turbo DFI Engines

[jrcowboys]

Guys:

Looks like the trend is toward this type of engine. Mileage requirements will drive us toward something like this or a hybrid system.

What is the overall opinion of the long term reliability of this concept engine? Some concerns include:
-sludge on intake valves
-reliability of turbo
-overall stess on engine
-reliability of high pressure fuel pump

Thoughts?

JR

 

[Quattro Pete]

I think all the issues you mentioned will get ironed out within the next few years, with intake valve deposits being the biggest problem right now, but it seems to be linked closely to fuel quality and emissions requirements. I don't think it's a big issue in Europe for example, or maybe we just don't have enough feedback from Europe on this?

Turbo reliability - probably not a problem assuming proper cooling is provided.

Engine stress? I wouldn't think so.

HPFP? Again, something that will get better and better with time.

 

[expat]

-sludge on intake valves
could require periodic maintenance (intake cleaner)

-reliability of turbo
How long have we had Turbo's?

-overall stress on engine
See abouve.

-reliability of high pressure fuel pump
Hummm....For me, this could be an issue, But fuel injection has been around for a long time (if only at lower pressure) When it first became popular, people were afraid. Today I don't think is really an issue for most manufacturers.

 

[JHZR2]

Take the audi DI engines - real issues with oil quality. Take the BMW engines - HPFP issues. Take the toyota DI engines - they actually use a classic injector to get some fuel spray on the valves... but then it isnt a true DI system.

Lots of trades. Our biggest issue with advanced tech is that we trade tons of overall emissions for a few ppm of NOx. Until we get past that, we are stuck.

When lean stratified charge is enabled in DI there will be fewer issues.

 

[cchase]

The BMW HPFP issue has been ridiculous. But, I haven't heard of many problems with the other makes and I'm confident things like that will be fairly insignificant within a few years.

I think the biggest problems with engine longevity with these schemes (as with any scheme) will be due to neglect.

 

[BuickGN]

Turbo reliability is a non issue.

Ultra high pressure fuel injection has been around for many years and very reliable in diesels. I'm sure it's not a huge stretch to make it completely reliable in gas form.

Intake valve deposits seem to be the big problem. I wonder if an oil with an ultra low NOACK like Redline would solve or reduce these problems. As far as the Toyota system, I'm under the impression the standard port injector only works part time still giving it the benefits of DI but without the intake valve buildup.

We should see higher boost levels on a given octane and with the increased average compression ratio and new turbo technology, turbo lag should be a thing of the past.

 

[SteveSRT8]

X2, modern turbos don't usually exhibit problems anymore.

I also agree about HP FI. They can make that work.

The new Porsche Turbo is an excellent example of DFI in a hi po engine. Allowed more boost and more timing while controlling knock and EGT's.

What I object to is it being shoved down our throats and then we're doing the manufacturers R & D!!!

 

[BuickGN]

Originally Posted By: SteveSRT8


What I object to is it being shoved down our throats and then we're doing the manufacturers R & D!!!


Absolutely. IMO, some of these engines were not ready for mass production.

 

[SteveSRT8]

This has been the way in this country for years by many auto mfgrs, just put out a few thousand and track them carefully...

Then if they're selling it is ok to make some more!

But the point is we drive them and develop the bugs out. Not every new car but many of them.

 

[Rickey]

It seems that GM has their technology sorted out concerning DFI.

I have yet to see even one IVD report on a GM DFI engine.
I research this quite a bit because I own one of these:
(LNF 2.0 Turbo DFI) 38 MPG Hwy if the driver does his part.

I have came to the opinion that IVD with this technology is strongly related to PCV system design and NOACK in that order.
I believe that intake valve stem sealing is another strong factor.

 

[UNC017]

Originally Posted By: jrcowboys
Guys:

Looks like the trend is toward this type of engine. Mileage requirements will drive us toward something like this or a hybrid system.

What is the overall opinion of the long term reliability of this concept engine? Some concerns include:
-sludge on intake valves
-reliability of turbo
-overall stess on engine
-reliability of high pressure fuel pump

Thoughts?

JR


The reliability of a turbo is not much of an issue, if the turbo installation is integral with the engine design and not an afterthought. The old Chrysler turbos of the 80s were reliable enough for non-gearheads to abuse them and survive. True, they weren't factory tuned to a lot of boost, but the basic bugs were solved and they didn't blow like popcorn.

Same for the overall strength of the engine- build the bottom end for the kind of power anticipated, and reliability isn't an issue even though the total displacement is small.

The high pressure fuel pump is a bit more suspect, but I think its a solvable issue after they've been around a few years.

The big question in my mind is keeping the intake valves clean without any fuel flowing through them. I think the whole way PCV systems operate will have to be re-thought a bit for this type of engine. Gasoline engines have relied on fuel to keep the intake valves clean more than people realized, so Diesel engine technology will probably have to come into play here.

 

[mechtech2]

The valve deposit issue won't go away.
When there is no fuel or cleaning agents washing the valves from a carburetor or fuel injector, there are going to be deposits.

Maybe sooner or later on some vehicles, but it's inevitable.

Tough to avoid, and tough to clean.

Cars will continue to run with deposits, and people will defend their purchases.
But I do not want one of these - I can't see a fix for it.

 

[BuickGN]

Originally Posted By: mechtech2
The valve deposit issue won't go away.
When there is no fuel or cleaning agents washing the valves from a carburetor or fuel injector, there are going to be deposits.

Maybe sooner or later on some vehicles, but it's inevitable.

Tough to avoid, and tough to clean.

Cars will continue to run with deposits, and people will defend their purchases.
But I do not want one of these - I can't see a fix for it.


I pretty much agree with you. Do any of these cars use some sort of a seperator for the PCV system in factory form?

I would love to see some long term results on an oil with an ultra low NOACK like Redline. It seems like the only way to truly get rid of the problem is to not have the PCV go through the combustion chamber or at least not via the intake tract. I guess dumping it pre cat would cause problems and post cat emissions would be too high.

 

[Rickey]

I wonder if GM 4718M has any positive effect on this?
I find it interesting that the detailed specifications on 4718 are not published.

Special cleaning agents in there? Hmmmmm

Just wondering...... Pure speculation on my part.

On my LNF there is a slight oil deposit on both the turbo compressor inlet and discharge plumbing interior surfaces.
The oil trail begins at the PCV inlet port so I know that is where it is being introduced. And it is a minuscule amount.
There is no noticeable consumption in 7K OCI's

With almost 40K on my LNF there are no apparent IVD effects.
Other marque's have had problems with only a few thousand on the odometer.
I'm thinkin' that frequent rice grinder challenges have assisted in intake valve cleanliness.

 

[SteveSRT8]

I would agree that volatility is a big factor in PCV cleanliness.