The following recipe is by no mean the only way or even the right way to turbo charge a 5mge, but it is simply my personal recipe. For a 7mgte transplant see Reg's GTE at SONIC for turbo charging a NA MKIII see Dean's TNA at Trponline. Note: Unless you are emotionally attached to your MKII Supra like I am, it is much easier and more feasible to just sell your MKII and buy a turbo MKIII. Of course you wouldn't be able to enjoy the power to weight advantage like my 5mgte, but it is the wiser thing to do. Enjoy...|
Any exhaust manifold from a 7mgte will bolt right up to a 5mge motor with no problem. The only minor modification required be a 0.5" radius notched -out in between the first and second exhaust port to clear a bolt. This can be accomplished by simply tracing the 5mge exhaust manifold gasket on the 7mgte manifold and grind off the excessive material. For manifold gasket, you can use either a 7mgte or a 5mge gasket. Before torquing down the manifold and mounting the CT26, it will be wise at this point to install a brass T fitting on the oil-sending unit for the turbo oil inlet. The oil-sending unit is located roughly 5" to the left of the oil filter. Once the turbo is on, a custom down pipe must be fabricated to connect the turbo to the rest of the exhaust system. Oh yes, if your MKII is an 85 or 86, then relocating or removal of the charcoal canister will be required (you don't need one anyway) in order to make room for the turbo elbow casting.
Before you start the plumping, you need to first relocate the oil filter, if budget permits, now is a good time to install an oil cooler. For oil inlet, see the exhaust section. For oil outlet, believe it or not, there is already a tapped hole on the oil pan ready for a turbo hook-up. The tapped hole is located on the same side as the exhaust manifold/turbo near the top of the oil pan lip and almost directly underneath the passenger side engine mount, "Perfect". Take the plug out, and run the oil outlet to this hole. For cooling inlet, you can T off the cooling line just before it goes into the firewall. For cooling outlet, once again there is a tapped hole ready for this too. It is located 90 degrees from the temperature sensor on the engine side of the thermostat housing. Take the plug out, and run the cooling outlet to this location. Unfortunately, this cooling outlet plug is located on the driver side of the car, so be creative and make the outlet line look nice.
Any IC from a 7mgte will do, however the hoses and piping will be slightly different from the different years. The IC mounting is a piece of cake, like Reg once said "once install, it looks nearly factory". It is too difficult trying to describe how to mount the IC in words. Trust me, it will fit just fine in front of the radiator, AC cooler and all the accessories but behind the front bumper. Once the IC is mounted, you can now measure up what you need for piping and hoses, you can always get a couple 2" - 2.25" mendrel U bent pipes from Summit and cut them up to your needs. A few tips on IC hoses: For the first hose (turbo outlet hose) get one from a 7mgte, this hose will fit very nicely clearing both the engine mount and the alternator. For the last hose (connecting to the throttle body) use your stock 5mge plastic pipe, this pipe will save you from having to fabricate special outlets for the power steering and the ISC air lines. Lastly, try to route the IC outlet through the inner fender lining like a 7mgte. With a little imagination you should be able to snake a pipe/hose through the 2.5" AFM hardness outlet hole.
The biggest down fall to a 5mge motor are the tiny injectors. However due to its superior pintle peak and hold design, when mated properly to a high ratio fuel management unit, it will do fine for up to 10 psi. For a FMU, I went with a 10:1 Vortech unit. This is a great product with an excellent responds time to boost, it normally comes with Vortech's Mustang super-charger kit. Mustangs from the factory are usually equipped with 19 lbs injectors, very similar to Toyota's 190 cc injectors at least in terms of flow rate. As for the fuel pump, I wouldn't worry about it. See Reg's fuel pump comparison for more detail.
Don't even go cheap when it comes to monitoring equipments! After all that money and hard work wouldn't you want to know exactly what is going on with your setup? There are two gauges that must be had. First is a boost gauge, just T off any vacuum line from the intake manifold will do the trick. Second is an air/fuel ratio gauge. A typical air/fuel ratio gauge utilizes the O2 sensor signal, splicing the O2 sensor voltage wire will take care of this gauge. For price and performance, I recommend AutoMeter. No changes to any factory sensors will be required for the turbo setup, however I would highly recommend on replacing the O2 sensor if it has over 50K miles on it. You can use one made for either a 5mge or a 7mgte, they both have the same flange mounts except their wiring is different.
Unlike most vehicles, for some odd reason the 5mge on a MKII Supra was not orginally equipped with a PCV valve. Therefore, force feeding a 5mge will cause boost to back-track into the crankcase through the throttle body. This is very bad, the easy fix is to just take the PCV hose off, plug the throttle body side and install a K&N crankcase vent on the intake cam cover exit.