Technical information on the Toyota D-4S system

[arghx7]

I'm only speculating here because the chart is cryptic, but I wouldn't be surprised if they introduce a 2.0 version with the same basic architecture. That 1.8 is going to be underpowered for an A4 type of segment in the North American market.

[Ryephile]

Ok, just FYI the EA888 1.8T's aren't in US VW/Audi's.

I think the EA888 Mk3 will end up being the powerplants for the forthcoming Audi A3 and Golf MKVII, both of which are due next model year. Who knows if we'll get the 1.8T's here, or if they'll make a EA888 Mk3 2.0T for the US market.

Nevertheless, thanks for sharing the technical documents.

[Tradewind]

All I need to know is how to get control of the system so we can boost the engine with some extra air and in turn some fuel

[Tradewind]

Technical info required on injection system

Are the any specs available on total fuel flow per minute per cylinder for the injection system?

[arghx7]

For the 2.0 boxer engine? No. This thread isn't about that engine specifically. It's about the preceding engines. There are D-4S fuel flow specs if you read through the material in the first post.

[arghx7]

Below are charts out of a very recently published study from the Sloan Automotive Laboratory at MIT. The study examines the cooling effects of direct injection under high load operation. The study took a Pontiac Solstice engine (GM LNF, direct injected 2.0 liter turbo) and equipped it with port injectors. Note that the Solstice uses a multi-hole type injector, not a fan-type like the Toyota D-4S system.

The researchers figured out an average combustion chamber pressure trace at a borderline knocking condition using direct injection only and then port injection only. They kept the rpm, spark timing, and intake air temperature constant.




Then they heated up the intake air and tried to figure out how much hotter the intake air has to be for direct injection to have the same borderline knock combustion chamber pressure trace as port injection. The method was used to calculate "effective charge cooling" of direct injection, especially with ethanol fuels.




The charts display the palpable benefits of direct injection in mitigating knock. You don't have nearly as much of the latent heat of vaporization being wasted.

[Dimman]

@Jeff Lange,

Jeff, I'm curious about the injectors of this car. Are the ports and directs the same parts as on the IS350 2GRFSE?

Reason being that the fueling situation sounds different in this:

Originally Posted by JP

And the Toyota Techinfo doc on the SFI system:
http://www.purcellperformance.com/Te...13%20FR-S).pdf

Than it does in an earlier press release for the IS350: (attached .pdf)

This is a 2nd gen application of the D4-S from what I've heard, and the FA20 sounds like it needs port to supplement the direct at high load/rpm, whereas the 2GRFSE didn't, relying only on direct.

2GRFSE direct injectors may be a higher flow? Possible upgrade?

Thanks,
D

[arghx7]

Here's the chart in question:



At very high rpm the most important thing they are going to do is try and keep the exhaust manifold and especially the cat from overheating. By overheating, I mean exceeding some target temperature--most likely a max catalyst temperature of 900C. It was probably easiest and cheapest to spray the port injectors, after performing tests to verify that there wouldn't be some kind of bad side effect from this strategy.

You have to be careful not to think of a direct injector like it's just a port injector mounted spraying into the cylinder. It's not. It's more complicated than that, because of the shorter time for mixture formation and because fuel pressure is variable. Direct injection tuning/calibration on a modern engine is exponentially more complicated than fuel injection tuning back in the days of say the 2JZ.

Generally speaking a port injection system relies on a constant pressure differential between the fuel and the intake manifold. On the early multi-port injectors, it was about 2.5 bar. Then it went to 3, and 4, maybe up to 5 bar. This pressure differential could be controlled mostly mechanically by a fuel pressure regulator on/near the rail, as in a conventional return fuel system like Mark IV Supra 2JZ engine. For discussion's sake, fuel is solely controlled through injector "ON" time on a 2JZ.

