AM I GOING CRAZY? gt500 not feeling right
06-10-2008, 03:03 PM
#1
5th Gear Member
Thread Starter
Join Date: Jan 2008
Location: MD
Posts: 2,544
AM I GOING CRAZY? gt500 not feeling right
So the weather here in MD is about 95 and ridiculously humid...the past couple times i have driven my car in this weather it hasn't felt like it had all its power...I usually spins all of first when i and running it hard through the gears and today no spin at all just didn't pull like it usually does. Then i tired 2 do a burnout and they didn't even wanna spin that much...Is the heat and humidity this much of a killer to my gt500? I also changed my oil last week and put the fully synthetic Castrol 5w-50 in it and changed the filter... ever since that day its been hot so i cant relate it 2 the heat or my oil change...im kinda freaking out here cuz i hope nothing is wrong with my car...its totally stock but a drop in k&n filter and corsa exhaust....any thoughts out there ppl? thanks
06-10-2008, 03:34 PM
#5
RE: AM I GOING CRAZY? gt500 not feeling right
ORIGINAL: howarmat
same thing happens to the GTs.....heat soak is a killer in these vehicles
same thing happens to the GTs.....heat soak is a killer in these vehicles
I'd imagine that heatsoak would be even more of a problem on a supercharged/turbocharged motor.
06-10-2008, 03:49 PM
#8
4th Gear Member
Join Date: Apr 2006
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Posts: 1,268
RE: AM I GOING CRAZY? gt500 not feeling right
I am sure the Ford tune pulls timing as the inlet air temps increase to the manifold. Even though you have an intercooler, you basically have the same approach temps.... so as the temp goes up outside, the cooling medium (water) in the intercooler circuit goes up, and therefore the inlet air exiting the intercooler goes up. As the inlet charger goes up to 110-115 degrees, you have to pull timing relative to the timing you can run when it's 60 degrees out, and your inlet air temps are 70 degrees.
In addition, the roots blowers are giant chunks of metal that also heat up, and act as a heat exchanger, increasing the air temp even higher... even after the intercooler (manifold is metal, and is heat soaked). To see this, put your hand (carefully) on top of the blower after a run during this weather (it will be red hot) and then do this again after a run when it's 40 degrees out (the blower will be very warm, but probably won't burn yourself). You will see a marked difference between just the temps of the blower metal itself... same for manifold, inlet piping, etc.
Just to give some perspective, air that is40 degrees warmer is (540/580 degrees rankine) only 93% as dense, so you lost 7% O2, and 7% power, more if timing is pulled. So you can probably easily lose 40 HP from the coolest days to the hottest (where temp range can be 60-70 degrees). You'll feel that.....
In addition, the roots blowers are giant chunks of metal that also heat up, and act as a heat exchanger, increasing the air temp even higher... even after the intercooler (manifold is metal, and is heat soaked). To see this, put your hand (carefully) on top of the blower after a run during this weather (it will be red hot) and then do this again after a run when it's 40 degrees out (the blower will be very warm, but probably won't burn yourself). You will see a marked difference between just the temps of the blower metal itself... same for manifold, inlet piping, etc.
Just to give some perspective, air that is40 degrees warmer is (540/580 degrees rankine) only 93% as dense, so you lost 7% O2, and 7% power, more if timing is pulled. So you can probably easily lose 40 HP from the coolest days to the hottest (where temp range can be 60-70 degrees). You'll feel that.....
