SparksLex

According to Wikipedia, "The 2GR-FSE is a 3.5L engine used in the Lexus IS, and GS 350, incorporate Toyota's latest D4-S twin injection fuel system. This system combines direct injection with traditional port injection."

That sounds pretty interesting and I didn't know that some cars combine both. Can someone give me a good explanation as to how it works? The car has fuel injectors, I assume, but it also has fuel lines that go directly into the combustion chamber?

Gville350

iTrader: (10)

VVT-i D4 – “Direct Injection” engine technology
Toyota’s award-winning VVT-i (Variable Valve Timing with intelligence) engine has been improved by a small, but very effective new idea. Petrol is now injected directly into each cylinder through a new slit-like nozzle (see diagram and photograph below).

Perfect distribution of fuel around each cylinder

You will probably remember playing with the hosepipe in the garden: Squashing the pipe flat causes the water to fan out at high pressure. Toyota’s new VVT-i D motor uses the same idea to atomise and distribute fuel around each cylinder. Avantages: Increased fuel spray atomisation for more uniform combustion Compression ratio is increased to 11.0 (compared to 9.8 for the VVT-i engine) Petrol no longer sticks to the injection port during cold fuel injection, which results in less hydrocarbons, meaning a cleaner and more efficient engine. The VVT-i D4 engine is 8% more efficient than Toyota’s award-winning, and very economical VVT-i engine. ut most importantly, D4 makes a difference you can really see and feel!

SparksLex

So "combined" isnt exactly the correct term? It's more like just pure direct injection, and not a combination of the two?

Edit: I guess combined is correct Apparently it uses the D4-S, and so does the FRS.

Jeff Lange

iTrader: (1)

The IS250 uses D4, the IS350 uses D4-S.

D-4 is direct injection only, with a single injector per cylinder.
D-4S is direct and port injection, with one of each type of injector per cylinder.

Jeff

SparksLex

Yep. Pretty wild stuff. I didn't realize how much of a focus there was on performance for these cars

jdmSW20

iTrader: (12)

yes the D4-S fuel system is pretty impressive. it also is the reason the the 350 doesnt get the carbon build up issue the the 4GR in the is250 get. the port injection somewhat washes it clean. thats not the point of the system but its a by product. i almost wonder why toyota didnt eventually give the 250 the same fuel system. it works in the 350 and the ISF

redspencer

iTrader: (1)

Here's a link to a very detailed tech brief on the 2GR-FSE D4-S that I've kept over the years:

http://www.sae.org/automag/techbrief...1-114-1-17.pdf

This is one of the primary technologies introduced in the IS350 that made it a Ward's best engine for four years straight.

Gville350

iTrader: (10)

I still wonder if the port injectors could be upgraded on the IS350s to handle increased boost figures others have not seen AND still have the factory ecu control it all effectively.

SparksLex

Great article, red. Thanks for linking that.

stewb10

iTrader: (3)

That, my friend, is the million dollar question. Ill have to look into that.

redspencer

iTrader: (1)

After looking at the original link that I posted earlier, I realized that it was not the full report on the development of the D4-S for the 2GR-FSE that I wanted to share. The PDF that I attached is what I originally meant to post and it should definitely answer your original question on how the fuel injection system works.

WylieKylie

iTrader: (2)

I think that question is basically answered in the first article posted by redspencer:

So if the port injectors aren't being used at high RPM, then putting bigger port injectors isn't going to get you any more fuel at high RPM, which you are going to need to make more power at high RPM. That is especially going to be the case for forced induction, where (usually) you make the most boost at high RPM.

Gville350

iTrader: (10)

^Tried finding that quote in the PDF, but couldn't locate it. Trying to see what the context is off that statement.

WylieKylie

iTrader: (2)

It is in the link from the 1st article redspencer posted:
http://www.sae.org/automag/techbrief...1-114-1-17.pdf

2nd page, last paragraph in the right column.

Gville350

iTrader: (10)

Hmmm, very interesting! Most just figured (myself included) that the port injection is scaled along with the rpms increasing; but according to the articles, it's far from that easy! In fact, they say is it constantly in flux.

I also read some interesting data in the second attached PDF from Red in sections 4.3 and 4.4. Something about they CANNOT do both types of injectors for extended periods of time due to the DI tips overheating and could possibly clog. So according to these articles the port injectors are really only used to maximize fuel efficiency, increase torque in certain areas within the powerband, AND during cold start-up to heat up the CATs as quickly as possible.

I enjoy reading such articles! You learn something new every day!