[SS 1LE]

Originally Posted by bballr4567

What does using top tier have to do with? It's not like the valves get washed with fuel. The problem is that they DONT get washed with fuel so that PCV air just collects on the hot valve and bakes there just like on a flattop glass stove.

Because of the injectors themselves. The extra detergents in top tier gasoline will keep them cleaner and more efficient...direct injection works at a much higher pressure than say, port injection.

Also remember, any sludge forming compounds formed in the crankcase are routed through the PCV system back into the intake, where they can sludge valves and everything else. So yes, gasoline can impact sludge formation all over the engine no matter where it is injected.

[bballr4567]

Originally Posted by SS 1LE

Because of the injectors themselves. The extra detergents in top tier gasoline will keep them cleaner and more efficient...direct injection works at a much higher pressure than say, port injection.

Also remember, any sludge forming compounds formed in the crankcase are routed through the PCV system back into the intake, where they can sludge valves and everything else. So yes, gasoline can impact sludge formation all over the engine no matter where it is injected.

Sure, we will go with that.

Sludge is formed basically when oil is never changed or there is a terrible design flaw that allows for oil to build up in one area of the engine. Gas has almost nothing to do with sludge because once gas becomes dissolved into oil it actually breaks it down into a thinner weight.

It's much more important to use a high grade oil in a direct injected engine than the actual choice of brand gasoline. Not the other way around.

Top tier gas is not really a concern anymore thanks to the way that the fuel is actually directed and aimed into the compression stroke. The higher PSI allows the fuel to be become a very fine mist instead of rain drops. Doing that allows for a much cleaner burn and less chance of residue sitting and burning on the actual injector.

[Speedy1975]

Meh, I only run top tier (Shell) in my supercharged Challenger because it's critical in that motor/setup, but for anything else any big brand should be fine. I have a buddy who's a pretty high up at Conoco Philips and he has told me there really is no difference no matter where you buy it outside of the detergent additive each brand uses. It all comes from the same supply chain. I've never checked, but figure he'd know. He also has a twin turbo 1000HP Challenger so not like he's not a car guy.

In my Camaro I just run a major brand that's cheapest for 93 octane.

For those talking about a dealer service to clean the top end, what about a Seafoam treatment yourself?

[asimpleguy]

Originally Posted by Bells

How many miles worth of oil is that?

I think a little over 6000

[SS 1LE]

Originally Posted by bballr4567

Sure, we will go with that.

Sludge is formed basically when oil is never changed or there is a terrible design flaw that allows for oil to build up in one area of the engine. Gas has almost nothing to do with sludge because once gas becomes dissolved into oil it actually breaks it down into a thinner weight.

It's much more important to use a high grade oil in a direct injected engine than the actual choice of brand gasoline. Not the other way around.

Top tier gas is not really a concern anymore thanks to the way that the fuel is actually directed and aimed into the compression stroke. The higher PSI allows the fuel to be become a very fine mist instead of rain drops. Doing that allows for a much cleaner burn and less chance of residue sitting and burning on the actual injector.

Well, the head Corvette engineer had said some of the same exact things I said on the Corvette Forum. He strongly recommended top tier fuel in the C7 and specifically mentioned one of the reasons being the DI. So, I don't know.

Bottom line is I only run top tier gas in all my cars, so there is no change for me. As for the oil, I mentioned that in my post on the previous page...

Originally Posted by Speedy1975

For those talking about a dealer service to clean the top end, what about a Seafoam treatment yourself?

Not the same thing.

[Ventmaster]

Originally Posted by SS 1LE

Because of the injectors themselves. The extra detergents in top tier gasoline will keep them cleaner and more efficient...direct injection works at a much higher pressure than say, port injection.

Also remember, any sludge forming compounds formed in the crankcase are routed through the PCV system back into the intake, where they can sludge valves and everything else. So yes, gasoline can impact sludge formation all over the engine no matter where it is injected.

With DI the top of the intake valves never see any gas so they don't get cleaned.

Any oil being recycled through the intake does have to go by the valve tops and contributes to the carbon build up.

[jamminj007]

I just checked my Mishi can and there was at least 2oz in it. So, in my case money well spent. And I do use "top tier" gas as well.

[Speedy1975]

Originally Posted by SS 1LE

Not the same thing.

RE: Seafoam

How is it not the same? It's a detergent that cleans the top end/valves through the intake. I'm not talking about pouring it in the fuel tank, I'm talking letting it be drawn through the intake via vacuum line. I've used it several times on other cars.

Any forum vendors I should consider for the Mishimoto?

[6spdhyperblue]

He's probably talking about walnut blasting

[Daves1SS]

Originally Posted by Nicul15

if you spend most of you time under 1500 rpm vs someone cruising through the neighborhood at 3200 and constantly engine braking, you will have much less oil in your can

This would explain why I never have any oil in my can. Most of the time I drive pretty relaxed or at least at lower rpms.

[StateOfMind415]

Originally Posted by Tr6

So this has been going on since catch cans basically became a thing. Some have seen it very useful and needed, some has seen it as extra and didn't do anything and then some has seen side effects which caused more issues than it has "fixed".

Figured we can talk about it in a civil manner about. To start off... I found this on the corvette forum.

Maxie2U asked:
Why did the Camaro design team decide to design in an Oil Catch Can on the 2016 Camaro with the LT1 engine? Will the 2017 C7 with LT1 engines also come with an Oil Catch Can, if not why not?

