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Parts to Use and Interchange FAQ

  1. My turbo needs a high pressure oil source, where should I get it from?  On a Turbo II motor, the turbo's high pressure oil inlet tube is fed by a hard pipe routed over the engine, just behind the water pump housing.  If you are using a Turbo II motor and Turbo II turbo, it would be best to re-use this configuration.  In the event that the hard pipe is not available, a hose barb fitting can be installed in the high pressure oil outlet hole and fuel/oil hose can be run to the turbo.  The turbo high pressure oil inlet fitting has a 14x1.5mm male threaded end.  If you are using a GSL-SE or other non-turbo 13B or 12A engine, you can get high pressure oil fed from the oil filter stand using Racing Beat's Oil Pressure Gauge adapter block.  This is an aluminum block that is sandwiched between the engine and the oil filter holder.  It has standard threaded holes to allow for oil outlet to the turbo or to an oil temp or oil pressure gauge.
  2. My turbo needs to drain the oil.  What is the best choice for an oil drain?  If you have the Turbo II block, the best choice is to use the stock oil drain hose.  You will have to provide an equivalent hole in the front cover for the oil drain.  Normally, the Turbo II drains oil back into the front cover.  Because you must use a 12A or 13B GSL-SE front cover for the motor mounts, you will not be able to bolt the oil drain hose to the front cover without providing the equivalent mount.  A very functional alternative is to drill a hole in the side of the oil pan and mount a drain tube to the oil pan.  You will then need to cut the original oil drain hose and replace the center flexible section with rubber hose suitable for oil & gas.  See this photo for an example.
  3. My turbo needs a high pressure coolant source, where should I get it from?  The normal GSL-SE and Turbo II engines provide a coolant system for the BAC valve and the thermal wax pellet system.  You can easily adapt these ports to provide a high(er) pressure coolant source for the turbo by using a heater hose "T".  These are readily available from any auto parts store, and commonly sold under the "Help!" brand.
  4. My turbo needs a low pressure coolant drain, where should I drain it?  The coolant drain on a Turbo II motor normally returns to the lower water pump neck.  If you are unable to use the stock hose and water pump neck from the Turbo II, you can use a 10" section of heater hose and connect the turbo coolant drain hose to a "Tee" installed in the small heater hose between the heater hose hard pipe that runs on the top of the frame rail and the lower radiator inlet.
  5. Will the stock radiator adequately cool my turbo car?  There is little additional heat demand placed on your car with the turbo.  The largest heat differential comes in the form of engine bay temperatures.  Because the turbo assembly and associated piping will bring additional radiant heat into the engine bay, consideration should be given on the basis of ambient heat, rather than cooling capacity of your radiator.  Although sufficient for stock 12A configurations, the "beehive" oil cooler from '83-'85 12A cars should be eliminated in favor of the more robust oil cooler from a GSL-SE or earlier 12A car.
  6. What front cover do I need to use to install my turbo motor in a 1st Gen Rx7?  You can use the existing front cover from your Rx7's engine.  If you supply your core to a rebuilder, make sure that they know to swap over the front cover.  You need to use a 12A or 13B front cover from the 1st Gen.  They will have the motor mount on the front, which is required to mount your engine.
  7. What do I need to do with the motor mount bracket if I have a 12A engine?  The 13B motor is 10mm longer (from front to back) than the 12A motor.  You'll need to add a slot to the bracket on both sides if want to use your existing bracket.  Racing Beat offers a replacement motor mount bracket that has the required slotting if you wish to purchase one.
  8. What compression rotors should I use?  If you're turbocharging a motor, the ideal configuration is a set of low compression rotors.  The compression ratio that is used for a 87-88 turbo engine is 8.4:1.  If you are rebuilding a 13B motor, the best choice is the 89-91 Turbo II rotors.  They are the lightest, and still provide a low compression ratio; as do the third Generation Rx7 rotors (9.0:1).  Remember, as the compression ratio goes up, the horsepower goes up and the reliability goes down. 
