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4A-GZE, All Things Considered Not as simply put as most see it to be…
The 4A-GZE is a supercharged version of the 4A-GE engine initially developed to provide added punch to the MR2 AW11 models. It was produced to the request of many critics sighting the MR2 to be underpowered at the time of mid-80’s power wars of the 1600cc class production engines. One year after the MR2 Supercharged introduction, the engine was used also in the AE92 Levin/Trueno siblings as a front drive power plant. Both of these first edition 4A-GZE produced 145ps JIS at torque curve of 21kg/cm, running at 8.0:1 compression rate. Indeed, it was the most powerful engine in the Japanese 1600 class. A first major revision of the 4A-GZE was done in the 1990 model year solely for the front drive setup as MR2 gave way to the newer and larger 3S-GTE power plant. This second generation of 4A-GZE utilized the now commonly available Japanese market pump gasoline of 102 octane. Accordingly, the compression and boost was raised to produce the 165ps JIS figure. The compression was upped to 8.9:1. The newer engine also utilized the new 4A-GE block and bottom components based on the 90 and later Levin engines, comprising of stronger larger crank and rod journals as well as piston pin and used semi-forged coated pistons. The new 4A-GZE also featured the only DLI (distributor-less ignition) used on the 4A series and the AFM was replaced by the MAP system (latter probably due, more to cost of production, as MAP systems are much cheaper to manufacture) In the succeeding years the engine was carried over to the AE101 Levin/Trueno Line up And now used dual-exhaust and slightly more efficient charge cooling to produce the 170ps JIS to make the most powerful 4A-GE engine ever to be produced for normal consumption. This was the final version as the 4A-GZE gave way to less powerful but more sophisticated 20 valve 4A-GE, for it’s normally aspirated pleasure and the lack of popularity for the supercharger engines in the Japan’s market (thanks to Honda’s VTEC…ughhhh!) The fact of the matter, however, is that both AE92 and the AE101’s were not the star in it’s era and the fun factor was better appreciated by the hard-core in the older, lighter, rear-drive AE86 series. Thus the craziness began. The list of transplant for the 4A-GZE now included the AE86 as well.
The following text will apply to projects considering the 4A-GZE to replace the 4A-GE in Front drive and rear drive Corollas in general. We will examine what is required to do the transplant, it’s inherent difficulties and few tricks I learned in my own AE86 to GZE project in the past. So read on if you care… The 4A-GZE’s engine will bolt into any location where the 4A-GE was installed before. The installation of the main body of the engine, i.e. the block and the head will be simple as removing the old engine and bolting on the 4A-GZE. This is as far as most people plan when doing this project. But there’s more… Lot’s more….
After the engine is in place, the first thing you will notice is that handsome black intercooler will not clear the hood to close fully. There are 2 ways to get around this… The easy way will be to cut a hole in the hood and clear away stuff until the hood closes. A hood scoop can be utilized to cover the gaping hole and to direct air through the intercooler. A popular method here is the use of the AE92’s OEM scoop…naturally, it fits well. This way, all of the induction pipes can be used and least custom work will be required. Plain and simple and surely acceptable method. The other, more advanced and expensive way is to design the intercooler to be front mounted as in most turbo cars of today… This will require a custom 50-60mm pipes to be guided and custom welded through the front cross-member and in front of the radiator. It is pertinent here that all piping will be similar in diameter and sharp turns avoided. Though there are significant outlays involved with such system, there are definite advantages to this setting. The main reason for this front mounting is the increased efficiency of the intercooler as it will feed air more positively across the entire surface. The second reason will be the ability to use a larger capacity intercooler. On my AE86 project this latter method was chosen to accommodate a 3S-GTE intercooler from a SW21 MR2. One note here… since the supercharger’s main advantage over the turbo is the instantaneous boost, an excessively larger cooler chamber will take too much time for air to compress. 4A-GZE is kind of nervous with manifold pressure irregularities so keep over sizing of the intercooler to minimum… The 3S-GTE one worked perfectly taken from a SW21 MR2 Turbo.
