INCON Twin Turbo Installation

a corral original article
Bob Cosby

Difficulty (Easy 1-10 Difficult) Difficult
Special Tools (Few 1-10 Many) Several
Price (Cheap 1-10 Expensive) Moderately Expensive
Quality (Poor 1-10 High) Excellent
Improvement (None 1-10 Alot) Alot
Customer Service (Poor 1-10 Good) Excellent

INCON recently provided The Corral with one of their Twin Turbo Kits for installation on our 1988 LX Coupe project car. For more information on the car's modifications, ET's, etc., please refer to

Upon receipt of the kit, we began the install and were able to accomplish it almost entirely without any additional help. Total install time for the turbos, including pulling the motor, took about 20-24 hours. Two people could do it in considerably less time.

The kit is very complete, and comes with all necessary hardware, including:
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- Twin Turbo assemblies
- Intercooler
- 190 LPH Fuel Pump
- 30# injectors
- Calibrated MAF meter
- Heat-shielded Spark Plug Wires
- Twin K&N Filters
- All necessary plumbing, clamps, and bolts

Here is a complete list of all the components that come with the kit.

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The kit was shipped in three large, well-packed boxes and is designed to be installed by a competent "do-it-yourselfer." No special skills are required. We had never done anything like this, and had minimal trouble completing the installation. As delivered, the turbos provide 8 psi of boost, and add around 150-200 RWHP to an otherwise stock 5.0.

This kit can be installed in one of 3 ways:

  1. With the motor in the car
  2. Pulling the motor, attaching the turbo's, and then replacing the motor
  3. Dropping the K-member for clearance.

We installed this kit on our project car by pulling the motor from the car and have also taken off and then reinstalled the turbos with the motor sitting in the engine bay, so it is possible, and actually not that difficult to install this kit. We do believe, that removing the motor is the easiest way to accomplish this installation (though not necessarily the quickest).

I have broken this up into the following areas:

- Required tools and equipment
- Pulling the motor
- Engine bay preparation
- Installing the turbo's on the motor
- Putting the motor back in the engine compartment
- Test drive
- Some notes

I had success doing the installation in the order that I have outlined. However, it is certainly possible to deviate from this and still get the job done correctly.


The following is a list of what INCON recommends for tools.

"Snap On" Tools:

  • Spark plug socket - P/N - S9706KFUA
  • 3/8" 12 pt socket - P/N - TMU121
  • 3/8" 12 pt wrench - P/N - XDH1214A
Any Brand Tools:
    1/4" drive ratchet
  • 1/4" drive extension
  • 3/8" socket and drive set
  • Screw driver set
  • Open end wrench set
  • 1/2" socket and drive set
  • Punch set


  • 3/8" NPT tap/handle
  • 3/16" drill bit
  • 19/32" drill bit (stepped)
  • 3/8" (min) electric drill
  • Cylinder leak down test equipment
  • Floor jack
  • Ford Mustang car shop manual
  • Ford Engine/emissions diagnosis manual
  • Small Hydraulic bottle jack


  • Cut off wheel or
  • Oxygen/Acetylene cutting set or
  • Plasma cutter
  • Welding equipment


  • Permatex Ultra Copper RTV Silicone
  • Teflon thread sealer paste

I didn't have the snap-on tools, and didn't need them because I did the install with the motor out of the car. I would recommend procuring them if you plan to do the install with the motor in the car. The punches and tap are certainly necessary, and you'll need to find a way to cut one of the shock towers and weld a small plate in the area that you cut (covered under the Engine bay preparation area).


I'm not going to go into a great deal of detail on how to pull the motor, but I will cover some basics.

