Is there such a thing as to cold of incoming air?
#46
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What is the ideal intake air temp in relation to the outside air cooling at the intercooler? Maybe it makes so little difference it's not worth the hassle? Winter time fuel mileage does go down so maybe just a winter front is all that is needed below what temp?
#47
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Lets see if I can confuse the issue with some too elementry information. In a gas engine, the colder air carries more dense oxygen which may pick up the efficiency some. But a diesel runs on heat, the colder the intake temp the colder the combustion temp. I am sure that the engines are engineered to run at a specific temperature. Obviously this temperature is above freezing for optimum efficiency.
#48
You guys got me to thinking so I ran some compression temperature numbers for comparison.
First off, it seems the boost value does not matter for compression temperature. What does matrer is only the compression ratio and the IAT. Certainly the compression pressure goes up with boost, in fact the pressure doubles for every 14.7 psi of boost. With zero boost the compression pressure should be about 250 psi.
For an assumption I said IAT was Ambient Temperature + 30F and that 14.7 psia was Ambient Pressure. I could not remember the CTD compression ratio so I assumed it was 18:1 with a compression efficientcy of 90%.
Hopefully these are ball park numbers in degrees F:
AMB = Ambient Temperature
CBT = Combustion Temperature (Cumminsbustion)
AMB = -20
CBT = 605
AMB = 0
CBT = 650
AMB = 20
CBT = 695
AMB = 40
CBT = 740
AMB = 60
CBT = 786
AMB = 80
CBT = 831
AMB = 100
CBT = 876
AMB = 120
CBT = 922
Jim
First off, it seems the boost value does not matter for compression temperature. What does matrer is only the compression ratio and the IAT. Certainly the compression pressure goes up with boost, in fact the pressure doubles for every 14.7 psi of boost. With zero boost the compression pressure should be about 250 psi.
For an assumption I said IAT was Ambient Temperature + 30F and that 14.7 psia was Ambient Pressure. I could not remember the CTD compression ratio so I assumed it was 18:1 with a compression efficientcy of 90%.
Hopefully these are ball park numbers in degrees F:
AMB = Ambient Temperature
CBT = Combustion Temperature (Cumminsbustion)
AMB = -20
CBT = 605
AMB = 0
CBT = 650
AMB = 20
CBT = 695
AMB = 40
CBT = 740
AMB = 60
CBT = 786
AMB = 80
CBT = 831
AMB = 100
CBT = 876
AMB = 120
CBT = 922
Jim
#51
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Well what does all this mean ?
Heck the air entering the air box on my 06 comes in thru the grill !Either way its cold in the winter.It enters behind the passenger headlight,it was engineered that way.So what now ? Did DODGE screw up ?
#52
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Nope. Just wonderd? Cold weather seems to decrease mileage so get warm air from inside the motor compartment. When it's warmer get it outside. What temp is optimum though?
#53
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Using Jim's math and assumptions, optimum combustion temperature (which I would rephrase as "optimum #2 diesel compression ignition temperature") is 825*F-875*F.
This would correspond to Cummins recommendation for most efficient ambient air operating temperature of ~75*F-95*F on their industrial engines.
This would correspond to Cummins recommendation for most efficient ambient air operating temperature of ~75*F-95*F on their industrial engines.
#55
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optimum temp?
Using Jim's math and assumptions, optimum combustion temperature (which I would rephrase as "optimum #2 diesel compression ignition temperature") is 825*F-875*F.
This would correspond to Cummins recommendation for most efficient ambient air operating temperature of ~75*F-95*F on their industrial engines.
This would correspond to Cummins recommendation for most efficient ambient air operating temperature of ~75*F-95*F on their industrial engines.
I've noticed since I put the fan in my intake the IAT has droped 2-5deg. Also noticed that when the motor is allready hot and I start it the IAT temp is allways very hot, but with the fan on it cools down a lot faster.
#58
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Yes heat soaking couldn't come up with the word. Since I put the intake fan in the temp drops much quicker, and doesn't get as hot in stop and go traffic.
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