After the intercooler problem is solved by one of 2 ways mentioned, the next task is installing the peripherals. As the supercharger effectively replaces the location of the alternator of the standard 4A-GE. All of the peripheral accessories sits on the exhaust side of the engine. From top, brackets hold the power steering pump, the A/C compressor, and finally at the bottom, the alternator. If you are using all of the above, you WILL need those corresponding brackets and accessories. So here, when you look for a 4A-GZE donor, you should patiently look for one with all of those in tact… An engine supplier will rarely sell you those separately later as it seems to be more rare than the engine itself. There have been no know alternatives but to build you own brackets if they are not there… It’s much simpler in this case to use just the alternator and devise a holster yourself at a machine shop… Make sure everything will clear the body of the car and all electrical are accessible.
Once you have taken your time to clear the install of the hardware, now it’s the software portion. Namely the electrical components. NO! the 4A-GZE will not function on the normally aspirated computer. That’s That! (Unless you are expert in designing all of the electrical system yourself to accommodate the missing triggers and sensors…) Make sure that the OEM computer (if you use it) matches the specific model 4A-GZE you are about to install. The OEM ECU is also the other device that’s really hard to find these days, but it’s out there so be patient… look for it as it will make things much simpler in the process following. If you are installing it n a front drive configuration, the wire harness from the Levin/Trueno GTZ will, mostly fit right in. If however, you are placing it in rear-drive car such as AE86, TE71, KP61… you will need to either cut or adjust the wires or make a new harness altogether. (A task easier said than done). All of the wires must be secure and of high quality as 4A-GZE is especially hot and sensitive to vibration caused wire failures. (Not to mention the ECU’s temperament with bad wires) Most malfunctions can be traced to bad wires in this project, because of the frequent necessity to make your own harness. 1990 and later 4A-GZE also utilizes the DLI system for ignition so obtaining the correct igniter is a must. The AE86 ignition, in this case is just as useful as a paper weight. The same goes for the coil packs and plug wires…
Frequently in transplanted 4A-GZE, the supercharger quits occasionally or frequently. This is caused by faulty reading of the manifold pressure due to altered piping or intake system. This can also be triggered by the excessive heat. It’s usually safe to override the ECU by feeding 12v manually to the supercharger clutch but it’s much nicer to let the ECU handle the controls by correcting what’s wrong… Frequently, it’s caused by faulty wires as well. Letting the ECU do the controls is also the safest, most reliable setup. When selecting the engine, rotate the supercharger by hand. The pulley should be free of warpage and should rotate freely with a slight hissing sound. If the supercharger makes gurgling noise or clatter, it is either worn excessively or has bad bearings. It’s the most expensive component so that should be your main concern when looking for that nice 4A-GZE.
The most notable mistake people make when installing the 4A-GZE is the lack of concern for the fuel system. The original fuel pump was designed to feed a set of 185cc-230cc injectors and falls dangerously short of the capacity required to run the 365cc injectors at full boost. Luckily, this can be sorted out simply by looking for a Mazda RX7 turbo (FC3S) fuel pump or from a 1988-91 Toyota Supra (MA70, 7M-GE/GTE). These pumps will be a direct replacement of the Corolla fuel pump and has well enough the capacity to feed most 4A-GZE, even in modified forms.
As most of you know by now, the 4A-GZE has almost 30% more torque that happens at 2000 rpm’s less than your original 4A-GE did. This causes the gears to feel really short as you run out of first gear in less than 2 seconds then second in less than another 4 seconds… Impressive! but busy… In the AE86, there’s a factory 3.6 final drive that works wonders on mileage as well as sorting out this problem… If you are inclined, there’s also a 3.9 which does less of a job on mileage but leaves that “I’ll smoke your pussy ass Integra in the dust” feeling… For front drive setups, the only choice seem to be TRD’s final drive sets but would require you to disassemble the transmission.