1) Drain the oil, tranny fluid, and engine coolant
2) Remove the H-pipe.
3) Remove the driveshaft.
4) Remove the shifter from the tranny.
5) Disconnect wiring from the transmission.
6) Support the tranny, then remove the crossmember. If you are pulling the motor and transmission as a unit, you're ready to go. Otherwise, take the tranny off the bellhousing.
7) Remove the starter.
8) Disconnect the fuel lines.
9) Disconnect the wiring harness. This is best done by pulling the wiring apart at the modules that hang on the back side of the intake, just after the throttle body. You can then remove the motor with the fuel injector wiring attached.
10) Remove the exhaust headers.
11) Unbolt the A/C and set aside.
12) Unbolt the P/S and set aside.
13) Disconnect and remove the MAF sensor and tubing.
14) Remove the fan shroud.
15) Remove the radiator.
16) Remove the fan.
17) Disconnect the heater hoses.
18) Disconnect all vacuum hoses and smog pump tubing.
19) Disconnect the coil wire, oil sending unit wire, temp sensor wire, distributer wiring, etc.
20) Disconnect the linkage from the throttle body.
21) Take the engine mount bolts off the studs.
22) Attach chains from the engine puller to the front and back of the motor, on opposite sides. Ensure you have a good hold on each.
23) Slowy raise the motor and pull forward, being careful to let the tranny clear the tunnel. It is usually necessary to tilt the motor back to allow the tranny to slide out.
24) Set the motor/tranny assembly on a steady surface. I "built" a small stand with 2x4's. It needs to be stable!


Much of the installation does not involve the engine at all, rather, it involves working in the engine bay. This is one area where having the motor out REALLY helps. Basically, you'll be installing the intercooler, the clearancing plate, and moving a few things around.

1) Remove the following:
- Flexible throttle body ducting and MAF sensor
- Entire air cleaner assembly
- Thermactor control valves, exhaust system check valves, and hoses

2) The most difficult part of this process (and possibly the entire install) is putting in the clearancing plate on the passenger side shock tower. Refer to the diagram. click to enlarge

It took about 30 minutes of cutting to get it just right. The key is to mark it well beforehand, using the provided plate as a template.
click to enlarge I cut it a bit too small at first, to make sure I didn't cut too much. I used a cutting wheel on an air tool.

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Then I fitted the plate, and gradually enlarged my cut area until it fit. The plate was then welded into place using a portable welder.
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Finally, I painted the new plate to match the engine bay.

3) Next you have to move the Evaporative Loss Cansister, as seen in the diagram.
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Simply unbolt it, measure out two new holes just in front of the sway bar mount, and re-mount the canister.

4) INCON provides two heat shields that are easy to install. They protect the master cylinder and proportioning valve. See the diagram.
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They are very easy to install.

5) One-way valves will need to be installed in two vacuum hoses - the one that goes to the PCV valve, and the large one that goes to the vacuum tree on the firewall. Simply cut the lines and put the provided valves in between. Make sure you have the valve mounted in the correct direction (marked on the valve).

6) Remove the sway bar end links and replace with the provided hardware.

7) Install the intercooler. This will eat up most of the engine bay time, but isn't that difficult, as you can tell by looking at the diagram. click to enlarge

- Install the fan wash shield on the upper face of the intercooler, as per the diagram.
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- The most important part of this procedure is measuring and lining up the intercooler mounts. The intercooler is mounted on two brackets that bolt on each frame rail. Once completed, it will lie flat, drawing in air from underneath. You need to ensure there is at least 1/4" of clearance from both the radiator support and the sway bar. click to enlarge

Be careful - once the motor is back in and the car is sitting normally, the sway bar clearance could change. I would suggest getting the intercooler about 5/16ths of an inch away from the radiator support.

- Take the plastic air dam off the radiator support and mount it on the back portion of the intercooler, as shown in the diagram above. This directs air into the intercooler.

- Next, install the tubing for the MAF sensor. It will run from the intercooler outlet, up through the fender well, and out towards where the old air filter assembly was. Use the clamps provided. Some cutting of the plastic fender liner will be necessary. Trial fit it first, then cut the plastic. After the trial fit, I would recommend clamping the tube onto the MAF sensor tubing, then snake the tubing down through the fenderwell, and finally connect it to the intercooler.

