Higgs Boson

Z06BAIT,

Mines a wet sump 2014 but it's a 416 with a blower and open breathers so....

COSPEED

Why don't you try this yourself and see firsthand? Anyone that wished to be present for the testing was invited as an open invitation for just this reason. We invited Tadge and any from the media that wished to witness and document. And as for the deposits, look at how the engineers design and describe the intake and exhaust valves and port design. They sent tns of time and $ to get the shape, size, and angles to provide the most efficient flow possible for power and economy. These engines are the most efficient and powerful of the 6.2 to date, and this is greatly due in part to the excellent design of the ports and valves. So to think flow is not affected detrimentally is absurd if you ask any flow bench operator or flow engineer. (I suggest contact a famous engine builder like Reher Morrison or Scott Shafiroff and email them the pictures and ask them. Just as pulling suction/vacuum n the crankcase VS venting that allows pressure to always fight the pistons movement results in more power as this video shows:

And that is only a small 5.0L engine at 8k RPM.

Here is a port injected LS engine at 142000 miles. Zero deposits:



The science of flow and velocity and how this affects the power and efficiency is not even a question in the industry. This is critical. Just look at the increased power gains of a CAI installed. Even a slight obstruction of the designed shape and size of a valve will have a definite reduction in efficiency, and those deposits (the ones closest to the point of the PCV connection) are quite severe in changing the valves shape, surface area, texture, etc. Even the angles cut onto the valve as small and insignificant as they appear make a large difference. The LT GDI engines all have 3 angle valve cuts and specific angles found to maximize flow.

But all of this aside, doing any of this yourself is not that difficult, take your car to the dyno of your choice and duplicate all done here and see first hand. If valve shape, port and valve volume, and surface texture did not matter, GM and all other would not waste so much time and money on the way they designed these, and they would not brag about it in the articles and advertisements.

Here is how the valve is designed and intended to remain and all aspects of the flow of the cylinder heads will be affected by this design. Look close at the angles of the cut for seating, and see how small the angles are? Even changing that angle a few degrees affects power and efficiency:

Read this direct from GM on how critical even the smallest changes in valve shape, design, texture all contribute to the efficiency of these engines:

"To deal with all of this, main combustion chamber variables that needed to be tweaked included chamber size, injector nozzle and spark plug placement, valve sizes and angles, and the intricate facets of the piston crown. According to Mr. Rydzewski, all of these parameters have influence and getting them just right was critical “to ensure that the air comes in in just the right way, that its motion is just right inside the cylinder, and that it exits in the right way.” Also crucial was ensuring that during the actual combustion process, “the ignition event is in the center of the chamber and you have a nice outward flame propagation where you can get as much out of what you burn as possible.” GM says computational analysis for the Gen 5 required more than 10 million hours of CPU time, with nearly two-thirds of that devoted to the combustion system, so a whole lot of iterations were evaluated before a near-finalized cylinder head design was even prototyped.
The resulting head features hollow valves spec’ing out at 1.59 inches on the exhaust and a large 2.13 inches on the intake, the former sodium filled and the latter nitrided in the interest of durability (this process was used on some LS engines, but this is its first performance application). The orientation of the valves is different too: each new generation of small-block has featured shallower valve angles than the previous, moving from 23 degrees on the original to 15 degrees on the Gen III and IV (the LS7 was shallowest at 12 degrees). The Gen 5 continues this tradition, with its intake valves being rolled to just a 12.5-degree angle from vertical and an even shallower 12 degrees on the exhaust. Hot rodders have long known that shallower valve angles allow for smaller-volume combustion chambers and help minimize valve shrouding as the valves near maximum opening, hence increasing breathing potential."


The entire article is here to learn more:

http://www.superchevy.com/how-to/eng...ngine-details/

So even the slightest amount of build-up will have a negative affect on power.

