Track Data from my Corvette

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I have been analyzing data from my ECU which was recorded at a track day at Calabogie Motorsports Park last August. Calabogie is a 3.05-mile, 20-turn track which is about 60 miles west of Ottawa in Ontario. I have been going there for 3 years, and always have a blast. On the chart are plots of Vehicle Speed, Engine Speed, Engine Load (%MAP), Intake Manifold Temperature, and Oil Pressure.

Since this is BITOG, I want to draw everybody's attention to the oil pressure trace. It's the noisy brown line in the lower part of the chart. Yes, my engine is running an overall average of 36psi during the lap, varying between a minimum of 21psi and a maximum of 50psi. Sounds pretty scary, doesn't it? The extended drops in pressure are occurring in long left-hand turns, which are Turn 8 and Turn 14.

While I am not an advocate of running high oil pressure, I am uncomfortable with this low amount. I would like to see a nice stable maximum of 55-60psi, with dropoff in the turns no lower than 30. On the other hand, I have been running the car this way for 15 years, and it hasn't expired yet.

I welcome questions, comments, and ideas, and look forward to a lively debate.

Calabogie-Lap.jpg
 
Sounds like oil starvation due to cornering forces uncovering the pick up. Any drop off, even if it doesn't go to zero is usually indicative.

Never a good thing, but I also used to track my 99 regularly and never had a lick of trouble in almost 50k miles.
 
Originally Posted By: SteveSRT8
Sounds like oil starvation due to cornering forces uncovering the pick up.


I thought all Vettes had dry sump systems. Or just the newer ones?
 
Can you do a plot of oil pressure vs engine speed from that data? That might tell you more about what's going on. If it's more or less a smooth line, then you're not suffering any starvation. If there's a deviation from smooth, then your pickup is sucking air.
 
Neat chart! it looks to me though as your oil pressure is dropping with rpms for the most part. Whats your oil pressure at super hot, just off the track idle? I'll guess 15 psi?
Your 21 psi is at ~2600rpm, which might be the same weither you are turning or not at track temps?
Must be fun to have a car that 2600rpm is actually useful on a track.
 
Originally Posted By: tpitcher
Which Oil & Filter ya running?



Mobil 1 5w30 and a Mobil 1 oil filter.
 
Originally Posted By: hate2work
Originally Posted By: SteveSRT8
Sounds like oil starvation due to cornering forces uncovering the pick up.


I thought all Vettes had dry sump systems. Or just the newer ones?


Just the newer ones: C6 Z06, the ZR1, and the new Grand Sport.
My car still has the factory pump, pan, and windage tray, but also a 2-qt. Accusump and an air-oil cooler mounted out front of the radiator.
 
Originally Posted By: IndyIan
Neat chart! it looks to me though as your oil pressure is dropping with rpms for the most part. Whats your oil pressure at super hot, just off the track idle? I'll guess 15 psi?
Your 21 psi is at ~2600rpm, which might be the same weither you are turning or not at track temps?
Must be fun to have a car that 2600rpm is actually useful on a track.


Oil pressure at hot idle is between 25 & 30 psi, but that is according to the mechanical gauge at the Accusump. I'll have to look at the logger data separately to see if it agrees with the gauge. I have doublechecked the cal factor that I used for the chart and believe it to be correct.

Yeah, about that 2600rpm; I was driving the car without a tach, so I was really in the dark about how much I was lugging it in some of the turns. This year, I'll do better. The torque in the engine is pretty good down there, but it doesn't come on the cam until 3600.
 
Originally Posted By: A_Harman
Originally Posted By: hate2work
Originally Posted By: SteveSRT8
Sounds like oil starvation due to cornering forces uncovering the pick up.


I thought all Vettes had dry sump systems. Or just the newer ones?


Just the newer ones: C6 Z06, the ZR1, and the new Grand Sport.
My car still has the factory pump, pan, and windage tray, but also a 2-qt. Accusump and an air-oil cooler mounted out front of the radiator.


Those pressures were with the Accusump??!!
crazy2.gif
(That was the first thing I was going to suggest.
wink.gif
)

Are you also running a quart over stock/street sump capacity (as many open tracking LS1/6 C5/C5 Z06 owners do as a matter of course), or do the L98s not like that??
 
Hi,
A_Harman - you said this:

"I have been running the car this way for 15 years, and it hasn't expired yet."

There IME lies your answer - when combined with suitable UOA results

Sometimes a little more knowledge leads to a lot more unnecessary stress and worry
 
Are you also running a quart over stock/street sump capacity (as many open tracking LS1/6 C5/C5 Z06 owners do as a matter of course), or do the L98s not like that??

THIS is nearly mandatory for older cars on a road race circuit!
 
Since I have the Accusump, I haven't been running the oil level over full. I have run a quart high on the Camaro, but had problems with oil getting into the PCV system. I found I can run 1/2-quart over and not have a problem. This may be worth trying on the Corvette.
 
Originally Posted By: A_Harman
Since I have the Accusump, I haven't been running the oil level over full. I have run a quart high on the Camaro, but had problems with oil getting into the PCV system. I found I can run 1/2-quart over and not have a problem. This may be worth trying on the Corvette.


I hear ya on that! I'm going to get a Moroso air/oil separator as soon as I can find a place to plumb it into the PCV system, and fit it under our negative space engine bays.
wink.gif
 
Originally Posted By: SteveSRT8
Are you also running a quart over stock/street sump capacity...or do the L98s not like that??...

My 89 Vette has an L98. When tracking the car for an HPDE, I won't put much more than a 1/2 quart of oil in the system. (A full quart will end up being sucked into the combustion chamber past the rings!)

The L98's HP peaks out at 4400 RPM and the gear ratios in the 6-spd require that I shift at 4700 RPM to stay within the engine's power band. Still, 5th gear (0.75) at 4700 RPM is a hoot!
 
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