Thread: Weather changes
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Old 03-14-2006, 11:30 AM   #2
ride5000
Scooby Guru
 
Member#: 32792
Join Date: Feb 2003
Chapter/Region: NESIC
Location: lincoln, ri
Vehicle:
2003 GGA MBP
12.9 / 105+

Default

let's take two scenarios:

a) it's cold as hell out. the turbo compressor works more efficiently due to colder iat. the intercooler works more efficiently due to colder ambient air. you have chilly manifold charge temps. the turbo is pumping a lot of air mass into the engine. this cool, dense charge will take a lot of advance before detonating, BUT the cool dense charge requires less advance to achieve minimum best timing.

b) it's hot as hell out. the turbo compressor works less efficiently due to warmer iat. the intercooler works less efficiently due to warmber ambient air. you have hot manifold charge temps. the turbo is pumpg a lot less air mass into the engine. this hot, rarified charge will not accept much advance before detonating, BUT the hot rarified charge requires more advance to achieve minimum best timing.

you can see how forced induction cars love cold air temps.

can you up the boost to get some of that power back? depends on what you're running now, on what turbo. if you can up it a bit to get some of your lost mass air flow rate back then you'll get a bit of torque in the process. however, if you push it too much you will exacerbate the issue of hot, rarified intake charge which requires more advance for MBT but will not tolerate it due to det.

as for me, i run about 2-3 psi less boost in the summer in rhode island.

hth
ken
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