And there are other examples all over the internet of Ford Focus GDI engines and the power regained at just 9k miles, and the 3 years BMW tech test on his new car. He did yearly dyno tests on the same dyno, same SAE correction factor, same time of year and he documents every year the reduction in power, and fuinally does a manulal valve cleaning and the end result falls in line with this LT1 test:



Tons of info out there to support all of this, but for those that still have doubts, see for yourselves. Do the same testing.

COSPEED

Even more reason to not allow that pressure to be present in the crankcase......why not try what I am sharing and see, do a dyno as is with the breathers, and then install a Monster system that evacuates in boost and non boost so no crankcase pressure can build and see the power form that alone. Will remove the damaging compounds that enter as blow-by before they can settle and mix with the oil contaminating it.

Nothing to loose, and a ton to gain by actually trying this yourself.

Higgs Boson

nah, i've yet to find a system that is going to relieve this kind of pressure under boost better than what I have, which is why I have it.

besides, the car is going up for sale within the next week or so....time for a new project! I think I like building them more than driving them. someone is going to save a LOT of money buying this beast!

COSPEED

These I guarantee do. Proven over and over again with other 1000 plus RWHP examples.

That is the sad part on a great car build, never get close to what you put in out of it, and I agree, going to make someone an awesome deal.

COSPEED

Another dealer experience:


"I just wanted to share a dealer experience today. It's not my GMC 6.2, but I brought my 2015 Corvette Z51 in for the second oil change. At my dealer you can walk to a block 1/2 wall and watch the Corvette specialist work on your car.
I was watching him open the hood and getting it ready to go up on the lift.
A little later he said, "Good to see you have a Catch Can -I like the Elite". I told him that I had wanted to ask his opinion because there is so much on the internet on both the Corvette and the GM truck site regarding their value or not.
He said he absolutely recommended them and started to describe what can happen if you don't have one, but stopped and said "hold on, come over to the bench".
He pulled out a couple of really coked up valves and said, "this is what you prevent from happening".
When I installed the Catch Can, it was because after hearing all of the Pros & Cons, it made sense to me, that it was worth the extra protection and added maintenance to take better care of the engine -so it was nice to have a Corvette specialist confirm, before I asked, that it is a good thing to do.
This is just MY experience and opinion."

robertf97

I appreciate much of this thread, very informative. I haven't seen the ECS method discussed though which is basically what I use on my supercharged 14 Z51 (but with 1/2" lines and AN fittings versus the 3/8" stock plastic ones). I feel its a good solution for a supercharged car but wanted to get the experts opinion.

The ECS system routes both valve covers to the air filter box upstream of the air filter near its base and removes the check valves. I've verified no oil is in the air box/the air filter/intake tubing and my oil stays clean for about 3000 miles at which point I change it. It has 13500 miles on it (TSP 416ci).

I also have a dual nozzle methanol injection system that I test every morning running 100% methanol.

COSPEED

And that defeats all evacuation and flushing of the damaging contaminants. A proper PCV/Crankcase evacuation system needs filtered fresh air entering one bank, and the foul damaging compound laden vapors evacuated (sucked out) the opposite.

Also, as it is upstream of the filter, and air entering your crankcase is unfiltered. Just look at your engine cover and other areas under the hood to see the amount of sand and dirt that accumulates there. Incoming air must always be filtered for long engine life.

Here is the proper way to do a Centrifugal SC system or turbo LS wet sump engine, LT1 depending on wet sump or dry sump is a bit different and can provide that if needed, but same principle:






What this does is provides for evacuation suction at all times, and does not allow crankcase pressure build and vent as you describe. This aids ring seal, reduces blow-by, and eliminates much of the parasitic power loss due to the pistons fighting pressure on the down stroke. It also keeps oil much cleaner longer by removing the contaminants whole still in suspension VS allowing them to settle and mix with the engine oil as you describe does.

The PCV system provides several critical functions to aid in engine longevity and only one is pollution control related.

