school me on DI engines please

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OK, This new design carbons up the valves and dilutes the oil. How can this be good ? Is there a plus factor I'm not seeing? I'm still in the last millennium car-wise
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Originally Posted By: andyd
OK, This new design carbons up the valves and dilutes the oil. How can this be good ? Is there a plus factor I'm not seeing? I'm still in the last millennium car-wise
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No plus factor i know of that doesn't evaporate quickly with use. It will be fine at some point but not something i want at the moment.
They are experimenting and you are the guinea pig.
 
I really think this technology will improve over time. I'm not sure its there yet. When we bought out 2013 hyundai, I bought the elantra that was mpfi.
 
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Thousands of PSI to inject at high atomization rates,possibility of catastrophic fires in a head on collision (that fuel pressure has to go somewhere),expensive mechanical fuel pumps,special (expensive) injectors,oil dilution....no,I am no fan of DI or new diesels.Wait until they get older and the repair bills start coming in....and the local shops cant fix it.
 
There is nothing inherently wrong with Direct Injection, just the current implementations which sound like they are using batch-fire mode instead of Timed injection.
 
Originally Posted By: loyd
There is nothing inherently wrong with Direct Injection, just the current implementations which sound like they are using batch-fire mode instead of Timed injection.


The unwashed intake valve may be a problem though, unless the figure out another way to feed the crankcase vapors into the motor.
 
Originally Posted By: spasm3
Originally Posted By: loyd
There is nothing inherently wrong with Direct Injection, just the current implementations which sound like they are using batch-fire mode instead of Timed injection.


The unwashed intake valve may be a problem though, unless the figure out another way to feed the crankcase vapors into the motor.


We ruled out Skyactiv Mazdas for our purchase earlier this year since GDI has such a short track record in the US. That said, I'm curious: how much would a catch can mitigate the intake deposit problem?
 
Originally Posted By: NHGUY
Thousands of PSI to inject at high atomization rates,possibility of catastrophic fires in a head on collision (that fuel pressure has to go somewhere),expensive mechanical fuel pumps,special (expensive) injectors,oil dilution....no,I am no fan of DI or new diesels.Wait until they get older and the repair bills start coming in....and the local shops cant fix it.


While I agree on the repair cost FUD aspect the fire aspect I don't. Diesels have used high pressure for years. And gasoline is as flamible as ever. Pretty sure cars have had issues with fires for ever, low pressure systems included. The high pressure loop is in a physically small area of the car, as compared to all the fuel lines. And of course that huge tank containing gallons of flamible liquid.
 
Originally Posted By: supton
While I agree on the repair cost FUD aspect the fire aspect I don't. Diesels have used high pressure for years...


It's not accurate to compare diesel fuel and gasoline in the manner which you did.
 
"OK, This new design carbons up the valves and dilutes the oil. How can this be good ? Is there a plus factor I'm not seeing? I'm still in the last millennium car-wise"

I don't believe this applies across the board.

Some manufacturers utilize this technology better than others.

Can someone point out a GM or Ford DI product that has a problem caused by the DI?

The oil dilution and Intake Valve Deposit problems mentioned were (are?) a very real issue for certain other brands.
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More power and economy are some of the noteworthy benefits of DI.
323 Flywheel HP and 30 MPG from the GM LFX 3.5 V6 in the 2014 Camaro for example.
This would be difficult or impossible to get with emissions compliance without DI.


I don't think anyone has used batch injection with DI.
Some older port injection engines did in the 90's and before.
If the DI engines injectors are under control of the ECM why not accurately time the firings?
 
Originally Posted By: Oil Changer
Originally Posted By: supton
While I agree on the repair cost FUD aspect the fire aspect I don't. Diesels have used high pressure for years...


It's not accurate to compare diesel fuel and gasoline in the manner which you did.


Yep different animal. Lots of DI threads tell me people are still unsure of it though. I hear its getting better.
 
GM reduced the OLM from a max of 10,000 miles to 5500 on 2011 chevy Equinox due to oil dilution and premature timing chain wear.

That said my 2014 Impala is DI and currently the OLM forecasts 8,000 mile OCI. With a 3.6 liter engine making 305 hp and getting 31.5 mpg on trips, with a full size car, I think they have made progress.
 
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Originally Posted By: Rickey
Can someone point out a GM or Ford DI product that has a problem caused by the DI?.


The GM 3.6L V6 (LLT and LFX) had timing chain wear problems, and Lubrizol had an excellent article on what DI engines are facing. GM cut the oil change intervals in half thru the oil life monitor olm on the GM V6s a couple of years ago.
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3413099/Re:_Filter_Direct_Injection_So#Post3411769
http://gf-6.com/sites/default/files/Turb...ig%20Hurdle.pdf

Also Ford Ecoboost has PCV problems that coke up the intake valves.
 
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Originally Posted By: Corvette Owner
GM reduced the OLM from a max of 10,000 miles to 5500 on 2011 chevy Equinox due to oil dilution and premature timing chain wear.

That said my 2014 Impala is DI and currently the OLM forecasts 8,000 mile OCI. With a 3.6 liter engine making 305 hp and getting 31.5 mpg on trips, with a full size car, I think they have made progress.


The GM 3.6L V6 did trace some of the timing chain problems back to a bad timing-chain supply part, they 'forgot' to carbonitride surface harden the chains properly for some parts, so GM cut the oil change interval to waste oil and be safe until a few years go by and they are able to solve the supply problems and maybe change(?) the ring design to help prevent soot carbon particles from entering the oil and increasing wear rates (and fuel dilution too).
 
Originally Posted By: Quattro Pete
Originally Posted By: andyd
Is there a plus factor I'm not seeing?

More power and better fuel economy, supposedly.


DI's do that. They allow higher compression ratios by using DI to cool the charge and control spray pattern in conjunction with variable valve timing, and get better thermodynamic efficiency as a result, which translates into more power and fuel efficiency.
 
Originally Posted By: Oil Changer
Originally Posted By: supton
While I agree on the repair cost FUD aspect the fire aspect I don't. Diesels have used high pressure for years...


It's not accurate to compare diesel fuel and gasoline in the manner which you did.


Oh? Please clarify.
 
We have a few in the family and we like them. My wife and I have our Caddy 6 years, still running like the day we bought it. 304 hp from a naturally aspirated V6 that gets 27 mpg highway (Real life) in a 4000 +lb car that boogies down the highway. A good quantity of the cars produced nowadays have them (DI engines).

GM cut the oil change interval to 7,500 miles which is not so "Wasteful" in my opinion. Many automakers use a 7,500 mile OCI.

According to my mechanic AND my Cadillac service manager, besides the bad run of chains, with the old OCI at 10,000 +, too many people weren't checking their oil and low oil or too thick oil (The VVT and timing chain tensioners use engine oil to function.) has been found to be the cause for most of the recent failures.

Just for fun, since I became a member here, I have been asking people; " When did you check your oil last?" The answers I get most are;
1) I only changed it a few months ago.
2) You don't have to check the oil in the newer cars, they have a light to tell you when it needs to be changed.

When I say that most owners manuals say to check it with every other fill up, I get; "Who reads the manual?".

Imagine $20,000+ and they don't even read the manual. I'll bet they read the manual for their $100 Bluray player though.
Sorry for the rant.
 
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