C6Z and Oil Starvation

[WhosUrDaddy]

I have noted louder tapping at idle, which has been making me think about oiling. Also, I read that the ZR1 has an "expanded dry sump tank to account for G forces in excess of 1.5G's". I think this was in Autoweek or Automobile Mag.

Reading through my ontrack data, I routinely see G forces near 1.5G's and have noted a few events beyond this level. I was unaware that it would matter until I saw the above quote. I was thinking of finding a set of track wheels and running with R compound for this coming season.

Am I starving the engine by putting it on the track and running it hard even on street rubber?

[DennyM]

Not my lane ... but I wonder if you might be experiencing the rocker needle bearing loss that seems all too common on the LS7? :

[WB6HRO]

It is only an issue when the high G forces are sustained for a long period of time like a very long sweeper.

With the C-5's we add an extra quart of oil for insurance when on the track.

My C-5 Z06 has seen quite a few track days and I've never seen the oil pressure drop. Typically you need to keep and eye on the oil temperture, mine got up near 300 degrees so I added an oil cooler.

[AlohaC5]

I would be surprised (no shocked) if the tapping in the valvetrain was due to oil starvation given their advanced dry sump setup. I agree with DennyM - I would pull the valve covers and inspect your valvetrain to examine your rockers, springs, etc. Do you hear the tapping every time you start and idle (cold and warm) or only after running a few hard laps at the track? What weight oil are you using? Could also be an exhaust leak - do you have headers installed?

[No Doubt]

As DennyM said, check for needle bearings in the oil. When a rocker fails you may hear a tapping that is not unlike a stuck lifter or a solid lifter that needs adjusting.

And I wouldn't call the dry sump system on these cars "advanced". It's unusual for a street car but as far as dry sumps go, it's pretty basic. "Advanced" would be a race system. In fact, it's being improved for '09 and more oil capacity is being added as well.

[WhosUrDaddy]

I notice the tapping at idle after its warmed up and idle speed is subsquently reduced. I've got an appt at Criswell Chevrolet on Monday to deal with that problem and a few others.

As for the sump, what differentiates the system on the 06 Z06 from a full on race system (other than lighter componentry)?

[No Doubt]

In principle they are essentially the same, but the design is different in that they usually use a multi-stage pump which is often belt driven vs. driven directly off the crankshaft. Of course, they are also a lot more robust and expensive.

[DJWorm]

The C6 Z06 dry sump system is an 8 qt. system with a dual stage pump, air/oil engine cooler and integral PCV system.

The problems with the C6 Z06 system are:
1. the 8 qt system is marginal for track, AutoX and skid pad operations with SUSTAINED high g loads. NOTE: on C5 Z06's we limited skid pad runs to 2 continuous laps ONLY; likewise for the C6 Z06.
2. Under high RPM's the PCV system can be overwelmed and cause aeration and foaming in the tank despite the internal baffeling.

The solution was to upgrade the system with:
1. A higher volume and flow ported and polished oil pump on both stages. NOTE the stages must be balancedas to flow.
2. Isolating the PCV sytem or installing an inline seperator
OR
1. replacing the dry sump pan with a racing dry sump pan (Dailey Eng.)
2. replacing the oil pump with a belt driven racing multi stage pump (Dailey Eng)
3. replace the reservoir with a larger volume racing reservoir (Peterson) brinnging the system to 12 qt.
4. Isolating the PCV system from the reservoir

The '09 ZR1 upgrades are
1. to increase the system capacity to 10.75 qt. using a larger reservoir tank
2. retaining the 2 stage gearotor crank snout driven pump but increasing the volume and flow out put 25%
3. changing to a water/oil engine oil cooler located on the driver side of the pan.
4. slight pan improvements for better scavanging
5. retains the same PCV system.
6. runs a higher system pressure due to increased demands such as the individual piston squirters on the LS9

Initially the LS9/ZR1 upgrades would seem to be adequate for track use.
Therefore those parts (revised pan, revised 2 stage pump and larger reservoir) could be used to update/backdate the LS6/LS7 for track use; otherwise the racing pan. racing pump and racing reservoir will need to be installed.

[WhosUrDaddy]

Originally Posted by DJWorm

The C6 Z06 dry sump system is an 8 qt. system with a dual stage pump, air/oil engine cooler and integral PCV system.

The problems with the C6 Z06 system are:
1. the 8 qt system is marginal for track, AutoX and skid pad operations with SUSTAINED high g loads. ...........

Great information, thanks. Sounds like adding race rubber might exacerbate the above shortcomings - so I'll go without.

[STAGED47]

I have alot of tapping at low rpms, I was thinking its the long tube headers. I ts driving me crazy, I think im going to check it out at my shop then try the dealer.

[AlohaC5]

I run with a lot of guys in the new Z06s that have R-compound tires and they don't seem to be experiencing this issue - perhaps I'm just not hearing about them. Hopefully the Corvette Tech at Criswell or Dave at Tonys Corvette Shop can identify and resolve it for you soon.

[WhosUrDaddy]

Originally Posted by AlohaC5

I run with a lot of guys in the new Z06s that have R-compound tires and they don't seem to be experiencing this issue - perhaps I'm just not hearing about them. Hopefully the Corvette Tech at Criswell or Dave at Tonys Corvette Shop can identify and resolve it for you soon.

Since mine is a daily driver I'm concerned that, while this isn't a readily visible issue, I'm damaging the motor unknowingly. I thought this might be manifesting itself as tapping in the valve train. I'll push the Criswell guys and hope that they actually do some due diligence on the matter.