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Discussion Starter · #22 ·
Hey all, have NOT had a LT4 in yet, but have had a few 2015 LT1's and we are seeing very little oil burping from the dry sump when run mid cross hatch!!! The improvement in the drysump tank appears to be working much better than the 2014. What is still alarming is the intake manifold is still getting saturated. We had in a 2015 with just over a 1000 miles on it, and the airbridge was dry...almost no oil at all, but the intake manifold was saturated with it. We did video as they bridge has changed a bit from the 2014 so we have both videos and we removed the TB to get into as much of the bottom of the IM as possible. The good news is the dry sump did NOT show burping!!!
 

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Hey all, have NOT had a LT4 in yet, but have had a few 2015 LT1's and we are seeing very little oil burping from the dry sump when run mid cross hatch!!! The improvement in the drysump tank appears to be working much better than the 2014. What is still alarming is the intake manifold is still getting saturated. We had in a 2015 with just over a 1000 miles on it, and the airbridge was dry...almost no oil at all, but the intake manifold was saturated with it. We did video as they bridge has changed a bit from the 2014 so we have both videos and we removed the TB to get into as much of the bottom of the IM as possible. The good news is the dry sump did NOT show burping!!!

Where is the oil coming from that gets into the IM?
 

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......and Rx has a dropout can for that so that it won't go to the IM?
I'm assuming Tracy was talking about the 2015's equipped Vette's with dry sumps that didn't have any kind of catch can system installed. In a separate thread a detailed description was provided on improvements GM made that addressed the oil burping issue made to the dry sump tank for 2015, and Tracy posted he was impressed with the improvement made. However, nothing was done addressing the introduction of oil (ingestion) through the PCV system, or at least that's how I understood it... Just reading allot and trying to understand based on logical thought from previous experience on this stuff. Could be wrong here, but it kinda makes sense to me..... All these oil ingestion issues weren't all that relevant prior to "Direct Injection" because any introduction of oil was diluted or washed down with the fuel being introduced into the intake tract prior to reaching the intake valves. It's existed for decades but wasn't as much of a problem if any.... Now it is because there's no fuel to mask it. My guess is the clean side separators may not be as relevant now with the improvements GM made to the tanks, but what the heck, why not go ahead and install it anyway as a back-up....
 

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Discussion Starter · #27 ·
Yes...the RX system is guaranteed to stop this ingested, and tmcternan is correct. We never wanted oil in the combustion chamber in the past as far as detonation and power, etc.....but now with everything direct injection the intake valve coking is so severe with no fuel spray showering the valves to keep them clean. I saw a guy today pour a bottle of fuel injector cleaner in his new Silverado, and I thought about what are CRC, Seafoam, BG, etc. going to do now that those treatments have zero effect on anything in the fuel system now with DI....these companies will have to find a new product set now.
 

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I saw a guy today pour a bottle of fuel injector cleaner in his new Silverado, and I thought about what are CRC, Seafoam, BG, etc. going to do now that those treatments have zero effect on anything in the fuel system now with DI....these companies will have to find a new product set now.
While it is very true the fuel system cleaners will not keep the intake valves clean, there are some that are beneficial for injectors, fuel level rheostats, fuel pumps, etc. If using gasoline without ethanol, it is beneficial to periodically use an additive to remove water, expecially in cooler climates or downright frigid like it is here this week.
 

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Discussion Starter · #29 ·
While it is very true the fuel system cleaners will not keep the intake valves clean, there are some that are beneficial for injectors, fuel level rheostats, fuel pumps, etc. If using gasoline without ethanol, it is beneficial to periodically use an additive to remove water, expecially in cooler climates or downright frigid like it is here this week.
A additive for freezing would your correct, but the rest of the fuel system is now coated against any corrosion, and the DI fuel injectors operating at 2,000-3,000 PSI seem to keep all varnish and deposits "pressure washed" so we have yet to see any clogging in the past 8 years of DI. We have seen a few failed injectors....but no clogging like old port injectors were prone to over time. Nothing in the fuel pump can benefit, but you are dead on that ethanol will sponge water into the system. Todays fuel systems have no parts uncoated anymore as far as the corrosion related issues from Ethanol....(I still hate the stuff.....corn is for far better things than a fuel supplement!) In the early fuel systems ethanol would attack the fuel level rheostats, look back at the C5 for plenty of example of that.

Most "heat" type products are mainly Methanol based and it sponges up water so it can be burned. Good reply.
 

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Just watched a video about a Canadian owner's experience with a Fiat/Chrysler EcoDiesel V6. Interesting to hear that turbo diesel application is having PCV oil saturation issues. He pulled the PCV tube and stuck his finger inside - saturated with oil. Per this owner, he installed a catch-can that didn't have sufficient diameter tubing, which blew out his oil pan gasket. Hmm...

In any case, per this owner, the primary concern with all this oil being sucked into the intake manifold is lost efficiency from oil clogged intercooler passages. He said PCV oil also passed across the turbo, but due to sealed turbo bearings, he did not anticipate problems. Could the turbo vanes accumulate oil crud, like coked intake valves? Hmm...

