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Oiling technology is far more advanced than just the oils used. You get your money's worth from a dry sump oiling system.

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Maxpowers

I've always liked this guy.

Never heard about dry sump increasing HP. GM hasn't noted a difference between the base and Z51 other than the NPP.

Kent1999

Except of course, not all the listed advantages apply to our C7 LT1 dry sump. For example, the LT1 Dry sump oil pan is not any more shallow than the LT1 wet sump version, meaning the dry sump engine is located at the same height as the wet sump LT1 = no CG advantage. And as Max mentioned, SAE doesn't rate the dry sump any different than the wet sump, so likely no HP advantage.

Still, a good feature to have.

JK 23112

Wouldn't the primary advantage of a dry sump have to do with preventing "oil starvation" during hard track use? Perhaps it also has a higher capacity of oil (i.e., 8qts vs 6 or what not).

For a normal street-driven car, I think the wet sump is going to be fine AND I won't have to change the oil at 500 miles. :-)

JoesC5

Actually the dry sump in the C6 and C7 raises the car's center of gravity. As you said, there is no difference in the engine height off the ground, but in the wet system, the oil is stored in the low mounted oil pan sump. In the dry system they added the extra weight of the reservoir(and oil) much higher than the wet sump.

If anything the dry sump has less horsepower(very little) because of having two oil pumps to drive, that takes more horsepower, leaving less at the flywheel.

JerryU

Yep, race car engines can gain ~20 hp (in a ~600+ hp engine) BUT that requires ~20 inches (~9 psi) of vacuum! The C7 does not achieve anywhere near that level with it's small scavenge pump. Race cars use multiple scavenge pumps that are much larger to achieve that vacuum level.

With that high vacuum there is less windage for the crack and spinning rod ends but to get the significant power gains race cars also use lower tension (friction) rings that the high engine vacuum allows.

GM, no doubt didn't list a hp gain because it doesn't exit! The pan design and windage try in the C7 wet sump probably does a good job of keeping he spinning crack out of pan oil.

PKI

So the wife asked, "why is it better?" Had a hard time with the answer.

So, aside from a constant bearing lubrication capability, what is the value? Are there more baffles in the pan? Does the pump pull the oil out of the pan so less oil is in contact with the crank? Is there more filtering, cooling, or foam prevention? Is the use of a more or less viscous oil possible with the dry sump? Is it easier or harder to change oil?

Really appreciate your tech on this. Thanks Pat

JerryU

My wife would never be with me when I perceive the benefit! If she were- she'd never drive with me again! Frankly it's not having possible oil starvation on sustained high speed turn.

I had a 260Z where I could see the problem in my favorite highway off-wrap! It, like my favorite today, was a sweeping 270 degrees. Not many like that even on a race track! With the Z, I could see the analog oil pressure gauge drop as I neared the end! The oil pump was no doubt sucking in air!

With my Z51 C6 (wet sump) I was concerned that it might be doing the same but that electronic pressure gauge would no doubt not pick it up as it is averaging over time.

With my Z51, C7 dry sump and the sticky Michelin tires it's achieving even high lateral "g" force! That for me is the biggest advantage, no possibility of oil starvation.

The other features are negative. It's harder to check oil levels, takes more oil per change, takes longer to heat up. So short trips to the store take longer to get it hot making it worse for the oil, oil life and engine life!

Specifically to your questions, pan baffles are not needed in a dry sump to manage oil getting to the pump. There is always oil in the dry sump tank to supply to the engine.
In the C7 wet sump with its well designed pan and windage try doubt that there is much oil in contact with the crank.
No real filtering benefits and perhaps at the race track the oil would be slightly cooler based on the extra volume.
One reason for perhaps more foaming in a dry sump is air and oil are being pumped together.
Oil viscous is only dependent on temperature and doubt mine is much lower than a wet sump.

mschuyler

In an attempt to fully understand this article I actually read it. And I dutifully listened to the video. As I understand it the dry sump has advantages. They are a shallower oil pan, which allows you to lower the engine and therefore the center of gravity. It also allows you to move the reservoir for potentially better balance, though frankly, I would think the low point at the center of the car would provide pretty good balance. You can also put more oil in it, plus the design means a heavy corner won't run your engine dry of lubrication. Lastly, the fact that oil isn't sloshing over the crankshaft to slow it down means a bit more HP. So overall these improvements just might mean an increase in performance that, all things being equal, could turn a loss into a win on the track.