Tadge answered:

To answer the second question first: No, the 2017 Corvette LT1 will not have the Camaro V8 PCV air/oil separator (what the questioner calls a "catch can") added to its oil management system. For those not familiar with the abbreviation PCV, it stands for "positive crankcase ventilation"

Even though the Corvette and Camaro share the LT1, they are very different in execution detail. The LT1 in the Corvette sits lower and very close to the ground to enable an industry-leading low profile hood and good sight lines despite a very low seated position. Having the engine close to the ground is great for keeping the vehicle's center of gravity down, but means the oil pan is relatively shallow. Having little depth in the oil pan means it is very challenging to scavenge oil in high G loading conditions. For this reason we add dry sump lubrication to our high performance models. The Camaro's higher engine position allows for a deeper oil pan and a reliable configuration for picking up oil for delivery to all parts of the engine. Thus the Camaro is able to avoid the cost and mass of the dry sump tank and resulting complexity of the lube system.

The Corvette's dry sump tank looks relatively simple on the outside but the internals are really quite complex. The top third of the tank contains a PCV air/oil separation system. On the Corvette, PCV lines route from the valve covers to the air/oil separator on top of our dry sump tank. Oil from PCV air is separated and returned to the lube system through the oil tank. The PCV separation system on Camaro V8 performs a similar function except oil is returned to the engine oil pan from the PCV separator's drain back tube. The Camaro V8 PCV air/oil separator is more complex than a "catch-can" since it not only separates oil from PCV air it provides a drain back path for this oil to be reused by the lube system. "Catch-can" systems that do not have a drain back path for separated oil run the risk of poor oil pressure performance over time as oil is removed from the lube system.

The bottom line is that both cars use optimized engineering solutions for their lube systems based on vehicle architectural considerations.

- End of Quote.

You can read this in a few ways, could say that Tadge is saying it's optimized due to his affiliation with GM, or you could say he is correct.

I personally haven't seen any oil issues with my car, TB+IM perfectly clean, no oil anywhere during and after break in, I do have a Mishi Catch Can sitting in the garage shelves as a "just in case" which can lead to warranty issues if installed. But that's something I personally would care AFTER warranty expires because if something happens to the engine or any other part... It will get fixed whether it's a brand spanking new engine or not, for free.

Anyhow, what do YOU guys think? Also, keep in mind. My stance is NEUTRAL and I am posting this to get a mature and civil discussion going on, especially for other forum members to gain some knowledge and opinion out of it.

Tadge also commented back in 2015 in the corvette forum about the LT1 the following below.
http://www.corvetteforum.com/forums/...on-valves.html

"Quote:
vettman96 asked:
Is there any issue known with deposit buildup on the back side of the intake valves due to not having a port injection system?

Is GM aware of, and if so do they have any plans for correction with the intake valve coking issue present in the direct injection platforms as a result of the PCV system. Many members of the community are seeing an excessive amount of oil and carbon deposit buildup on the intake valves after only 5,000-10,000 miles and worse with even higher mileage engines on the C7. While I understand the purpose of the PCV system as it relates to emissions, with the introduction of direct injection there is no longer a cleaning process in place that would be naturally present such as from a port injection system.

Quote:
Tadge answered:
Good technical question vetteman96. The short answer is: No, we have not seen any issue with deposit buildup on the back side of the intake valves due to not having a port injection system.

You correctly point out that the continuous flow of clean air and gas over the intake valve tends to keep it very clean. That has been a characteristic of small block V8's for decades. Of course, appreciation of that characteristic is limited to those who disassemble their engines. Most customers are unaware.

Given that all SIDI engines give up that benefit in favor of other important attributes, we did extensive testing to make sure there were no customer-observable penalties. We intently looked for unusual deposit formation during the entire Gen 5 Small Block development phase (4 years) as well as the 200,000 mile in-vehicle long term testing. We have not seen anything unusual and zero performance degradation. Granted, deposit formation on SIDI engine intake valves is greater than what is seen with PFI engines, but the Gen 5 engines are typical for SIDI engines, and in fact better than other SIDI engines we have benchmarked. So the bottom line is that we believe the carbon build up is only an internal cosmetic issue, not anything that will affect customers over the life of their cars."

[Speedy1975]

I take it Tadge is a Chevy engineer? I don't know how forthcoming Chevy engineers are on these forums, but we had Dodge engineers answer questions on our Mopar forum and those of us that know anything about cars got a good laugh at their answers. It got so bad the engineers were heckled when they dared show up to events.

I don't know enough about this to discount anything Tadge posted, however, so take what I say with a grain of salt and as an experience on a completely different platform.

However, being an engineer myself, I do know there are design criteria and acceptable levels of variance (think power loss) built in to a project. As long as those variances remain within the project tolerance they consider it a success. Obviously this almost always becomes a battle between the bean counters and the engineers who actually want to build the best product available and are forced to compromise to meet budget and timeline.

[StateOfMind415]

Originally Posted by Speedy1975

I take it Tadge is a Chevy engineer? I don't know how forthcoming Chevy engineers are on these forums, but we had Dodge engineers answer questions on our Mopar forum and those of us that know anything about cars got a good laugh at their answers. It got so bad the engineers were heckled when they dared show up to events.

Tadge is the Corvette Z06 Chief Engineer (Been with GM for 36 years). There is credibility behind what he says since he helped develop the LT1 inside and out throughout the whole process.

Originally Posted by Speedy1975

However, being an engineer myself, I do know there are design criteria and acceptable levels of variance (think power loss) built in to a project. As long as those variances remain within the project tolerance they consider it a success. Obviously this almost always becomes a battle between the bean counters and the engineers who actually want to build the best product available and are forced to compromise to meet budget and timeline.

He did mention that there was "zero performance degradation", so might be one of those best products available. =)

[SuperSound]

Tadge and his team also rated the C7 A8 as track ready. It is not exactly. So take everything everything with a grain of salt. GM is just following in line with all the other OEMs on saying it's not an issue. Because loosing a few MPG or slight loss of engine efficiency is not a concern, especially when it occurs close to the end of the warranty or just beyond.

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