Running 10C cooler in Sport than in Normal - Page 2 - Rennlist - Porsche Discussion Forums

Go Back  Rennlist - Porsche Discussion Forums > Turbo Technical Discussion Areas > 991 Turbo
Reload this Page >

Running 10C cooler in Sport than in Normal

Notices
991 Turbo Turbo and Turbo S

Running 10C cooler in Sport than in Normal

 
Old 10-31-2018, 08:04 AM
  #16  
JR956678
User
 
JR956678's Avatar
 
Join Date: Dec 2016
Location: Florida
Posts: 111
Default

Originally Posted by the_buch View Post
Weird - you'd think Porsche would want to reduce drag in the sportier modes? Plus, how much difference could that bit of drag make at average speeds more typical of running in Normal?
I would think it would be a small effect, but these days manufacturers have to operate within a number of sometimes conflicting regulations (CAFE, emissions, etc) where even small effects make a difference when combined. For what it's worth, this link https://www.porsche.com/usa/models/911/911-carrera-models/drive/active-cowl-flap/ is what I alluded to having read where Porsche says they do this with louvers for drag reduction purposes. While drag reduction is certainly valuable in sportier modes, the engine is more likely to be generating higher output and oil cooling would be more important in sportier modes. In addition to what happens in Sport or Sport+, this is also an "on demand" situation in Normal - based I would suppose on oil temperature.
JR956678 is offline  
Old 10-31-2018, 01:08 PM
  #17  
the_buch
Addict
Rennlist Member
Thread Starter
 
the_buch's Avatar
 
Join Date: Mar 2005
Location: Vancouver, Canada
Posts: 1,002
Default

Originally Posted by JR956678 View Post
I would think it would be a small effect, but these days manufacturers have to operate within a number of sometimes conflicting regulations (CAFE, emissions, etc) where even small effects make a difference when combined. For what it's worth, this link https://www.porsche.com/usa/models/911/911-carrera-models/drive/active-cowl-flap/ is what I alluded to having read where Porsche says they do this with louvers for drag reduction purposes. While drag reduction is certainly valuable in sportier modes, the engine is more likely to be generating higher output and oil cooling would be more important in sportier modes. In addition to what happens in Sport or Sport+, this is also an "on demand" situation in Normal - based I would suppose on oil temperature.
Thanks - I hadn't seen that info from your link before. The only question I still have is what oil temperature is better for wear and tear on the engine itself - higher oil temp=less friction=lower wear (though probably slightly higher oil consumption) ... or ... lower oil temp=lower heat stress on components? Or, more likely, I'm having heat-stress over nothing material
the_buch is offline  
Old 10-31-2018, 01:17 PM
  #18  
worf928
Addict
Rennlist Member
 
worf928's Avatar
 
Join Date: Oct 2003
Location: New England
Posts: 11,550
Default

Originally Posted by JR956678 View Post
For what it's worth, this link https://www.porsche.com/usa/models/911/911-carrera-models/drive/active-cowl-flap/ is what I alluded to having read where Porsche says they do this with louvers for drag reduction purposes.
Ah, My bad. I didnĺt realize the louver tech had reappeared on the 991.2s.

worf928 is online now  
Old 11-01-2018, 07:19 AM
  #19  
JR956678
User
 
JR956678's Avatar
 
Join Date: Dec 2016
Location: Florida
Posts: 111
Default

Originally Posted by the_buch View Post
The only question I still have is what oil temperature is better for wear and tear on the engine itself - higher oil temp=less friction=lower wear (though probably slightly higher oil consumption) ... or ... lower oil temp=lower heat stress on components?
I think it's a range rather than any specific temperature. You want the oil to get hot enough to vaporize any water that has accumulated in the oil which means that at some point in the engine it has reached 212 or higher, and that defines the lower limit. As temperature increases the viscosity decreases and the oil film gets thinner, increasing wear on the engine; the lowest acceptable viscosity for proper lubrication defines the upper limit.

The indicated temperature is where the temperature sensor is which may not necessarily be the hottest point. This link suggests the range is 180-210 and also explains this relationship between oil temperature and engine life.
JR956678 is offline  
Old 11-01-2018, 01:50 PM
  #20  
the_buch
Addict
Rennlist Member
Thread Starter
 
the_buch's Avatar
 
Join Date: Mar 2005
Location: Vancouver, Canada
Posts: 1,002
Default

Originally Posted by JR956678 View Post
I think it's a range rather than any specific temperature. You want the oil to get hot enough to vaporize any water that has accumulated in the oil which means that at some point in the engine it has reached 212 or higher, and that defines the lower limit. As temperature increases the viscosity decreases and the oil film gets thinner, increasing wear on the engine; the lowest acceptable viscosity for proper lubrication defines the upper limit.

The indicated temperature is where the temperature sensor is which may not necessarily be the hottest point. This link suggests the range is 180-210 and also explains this relationship between oil temperature and engine life.
Thanks for the link and your continued interest in this topic. My earlier link suggested the best range is 230-260 and this has it at 180-210 (i.e., below the magic 212 target to evaporate any moisture). Plus, why would Porsche purposely engineer the car to run at 230 in Normal mode, including if it helps fuel mileage there must be less friction? I'm compelled by your link to ensure I use an oil (thinking Motul 5W40) that retains reasonable viscosity at the 'Normal' operating temperature. Many thanks, Doug
the_buch is offline  
 


Thread Tools
Search this Thread

Contact Us About Us Advertising Cookie Policy Privacy Statement Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: