Car tuning tips:RZ Modifications"

RZ Modifications Guide

How to modify and upgrade the Toyota RZ

"Comprehensive guide to tuning and performance parts on the Toyota RZ engine!"

Popular tuning sites like TorqueCars are regularly seeing threads about how to improve the RZ from people wanting to know what are the best tips on RZ mods that work. So let us look into Toyota RZ modifications and outline the best modifications on this great engine and point out some common pitfalls along the way.

The Toyota RZ great bases for a tuning project and with the right uprated mods like remapping, turbo improvements and camshafts you will greatly improve your driving experience.

Here we outline options for your RZ tuning and summarise the greatest mods that work.

The optimum RZ mods on an engine are obviously the ones that give the best gains for your money.

We won't be swayed by popular RZ mods, they need to be cost effective.

RZ induction kits

Improving air intake on the RZ

You need air and fuel for an engine to work. If there is too little fuel then it will run lean, if there is too little air it runs rich sapping power which risks damage to the RZ. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the primary aim to any engine upgrade task to force air and fuel into each cylinder but this has a knock on effect with the air flow sensor.

It is common that there is a limitation in the air flow sensor (AFM/MAF/MAP) on the RZ when loads more air is being fed into the engine.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped bhp and torque at a much lower level.

Intake manifolds transmit the air from the air cleaner and allow it to be pulled into the engine cylinders.

Shape and rate of flow of the Intake can make a large effect on to fuel atomisation on the RZ.

It's not uncommon that headers are in desperate need of aftermarket parts, although some car makers provide well optimised headers.

Increasing the RZ valve size, getting port work and head flowing will also boost torque, & importantly will afford you raising the torque increase on other tuning mods.

RZ performance cam tips.

Some RZ engines respond better to more or less aggressive camshaft durations than others.

The map and fuel pump and injectors also will say much on the torque gains you'll achieve.

Altering valve durations can alter the torque band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

The camshaft profile plays a big part in the engines power output so camshaft upgrades make quite a large difference. The intake & exhaust durations will alter depending on the chosen camshaft profile, so large bhp gains are on offer for camshaft upgrades.

NB: Fast road camshafts usually boost the bhp and torque across the rev band, you could drop a little bottom end torque but your high end rpm power will be higher.

Competition camshafts, boost the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a car used daily you must carefully try to match your engines power to your preferences.

I'd be amazed if you have ever thought a RZ Race cam is a pleasure to live with when on the daily commute.

Stage 1, 2 and 3 mods for the RZ

Stage 1 RZ parts:

Sports exhaust manifold, Remaps/piggy back ECU, Fast road camshaft, Intake headers, Drilled & smoothed airbox, Panel air filters.

Stage 2 RZ parts:

Sports catalyst & performance exhaust, induction kit, fuel pump upgrades, Fast road cam, high flow fuel injectors, Ported and polished head.

Stage 3 RZ parts:

Competition cam, Crank and Piston upgrades to alter compression, Internal engine upgrades (head flowing porting/bigger valves), Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Engine balancing & blueprinting.

The RZ power trains make great tuning projects and we're pleased to see that there are plenty of mods and performance parts out there.

Remaps should help to unlock the full potential of all the upgrades you've done to your RZ.

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the end result may depend much on the upgrades you've fitted and the condition of your engine.

Turbo modifications on the RZ

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the RZ.

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes major power gains.

When your motor has forced induction parts are relatively easy and you will discover turbo engines are built using stronger components.

However every engines will have power limits

See where you'll find these restrictions and fit better pistons and crank to handle the power.

We see many tuners spending a loads on turbocharger upgrades on the RZ only to experience the RZ explode when it's first rolling road session.

Bigger capacity turbochargers often experience no power at low rpm, and smaller turbochargers spool up more quickly but won't have the peak end power band gains.

Thanks to progress the selection of turbochargers is always developing and we commonly find variable vane turbochargers, allowing the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbochargers divert the exhaust flow into a couple of channels and flow these at differently profiled vanes in the turbocharger. They also boost the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large power gains, although more complex to get working. We have this guide to twinchargers if you want to read more.

Tips about fuel supply on the RZ

You will need to ensure that the engine is not starved of fuel so need to uprate the fuelling when you start exceeding 20% of a power hike. It makes sense to be generous with your injector capacity.

As a rule of thumb add 15% when fitting an injector, this takes into account injector deterioration and gives you some spare capacity should the engine require more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended RZ performance exhaust upgrades

Only look to increase your exhaust system with an upgraded one is if the current exhaust is creating a restriction.

On most factory exhausts you'll find the flow rate is still fine even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Sports exhausts generally help improve air flow out of the engine but do not go too large or you could will reduce the flow rate. Stick to one and a half to two and half inches as a rule of thumb.

The usual suspects causing problems in your exhaust flow rate are in the catalyst and filters installed, so adding a faster flowing performance alternative will help avoid this restriction.

Catalyst removal (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the RZ

Like most engines an RZ, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the RZ, failure to do this will exacerbate engine wear, on a tuned RZ this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your RZ why not pop over to the forums at TorqueCars where you can chat about RZ tuning options and read about others projects who may be planning to do similar modifications on their RZ.

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