Let us know if you need more details, PM your email and we can send detailed instructions.

mirage2991

From doing some research of this carbon deposit issues with all GDI, it seems that Audi had the worst BUT it seems that THEY are the only one that added an injector in the intake to solve the issue. From my readings, i believe that injector is used during cruise only. (maybe somone already posted all this but i did t read all 10 pages of this thread !).
It is bothering me enough that shopping for my next car has be haltered a bit.
One has to realise that automakers are most concerned in meeting outrageous epa standards, and less concerned if your car looses 1/2 of it's power by 60k miles due to carbon build up. Of course soon enough it will be a routine maintenance to have your intake pulled off and valves cleaned... yet another expense for us the consumer...

COSPEED

Audi was the first that we are aware of, but Toyota, BMW, Ford (for 2017) and several others are currently using the same. The issues that arise with this "blend: is one, it dose not make a huge improvement. Although deposits currently are far less than the early BMW's, etc. that were the worst offenders, all still show the small port injectors are not nearly enough to keep the valve cool and clean as pure port injection. The other issue is the increased incidence of detonation, and that results in knock retard pulling timing and less power and economy results. Pure DI is a great improvement in so many ways over port injection except this one main con. These engines are 11.5:1 compression ratio and more (Audi in the lab is testing 18-19:1!!). Toyota has different sized pistons/displacement in experimental engine design where they can activate and deactivate up to 15 combinations so only the displacement needed is used (not to be confused with DoD).

You are dead on correct on the automakers, and the added maintenance cost to the consumer, and seeing the Big 3 and some imports dropping warranty coverage on the engines to nearly 1/2 recently is not a good sign of confidence in a truly robust solution. But as Hillary states, we won;t have internal combustion engines in the future and will all have to rely on electric and public transportation.

Good post!

mirage2991

Yes, unless you are part of the gov and then you can excuse yourself of these silly laws and have your internal combustion engine....but yes, how do you make Public drop something, you make it impossible to have/own....soooo having to clean your valves every 30k miles at the cost of 600-3k depending on labor involved is a sure way to make Public not want a car....though I laugh as I saw the new LT1 intake conversion to run a Carb or PFI on it for us hotroders...love it....but then again, 99% of the populace don't care about performance...so as long as no CEL comes up and mpg stays ok, most won't notice....ignorance is bliss....
IDK it really pisses me off, I was dead set on buying a '14 Cayenne GTS but they too have that issue...the saving grace is their intake is built/bolted on similarly as an LS motor, not very hard to remove...but still...
I particularly love GM's stand on, how "we won't notice"....they are right, most will not...until your buddy with the slower car start pulling you then you'll wonder wth is wrong with your car....

xxaarraa

I stopped watching right when he said "there is a 2-3% degradation at 5500 miles" You do the math and that's a lot of miles before it becomes a significant problem. Too many miles that most corvettes will never see.

MikeLsx

I would be ok with DI causing problems as long as there is a real cleaning process in place from GM. Something that is at nation wide dealership level.

TennisFreak

Everyone has their opinions.

FWIW I just got back from Spring Mountain owners course.

I talked to several of the instructors, who are all race car drivers at some level, that drive the hell out of these cars every day.

They all were unanimous in the opinion that a catch can was unnecessary unless you are driving the car at 10/10ths.

COSPEED

How do you/they explain this?:



Before and after dyno showing the results of intake valve coking at just 20k miles. 2-3% at 5500 miles, is 4-6% at 11k, and 8-12% at 22k miles. Adds up pretty quickly, but the average owner that rarely drives and never puts the car through it's paces will most likely not notice this.

TennisFreak

I have a catch can myself so I'm not trying to argue against them.

I was merely telling you the opinion of the instructors at spring mountain who track these cars every day of the week and push them to the limits.

They claim that the lines on the clean side that drain back into the dry sump are more than enough.

This is their opinion.

And FWIW IMO That dyno chart looks quite crazy. Just very hard to believe that much of a whp change due to just "coking". I think there are a host of other factors besides just the coking which could be contributing to the HP loss.

