This is a very common question (possibly our most common) and one we hope to answer here, so we don't have to answer 100 emails a day about this same question. Many people start their search for a Supra Twin-Turbo and begin to find out that the search can be a bit difficult and expensive. At some point, people begin to see that the non-turbo version of the Supra, while it has the same body style (looks) as its big brother twin-turbo, it is certainly much less expensive.
The question then always comes: can I add the turbo kits you have listed on your website to my non-turbo Supra? Because if I can, then I can save a great deal of money!
Answer: NO, and do not expect to save much money at all. The non-turbo engine is called a 2JZGE, and while it has a shared basic design (inline 6) of the twin-turbo (2JZGTE) engine, it is a different beast. You CANNOT utilize turbo kits designed for the 2JZGTE Twin Turbo Supra engine on a non-turbo Supra engine (at least without a lot of work, time and money). The cylinder head manifold mounting is different, clearances are different, it has smaller fuel injectors, is a higher compression engine, has a different intake routing design, and a few other changes that make it not feasible. The non-turbo car is rated at 225HP from the factory, and has a very limited path forward for upgrades. We have a separate section on our website for Non-Turbo - NA Supras, which will lead you in the right direction on that car.
Why don't I just buy a N/A car and install a turbo kit to it?
Answer: You can do this, but you must be ready to spend a great deal of money, usually about as much total as purchasing a car with a turbo setup already! 1993-1997 N/A Supras, SC300s, and GS300s have distributors instead of coil-over-plug direct fire ignition, which is both inferior for spark and often an issue for turbo/intake fitment.
You can expect to have transmission issues with even moderate turbocharging. With a weak 5 speed and an automatic that isn't much stronger, be prepared to do a swap, or to replace your transmission on many occasions as a weak link of the drivetrain.
N/A cars have much smaller injectors and a tiny fuel pump. Even the JDM 2JZ-GTE's 440cc injectors are pushing it at 400 HP. The TT fuel pump is usually good until around 500 HP and is so good, many other car cultures use it in their projects. If you plan to install a turbo kit, plan on replacing the fuel system, including fuel rail, injectors, pump, pressure regulator, etc.
Factory turbo Supras have 8.5:1 compression, which is very conducive to a decent amount of boost. Early N/As have a 10:1 compression ratio, which is great for E85 builds and lots of power, but awful for pump gas (even 93 octane). The inexpensive way is to install a thinner head gasket (we offer a 2.5mm gasket for this reason), which involves taking off the head, intake and exhaust manifolds, and quite a bit of work, not to mention prepping the head and block for a multi-layered steel head gasket needed to properly handle boost. While you're in there, expect to replace various gaskets as necessary, and upgrade to ARP head studs...and that's the LESS expensive option. The CORRECT way is to install lower compression pistons. Although you can use a used set of GTE pistons, it is very likely that you would end up wasting your time instead of rebuilding the engine the proper way with a new set of forged aftermarket ones.
1998+ Supras, IS300s, SC300s, and GS300s come equipped with VVTi. Although VVTi features are entirely superior to non-VVTi setups, they also have other changes as well. The distributor is eliminated for a wasted spark setup (like the 1987-1992 turbo Supras), compression is bumped up from 10:1 to 10.5:1, and the connecting rods are thinner/weaker. They also use a drive-by-wire throttle, instead of a cable actuated throttle. As Toyota's first foray into electronic throttle control, most find the DBW system and pedal to be lacking in response and rather annoying. Although this system eliminates the often-troublesome IAC valve, it isn't ideal for swaps or most applications. If your car does have an electronic throttle pedal however, we do recommend using the AEM Infinity or Haltech Elite standalone ECUs to control the engine as well as throttle.
VVTi cars also have 5 speed automatic transmissions, which aren't known to be very stout, and have almost no aftermarket options to strengthen them at all. We usually have 5-6 of these in good working order, and have trouble getting rid of them because demand is so low. Another issue is the Multiplex CANBUS system on VVTi equipped cars. This system (which is now mainstream on all new cars) involves all of the different computers "talking" to each other. The transmission has its own dedicated ECU now, instead of being integrated with the engine management box. This causes issues with tuning, and can cause failure of the instrument cluster, ABS, cruise control, and various other features.
2JZ-GE cars have a side facing throttle instead of a front facing intake manifold, which makes installing an intercooler setup both annoying and needlessly lengthy. A 2JZ-GTE intake manifold setup will NOT bolt up. Just like the exhaust manifold, the flange uses a different bolt pattern. There are some cheap knockoff intake manifolds that are out there that can be used, but quality is often questionable at best, and a custom manifold is pricey as well.
N/A cars also had the inferior brakes. How good are the twin turbo brakes that would necessitate a conversion? The MkIV Supra, although not the lightest sports car out there, reigned supreme with the best braking distances right up until the Carrera GT came out with an extremely expensive and advanced ceramic silicon carbide braking system. From 1993-2003, no production car had better brakes, including Porsche, Ferrari, BMW, Lamborghini, or Lotus. The only advantage of the N/A brakes is that the rear ones will fit a 16" wheel for drag racing.
Although the 2JZ shortblock is pretty much the same for N/A and turbo setups, the GTE shortblock does come equipped with oil squirters for the pistons, whereas the GE does not. All GE pistons are higher compression, and the VVTi rods are weaker on the N/A cars. Fortunately, the 2JZ-GTE VVTi rods are the same as the non-VVTi 2JZ-GTE.
Turbo automatics had the same size differential as the non turbos, the 6 speed turbo cars had a larger ring gear (220mm vs 200mm) with a nearly bulletproof assembly. The only issue reported with these is the rear cover breaking under numerous heavy drag launches with 1200rwhp+ and very sticky tires. An easy fix with a billet cover.
After all this work, why not just start off with a turbo car and save yourself the hours of labor, thousands of dollars spent, various road blocks and unexpected issues, and so much more?
Another question we get is: Can is just go to Toyota and have them convert the engine to a TT?
Answer: NO, in most cases, no. You can perform a costly engine transplant, where you get the computer, entire engine, transmission, harness, and mounts from a twin-turbo car ($10,000+) and do an entire engine swap, but by the time you did this it would have been better to start with a twin-turbo car. Twin-turbo cars have larger brakes and other goodies as well (6 speed cars have a larger, stronger differential).