine lift, which most people may not have. Normal maintenance may take a bit longer, but after the first few times it will become easier and easier.

Q: What special tools are needed to complete the installation?

A: The installation will require you to notch your framerail as outlined below. To do this you will need a Mig welder, and some sort of cutting device. These tools can usually be rented locally. If you read through the installation instructions there are some tools listed that will be invaluable reguarding plug changes.

Q: What does the finished product look like, and has anyone documented an install?

A: Yes, Mike Herceg, and Tim Ellis were kind enough to document an install on a 1986 Mustang Gt.

Q: How long will it take to install the turbos once I purchase them?

A: For the average "Joe" the installation will take around 20 hours. It requires no special tools, other than a welder, and some sort of cutting device for the notch in the frame rail.

Q: Where can I get more information about the twin turbo system?

A: If you scroll down to the bottom of the FAQ, we have supplied a couple dealers to help answer your questions.

Q: What modifications will need to be made to install the twin turbos on my fox bodied mustang?

A: Given the design of the turbo system to place the turbos as close to the heads as possible, and to support 850hp, you will need to make a small notch in your frame frail to give the proper 3/8 clearance. A clearance plate is included with the kit.

Q: Is the Incon twin turbo system emissions legal?

A: Yes! In fact its legal in all states including California! Remember that with the new price restructuring in 2000, people building partial kits will have to purchase the emission kit additionally. The CARB exemption number is 469, issued Nov. 1998.

Q: I noticed several other twin turbo kits are ceramic or hpc coated. Does this make a difference, and does Incon offer such coatings as an option?

A: Yes, Given the price point Incon was shooting at, the hpc coating would have driven the price further out of some peoples reach. You can however have this coating performed on the manifolds and dumps. It is highly recommended to send your manifolds to Incon for disassembly prior to the coatings(they won't coat them unless you do.) Hpc coatings can decrease underhood temps and also help the turbos spool faster, as they are driven off expanding gases and heat.

Q: What motor mounts will be needed to install my turbo system?

A: The twin turbo system was designed around the stock motor mounts found on the majority of mustangs, however new "upgraded" or "convertible" mounts do not work. These are shorter in height and will not provide enough drain clearance for the oil drain lines. The correct Ford part numbers are: E7ZZ-6038-E & E7ZZ-6038- F. You will need to specify these part numbers at the dealership or they will substitute the convertible style(newer version) mounts. The correct mounts look like a huge square of rubber and the motor bracket is bolted on. The convertible style are riveted together.

Q: What cam works best with the Incon system?

A: Surprisingly enough, the stock cam does a great job making power. There are only few other cams that we would recommend, the crane 2031, the FMS E303, and the FMS F303..

Q: What mufflers are the best to run with my twin turbos?

A: Thus far it seems that dynomax race magnums, and super turbos are the best choice. We've found that flowmasters can cost you up to 50rwhp. Use caution though, a stock 302 with heads and free flowing exhaust can produce enough power to damage the stock 302 block or components. Other straight through designs may work great, but testing is the key. A simple test to see how your exhaust is performing is to drill and tap a hole in your turbo dump. Attached a fitting, connect a piece of brake line to the fitting and then connect the end of the brake line to a boost gauge. This will show your backpressure, we want no more than 3psi of backpressure. The higher the pressure the less power you will make, the turbos will spool slower, and it will greatly effect your throttle response.

These are the part numbers for the dynomax kits:

'86-'93 GT part # 17394
'86-'93 LX part # 17393
'94-'95 GT and Cobra part # 17385
'96-'97 GT and Cobra part # 17341
'98 GT and Cobra part # 17333
'99 GT(and should be '00) part # 19311
'99 Cobra part # 19314

Q: What spark plugs are recommended for my twin turbo car?

A: NGK spark plugs have worked very well in all of our boosted motors. Here is a list of commonly used motorcraft part numbers and also the NGK part number for the same plugs.

Motorcraft NGK

The missing numeral from the middle of the NGK part number, is 5 for street only, 6 for street/strip, 7 for drag race only!!

Q: How long will my transmission last behind my new found power?

A: Unfortunately Fords' T5 transmission and AOD are far inadequate to use behind the torque that the turbos produce. This goes with any high performance vehicle though. You make a lot of power, and your going to have to take some steps to ensure reliability. We would recommended upgrading to a tremec, jerico, t56 or some higher performance transmission and clutch. The AOD can be rebuilt with better parts to withstand the power you produce.

Q: I have quite a few other modifications done to my car, how much power will I make?

A: Unfortunately that is a tough question, but we'll try to give it a shot. Keep in mind power changes from car to car, but these values below do hold some merit.

