Lifting Engine Hood
08-04-2013, 03:08 PM
#1
Rennlist Member
Thread Starter
Lifting Engine Hood
I saw it on an earlier thread somewhere where some of the guys open the engine hood after driving to help cool the motor. I don't live in high temp climates but after some spirited driving I did open the hood for about an hour or so and was amazed how much heat continued to rise out of the engine bay for some time after. My fan has never turned on in the past after shutdown but is it a waste of time or is this something one should do?
Sure the bulb lights up but goes out after about 30 minutes.
What do you guys do?
Sure the bulb lights up but goes out after about 30 minutes.
What do you guys do?
08-04-2013, 03:14 PM
#2
Drifting
Yes it is amazing how much heat comes out! I open mine after every spirited drive. I guess you can look at this way.. Heat eventually ruins everything. So the more heat you can dispel the better. Whether this (opening the engine compartment) really makes a significant difference over the fan I have no idea.
But I am convinced it is a logical thing to do. I have been doing it for 3 years now and have replaced the bulb once. The engine actually heat my garage in the winter!
But I am convinced it is a logical thing to do. I have been doing it for 3 years now and have replaced the bulb once. The engine actually heat my garage in the winter!
08-04-2013, 03:48 PM
#3
Trucker
Rennlist Member
Rennlist Member
The heat rise is normal. Remember that you have this "good size" thermal mass (engine block, head, and turbo) sitting down low. You can have coolant at 220F, oil at 200F, turbine at 500F, the block skin temp at 300F+ and with key off the heat will conduct to all parts and rise.
The question is do you leave the decklid closed and allow the fan to force convection or open the decklid for natural conduction and cool down?
I used to beat the heck and track my 6GT2 very hard and that sucker always had that fan cycling on and off all the time. So I had parts of the engine including intake manifold thermocoupled and we made temperature measurements. The data showed that in a 6GT2 (circa '03) that forced convection causes things to cool down faster initially (first 15min) but the closed decklid kept the average temperature higher since the air had less room to escape once the fan cycled off. Opening the decklid had a slower initial temperature drop off, but then it fell and went lower....
I am not sure if this makes sense to anyone? But since then I have always popped my decklid open when I pull in the garage... right or wrong....
PS: I love WiFi in flights!
The question is do you leave the decklid closed and allow the fan to force convection or open the decklid for natural conduction and cool down?
I used to beat the heck and track my 6GT2 very hard and that sucker always had that fan cycling on and off all the time. So I had parts of the engine including intake manifold thermocoupled and we made temperature measurements. The data showed that in a 6GT2 (circa '03) that forced convection causes things to cool down faster initially (first 15min) but the closed decklid kept the average temperature higher since the air had less room to escape once the fan cycled off. Opening the decklid had a slower initial temperature drop off, but then it fell and went lower....
I am not sure if this makes sense to anyone? But since then I have always popped my decklid open when I pull in the garage... right or wrong....
PS: I love WiFi in flights!
