Dreamin

To determine how common Oil Starvation / Oil Pressure Drops are on track... i very accurately logged my oil pressure around a number of tracks.

I plumbed an aftermarket oil pressure sensor into the block and attached the output to my Traqmate. I used a very accurate, fast responding oil pressure sensor. Having seen logs of the output voltage from the factory oil pressure sensor, I knew it was not fast enough to catch very short pressure drops.



DIY oil pressure install: http://forums.corvetteforum.com/c6-z...tarvation.html

Tracks tested
* Laguna Seca (No. Calif) twice
* Infineon (No. Calif)
* Willow Springs (So. Calif)
* Buttonwillow (So. Calif)
* Thunderhill (No. Calif)
* Calif Speedway (So. Calif)... will be tested with LPE tank only

My findings
* Oil pressure drops are very reproducible on high-G LEFT hand turns
* Banking / elevation change is not needed for the pressure drops
* The pressure drops are very short duration (~0.1 sec) then the pressure recovers (this repeats)
* The oil pressure shown on the dash does not change during the drops
* Pressure drops do not appear to be oil temp related (I see drops at 260 deg and 290 deg oil temps)
* I'm seeing 15-20psi pressure drops, but pressure does not go to 0 psi. This would imply that any damage being done is slow and progressive... ultimately leading to a failure. (Though with higher G's or longer sustained G's pressure drops could get to 0 psi.)
* No conclusions if oil level is a factor in the pressure drops. I always run my oil full (at the top hole) and check/refill after every session.
* No conclusions yet if "hard braking" needs to precede the left hand left. (All the tracks i tested have hard braking zones before the high-G turns)
* IMO the LS7 is NOT a lemon. The oil system appears to have a weakness in one very specific scenario; avoid this scenario and you should be fine (as evidenced by people who have done 100s of track events without issue).

My conclusion
After pouring through hours and hours of track data:
You will get pressure drops on: left hand turns, when sustaining greater than 1.0G for 4 seconds.
It appears to be this condition exactly: >1.0G but <4 sec and no pressure drops... <1.0G but >4 sec and no pressure drops. But >1.0G and >4 sec and the problem occurs lap after lap, without fail.

Rule-of-thumb
* Monitor the G-gauge in the HUD... it's pretty accurate. If it shows >1.0G for longer than 4 seconds... SLOW DOWN on that turn (note: you need to stop 'counting seconds' when you unwind the wheel, the HUD 'locks' the high-G number for about 2 seconds after the turn)
* Or upgrade your oil tank / oil system




*** Standard disclaimers apply. I assume no responsibility for any damage. This is simply my opinion, backed by my data. I have no GM nor vendor data. You can follow this advice and still lose your motor ***


As a result of my testing, i decided to install an LPE High Capacity Oil Tank.
DIY - LPE Tank Installation Instructions are HERE

Dreamin

Track: Laguna Seca (No. Calif)
Car: '07 Z06, MPSC tires, Brembo Brakes, stock powertrain
Air Temp: 80-90 deg
Oil Pressure Drop: YES, 15-20psi drops on turn 2; numerous occurrences through-out the day

Unfortunately, this was the first oil pressure sensor i tried... and it turned out to be very non-linear over temperature, which i did not realize until after saving the oil pressure data. I have tweaked the Oil Pressure numbers on the graph to make it accurate.
All other tracks use the better oil pressure sensor.

2 Laps Shown:



Lap 2 pressure drop zoomed in:

Dreamin

Track: Infineon (No. Calif)
Car: '07 Z06, MPSC tires, Brembo brakes, Stock powertrain
Air Temp: 70-80 deg
Oil Pressure Drop: NO, but turn 6 is borderline; sticker tires or suspension will produce >1.0G and >4 sec.

Dreamin

Track: Willow Springs (So. Calif)
Car: '07 Z06, MPSC tires, Brembo brakes, Stock powertrain
Air Temp: 70-80 deg
Oil Pressure Drops: NO, no left hand turns which exceed 1G

Dreamin

Track: Laguna Seca (No. Calif) - 2nd Test Day
Car: '07 Z06, MPSC tires, Brembo brakes, stock powertrain, stock oiling system
Air Temp: mid-60 deg
Max Oil Temp: 270.3 deg
Oil Pressure Drop: YES, 12psi drops on turn 2

Oil Starvation is reproducable on turn 2 (same location as first test day). Lowest pressure seen was 20.7 psi.
Note: I remounted my traqmate, so left-hand turns are on the TOP-sde of the graph now.


