If you look at Toyota’s track record for their modern sports car, it’s been heavily based on working with other companies. The FRS and GT86 use a motor from Subaru, and the Supra is a Z4 in fancy clothing. While both of those cars are great in their own right, the Yaris GR is different in the fact that it’s a Toyota product through-and-through, something we haven’t seen in a long time.
The Yaris GR has a ton of really cool stuff that makes it interesting, but today we’re here for the motor. Under the hood, you’ll find a Toyota G16E-GTS, which a 1.6-liter three-cylinder engine, unlike anything we’ve really seen before, in the sense that it’s literally the most powerful product inline-3 engine ever, a title which was previously held by BMW.
As you probably know, Toyota really hasn’t been making much of anything in terms of performance engines for quite a while now. They pretty much peaked out at the 2JZ, and it’s been a decline ever since. At the end of the day, this makes sense because Toyota is more focused on producing economical cars that sell well and turn a profit. The money just isn’t there for performance cars anymore.
Of course, that sentiment was really flipped on its head with the G16E-GTS, a small 1.6-liter three-cylinder engine, unlike really anything Toyota has built for production road car use.
Something that is worth noting is that this engine had to comply with Euro6 emissions standards, which meant that Toyota had to make a lot of changes and design choices in the name of improving efficiency. Taking a closer look at this engine, let’s take a look at it from the top-down, starting with the cylinder head.
Starting with the most basic information, the G16E-GTS is a dual-overhead-cam, 4-valve per cylinder engine. Since it has only has three cylinders, this brings the total valve count to 12. It’s a little weird seeing that number if you’re used to four-cylinder engines, which almost always have 16 valves, but that’s a little off-topic.
The head itself is constructed from cast aluminum, as most modern engines are. This is done for weight savings and thermal efficiency. Inside the head casting, you’ll find a two-level coolant jacket for improved flow. Toyota obviously needed to put an emphasis on keeping this engine cool, especially considering it was designed with track use in mind, where your engine is under extreme loads for extended periods of time.
Cams and VVTi-W
Something that did kind of surprise me during the research phase for this article is that this engine doesn’t have variable valve lift. Over the last 30 years, variable valve lift could be found on most small performance engines, but with this motor, it’s not a thing.
Rather than variable valve lift, Toyota opted to give this engine variable valve timing through the use of cam phasers on the front of the camshafts, which by the way, are hollow to save weight and reduce parasitic loss ultimately being used to help improve efficiency even further.
On the intake cam, this system gives the G16E-GTS 70 degrees of camshaft timing adjustment, and on the exhaust side, it has 41 degrees of camshaft timing adjustment.
You might be wondering why the intake side has more adjustment, and that’s because the intake side uses VVTi-W and the exhaust side uses VVTi. It’s also worse noting that you’ll generally see more performance and efficiency benefits from having a larger adjustment range on the intake side as compared to the exhaust side.
Ports and Valves
Taking a closer look at the ports on the cylinder head, you’ll notice something very different from what you’re used to seeing on small performance engines, and that’s the path of the port itself. This is different from what you typically see because the G16E-GTS is part of Toyota’s Dynamic Force engine lineup, which uses a much wider valve angle than the average engine.
To put that simply, the intake basically less straight on and more angled down. That, combined with the wide valve angle, gives this engine some very unique characteristics, which are done in the name of efficiency and power. By using a steep intake port and an increased valve angle, air really flows more over the back-side of the valve into the cylinder, rather than going around the back-side of the valve.
When you visualize this, you’ll see that the result is actually a much better path for intake flow, which ultimately results in much better flow, fuel atomization, and ultimately more efficiency and power. The exhaust valves are sodium-filled for improved cooling, which is something you’ll find on a significant portion of performance-oriented engines.
Where things get even more interesting with the ports on the head is that Toyota is using CNC machines to partially smooth out the intake ports. When the head is made, it has a rough finish because it’s a cast material, so it’s a little bit porous.
A process that used to be more popular, known as porting and polishing, is a process where the ports would be enlarged and smoothed out. The smoothing is done to help improve airflow by letting the airflow more smoothly into the cylinders, at least in theory.
On the G16E-GTS, Toyota isn’t hand polishing the ports, but they are using CNC machines to smooth out the entrance of the intake ports while leaving the rest of it rough. In theory, this should help with performance and efficiency. It’s just strange that they’re doing it at only the entrance of the port and not the whole thing.
This could be to just improve the transition from the intake manifold to the intake runner, but that’s just speculation on my part.
The intake manifold itself uses a variable-length system, which is pretty common to see from Toyota and modern engines in general. To put this system simply, there is a bulkhead to divide the intake manifold into two stages and an intake air control valve in the bulkhead, which opens and closes to change the effective length of the intake manifold runners according to engine speed and throttle valve opening angle.
