As we all know and fear, the next big wave of emissions controlls are coming. It becomes more and more evident in every new model year. the 05 mustang for example has this "filter" in the intake duct that just screams 1976. It is to do something or another to the EVAP and such that is being recirculated.

so what is the next thing? Has anyone played with direct injection?
Are we looking at another late 70's era drop in vehicle ... ugghh everything?

It seems like this is going to be the beginning of the end. Luckily GM is a bit more prepared for it with DOD, hybrid stuff in the works and generally clean burning gen 3/4 motors. Even still, is it enough?

 

I Gotta tell you....They will NOT be happy till man no longer lives on Earth. Little do they realize that means them too

 

I know every OE is doing more than looking at direct injection. You will see many of them out on the market in the next 2 years or so. It typically takes about 4 years to develop a new engine, as a reference.

 

Ultimately, hybrid powerplants are the wave of the future. Most likely a diesel/electric combo like on a locomotive, although a gas turbine running on propane is another possibility.

The simple fact is; it takes VERY little horsepower to maintain highway speeds. The main need for power is in acceleration. A hybrid motor gives a car a way to have decent acceleration while still being very fuel efficient on the highway.

 

Ultimately, fuel cells are the wave of the future. Hybrids are just an interim. After fuel cells I'm sure there will be something else.

 

well its about time the traditional internal combustion engine got the boot. its so... 'industrial revolution".


compared to most every other major technological advance, its pretty much made no progress. A lot of that is oil companies buying patents and such, but what do I care as a consumer. I want results!

Fuel injection is pretty much the only "advance" the ICE has seen in production vehicles. Diesels made some progress with direct injection and such... after GM scared off half the universe with the 350 diesel

 

I disagree. Unless you mean that hybrids are a multi-decade interim.


I don't have ANY realistic way to prove this, but I suspect that when battery technology advances to the point where you can have a 300 mile range, a fast fill-up (less than 5 minutes) and good power, you will see a switch to all electric cars.

 

I would like to revist this subject mostly bcuz the new Lexus IS now uses Direct Injection. From what I last hear, there are two different versions of it. Is there a good performance aspect to direct injection?

 

Yes, the main performance aspects for direct injection are the increase in charge cooling and volumetric efficiency. The air in the cylinder is cooled more with direct injection because it is hotter when the cool fuel encounters it vs. the port fuel injection method where the air is close to ambient when the fuel merges with it. The volumetric efficiency improvement is a result of fuel not stealing "space" from the air when the intake valve is open. More air can be drawn in since much of the fuel is injected after the intake valve is closed.

The increase in charge cooling has a two fold improvement. You can generally also increase the CR of the engine as a result (approx. 1 point), or run closer to MBT for spark timing.

It's hard to generalize a performance improvement from the above factors, but in the engines I've seen (pushrod V8s) that have tried this they've seen 5-10% increase in TQ, especially if they were spark timing limited in this region, and 3-5% in power.

Of course all the above is referring to homogeneous injection, where the A/F is kept what it is generally for PFI. There is a stratified GDI where under light load conditions the A/F is much leaner. This strategy is done for fuel economy. To enable this strategy many times other things are done that compromise power, such as more swirl in the intake port, piston dome shapes, etc. This approach seems to be losing interest as the observed fuel economy gains are not as much as originally hoped for, and the emissions issues drive more expensive aftertreatment.

 

What psi do these systems work at, I'm assuming something similar to that of a desiel?

Is there any gain in milage seen from DFI?

 

All that extra electricity has to come from somewhere.

There's no such thing as a free lunch.

 

From what I have heard direction injection itself doesn't improve power, the higher SCR does, and usually the BSFC numbers in the motor are improved as well.... if it made power the F1 V10 engines would have used it. I doubt we will see it in F1 later on since the new V8 rules limit the max fuel pressure, but you never know.

In terms of airflow improvements... well you don't have to worry about wet flow so it would really make that part of development easier.

FWIW the direct injectors would be great to try on a traditional engine design, but getting the parts commonplace enough to do it is going to be the key.

Bret

 

The benefits of direct injection have been known for a long time. One problem has been to make injectors that can handle the extreme conditions in a spark-ignited engine. They've been able to do it for a long time with diesel injectors, but the fuel there also acts as a lubricant. Gasoline is a different story and over time the materials in the high-pressure injectors just haven't been able to live. Until now. Lexus is doing it and Audi is doing it as well in Europe. There are others that will be introducing their versions.

It will be interesting to see if the aftermarket comes up with the componentry necessary to retrofit cars. Heads, intake, fuel rails, engine management systems, etc., would all need modification to take DI into account. I wonder if the demand will be there.

 

Mazda also uses a direct-injected turbocharged engine in the new mazdaspeed6

 

GDI (or SIDI, as it is also known), generally operates at about 1200-1500 psi. DI diesels generally operate around 20,000 psi. Big difference huh?

Homogeneous GDI can see about 2-3% improvement in fuel economy, but a lot of this comes from an increase in CR, which is enabled by the increase in charge cooling.

Regarding the life of GDI injectors, it's not an issue anymore. As was stated, production engines have been being built for quite some time now with the technology, and with no issues.