Oil Temp Data
I am now logging my oil temperature using the stock oil temp sensor. This is to see if the LPE tank reduces oil temps. I have the oil temp range narrowed in my traqmate for more accuracy... so it shows temp starting at 200 deg.

This is the entire 20+ minute session. I warmed up the car for 5 minutes (~300 sec mark on the graph). Max oil temps are reached after 10-12 minutes and stay there:



Track: ButtonWillow - 13CW (So. Calif)
Car: '07 Z06, MPSC tires, Brembo brakes, stock powertrain, stock oiling system
Air Temp: mid-90 deg
Max Oil Temp: 276.4 deg
Oil Pressure Drop: NO, no sustained high-G left-hand turns.




Oil Temp Data
Last 6 laps zoomed in:



Track: Thunderhill (No. Calif)
Car: '07 Z06, MPSC tires, Brembo brakes, stock powertrain, stock oiling system
Air Temp: mid-80 deg
Max Oil Temp: 273.5 deg
Oil Pressure Drop: YES, 20psi drops on turn 2.

Oil Starvation occurs at ~6 sec of >1.0G. What's disturbing is that the starvation occurs at the exit of the turn, just as i start applying power and speed increases. When i need the oil pressure... it's not there. At the exit i'm doing 90-95mph in 3rd gear. So the question is, how much damage is being done with only 20psi of oil pressure at ~5000rpm.

Graphs of G's, speed, and oil pressure are shown. Oil pressure follows speed (rpm) exactly... except at turn 2.



Oil Temp Data
Entire session:

VetteFish

wow, this is a monumental write up and should be put as a sticky asap. keep up the good work and i know your saving future motors for people by doing this!

i know with the recent engine failures due to HPDE's, many people have taken a few steps back. this is seeming to really bring out the truth and the weakness that can be avoided.

rustyguns

what upgrade would help? the bigger oil reservoir or ???

fantastic write up

linutux

Excellent data. Thank you!

Luweegy

Very interesting.Thanx for all the work and time you've put into this.

LSs1Power

Thanks for doing this. Once you finish running on all these tracks, try to redo with an 09 system. That would be interesting to see.

songman3

Dreamin! - I think you should be crowned as 'King of the forum writeup' - having produced yet another great effort

It is really interesting to see the credibly sourced hard data you produce regarding the crucial issue of LS7 oil pressure - and at last add some 'meat on the bone' of an issue which has been debated at great length in the forum.

Well thought out, well presented - all in all well done!

A great read -Thanks for taking the time to post it

C5 Frank

Even though I don't track my Z I have to applaud this!!! Awesome job!!!! Stuff like this is what makes this forum great.
I am to assume the after market oil tanks seem to alleviate this condition? Also might the '09 tank too?
If so then capacity is the main issue. So running the oil level down a 1/2 quart as many Z06 owners might, would agaserbate the issue.
Again though... Nice job

patch68

Awsome writeup !

GMuffley

VERY much appreciated!!

Adam@Amp'dAutosport.com

VRedZ06

Dreaming, You have done a GREAT job here. This should become a permanent post
While I was down in Ft. Lauderdale in Feb. I had a chance to check out the BP GT2 2 Pipe diffuser, (I purchased one). During the trip Ernie from BP discussed his new Oil starvation solution and he has now put it on his web site. The cost is under 1K and the solution , (base solution), looks like it will solve the weekend warrior problems and may also work for even more agreesive racing situations.

I have been waiting for some additional data points from BP and called to see how it's been working. So far so good. Also for the guys that are racing in very hot climents they also have a dual oil cooler solution that looks great also. (It's not cheap but from the pictures and placement it will be a great solution.

I hope this helps.

ErnieO

nzk

great writeup and thanks for all your hard work!!

this needs to be in the faq and stickied...

'06 Quicksilver Z06

As a Z06 owner who loves to do HPDEs, thank you so much for this effort. Fantastic write up.

Until now, there was still a lot not understood about this potential issue. This write up clears a lot of that up.

It most certainly should become a sticky.

tjwong

WOW! you would have thought GM would have done this during their development R&D test sessions. I am sure they have millions in high tech data logging equipment.

Silver05GTO

Amazing writeup! Not only should this be a sticky but IMO should be forwarded to GM's Corvette R&D department.

Would be interesting to hear what an engineer would have to say about this and what can be done to correct it. If it's just as easy as a larger tank as the ZR1/09+Z06's have this should be a recall or TSB at least.

With the cost to GM of replacing blown LS7's this would probably cut down on their costs just to upgrade the dry-sump on previous Z06's.