Temperature in 6th/5th gear...
Thread Starter
Racer
Joined: Nov 2006
Posts: 251
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From: SAN JOSE CALIFORNIA
Temperature in 6th/5th gear...
Many talk about the mechanic water pump not be efficent at high rpm.
Some are gonna say duh....but....
I tried something:
-Driving 65 mph in 6th gear (about 1600rpm) -> temp = 197 deg
-Driving 65 mpg in 5th gear (about 2100rpm) -> temp = 193 deg
-next, shift back to 6th and saw temp rise to 197 deg (within 2min)
-next, shift back to 5th and saw temp lower to 193 deg (within 2min)
repeated and same result.....
So duh, the water pump is driven by the motor turns faster at higher rpm thus cooling motor more.
So,
The electric water pumps would give lower tempatures. At stop-n-go and freeway.
Does that mean the GM water pumps for these are not very efficent under 2000 rpm and over 5000 rpm? Maybe GM cooling system as a whole has short comings?
hmmm...maybe this post doesn't mean anything.....just figured I'd share and maybe start a fight. hehe
Some are gonna say duh....but....
I tried something:
-Driving 65 mph in 6th gear (about 1600rpm) -> temp = 197 deg
-Driving 65 mpg in 5th gear (about 2100rpm) -> temp = 193 deg
-next, shift back to 6th and saw temp rise to 197 deg (within 2min)
-next, shift back to 5th and saw temp lower to 193 deg (within 2min)
repeated and same result.....
So duh, the water pump is driven by the motor turns faster at higher rpm thus cooling motor more.
So,
The electric water pumps would give lower tempatures. At stop-n-go and freeway.
Does that mean the GM water pumps for these are not very efficent under 2000 rpm and over 5000 rpm? Maybe GM cooling system as a whole has short comings?
hmmm...maybe this post doesn't mean anything.....just figured I'd share and maybe start a fight. hehe
Elite Torch Red Member
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I've experienced the same, 5th gear gives higher revs, turning the pump faster.
Racer
Joined: Dec 2006
Posts: 292
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Since the water is traveling slower through the radiator at lower rpms it would be cooler when it went back into the engine and hotter when it returns back into the radiator. If the temperature differential went beyond a certain limit perhaps the engine would not be of a uniform temperature.
My 2 cents worth.
My 2 cents worth.
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
Many talk about the mechanic water pump not be efficent at high rpm.
Some are gonna say duh....but....
I tried something:
-Driving 65 mph in 6th gear (about 1600rpm) -> temp = 197 deg
-Driving 65 mpg in 5th gear (about 2100rpm) -> temp = 193 deg
-next, shift back to 6th and saw temp rise to 197 deg (within 2min)
-next, shift back to 5th and saw temp lower to 193 deg (within 2min)
repeated and same result.....
So duh, the water pump is driven by the motor turns faster at higher rpm thus cooling motor more.
Some are gonna say duh....but....
I tried something:
-Driving 65 mph in 6th gear (about 1600rpm) -> temp = 197 deg
-Driving 65 mpg in 5th gear (about 2100rpm) -> temp = 193 deg
-next, shift back to 6th and saw temp rise to 197 deg (within 2min)
-next, shift back to 5th and saw temp lower to 193 deg (within 2min)
repeated and same result.....
So duh, the water pump is driven by the motor turns faster at higher rpm thus cooling motor more.
Interesting, but this is not what I would have expected and is not consistent with my LT4 experience-----although I never ran a controlled experiment like you did....
My guess is that either this would not have made a difference or if anything the extra heat from over-reving the motor in 5th might have made it run a little warmer in 5th????
With 4.10's my motor never ran any hotter than with the factory 3.45's?