Fuel could also be controlled through an in-tank regulator with injector pulsewidth corrections, as in a conventional returnless system. In both situations, the fuel pressure isn't a major determinent of injector mass flow except in the sense that the injectors run right around whatever base pressure the system was designed for.

With direct injection it's different, in part because you have shorter crank angle duration for mixture formation. Instead of having many crank angle degrees for the fuel to vaporize on the back of a valve (like typical closed-valve port injection), you have a narrow crank angle window. Maximum injector pulsewidth is therefore limited. To increase fuel delivery and appropriately size the injectors, you may have to increase fuel pressure. Since it's a mechanical fuel pump, there could be significant energy consumption involved in that.

The calibration engineers may have decided that they didn't want to crank up the fuel pressure at very high rpm because of energy losses. It could have been easier to just spray the port injectors and then verify that doing this doesn't cause some other kind of problem.

What I'm trying to say here is, it's a bit premature to call the direct injectors "maxed out."

[Dimman]

I just zeroed in on one tiny bit of the whole thing...

(4) By combining both methods in the light engine load range and using direct injection in the
medium engine load range, a uniform air-fuel mixture is achieved throughout the entire engine
revolution range, stabilizing combustion to improve fuel consumption and reduce emissions.
During high loads, port injection and direct injection are combined to ensure fuel flow volume.

The 'to ensure fuel flow volume' bit.

I understand that it is different than the original 2GRFSE application, and am still curious if they are different injectors. If the 2GR's do flow more, (and are even compatible) it is the closest thing we may have to an upgrade for the direct injector if we want to keep a similar fueling strategy instead of just dumping tons more in via the 'normal' way.

I hadn't thought about the mechanical nature of the high-pressure pump though... It may not like the higher rpm of this motor compared to the 2GR? Or the mechanical in-efficiency at high rpm costs more in loses than a full DI fueling gains from better combustion?

[Boosted2.0]

1 - that chart is a bit misleading, and they say as much in the new model training. This thing is in blended injection mode a lot more than indicated.

2 - one of the main reasons for the port injectors is largely to keep the intake valves from carboning up and possibly to cool them and the intake charge a bit as well.

[serialk11r]

Say @arghx7 (is that how you tag people lol), that pdf tells us that the direct injection happens late in the compression cycle...which means it has barely any time to vaporize! Does the fuel actually end up completely vaporizing? If not, that seems like it would be even worse than port injection, which only wastes the cooling power of the fuel, whereas not being able to fully vaporize the fuel would mean losing a significant amount of heat of combustion.

[arghx7]

^ They are talking about late injection for catalyst light off. I haven't seen data on the FA20 yet. Typically you will see spark timing around 15 degrees ATDC and a late compression stroke direct injection to warm up the cat. Read about the weak stratification in the emission reduction for 3GR-FSE paper

[serialk11r]

Under normal operation then, do you think they are sprayed during compression stroke or intake stroke, or does it depend on load? Seems like the piston bowl being near the injector is important, so it seems like it'd have to be either towards the beginning of the intake stroke or near the end of the compression stroke (which seems like the fuel wouldn't have time to vaporize correctly...).

[Boosted2.0]

The fuel is being injected at up to 2600 PSI into a heated air fuel charge in a super fine fan pattern. I would be very surprised if it wasn't vaporizing and mixing better than with port injection. Hell, simply going from 2600 to cylinder pressure in the super fine fan pattern would probably allow for full vaporization, even if the gases werent already heated from compression

At the engine development lab in their Higashi Fuji test center Toyota actually builds glass composite cylinders and uses High speed cameras to photograph fuel propagation throughout the cylinder and flame front propagation. In that way they can be certain of these things.

I don't know if you have seen the piston shape for the FA20, but there is a special fan shaped depression with a ski jump curve on the outer arc. They wait until that jump will be in the injection path, and the fire the injector, which allows the ramp to redirect the fuel straight up at the spark plug and mizing it into the air charge which is compressed into that area.