Top 5 Mods for Your Toyota Supra MKIII

Launched in the mid-1980s, the third-gen Toyota Supra is a car still praised today for its alluring looks, blistering performance and tunability. The car was among the first to get the inline-6, 3-litre 7M-GE engine, either as the 200hp aspirated or 270hp turbo variant, with Australia being one of the few markets outside Japan to get this.

Lower displacement 2-litre twin-charged 1G-GTE with 210hp and a later 2.5 litre 280hp 1JZ (the basis for the legendary 2JZ in the fourth-gen Supra GT3) were exclusive to Japan. But a few rare homologated imports can be seen on Aussie streets.

All cars featured advanced tech for the time. ABS, electronically adjustable suspension, coil packs, and LED lights were just some of the few innovations Toyota showcased. What is appealing today is that the Supra can take on numerous Toyota auto parts that bump up the already stout engine numbers in a car that can still take on today’s performance cars, including the renewed, fifth-gen namesake released in 2019.

If you’re lucky enough to have your hands on any of the MK3 or MK4 Supras, a few mods provide for crisper throttle response, widen the power band for both low-end torque and high-end power and improve fuel delivery. Even subtle changes can add 60 or so more horsepower down to the wheels.

These are numbers that get you higher top speeds and better acceleration. Keep in mind that any power additions mean an increase in heat, so also look into the appropriate cooling system parts to balance things out. Here’s a short list of Toyota auto parts that add more push:

1) Revised Turbo Boost Manifolds

Toyota supra turbo boost manifolds

We all know turbos work by reusing exhaust gases. These are redirected back into the turbo manifold to drive a compressor and spin a shaft that creates what we all want in a turbocharged engine – boost. Revised Supra boost manifolds don’t exponentially increase drive pressure or the boost required to spin the turbine (and in effect blow the turbine).

They manipulate the volume of air at varying engine speeds with better distribution. This has a knock-on effect in increasing exhaust scavenging and therefore allows for improved intake rates with oxygen-rich air further aiding combustion.

Real-life results are reduced turbo lag, specifically for the single-turbo 3-litre (but also the twin-scroll turbo in the 1JZ), better throttle response and more low-end torque for a Supra that’s willing to pull hard even at lower engine speeds.

2) Improved Fuelling with High-Flow Injectors

To get more out of changes to turbo configurations, fuel needs to be available at the right time and at the right pressure. More air implies more fuel, and the stock Toyota injectors may be wanting. Aftermarket high-flow injectors provide more fuel when you need it, so improved combustion rates and efficiency are a given. In simple words, spraying more fuel (with the increase of cool air) increases power by up to 10 per cent or roughly 30 horsepower in the 7M-GE engine.

3) Forged Internals

Bigger bangs need to be handled with poise. All Supra engines can benefit from the uprated forged piston and connecting rod combos that essentially transfer that new-found power to the crank without the risk of bending, snapping, or seizing the engine. While they won’t add power gains as is, it’s these Toyota auto parts that make other power additions possible.

Forging and heat treatment significantly increase strength, leading to pistons and conrods that perform optimally even under higher loads (a given with power mods) and will do so without issue. Newer forged internals additionally imply lower weight – an engine that’s ready to rev harder.

Varying piston and connecting designs and sizes mean options for any engine that’s seen previous mods, such as cylinder boring, or changes to the camshaft and valve springs for increased lift (and inlet/exhaust overlap).

4) Aftermarket ECU

aftermarket ECU for Toyota supra

The early Supras coped well with the 200 to 300-horsepower numbers without ever getting into trouble. The stock ECU allowed for crisp timing and fuelling, but will struggle with aftermarket mods. To tune powerbands, low-end torque and how the engine revs, aftermarket ECUs iron out any power dead spots and just balance things out for a more enjoyable ride. They’re a necessary upgrade when toying with turbo layouts and designs, specifically to control boost pressure, as well as calibrate fuel pressure from high-flow injectors.

5) Harmonic Balancers

I haven’t thrown in a revised crank in the whole mix, but there will be changes to how the stock, forged crankshaft reacts to the new piston and conrod combo being pulled and pushed harder in each stroke. A harmonic balancer, essentially a round disc of rubber and metal, is attached to the front of the crank and nulls excessive vibrations at specific engine speeds.

Torsional vibrations from twisting, turning and rebounding cranks can result in damage to parts like bearings and drive belts (as well as connected parts) in mild cases or the crank snapping in two when vibrations equal the natural resonance of the turning assembly. To exclude any surprises, and to remove elevated NVH levels, harmonic balancers keep the engine purring.

Summing Up

The MarkIII Supra was an instant hit for Toyota, marking a significant step up in performance from anything the Japanese carmaker had produced to date. This also coincides with the launch of the Lexus brand of luxury and performance vehicles, with many engines being carry-ons from the work put in for the Supra. Today, both the Mark 3 and 4 cars have a cult following, not just in Australia, but globally, and a dedicated tuning network striving to get even more from an already powerful and capable car.