Why OE's are using PFI/DI in the same engine - EE

[CR94]

Originally Posted by yugrus
Originally Posted by wemay
...Well, that's why i mentioned a variation of a CCan that doesn't require continuous maintenance. But they haven't...
They do though. Look at Mazda SkyActiv engine, there's substantial catch can built right in. GM has variation of baffled separator in the valve cover, ...
Many manufacturers do include separators, but to make the whole assembly compact and maintenance-free they have to drain the condensate back into the sump. This makes the catch can a part of the engine. And it is not very effective ..., partially because of the heat. This is why external cans collect at least something, the stuff left behind by OEM separator. ...
Good point. Mine seems to work adequately, judging by the very low oil consumption so far.

Not catching a lot of condensed moisture doesn't mean it's "not very effective." Blowby inevitably contains water vapor, and it's harmless in the intake, as long as it's still vapor. The objective of oil separators is to catch the oil and other junk that can make trouble in the intake, not water.

 

[DriveHard]

Originally Posted by dbias
I dont feel a catch can is worth the time, money and effort especially considering it would present freezing problems in the winter. Using a good oil, good gas and ensuring the PCV valve is in good shape will certainly help keep deposits down and also ensure that short tripping is kept to a minimum. Then there is also the VW version of the italian, keeping the RPM at 3K for 20 minutes. I do this each weekend with the A4, put the DSG into manual mode on the highway, select 4th gear, set the cruise and have at it.

https://patents.google.com/patent/US6866031?oq=valve+coating+carbon+VW


For those not willing to dig through a patent (one of my rare pleasures...

An additional approach for reducing the formation of carbon deposits on the intake valves 20 is to increase the intake valve temperature, at least temporarily, since, surprisingly, it was found that any carbon deposits possibly present are removed at temperatures above 380° C. To this end, the intake valve unit, which comprises, among other components, the intake valves 20 and the valve stem guide 28, is designed with means that hinder heat dissipation in such a way that increased surface temperatures of more than 380° C. develop at least in the area of the neck 68 of the intake valves 20 in at least one predetermined region of the load characteristic diagram 74 of the internal combustion engine. This is illustrated in FIG. 4. The intake valve temperature is above 380° C. in the shaded region 112 b of the characteristic diagram. At these temperatures, carbon deposits on the intake valves 20 are removed. This region 112 b of the characteristic diagram occurs, for example, at speeds over 3,000 rpm, and in that speed range. extends essentially to full load. Even if the internal combustion engine is not operated most of the time in the region 112 b during normal driving operation of a motor vehicle, nevertheless, carbon deposits that could adversely affect the operation of the internal combustion engine cannot build up, since their removal in the shaded region 112 b of the characteristic diagram occurs very quickly. For example, operation of the internal combustion engine in this region 112 b of the characteristic diagram for a period of, for example, 20 min., is sufficient to remove even a thick layer of carbon deposits. In other words, a routine expressway trip cleans the intake valves 20 sufficiently. In addition, this region of the characteristic diagram can be entered in the course of maintenance or repair work on the internal combustion engine in an automotive workshop.

 

[StevieC]

The only problem I see with the 3,000 RPM is that most engines operate much lower than this typically for fuel conservation with the tons and tons of gears modern transmissions have and where is 3,000rpm possible for 20 minutes at time in heavily congested areas. But it speaks well to what Mazda and the German Automakers that aren't having valve build-up issues must be doing to counteract it.

 

[DriveHard]

Originally Posted by StevieC
The only problem I see with the 3,000 RPM is that most engines operate much lower than this typically for fuel conservation with the tons and tons of gears modern transmissions have and where is 3,000rpm possible for 20 minutes at time in heavily congested areas. But it speaks well to what Mazda and the German Automakers that aren't having valve build-up issues must be doing to counteract it.


Every car I have ever driven has a method to hold a lower gear at the drivers discretion. It just takes a driver that cares for their vehicle...like checking the oil.

 

[StevieC]

Originally Posted by DriveHard
Originally Posted by StevieC
The only problem I see with the 3,000 RPM is that most engines operate much lower than this typically for fuel conservation with the tons and tons of gears modern transmissions have and where is 3,000rpm possible for 20 minutes at time in heavily congested areas. But it speaks well to what Mazda and the German Automakers that aren't having valve build-up issues must be doing to counteract it.


Every car I have ever driven has a method to hold a lower gear at the drivers discretion. It just takes a driver that cares for their vehicle...like checking the oil.

Because your average car owner is going to do this and not just the informed BITOG crowd?

 

[yugrus]

Originally Posted by wemay
Not catching a lot of condensed moisture doesn't mean it's "not very effective."

Oh, I didn't mean just moisture condensate. The stuff that is caught is condensate of oil, water and fuel vapors. Everything that comprises crankcase gases. Oil mist too, although the majority of that is caught by OEM measures.

 

[PandaBear]

Originally Posted by SteveSRT8
But don't forget the added complexity of two completely different fuel delivery systems in a computer controlled engine. Not just a few injectors tossed in!

Both Toyota and Porsche are on record as saying that DI engines can have part throttle cylinder filling issues, that's the real reason behind it.

Seems a bit crude but it will solve the dirty valve issues, eh?


ECU should not cost anywhere close to $20 extra for an extra set of injectors. R&D cost is fixed cost, you do it once per model / engine, and that's it. Probably only a few man monthof engineering time extra per model, less than 100k R&D cost.

 

[SteveSRT8]

Originally Posted by PandaBear
Originally Posted by SteveSRT8
But don't forget the added complexity of two completely different fuel delivery systems in a computer controlled engine. Not just a few injectors tossed in!

Both Toyota and Porsche are on record as saying that DI engines can have part throttle cylinder filling issues, that's the real reason behind it.

Seems a bit crude but it will solve the dirty valve issues, eh?


ECU should not cost anywhere close to $20 extra for an extra set of injectors. R&D cost is fixed cost, you do it once per model / engine, and that's it. Probably only a few man monthof engineering time extra per model, less than 100k R&D cost.



IIRC any time you make an alteration to a major component of an emissions controlled vehicle you need to get it certified by the EPA. That alone may cost quite a bundle! There are costs here based on size, a larger company may get the cost per unit down but the overall numbers could be quite large IMO...

 

[PandaBear]

Originally Posted by SteveSRT8


IIRC any time you make an alteration to a major component of an emissions controlled vehicle you need to get it certified by the EPA. That alone may cost quite a bundle! There are costs here based on size, a larger company may get the cost per unit down but the overall numbers could be quite large IMO...


You need to do it to each generation of a particular car anyways, if you switch it from one power train generation to the next it would be the same cost.

And you know they have to update it every 5 or so years anyways.