I think that covers the basics. What I don't understand is how this is an "unfair" advantage. Is superior design now considered "unfair" to inferior design? If I have more horsepower, is that now considered "unfair" to those with less horsepower? OP, please explain why a dry sump has an "unfair" advantage.

JoesC5

The dry sump only has the lower center of gravity advantage if the remainder of the car is designed to take the advantage of lowering the engine.


In the Corvette, the flywheel diameter is 14" for both the dry sump and the wet sump.

You can make the pan as shallow as possible, but you can't lower the engine in the corvette because there would be a problem with ground clearance with the bellhousing. Also the oil filter would have to be relocated.


Also, the design of the engine cradle(front crossmember) in the Corvette doesn't allow for the lowering of the engine. With lowering the crossmember(in order to lower the engine), there goes the ground clearance.

JerryU

Yep, in a race car they use a lower profile oil pan, allowing a lower engine placement gaining a lower center of gravity. In the C7 they do NOT! Probably did not want to lower the whole drive train just for dry sumps!

With a good oil pan design, like my C6 Z51 wet sump, GM has patents on pan and baffle design. They use a metal plate with holes that allow draining oil to enter the pan and not splash up to hit the crack. That is called a windage try. Probably does a very good job.

As mentioned previously, in a race engine they can use lower tension (friction) piston rings if they generate a ~9 psi vacuum. In addition the air drag of a spinning crack and rods is less in a 9 inch vacuum than at atmospheric pressure. Doubt the small C7 oil scavenge pup is achieving a significant vacuum to help in that regard.

Just my thoughts!

rogergcam

THE REAL ADVANTAGE of DRY SUMP is that the dealer can charge you $150.00 for an oil change. Thats the real advantage!!!!!

mschuyler

Excuse me but I was simply summarizing what the video said. I wasn't questioning it. If you actually listen to the video I trust I have summarized what he said fairly, which was my intent. If you have an issue with what the video said, take it up with the video author. My question concerns why such a system is an "unfair advantage."

village idiot

oil windage is fair substantial, way more than pumping losses of the dry sump.
Keep in mind, the wet sump has one pump doing all the work. I don't imagine the amount of work done with the dry sump is substantially more than a wet sump.

Of course, we're only talking a few horsepower, but it's free hp! Heck, it might be more than free- it gets you better mpg too! It's a really big deal in racecars, to the point where older wet sump racecars would knife edge cranks. Cutting through oil at high rpm takes energy. Heck, some cars would run really thin oil (engine, trans, diff) for qualifying to gain an advantage. Then they'll switch back to the proper weight. I don't think that's permitted in most racing classes now but I could be wrong.

JerryU

Recall when visiting with the Petty Race team years ago, Dale Inman mentioned the use of 000 or some designation of a very thin viscosity oil they used.

I asked if that is satisfactory for the engine? He said, "It is for 500 miles!

maghall66

I got a good laugh as soon as I read the headline. I imagine all of the Z51 guys hyperventilating in a complete panic. Just a little needle from a base 1lt guy

hangman

Good plug for Shell/Pennzoil.

Astrowing

My Z51 does take a really long time to warm up on a cool day. Water is at temperature in 5 minutes or so but oil may be 15 minutes. It was interesting to watch the first time. I had not had a dry sump before. The engine itself doesn't have any tendency to heat even when driven hard. Now the differential is another story.

2016_Z06

Totally wrong

The engine sits considerably lower with a dry sump and has a lower CG due to that effect... The mass of the reservoir and the oil therein is trivial compared to the lowering of the engine.

The dry sump engine doesn't have to overcome the losses associated with the crankshaft being submerged in oil which is much more parasitic than needing a second pump. Hence it will have more power.

village idiot

This would require different motor mounts or mounting position of the engine AND lowering the drivetrain for it to mount up to a lower engine. I don't think that's the case here, although, in theory, it could be mounted lower.