How to cool down your tt after a hard run?
06-30-2009, 03:39 PM
#4
Race Director
Best way is follow hard run with soft one to allow engine internals...
and engine to shed its heat load as engine runs.
It will do this faster if running at moderate RPMS which results in water pump circulating a high volume of coolant through engine and radiators.
Oil pressure remains high and a high volume of oil also routed through oil/water heat exchanger. With oil pressure high piston oil jets have sufficient oil pressure to operate and thus the pistons/cylinders treated to a nice cooling spray of relatively cool oil. If hot engine just allowed to idle, oil temperature may be high enough oil pressure low engine oil jets may not be active in order to route more oil to main/rod bearings.
Plus if car moving at moderate pace air flow carries heat from radiators and away from hot air-cooled components like exhaust pipes and such away.
A few minutes of idling better than nothing but not ideal.
Sincerely,
Macster.
It will do this faster if running at moderate RPMS which results in water pump circulating a high volume of coolant through engine and radiators.
Oil pressure remains high and a high volume of oil also routed through oil/water heat exchanger. With oil pressure high piston oil jets have sufficient oil pressure to operate and thus the pistons/cylinders treated to a nice cooling spray of relatively cool oil. If hot engine just allowed to idle, oil temperature may be high enough oil pressure low engine oil jets may not be active in order to route more oil to main/rod bearings.
Plus if car moving at moderate pace air flow carries heat from radiators and away from hot air-cooled components like exhaust pipes and such away.
A few minutes of idling better than nothing but not ideal.
Sincerely,
Macster.
06-30-2009, 03:54 PM
#5
AFAIK, you idle cool down 1-2 minutes (not more than that as you have reduced your temps as far as you can) to keep the oil running through the turbos and to allow the turbos to spin down (which they don't do while driving). So, yes at the track cool down lap is good, but still idle 1-2 minutes. In the words of my tuner...cool down every time, always.
06-30-2009, 09:03 PM
#6
Rennlist Member
After track I run relatively slowly up and down the "pit" area and then let it idle for a moment or two in my stall. I am just an intermittant autocrosser and usually the water temperature rises during the run sessions as you sit at idle in line in between each of 3 to 4 runs. And usually running up and down the pit area will bring the water temp gauge back down abit. Like what "Macster" says above.
Also do not set your parking brake when you come in from some hot runs. If you've been using the brakes they are plenty hot. So find a place where you can leave the car in neutral without having to set the parking brake to hold it there.
Also do not set your parking brake when you come in from some hot runs. If you've been using the brakes they are plenty hot. So find a place where you can leave the car in neutral without having to set the parking brake to hold it there.
06-30-2009, 09:38 PM
#7
RL Community Team
Rennlist Member
Rennlist Member
The idle time is really better identified as "turbo spin down" time, not "turbo (or engine) cool down" time.
The parking brake does not use the normal braking system.
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07-01-2009, 02:42 AM
#11
Race Director
How fast can turbos be spinning if turbos not making boost?...
The driving slowly up and down the pit area is not the answer to with regard to the turbos. The primary objective of the 2 minute engine idle is to allow the turbos to spin down closer to their associated "engine idle" RPM prior to depriving them of their lubrication by shutting down the engine.
The idle time is really better identified as "turbo spin down" time, not "turbo (or engine) cool down" time.
The parking brake does not use the normal braking system.
The idle time is really better identified as "turbo spin down" time, not "turbo (or engine) cool down" time.
The parking brake does not use the normal braking system.
Turbos are of course spinning but fast enough to require 2 minutes of idling to slow down?
Sincerely,
Macster.
07-01-2009, 08:31 AM
#13
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This topic is much to do about nothing IMHO.
As far as longevity (daily driver and occasional track use), Rennlist member 'T2' has ~ 225K miles on his 03 X50 (still original engine, original clutch, etc).
Ask him about cooldown.
IMHO, PAG's recommendation has more to do with circulating some oil thru the turbos at idle for 1-2 minutes and perhaps the same for the coolant than anything else.
If it were a water cooled turbo (951), then the recommendations would be a bit different.
07-01-2009, 09:28 AM
#14
Rennlist Member
07-01-2009, 10:34 AM
#15
RL Community Team
Rennlist Member
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The rpm of the turbos is a function of engine rpm. If you are driving at say 2500 rpm under no boost, the turbos are at that time spinning at rpm's substantially higher than their idle rpm. If you motor along easily (no boost) at 3500 rpm, the turbos are spinning at an even higher rpm. Once the engine reaches idle rpm the turbos do not immediately decelerate to their idle rpm...they are very free spinning and decelerate only by friction. The heat created by this friction is reduced by the oil in the turbos...but this oil is not provided once the engine is shut down. So the higher the "motoring around rpm" the higher the turbo rpm...and the longer it takes the turbos to spin down to their idle rpm once the engine reaches idle. If the turbo is deprived of oil during this spin down period, the heat generated can cause damage to the turbos.