COSPEED

The owner of the car used is an aircraft tech and aerospace engineer. Takes unreal care of the car and he wrote details of the testing. He was present for every step. Came in early, did base dyno, then helped with the manual intake valve cleaning, then IM was reinstalled and after dyno performed. Nothing else changed.

I agree that most out there are ignorant to the effects, and all anyone has to do is look at the oil ingestion to see what is happening when tracking the cars.

https://www.corvetteforum.com/forums...or-test-2.html

Start at post #38 as Warship is the owner of the car that performed the testing, and all that wanted to attend were invited for weeks ahead of time. Also invited Tadge or any GM engineers that wanted to attend to watch the entire process. Not much else could have been done to be more accurate, but would like to see more with higher miles on them do the same. This falls into all the other before and after dyno testing on other brand GDI engines as miles accumulated. GM LLT engines are showing the same percentage of loss as the others. Hard to argue opinions against actual fact, but as you saw first hand, most have no idea. They are only making assumptions. No one else seems to actually be doing real testing and documenting this that are claiming there is no issue with the coking.

Look at the other dyno charts of other vehicles in that thread. The BMW example was a actual BMW tech that did his 3 year study and testing, and he used the crushed walnut shell blasting method for cleaning. The dyno shop also has a Ford Focus ST at 9k miles, and a BMW Mini with 22k miles.

Remember, the owner of the car was present for all to verify what was done, actually helped with the cleaning and the dyno's.

Bottom line is until the public gets educated, there will always be those that do not understand and are not aware, and even if shown undeniable proof will still refuse to believe.

Thanks for the input! Show those you talk to these threads and see what they say, or better yet, get one that thinks there is no issue to bring there car in to do the same testing with them present.

MikeLsx

Let's put aside the DI engines found in economy cars, where people probably NEVER see redline. They probably drive the car around town without caring about the engine.

GM now has DI engines in all trucks, camaros and corvettes.
All these engines are going to see 20WHP loss at 20k miles according to this logic.Meaning at 50-100k miles they are going to have lost so much power people driving these cars have to notice. It's hard to believe that GM put so many of these cars on the road that are risk of getting a bad reputation.

COSPEED

And that is what we are facing. Just watch and see. When I first started to bring this issue up here, most claimed it was pure BS and there was no coking issues or oil ingestion issues, Now we have see all the members sharing what they are finding, that was proven incorrect. And as more get more miles accumulated, the more this will become evident. Keep in mind the car owner in this test made the statement several times leading up to this, and even the day he participated that he highly doubted his engine had any power loss as he could not notice it. But soon found that having it suddenly restored it was evident how noticeable it was. When t is slowly degrading, it is very hard to notice....but the difference after a manual cleaning is night and day.

Now, we still need to see many more to get a better overall picture, and of cars that did NOT run the full synthetic oil and kept with GM's recommended cheap Dexos blend and compare that. The recent dropping of the engine warranty to almost 1/2 speaks volumes in how they and others are working to reduce future financial exposure from this, but as GM is not alone, and this impacts every automaker...and all have performance models, this will hit all hard when it becomes more known. Until then the small cost to take steps to avoid it seems like a small hassle VS what is spent in other areas. And until more are willing to inspect their own valves (again, minimal tools and little skill is needed) and take pictures documenting this, the assumptions on the side that it is not an issue are only that, un-proven assumptions that are being proven wrong every step.

As I have done for the past few years here, just watch and see. And those seeing enough to want to take the steps, the cost is minimal to want to care for their "baby" the best they are able to currently. If you are dead set against this then that we are fine with. We did not pay for your baby, you did and only you can decide what you wish to do.

MikeLsx

The data speaks for it self, and the data posted here is probably "real".

most people arent going to notice the 20HP drop. But if you have millions of cars on the road, and half of them are over 50k miles. They are down 50WHP, and the car has misfires. The sky is going to fall.

either the sky falls, or guys like you are just full of ****. Thats what i am saying. because this data is showing 20WHP at 20k miles, not a single engine will make it to 100k miles without major power loss. (with no catch can or cleaning done.)