AE 86 Engine Swap Considerations.
While it is possible to make almost any engine fit inside the engine bay of an AE 86, even Lexus V8’s, the wide range of engines that have been successfully fitted to the platform makes it impossible to say which engine is the “best” choice, since much of the validity of the answer depends on factors such as the purpose of the engine swap, the purpose to which the car is put, personal preferences, available budgets, and perhaps most importantly, the reliability of the replacement engine, as well as the availability of spare/performance parts for the replacement engine.
Merely swapping an engine for the sake of having something to do over weekends is pointless: with some minor modifications, standard 4A series engines can develop enough power to satisfy most needs- therefore, the driving force behind an engine swap must be the need for ridiculous amounts of speed and power- hence the requirement that the replacement engine be modifiable without sacrificing reliability.
Which Engine Then?
As is the case with all engine swaps in all cars, the overriding consideration must be how well the car will handle after the conversion. In the case of the AE 86, much of its success has to do with its favorable power/weight ratio on the one hand, and it’s above average handling characteristics on the other.
If you are planning to build a dragster to run quarter miles, fitting any of a range of lightweight V8’s (including the Toyota Lexus and GM’s LS1s might be the answer, but for spinning, drifting, or street racing, the choices become more dependent on weight, as opposed to power output. Even though complete and undamaged AE 86’s are not as plentiful as they used to be, many are sold without an engine, which makes the decision on which engine to fit somewhat easier. However, possible and viable engine choices number in the dozens, if not hundreds, which makes it impossible to list more than just a few popular choices, some of which are featured below:
Toyota 4A Series.
Depending on the market where these engines were sold, they are often referred to as the 4A-GTE version when they were equipped with turbos. Most engines in this list can be fitted to the AE series without modification. However, due to its almost bombproof internals and proven reliability, the 4A-GZE is by far the most suitable.
The 2.0-liter turbo charged engine from a GT 4 requires a Camry transmission for the best results. Alternatively, the MR 2 variant can be used- albeit with some modification to mounts and other components. Both choices are good for lots of torque at relatively low RPM’s.
Nissan CA 18-DET
These engines are plentiful, cheap, and easy to upgrade with plenty of performance parts available from a host of suppliers. However, this engine requires the use of a CA 18 transmission for best results. With some minor trouble, the front suspension from a S13 can also be used, although exactly why some builders do this is not clear, since there is no discernable advantage over the standard, easily upgradeable AE 86 suspension.
While this engine is not as cheap as most others, it is reliable, and can be modified to develop insane amounts of power. However, it requires a lot of medication to fit, with the cross member, gear shift position, and drive shaft all requiring some modification to work properly- all of which have potentially negative impacts on final weight distribution.
Mazda 13B, 20B Rotary Engines
Due to the high-up position of the transmissions relative to the engine, the fitment of rotary engines requires extensive modification of the firewall and transmission tunnel of the AE 86 platform. However, the huge power output of even a standard 20B engine might make the extra work and expense that goes with fitting more than worth the trouble.
Is An Engine Swap Worth It?
There are many possible reasons why an engine swap into an AE 86 may be required, but the truth of the matter is that in almost all cases, an upgrade of an existing 4A series engine is more cost effective, and it does not upset the car’s balance.
4A series engines are almost bombproof, and reliable, which makes replacing one bombproof engine for another bombproof engine that has to be modified to develop the same power that can be had from an upgraded 4A engine, seem utterly pointless. To illustrate the point, we have gathered below some proven ways and means to tweak a 4A-GZE to deliver 160 - 180+ HP without sacrificing reliability in any way:
Fit a bigger diameter crank pulley.
This will speed up the supercharger but be sure the supercharger does not spin at more than 10 000 RPM, to prevent damage to the rotors.
Remove restrictions from the inlet manifold.
To prevent turbulence in the manifold that can seriously hamper airflow, have a custom manifold made to deliver the intake air to the cylinders evenly. Alternatively, use a manifold from an earlier 4A series engine in which the individual inlet ducts are parallel to each other, and have the same length.
Match camshafts and vacuum sensing.
While camshafts with duration angles of up to 2640 are good for lots of extra power by themselves, exceeding this angle will start to interfere with the standard ECU’s ability to sense the manifold vacuum accurately. The answer to this problem lies in using an aftermarket ECU that uses the combination of throttle position and Absolute Manifold Pressure (MAP) sensing, in conjunction with a closed-loop, oxygen-sensor feedback system.
These minor modifications are relatively cheap, but of course, they need to be done in conjunction with other tweaks, such as fuel pressure and injector upgrades, but even so, all these modifications can be done for less than the price of a replacement engine alone- at a price than can be more than an old AE 86 might be worth on the open market.
The Last Word.
Similar tips and tricks have been developed and perfected for other engines in the 4A series, so there is really no need to go to the trouble and expense of cutting up the bodywork of your beloved AE 86 just for the sake of having a Toyota with say, Mazda rotary power.
In the final analysis, it seems pointless to upset the almost perfect balance of an AE 86 with a heavier engine, when the same power can be extracted from a 4A series engine with no negative effects on handling, which seems to be win-win situation against which it is hard to argue.