Another GDI issue: high particulate emissions

[Frank Lee]

The first one I mentioned being, dirty intake valves:

http://ecomodder.com/forum/showthrea...ves-25607.html

New petrol engines cause more air pollution than dirty diesels | Transport & Environment

And here I thought it was only the diesels... :/

[oil pan 4]

Diesel engines, often imitated by GDI but never duplicated.

[Miller88]

Ford Eco-Boast engines soot their tailpipe up pretty good - that definitely comes from the particulates being sent out the back.

[ksa8907]

I'd like to see the data. I get the feeling this is a sensationalist claim based on poor testing.

Just my gut feeling, I may be wrong.

[oil pan 4]

Originally Posted by Miller88

Ford Eco-Boast engines soot their tailpipe up pretty good - that definitely comes from the particulates being sent out the back.

Turbo gas engine have to run a lower air/fuel ratio so they don't destroy them selves. Your typical lowest N/A gas motor air/fuel ratio is between 12.5:1 to 13.2:1. A turbo charged gas engine can hit 10:1 or 11:1 during normal operation under demand for more power and there are several reasons this must happen.

Diesels are totally different and do not have to come any where close to gas engine air/fuel ratios for any reason.

[gone-ot]

....trading gasoline for combustion-charge cooling is NOT very economical; it's something that airplane engines do all the time however.

[pgfpro]

Originally Posted by oil pan 4

Turbo gas engine have to run a lower air/fuel ratio so they don't destroy them selves. Your typical lowest N/A gas motor air/fuel ratio is between 12.5:1 to 13.2:1. A turbo charged gas engine can hit 10:1 or 11:1 during normal operation under demand for more power and there are several reasons this must happen.

Diesels are totally different and do not have to come any where close to gas engine air/fuel ratios for any reason.

Cooling combustion temps by means of running rich for knock control is kinda a thing of the past. Even the Ecoboost F-150 3.5L twin turbo engine runs at only 13.5 A/F at peak torque.

One of the main reason GDI engines were built was to run at a leaner A/F ratio to improve BSFC to help improve fuel efficiency. GDI engines utilize the boost to lower combustion temperature (valve overlap, cycling air only) and add the fuel much later in the cycle to prevent knock. This also makes the GDI engine able to run a higher compression ratio that improves efficiency. Plus the GDI fuel atomization is much higher then what we see in today's PI engines.

The new valve seal and valve guide technology will help with particulates emissions. But keep in mind the problem is the oil getting past the valve guide no matter what engine it is, GDI, PI or Diesel. This oil will be burned in all three types of engines. The cleaning of PI injection might keep the valve clean and prevent intake valve soot build up but the oil is still being burnt.

IMO the problems were seeing with the Ecoboost engine is more of a combination of the above intake valve soot build up and the EGR system.

No matter what the GDI technology is here to stay and all the major manufacturers are going this direction.

I have a good friend that owns a F-150 Ecoboost truck that is at 80K now with no problems at all, so its not all the Ecoboost engines that are having these issues.

[Miller88]

Originally Posted by pgfpro

Cooling combustion temps by means of running rich for knock control is kinda a thing of the past. Even the Ecoboost F-150 3.5L twin turbo engine runs at only 13.5 A/F at peak torque.

One of the main reason GDI engines were built was to run at a leaner A/F ratio to improve BSFC to help improve fuel efficiency. GDI engines utilize the boost to lower combustion temperature (valve overlap, cycling air only) and add the fuel much later in the cycle to prevent knock. This also makes the GDI engine able to run a higher compression ratio that improves efficiency. Plus the GDI fuel automation is much higher then what we see in today's PI engines.

The new valve seal and valve guide technology will help with particulates emissions. But keep in mind the problem is the oil getting past the valve guide no matter what engine it is, GDI, PI or Diesel. This oil will be burned in all three types of engines. The cleaning of PI injection might keep the valve clean and prevent intake valve soot build up but the oil is still being burnt.

IMO the problems were seeing with the Ecoboost engine is more of a combination of the above intake valve soot build up and the EGR system.

No matter what the GDI technology is here to stay and all the major manufacturers are going this direction.

I have a good friend that owns a F-150 Ecoboost truck that is at 80K now with no problems at all, so its not all the Ecoboost engines that are having these issues.

They make amazing power with the 3.5 Ecoboost, that's fore sure!