- Finally, clamp the provided K&N filters onto the intercooler mounts, as shown in the diagram.
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I would wait on the other hoses until the motor is in the car.

8) Install the new 190 lph fuel pump. There are numerous articles written on how to do this, so I won't go into any detail.


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1) Remove the following:

- Distributor (make sure you are at TDC with the timing mark at 0 deg).
- Spark plugs, wires, and looms.
- Oil pressure sending unit
- Dipstick tube assembly

2) Remove the upper intake and replace the fuel injectors, then re-install the upper intake.

3) Gap a set of new spark plugs to .035". Set aside.

4) The metal exhaust tubing coming from the back of the heads will have to be moved. I believe it is best to heat up the tubing and bend it outwards from the head just after the 90 deg turn. It might be necessary to cut this tube (just after the 90 deg bend) instead in order for the turbo housing to clear. If this is necessary, INCON supplies plenty of flexible tubing to re-attach the stock check valve.

5) Drain the water from the block by removing the drain plugs from each side of the block.

6) Install new fittings in the water drain holes, as shown in the diagram.
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Use teflon tape for sealing.

7) You have to punch a hole in each side of the oil pan. Refer to the diagram for positioning of this hole.
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It is very important that the holes be as shown in the diagram so that the oil-return tubing will fit properly.

It is best to do this with a tapered punch to create a 9/16" hole. You will then need to tap the holes using a 3/8" NTP tap. Make sure you liberally grease the tap to catch as much of the metal shavings as possible. Then install the supplied drain fittings, using RTV to seal.

8) Another hole must be drilled in the intake manifold for coolant. This is done just behind the thermostat, being careful not to concact the thermostat itself. click to enlarge

Use a 19/32" drill bit. Liberally cover the drill bit with grease to catch as much of the metal filings as possible. Then tap the hole with the 3/8" NPT tap. Finally, install the provided fitting.

9) Install the new oil pressure sending unit. It has provisions for two lines to be connected that supply oil to the turbos. Use teflon tape to seal each. click to enlarge

10) Install a new oil filter.

11) Next, prepare the turbo manifold assemblies for installation. On each side:

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- bolt on the oil return fittings to the turbo's.
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- clamp the hoses to the oil return fittings on the turbo's, as show in the above diagram.

- bolt on the water feed fittings to the turbo's, but not the braided feed lines.
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- bolt on the water return fittings, and clamp the hoses to these fittings (this can be later if desired).

- Install the #3 spark plug.

- clean the area around the exhaust ports very well. You won't use a gasket when assembling, rather, they will be sealed with RTV.

- Put a bead of RTV around the exhaust ports as evenly as possible.

12) Install the turbo's on the engine:

- Carefully lift the turbo assembly up to the head, starting a bolt (supplied) on each side to hold the assembly on the head. Then install and begin tightening each bolt. Make sure you get them tightened before the RTV has time to set.

- Repeat for the other side.

- Connect the cooling feed lines to the fitting you previously installed in the manifold, then install the other end to each fitting on the turbo. Refer to the diagram shown above.

- Clamp the water return hoses to the fittings on the engine block.

- Connect the oil feed and return lines. Refer to the diagram shown above.

13) Install the remaing spark plugs.

14) Put the distributor back in the motor. This can be done later if desired.

15) Re-install the oil dipstick tube. There is a supplied fittting that will allow you to hook up the existing bracket,


The motor is now ready to go back in. It fits pretty easily, but close attention must be paid to the tranny tail shaft, the turbo's on each side, the steering shaft (which I did NOT have to remove), and the front of the motor. Also, you will be putting spacer plates on the engine mounts.

1) Carefully lower the motor into the engine compartment, being mindful off all clearances. DO THIS SLOWLY!

2) Once the motor mount bolts are through the holes, but before the engine is completely down, put the spaces in-between the mount and the frame. The thick one goes on the passenger side, the thin one on the drivers side.
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3) Re-connect all the tranny mounts, wiring, shifter, and driveshaft.

