Installation Procedure: YH Fuel Injection Throttle Body for Turbocharged Corvair Engine

1. Install a larger fuel return line. The original fuel return line is too small for a recirculating system.  After trying to add a Tee to the vent line or brazing a return line to the gas gauge sender, I ended up brazing a tube to the gas filler neck.  The tube extends down inside the gas tank well to make connection easier.  The next one I try will have the fuel return line on the same side as the vent line.  The version shown cannot be installed when attached to the tank.  The gas tank must be removed before removing the filler neck and the sway bar must be removed before removing the gas tank.  Be sure to spray all of the fasteners with a rust penatrent before attempting to remove the fasteners.  It took longer to drill out a broken sway bar mounting bolt than the remainder of the task.




2. Mount the high-pressure fuel pump.  I mounted the pump under the floor pan near the gas tank.  The pump is attached to a block of blue energy absorption material that is attached to the floor plan.

The high-pressure fuel pump under the floor was so loud that I finally mounted it in the engine compartment on a double isolation mount to reduce the noise transfer. I put a low-pressure fuel pump under the car to feed the high-pressure pump. The fuel filter is mounted below the pump.

In the future, I will mount the fuel pump in the tank to reduce the noise. Ray Sedman of American Pi is planning to offer an in-tank conversion kit. These will be available as complete conversions with new tanks or as a kit for customers who would like to weld the adaptor plate in their tank..

3. Mount the air temperature sensor on the intake crossover manifold.  I drilled and tapped the manifold ¼-20 and used a bolt to hold the threaded adapter in place while brazing.  Then I drilled the hole larger and touched up the edges with a die grinder.  The sensor could be also mounted on the throttle body but that will reduce accuracy since it would not measure the heat added by the compressor. This is a 1962 manifold with a port that I used for the pressure sensing hose. If you have a later manifold, you could tap one of the extra ports in the cylinder head "carburetor" pads and install a threaded hose fitting there.

This photo shows the original version of the throttle body had the injectors before the throttle plate. This resulted in fuel dripping out at the air filter flange particularly in cold weather. For the current version, the injectors are mounted after the throttle plate. Since the injectors are mounted on the vacuum side of the throttle plate, there have been no more fuel leakage problems.

4. Mount the “coolant temperature” sensor in the lower shroud.  I used a simple angle bracket attached using the thermostat mounting stud.  This location may get a little too warm.  The previous location in the front heater duct did not get warm enough to turn off cold enrichment.


5. Mount the MegaSquirt controller and relay box in the interior.  I used the shelf above the transaxle.  From left to right in the photograph: SafeGuard ignition controller, Innovate Motorsports LC-1 wide band oxygen sensor controller, terminal block, MegaSquirt relay board and the MegaSquirt fuel injection controller. For the next installation, I will mount everything on a plate and connect as many wires as much as possible before installing the plate.


6. Cut close fitting holes in the firewall for the wiring harness and vacuum/pressure hose grommets. The wiring harness contains 8 wires for the fuel injectors (2 each), 3 wires for the throttle position sensor, 2 wires for the manifold air temperature sensor and 2 wires for the idle air control if used (15).  There are also 3 wires for power, switched power and ground, 2 wires to the fuel pump, 1 wire to the ignition coil and 2 wires to the “coolant” temperature sensor (another 8).  The wide band oxygen sensor cable has 7 wires.



7. Remove the YH carburetor and the original mechanical fuel pump and fuel lines. Remove the choke heat tubes. Remove the studs from the compressor housing. Install the throttle body using the supplied socket head cap screws and O-ring.  Install the fuel injectors and fuel distribution block. Form connecting fuel lines for the fuel supply and return.  Attach the wiring harness connectors to the fuel injectors and sensors.


8.  Install the wide band oxygen sensor.  Weld a sensor bung into the turbo outlet pipe just above the engine seal.  This one was installed too close to the turbo before I learned that the distance should be significantly greater than 6 inches.


9.  Verify that there are no leaks in the fuel system under pressure.  Connect a computer running MegaTune software and verify that the sensors are giving correct readings.  Then start it up.  The engine should start within a few tries as soon as the fuel lines are primed with fuel.

10.  Tune the fuel table using the MegaTune and MegaLogViewer software.  A attach a laptop computer with the MegaTune software to the MegaSquirt controller using a serial cable and then drive the car while data logging.  The datalog file is then opened with the MegaLogViewer software and the fuel table is recalculated using VE Analyzer.  The new fuel table is then downloaded to the MegaSquirt controller and the test is re-run.  Individual cells in the fuel table can be fine tuned as required.  The data can be graphed for analysis.


MegaTune Screen

MegaTune VE Table Tuning

MegaLogViewer screen

MegaLogViewer output graph

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Last Update:  December 15, 2008 2:05 PM
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