  9. Do I need a 13B engine, or can I turbocharge a 12A?  If you have a 12A motor, the best option for a turbo application is the use of 12AT rotors.  However, they are not readily available, as the number of 12AT motors with good rotors is quite limited. 
  10. How can I manage my EFI properly?  If you are installing a stock Turbo II setup, you can use the Turbo II ECU very effectively.  However, increased boost levels mean increased fuel consumption, and the stock ECU was not designed to handle more than four 550cc/min fuel injectors.  If you are considering upgrading your injectors and fuel, you should strongly consider an aftermarket EFI computer.  See the EFI FAQ page for more details.
  11. What systems are available for aftermarket EFI?  There are many options available for aftermarket EFI.  The most commonly used systems are from Wolf EMS, Electromotive, Microtech, SDS, Motec, Haltech, Megasquirt, and AEM.  See the EFI FAQ page for more information about these systems.
  12. Should I use the stock 1st Gen distributor?  If you are planning to use a fuel only management system (SDS or Megasquirt), then  you could consider using a distributor.  The biggest challenge will be timing retard while on boost.  There are two common alternatives.  The first is to use a MSD BTM ignition module.  This will allow some retard under boost.  However, the total degrees of retard is only about 3 degrees, which is not enough for any boost over 7 psi.  Another alternative is to use a distributor from the 12A Turbo.  This distributor contains diaphragms that specifically retard timing under boost.  Again, this solution is really only good for up to 8 psi of boost.  Beyond that level, more accurate control of timing should be performed by a computer.
  13. Should I use the 2nd Generation coil packs?  The second generation coil packs are a great way to provide spark for your TurboFB.  They have integrated ignitors, and are very reliable.  The wiring for the coils is straightforward, and can be easily adapted to any EFI computer that provides spark control.  A note: The Electromotive TEC systems have integrated coil packs, and as such, do not require external coils.
  14. Will my 12A transmission hold up to a turbo?   The 12A transmission is a fairly strong transmission.  Although it was designed to handle power up to around 150 HP max, it can provide adequate support for a system with lower boost levels.  If you are planning on being aggressive in your driving, don't consider a 12A transmission as your first choice. 
  15. Will my GSL-SE transmission hold up to a turbo?  A GSL-SE transmission is stronger than the 12A transmission, as it was designed to handle the stock 135HP engine.  This is a better choice for your TurboFB.  Again, aggressive driving habits will not be kind to your transmission, so consider upgrading to a stronger transmission.
  16. What is the ideal transmission to use in my TurboFB?  If you can find a Rx-3 transmission, this will provide a stronger transmission and housing than either of the 1st Generation Rx7 transmissions.  Although not as strong as the Turbo II transmission, it can provide solid support for a more aggressive driving style.  Cost considerations may make one transmission more "ideal" than another.  If you have sufficient funding for your project, just install the Turbo II transmission.  If costs are a bigger concern, work your way down through the Rx3, Rx7 13B and Rx7 12A choices.
  17. How can I fit a Turbo II tranny in my 1st Generation Rx7?  The biggest problem with the Turbo II transmission is the mount point.  A stock Turbo II transmission will bolt to the engine, and the shifter will fit within the stock opening if you have an '81 - '85 Rx7.  The '79-'80 shift location is different, and requires a "custom fit" to get it squeezed in there.  In either case, a custom mount adapter must be made in order to allow the mounting bracket to bolt up to the mount points on the car.  An example of this type of custom mount is visible here.
  18. Can I use the Turbo II stock exhaust manifold on a GSL-SE motor?  In the normal configuration, the answer is no.  The exhaust manifold casting has a large section of cast iron between the two lower stud holes which blocks installation of the Turbo II manifold on a GSL-SE block.  There is a large portion of metal that must be ground out of the exhaust manifold, and a corresponding section of metal that must be removed from the intermediate plate on the GSL-SE engine.  A photo of the exhaust casting can be viewed here.  The corresponding intermediate plate modification is visible here.