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Old 09-07-2021, 07:37 PM   #3
PaulE
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Join Date: Jan 2014
Location: New Jersey
Posts: 1,631
Quote:
Originally Posted by ike84 View Post
https://cdn4.pelicanparts.com/techarticles/Porsche-996-997-Carrera/26-FUEL-Replacing_Engine_Sensors/images_small/pic03.jpg
Here's a pic of the sender. I think you need to remove the intake crossover to get to it (it's right next to the knock sensors). It's a long tube that runs through the engine itself down to the sump pan where a loop is submerged in the oil and the level changes resistance on the loop, which changes the voltage read by the sensor. I'm not sure how a different viscosity oil would affect that reading. I run 20w50 in mine and now that I think about it the sensor did read a bit wonky at first but after a few runs the levels match up well between the digital guage and the dipstick.

Running a high oil level isn't what caused your blue smoke though. I realize that accusimps and deep pans are popular, but the Achilles heel of our moist sump (of whatever the hell porsche called it) is in the scavenger pumps - more specifically, their location. Random tangent (which will come back to a point) in 3....2....1....

Bank 1s pump is located in the flywheel end of the bank, bank 2s pump is located on the pulley side. The problem comes with high g cornering and bank 2 - all the oil winds up in the flywheel end of the bank and can't get back to the scavenger pump.

Why did this matter? The main pump moves 20L+ per minute at high rpms, which means 10L/bank/min. Which means that if you hold a high g turn and starve that pump for 60 seconds, your entire oil volume is sitting in that head cover (and yes it will hold that much). This is why accusumps and be deep kits don't work on the track - were talking the ENTIRE oil volume, not 2L.

You got lucky. By overloading the valve cover, you sucked oil into the aos and you smoke bombed the track. You probably slowed down at that point, which saved your engine. If this hadn't happened, you would have needed a ride home.

If you don't believe me about this, look at the oiling modifications for the x51 series 996. There were a few, but the most important one was replacing the bank 2 scavenger pump with a dual stage pump that had a second feed line that came from - you guessed it - the flywheel end of the bank. My point is don't drop your oil level. If you're worried about smoke bombs, put in an oil catch can between the AOS and your intake. But, then you won't have your warning signal either.

If someone wanted to do something REALLY NEAT there would come up with a sensor that alerted the driver to that pump sucking air! Or figure out how to retrofit a 2 stage pump to bank 2. That would be sweet.

Diatribe over. Thanks for those 2 minutes of your life

Sent from my SM-G970U1 using Tapatalk
Thanks, I hear what you're saying. Why do you suppose other M96 and M97 powered Boxsters and Caymans driving on this track much faster and pulling higher G's than me weren't also smoke bombing? I doubt they all had any modifications to address this issue.
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