Aside from excessive tire wear (smile) there are just a few more things to note here. The 4A-GZE has a tendency to go through OEM clutches really fast because of the extra, EXTRA torque. So installing an aftermarket clutch such as HKS or other notable manufacturer makes sense. Centerforce, Dual Friction (a centrifugal weighted clutch) doesn’t hold well in low-rev, high-torque situations in 4A-GZE so avoid it if you can. The flywheel should be on the heavier side as idle sometimes becomes erratic. (It’s one that Toyota never fixed to this date) and throttle response won’t improve too much by lighter wheel due to the supercharger being driven off the crank pulley. (Don’t worry though, you can catch and pass that Honda quickly because you shift less and you have maximum torque from 4400rpm… NO VTEC necessary here! In the fluid department, the 4A-GZE runs at significantly higher operating temperatures than the 4A-GE so always select the “turbo approved” engine oils and make sure the transmission gets a good quality oil too. SH grade 10w-50 or 15w-50 is fine. It doesn’t have to be racing oils as the 4A-GZE produces all the power well before the redline of 7500rpm, and friction isn’t too much of an issue as temperature.
If you can, watch your exhaust temperature by installing an accurate gauge so you won’t fry your engine if the fuel becomes lean due to malfunction… This usually occurs after you lend your car to a friend who returns it to you with a full tank of sub-80 octane gasoline at your local Bob’s Gas Stop…it really causes a havoc…Ping o’ Rama! (I say EGT gauge is a must on any 4A-GZE!!!) Always get 92 Octane or higher! The original engine was designed to take solely the 100 octane Japan premium grade. Finally, if you do any kind of extended runs on autocross, racetrack, or illegal speed blasts, you will need a larger radiator (3 core is excellent) and a good oil cooler. That is if you don’t want to overheat and spray coolant after 30 minutes of really spirited runs… Do not consider any modifications to the engine until you have successfully installed the OEM setup. There are many bugs to figure out once the engine is in and running even in bone-OEM form… After you are familiar with it’s operational characteristics, and are really comfortable, you should be ready for some step up. It’s a rather complex setup if you are used to the simple 4A-GE, the 4A-GZE is quite different and it will monitor and throw complexities in your face if you don’t respect it. I really don’t mean this to say it’s not reliable, it really is… Just study it carefully to manage it properly. It CAN be broken fairly easily if you do something wrong just as with any force-fed induction engine… Figure on the project to take 3 times longer than installing a regular 4A-GE. Also the cost of the engine isn’t near the full installation cost of the engine so figure the engine itself to be about a third of the whole project cost, not including drivetrain nor installation. Don’t ask me exactly what but trust me, you won’t be happy with a sub-$3000 install job…
OK, everything checked out well, fuel pressure OK, injectors pulsing, igniters firing, manifold pressure and compression OK… You turn the key… Vroom… YES! The bugger runs! Then you step into the cockpit…. Hey! That tachometer is dead… This is a problem that occurs in the 4A-GZE late models using the DLI. The single pulse tach is incompatible with the dual pulse that runs the DLI. Where can I get the tach signal…? Well, if you use the OEM computer correctly, there’s no place you can do this… You think… ”easy! You just tap off of both the coils to get the standard readings!” Well, no… this method effectively kills the igniter and no sparks fly…
(Diagram by Sam Crosse) There’s a solution to this. There’s a way to modify the OEM tach slightly to operate directly out of the ECU but this is different in every gauge set so I’ll leave that out here. Most aftermarket tachs work fine off of the ECU’s rpm signals so that’s another safe way to run if you don’t feel like hacking up the OEM dash… Well, I hope you have somewhat of a grasp to what it takes to set up a nice 4A-GZE in your car and how to make it work for you… You can e-mail other questions to Moto-P, the Webmaster…that’s me… at Trueno@club4ag.com Thanks… --Moto-P
“The 4A-GZE is just powerful! If it makes a crappy driver out of you for cheating ALL the time…it’s just plain awesome!” -- Keiichi Tsuchiya, professional GT driver, the King of drift “That crazy-ass Moto wouldn’t let off the gas so the car was sideways at over 60 miles an hour in the straight! I thought I was dead!” -- Mike Urbano, a Toyota nut... “This is just too fun to loop around and around that orange pylon, all day long…at half throttle?!” -- Hiro Hatada, an avid AE86 nut in Southern California “Okkane---!” (“that’s pure danger in Japanese language”) -- Anonymous guy who test drove near my house