4) Re-connect the vacuum fittings, wiring harness, fuel lines, oil sending unit, water temp wire, distributer wiring, etc.

5) Install the new spark plug wires. #6 will route underneath the turbo's, as shown in the diagram.
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Make sure they are all well-away from the turbo and exhaust assembly. They are shielded well, but can still burn. INCON supplies mounts for the stock wire looms. I also used tie-wraps to make sure the wires were off everything that was hot.

6) The turbo wastegates are operated with vaccum. Use a good source, such as the front vacuum tube the comes out of the bottom of the upper intake. You need to connect a line to it, then split it off to each turbo's vacuum soleniod. Make sure you use clamps on each of these conncections.
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7) Next is the routing of the thermactor valves. Much of this stuff has to be relocated. Refer to the diagram for proper routing of the plumbing. click to enlarge

INCON supplies all the new parts that are necessary.

8) replace the throttle linkage.

9) Connect the mass air tubing to the throttle body and clamp tightly.

10) Install the remaining air ducting for the turbo's. There is really no "good" order to do this in. Refer to the various diagrams above for exact locations. Some of the tubing may have to be trimmed a bit, but be careful not to trim too much. Ensure you clamp each securely.

11) Refill the engine with quality, synthetic oil.

12) Replace the fan, radiator, and shroud.

13) Refill the engine coolant.

14) Set e timing at 6 deg.

15) INCON highly recommends the installation of a fuel pressure and boost gauge. I also very highly recommend this.


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You're ready to fire it up! Mine ran fine as soon as I started it. There were lots of new smells, which is to be expected, but they went away after idling for a while. I did have a lot of vibration, which I later found was being caused by the passenger side turbo lying on the clearance plate. This was solved by shifting the motor slightly in its mounts.

INCON Recommends the following:

- With the engine at normal operating temperature, put the it in 4th gear or drive and apply WOT from 1000 rpm.

- Maximum intake manifold pressure should be as follows:

- 1000 rpm 0 psi
- 1500 rpm 4 psi
- 2000 rpm 8 psi

NOTE - Those are listed as max. My car does not develop a full 8 lbs till around 3300 rpm, which am I told is pretty normal.

- Check the fuel pressure in the same manner, getting the engine up to at least 5000 rpm. Obviously safety is a concern here. Be very selective about where you do this!

- You should see 40 psi when not under boost, and 1 psi per lb of boost when boosted.

- If the fuel pressure drops under boost as the rpm decreases, the fuel pressure is NOT adequate and MUST be updated before proceding! This is VERY important, as a blown head gasket, or worse, can result.


- I am VERY impressed with the quality of this kit. Almost everything needed is included. It is very complete.

- I have had zero cooling problems. I run a stock replacement radiator, stock crank pulley, underdriven water pulley, and 180 deg thermostat.

- I initially had problems with a bad miss under load at high rpm. This was diagnosed as improper plug gap. Once the plugs were gapped to .035", the problem disappeared.

- Contrary to what you might think, the plugs are accessible, though #3 requires some work. INCON recommends a specific snap on tool for the job (see the list at the top of this page). However, I simply cut a cheap spark plug socket enough to slide it onto the plug. Then I used a wrench on the end of the socket to loosen, and then tighten the plug. It took about an hour to change all 8 plugs. Not bad considering.

- The car is still very streetable. The turbo's make almost no noise until you put them into boost.

- Power is awesome. With 3.73's and 28" tall street tires (VERY tall), I can break the tires loose at will in 2nd gear. It will occasionally go sideways in 3rd gear at 60 mph. This with only *8* lbs of boost!

Incon has an informative brochure that we have scanned. It includes contact and pricing information. Click HERE to view.

They have also recently announced a 1999 Contingency Program. Details HERE!

That's it! Enjoy your new Twin Turbo-charged Mustang!

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