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In a message dated 9/2/2003 8:12:46 PM Eastern Daylight Time, Lehanover
writes:
> The second factor, the flow rate of the oil and water, could be negatively
> > affected by the use of the water thermostat. The thermostat works by
> > restricting the flow of water from the engine through the radiator,
> therefore
> > when you reach 180 degrees, it slows down the water flow. This means
that
> the
> > water flowing by the oil cooler tubes (in the headers) is going slower.
> This
> > reduces the *rate* of heat transfer across the tube (the heat transfer
> > coefficient), so that it may reduce the cooling effectiveness of the oil
> > cooler. If we take your 240 degree oil, expose it to the radiator inlet
> tank
> > (180 degree) you only have 60 degrees delta T to work with. On the other
> end
> > of the radiator, you have much cooler water (any measurement?) which
would
>
> > improve the delta T, but if the heat transfer coefficient is small, that
> won'
> > t help much.
> >
> Actually the thermostat restricts flow until the coolant reaches the rated
> temp, and then opens to allow nearly unrestricted flow. The oil temp in the
> pan is of no interest.
> The oil temp measured as close to the rear main oil gallery as possible
> should be 210 or below. That is because the bearing overlay material is
> loosing strength with higher temps. This is a rule developed based on
racing,
> (Racing Beat) where RPMs will be around 9,000 for 13Bs. Or 9,500 for 12As.
> Bearing stress is lower around 6,500 RPM. Still, it's not a bad idea to
keep
> the oil well under 200 degrees. The engine builder reports power lost above
> 160 degrees on the oil temp. Water under 200 is OK. Power loss above 180,
but
> no damage.
>
> This Sunday at Mid Ohio we finished 4th. Had a chance at 3rd but got
bumped
> off on the second lap, and came back on in last place. Oil pressure was 85
> PSI. oil temp was 190 degrees. Water was 170 degrees with a restrictor but
no
> thermostat. Rev limiter is at 9,500. Shifting at 9,400. HP is about 240. We
> need about 250.
>
> Lynn E. Hanover
>
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In a message dated 9/2/2003 7:43:15 AM Eastern Daylight Time,
wschertz@ispwest.com writes:
> The second factor, the flow rate of the oil and water, could be negatively
> affected by the use of the water thermostat. The thermostat works by
> restricting the flow of water from the engine through the radiator,
therefore
> when you reach 180 degrees, it slows down the water flow. This means that
the
> water flowing by the oil cooler tubes (in the headers) is going slower.
This
> reduces the *rate* of heat transfer across the tube (the heat transfer
> coefficient), so that it may reduce the cooling effectiveness of the oil
> cooler. If we take your 240 degree oil, expose it to the radiator inlet
tank
> (180 degree) you only have 60 degrees delta T to work with. On the other
end
> of the radiator, you have much cooler water (any measurement?) which would
> improve the delta T, but if the heat transfer coefficient is small, that
won'
> t help much.
>
Actually the thermostat restricts flow until the coolant reaches the rated
temp, and then opens to allow nearly unrestricted flow. The oil temp in the pan
is of no interest.
The oil temp measured as close to the rear main oil gallery as possible
should be 210 or below. That is because the bearing overlay material is loosing
strength with higher temps. This is a rule developed based on racing, (Racing
Beat) where RPMs will be around 9,000 for 13Bs. Or 9,500 for 12As. Bearing stress
is lower around 6,500 RPM. Still, it's not a bad idea to keep the oil well
under 200 degrees. The engine builder reports power lost above 160 degrees on
the oil temp. Water under 200 is OK. Power loss above 180, but no damage.
This Sunday at Mid Ohio we finished 4th. Had a chance at 3rd but got bumped
off on the second lap, and came back on in last place. Oil pressure was 85 PSI.
oil temp was 190 degrees. Water was 170 degrees with a restrictor but no
thermostat. Rev limiter is at 9,500. Shifting at 9,400. HP is about 240. We need
about 250.
Lynn E. Hanover
JessiesRacer_WEB.jpg
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