To put that even more simply, it’s just a system to help improve power regardless of engine RPM by optimizing the intake runner length and air velocity. For people modifying their engines for absolute peak performance, this is something which is often, but not always, removed entirely.
In terms of injection, the G16E-GTS isn’t anything particularly special since it uses Toyota’s D-4S fuel injection system just like all other Dynamic Force engines from Toyota, which consists of both direct and port injection for the best of both worlds.
To put that simply, direct injection offers more accuracy and precision regarding fuel spray and timing, while port injection helps to minimize carbon build-up on the valves, and port injection is much easier to upgrade for aftermarket performance compared to direct injection.
In terms of the turbocharger, again, it’s kind of surprising to see such a simple setup. Like you’ll find on many modern cars, the turbo is integrated with the exhaust manifold as one large unit. This is something you’ll see on other Toyota engines like the 3SGTE but also on other performance engines like the BMW N55.
The turbocharger is a relatively small unit to help give this engine great low-end power and throttle response. It features a ball-bearing setup and uses a single-stroll design. You might be wondering why it doesn’t use a twin-scroll as you’ll see on other modern performance engines, and that’s because there is effectively no benefit to a twin scroll when used on an engine with only one bank.
What I mean by that is that this engine only has three cylinders which means there’s only one bank. A twin scroll really only benefits where there are two banks of cylinders, which as with an inline-6, where three cylinders can power each scroll of the turbo.
Block and Internals
Moving down from the cylinder head, let’s take a closer look at the cylinder block and internals inside the engine. Just the head, the block is constructed cast aluminum, which again is pretty standard across all modern engines. It’s basically just done for weight savings and thermal efficiency, and because there’s really no good reason to use cast iron in this type of application unless the potentially reduced manufacturing cost is a priority.
The block uses an open deck design, which did surprise me a little bit, considering how performance-oriented this engine is. We’ve covered this in detail in other articles, but basically, the closed deck design provides more cylinder stability, especially at the top of the cylinder where in-cylinder pressure gets the highest. The open deck design improves cooling and reduces hot spots in the cylinder but provides much less strength and rigidity at the top of the cylinder.
Considering how high cylinder pressure is on this engine, you’d think Toyota would use a closed deck design, but they just didn’t. The sleeves for the cylinder are made from cast iron, and they’re super thin, to the point that you can’t really bore this engine out. If there was terminal failure somewhere in the engine and the cylinder needed to be bored out as part of the rebuild process, you’d just have to buy a new block instead.
The pistons are constructed from aluminum and use a T-shape design. Another thing that surprised me during the research for this article is how high the compression ratio of this engine is at 10.5:1. That used to be considered pretty high for a naturally aspirated engine, so seeing that in an application with upwards of 20 to 30lbs of boost was pretty wild.
The pistons also feature thin inner walls for reduced weight on the rotating assembly. The groove of the upper compression ring is made in a ni-resist insert, and the edges of the pistons are coated with DLC (Diamond-Like Carbon).
The connecting rods are forged as you’d expect from a small engine producing such high power levels, and the crankshaft is forged steel induction hardened. The really interesting thing Toyota did with this whole rotating assembly is offset the centerline of the crankshaft from the centerline of the cylinders by 10 degrees.
This was done to reduce the lateral force exerted by the piston to the cylinder wall, reducing friction and wear. This isn’t something I’ve really seen on any other engines, so it makes me curious if it’s something we’ll start to see more often in performance applications.
The crank throw on the engine is 120 degrees, which is typical for a three-cylinder engine, so nothing really special in that regard. Because of the inherently unbalanced nature of engines with odd numbers of cylinders, Toyota did add in balancing shafts to help reduce vibrations felt in the cabin.
The bottom-end features nine piston oil squirters, three per piston. This helps keep the pistons cool which is especially important for the amount of boost and power this engine makes, and all that power is spread across only three cylinders. That puts a ton of load and head in each piston as compared to an engine of similar power output with more cylinders.
The last thing worth noting on the block and the bottom end has the massive girdle, which holds everything together. The block is essentially a rigid 3-piece design, with one main bearing girdle holding the entire bottom-end together, rather than individual main caps. Ultimately this is just way stronger and overall better.
A few things I didn’t mention earlier in the article is that this engine is Toyota’s most powerful engine ever, in terms of power per liter at 167.5. This record was previously held by the 3SGTE. The bore is 87.5mm and the stroke is 89.7mm, which is a surprisingly long stroke for a small performance engine like this.
Overall, this engine is pretty awesome. In terms of power per liter, it’s on another level compared to anything else Toyota has ever produced, and for three-cylinder, that’s even more impressive. You have to consider that the load per cylinder is higher than a similar displacement four-cylinder, meaning everything has to be stronger and deal with more heat.