Why do I post this information on a Z06 catchcan thread? Well, up to now, my main concern with PCV oil mist being sucked into my intake has been valve coking. But, with an intercooled supercharger perched on top of my engine, should a new concern be lost intercooler and supercharger efficiency due to PCV oil mist and crud accumulation?
 

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So, where does any PCV oil mist end up on the LT4?

Does the intake air always pass through the supercharger and intercooler, or only when boost is being produced? I believe those screws are always turning, so there is not a pulley clutch engagement like superchargers from a prior era, correct?

If no boost is being produced, does the intake air still pass through the intercooler bricks?
 

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No interest in this?

Was discussing this issue with a friend last night. If the intake air and PCV air always pass through the supercharger and intercooler bricks, then the lack of fuel wash over the back of the intake valves is far less of an issue. Essentially, the supercharger/intercooler assembly becomes the LT4's "catch can", right?

And, all TVS style supercharged engines would have the same issue of collecting PCV contaminants in the supercharger assembly, regardless of direct injection or not, true?

I'm (educated) guessing at this point, so hoping someone with greater knowledge will chime in...
 

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I had a check engine light come on with my 2009 Ram cummins diesel which was due to restriction of some sort in the turbo. It was cleaned and covered under warranty at about 70,000 miles. I am sure this was partially due to the EGR system, so your statement about turbo clogging is absolutely a good question. I don't have a zo6 is this is not a concern for me personally but it is a good topic of discussion.
 

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Suspended oil and contaminants has always existed and when the PCV system was created, taking the vacuum from the intake manifold, it naturally sucked all these contaminants into the otherwise clean intake, contaminating the air and fuel. I think the theory behind it was to reintroduce these contaminates into the combustion chambers, thus burning them, therefore extracting them through the exhaust. The downside was the introduction of suspended oil being introduced into the intake charge that lessened power and actually promoted detonation. But for years this situation was manageable because the fuel in the intake diluted and washed down most of the oil and contaminants.

However, when automakers began converting to "Direct Fuel Injection," thus eliminating fuel in the air intake tract, the fuel that otherwise broke down the suspended oil and contaminants from the PCV system is no longer present. The fuel also washed down the backsides of the valves as well, which helped to prevent the "Valve Coking" issue. So, by eliminating the fuel by directing it direct into the combustion chambers, all those contaminates and oil accumulates into the intake tract and builds up on the backsides of the intake valves. If the inter-cooler bricks were to stop or act like a catch can, it would take no time for those to become clogged, which is something you wouldn't want to happen. The aftermarket catch cans collect much or most if properly designed, pulling the suspended oil and contaminants from the air intake tract at the air bridge just prior to entering the throttle body. Read further in the catch can and valve coking threads for further information.
 

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Thanks, Tom!

Wonder if there is any way to look inside the supercharger screws and intercooler bricks after a Z accumulates some miles?

Would a scope have sufficient room to pass into those areas?
 

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Maybe by unbolting the top plate of the supercharger you can reveal quite a bit. And then if you wanted to check out the intake runners remove the bricks, or the backsides of the valves by removing the entire intake supercharger assembly....
 

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Lots of discussion and lots of FUD floating around the Internet but when you ask the engineers who designed and built the motors their response is muted. Does anyone here really think that GM wouldn't install a $20 can (that's the MOST they would cost if mass produced) if it was proven to actually make a difference?????

Step back and realize that the people pushing these the most also happen to sell them and have done a damn good job convincing enthusiasts they need them.

258852d1395962050t-lets-stop-hurting-blackberry-triple_facepalm.png
 
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mjw930...at 1st, not sure I agreed with you...there was talk about reasons GM, or other manufacturers, were not installing catch cans; additional maintenance and possible EPA issues with the oil collected.

But, in thinking about it now, there's no reason catch can emptying intervals couldn't match oil change intervals. And, how much used oil is generated by a typical oil change as compared with a catch-can?

So, this issue is not really new to TVS boosted motors. Looking forward to seeing empirical data on the subject, if any makes it to the Internet. (ha!)
 

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I am very interested to see how this thread continues to develop. I've seen the intake valves on a 335i that was direct injected and I could not believe the amount of buildup on the back of the valves and stems.......the car had less than 15k miles on it and I couldn't believe it would even run with that much carbon build up. I've had fears of direct injection ever since I saw it. I'd strap a HEPA filter on my car if I thought it would prevent it.

Derik
 

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I am very interested to see how this thread continues to develop. I've seen the intake valves on a 335i that was direct injected and I could not believe the amount of buildup on the back of the valves and stems.......the car had less than 15k miles on it and I couldn't believe it would even run with that much carbon build up. I've had fears of direct injection ever since I saw it. I'd strap a HEPA filter on my car if I thought it would prevent it.

Derik
And yet there are tens of thousands of cars on the road with direct injection that are running just fine by different OEMs. Porsche switched to direct injection in all of their models in 2009 or 2010 without adding any supplemental catch cans todate. Perhaps in spite of the apparent build up on the back of the valves these engines still run strong. As with any accessory or insurance it is an option for each individual to decide whether they need, want or pass on it.
 
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