Toyota GR Yaris Tuning Guide

Modification ladder

The Gen 1 Toyota GR Yaris comes with 256bhp from the factory and you can give it an easy power boost with just a few mods. Now our dyno reads the power at the wheels (whp) so to get a flywheel figure that most people like to use we need to convert it using a pretty accurate calculation we do. Below is a dyno graph of a completely standard car making 212whp which is estimated 258bhp at the flywheel.

The first parts to fit to your GR Yaris are the intake and exhaust system for both power and vocal reasons. The exhaust system which fits from the GPF back doesn’t make a huge amount of difference to the power at the lower end of the tuning ladder but it does transform the way the car sounds. From the factory sound what is best described as hoover like! We sell a variety of exhaust but easily the most popular is our own Whifbitz exhausts, made in stainless and lightweight titanium.

By far the best intake kit we’ve tried is the Eventuri, it may be one of those most expensive but it really does work, we’ve seen gains of 15/20bhp compared to the OEM Toyota air box. And they look and sound rather good too! We’ve seen some intakes actually loose power over standard and some given 1/2bhp gains, most of them really are made to make noise only. If you want the best you’ll need to pay for it and buy the Eventuri.

We also highly recommend a GPF delete pipe, these release about 10/15bhp and again increases the noise and makes the engine feel more alive. We sell our own versions of these in non resonated and resonated if you want to keep the noise down and as per our exhaust systems they come in stainless steel or lightweight titanium.

So with these 3 mods you will putting out an estimated 285bhp with gains of about 30bhp over the factory car as shown in the graph below. Torque has also risen from 230 lb/ft to 245, nice gains and getting it breathing ready for an ecu remap.

Next step would be to remap it using the Ecutek tuning software, this basically allows us to turn up the boost and retune engine parameters to give the G16E-GTS engine a power gain. A remap on a totally standard factory car will give it around 290bhp and with the mods mentioned already above we normally see on average around 330bhp. This as you can imagine really transforms the way the Toyota GR Yaris drives, giving it a big gain in performance. These figures are all made using the highest octane fuel available in the UK which is 99ron, if you use 95ron fuel you’ll lose around 20/30bhp in comparison. The dyno graph below shows the gains achieved with the 3 mods listed above making a nice 270whp which is an estimated 326bhp.

The next stage is to max out the standard turbo and to do this we need to fit a set of Kelford 267EZ or 267A cams, Kelford valve springs and a Syvecs stand alone ecu.

As you can see from the dyno graph below we normally get around 300-310whp which is 370bhp and still maintaining low end power and torque.

The turbo is the next area to look at, if you want to get to the next level you’re going to fit a larger one, either with a hybrid stock turbo or a turbo kit like the one we make which can take your power to over 600bhp if desired. We normally get around 400bhp out of a hybrid turbo running about 1.9 bar boost and even though we have a massive increase over the standard car the power delivery remains very very useable with no loss of low down power and major gains at the top end of the rev range as the standard turbo drops off. The dyno graph below is making 335whp which is 401bhp and it could make more depending on how far the owner wants to push everything.

Next step to make more power is to ditch the factory style turbo and fit a Whifbitz turbo kit which utilises the Garrett G25-550 & 660 turbos with the 550 turbo rated at 550bhp and 660 rated at 660bhp, hence the names.

The G25-550 unit is still surprisingly useable, in fact it loses nothing with compared to stock and hybrid turbos. The dyno graph below shows a Yaris making 363whp which is an estimated 434bhp at 1.9 bar boost on 99ron fuel with the same mods as listed above already. Just look at that torque graph, its making 320lb/ft torque at 3000rpm versus the hybrid turbo making 310 lb/ft torque at the same rpm. It just shows there is no loss in low down power and response even though its making 434bhp, what a remarkable engine!

The below graph is of G25-550 turbo kit on a GR Yaris running E70 ethanol fuel making a stonking 419whp which is 500bhp, this is made using 99ron pump fuel at 2.1 bar boost and it will make more power depending how brave the owner wants to be with reliability.

But that’s not it, there’s more to come when using the G25-660 turbo but it does start to lose some low down torque and response with the offset being big gains in bhp up the top end of the rev range. The below graph is of a GR Yaris running 2 bar boost on 99ron fuel making 392whp which is 467bhp, quite a gain over the G25-550 turbo which makes around 415bhp at the same boost level and fuel. But look at the low down torque gone, at 3000rpm the G25-550 is making 320 lb/ft torque but with the G25-660 its making 220 lb/ft but as you can see from the graph it gains in torque and horsepower higher up the rev range.

And then when you add ethanol to the party it really gets serious! With E70 fuel added at 2.6 bar boost power shoots up to 530whp which is 628bhp and its still not maxed out, this particular car started to drop fuel pressure so we had to leave it there but with that fixed more is possible. And of course you could always put a bigger turbo on!

Reliability

Now this is a hot topic, there’s one particular video on YouTube that seems to hit the nail on the head with the issues that affects a minority of engines, we’ve seen it here ourselves where we took a standard GR Yaris to 400bhp and it only lasted 2 days. The car was fitted with a Syvecs ecu which datalogs everything and we could see there was nothing untoward before the engine let go. We’ve done countless 400bhp conversions with zero issues and then we get one which randomly decided to fail and fail in a big way with the piston going through the side of the block destroying the engine.

So its a difficult one this, 99.9% of the engines will be ok but there are some out there with a piston issue which you wont know about until you tune it. Saying that we’ve heard on the grape vine about standard engines failing and we’ve also had a car delivered to our workshop which had a 320bhp remap do the same thing. So its not just big power cars suffering from this.

If you want to be 100% safe and reliable when tuning the only option is to fit forged pistons and conrods, we offer a full engine build service here along with other mods like a closed deck conversion which gives more strength and reliability. We also port the cylinder head, fit uprated head studs and an uprated head gasket, with this lot done your G16E-GTS will take 500bhp all day long. Above that and it does need some maintenance, regular head gasket changes for instance.

If you’d like your Toyota GR Yaris tuned then please get in touch.