Approximate Power Output Head used Intake used Exhaust components Amount of boost required Fuel system requirements
400rwhp Stock Stock Stock


255lph pump, 30lb injectors
450rwhp Aftermarket Stock 2.5 inch Aftermarket


255lph pump, 30lb injectors
500rwhp Aftermarket Aftermarket 2.5 inch Race magnums or Superturbos


255lph pump, 36lb injectors
550rwhp Stage 2 ported aftermarkets Stage 2 ported aftermarket intake 3" Race magnums with off road x or h pipe.


255lph pump, T-rex in-line and 42lb injectors.
600rwhp Race ported aftermarkets Race ported aftermarket intake 3" Race magnums with off road x or h pipe.


Upgraded Fuel lines, Rails, New 1/2 pickup and large pump,

More specific systems:

  1. Stock GT/Cobra, including stock exhaust: 400 - 430 RWHP
  2. Stock GT/Cobra, no cats, dual 2 ½"/good mufflers: 430 - 460 RWHP
  3. Add good inlet, no cats, dual 2 ½"/good mufflers: 460 - 475 RWHP
  4. Add good heads, no cats, dual 2 ½"/good mufflers: 490 RWHP
  5. Add camshaft, no cats, dual 2 ½"/good mufflers: 520 RWHP
  6. Lift boost to 10 PSI, no cats, dual 2 ½"/good mufflers: 550 RWHP
  7. Lift boost to 12 PSI, no cats, dual 2 ½"/good mufflers: 580 RWHP
  8. Lift boost to 12 PSI, good dual 3" system: 610 RWHP
  9. Lift boost to 14 PSI, good dual 3" system: 640 RWHP
  10. Lift boost to 16 PSI, good dual 3" system: 670 RWHP

Checking for proper fuel requirements, each system listed above or power output is listed numerically.

a) Disconnect vacuum line to regulator.
b) Start engine and ensure fuel pressure is 40 PSI (stock), using a quality gauge.
c) Stop engine, disconnect fuel return from regulator and put line from regulator into one gallon container.
d) Have friend start car, at idle and you measure flow with stop watch. The following (related to the above configurations) is the absolute MAXIMUM > time acceptable to fill the one gallon container. Repeat three times and average.
1. 40 seconds 2. 38 seconds 3. 36 seconds 4. 34 seconds 5. 32 seconds 6. 30 seconds 7. 28 seconds 8. 27 seconds 9. 26 seconds 10. 25 seconds


Troubleshooting Faq Tips:

Q: I am concerned with my clutch cable being so close to the manifolds...How should I route my clutch cable to prevent it from burning or melting?

A: You can do the following to prevent failures. Heat shielding is a good way to prevent the burns, but proper cable routing is a better idea. The ford OEM cable or accufab version tend to resist heat. Please ensure your cable is routed in the following manner: 1) Out of firewall. 2) Between master cylinder and shock tower 3) Between brake lines and frame 4) Zip tie to "K" member, to keep off steering column 5) To bell housing.

Q: I am installing a custom fit set of wires, or the Incon wires provided but they are not marked, which boots are to be used on each cylinder, and how long should they be?.

A: If your using a custom set of wires here goes:

cylinder Number

Wires length

Boot angle
























Q: I have lots of smoke coming out of my tail pipes. What is causing this?

A: You need to verify you have the correct motor mounts installed and you have done everything in THIS page. The smoke is caused by improper clearance on one of your oil drain tubes. The oil is backing up in the turbo and leaking through the seal. If you are seeing this discontinue driving it till you have it sorted out. You can damaged the turbos if you don't.

Q: I think I have a vacuum leak, how can I track it down, and what are the signs will I notice?

A: There are many ways of doing the vacuum tests. If you have a boost/vacuum gauge attached, you can tell exactly what your vacuum is at. Locating the source of the vacuum leaks can be a bit more tricky. Here are some tips: Using starter fluid or carburetor cleaner spray around cracks and seals around motor, intake, valve covers, heads, throttle body, MAF ect. Your motor will surge a bit once you have located the source of the leak. Signs you have a vacuum leak are as follows: surging idle, detonation at higher rpms, manifolds and car run excessively hot.

Q: I have heard that the stock fuel rails can flow quite a bit more fuel if I remove the restrictions. Where and how do I perform this operation?

A: To simplify the FAQ we have included a link to the fuel rail modification page.

Q: What is a good air to fuel ratio to maintain?

A: If you don't want to be on the ragged edge a a/f of 12.0-12.5:1 is recommended.

Q: I am still stuck, what can I do and who should I call?

A: Here is a list of the Authorized Incon dealers, if your stuck give them a call.

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    How to Use This Document:

  • PROS:

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  • Introduction:

  • c/o = carry over

    Year 1979 1982 1983 1984 1985
    Output - SAE net Horsepower


  • Now it’s time to wire up the 3 wires coming from the NMU which are Red, Black & White. Connect the black wire to a good ground anywhere in the area of the NMU.