DeTomaso Mailing List: June 2001, Message #44

John,

I think you numbers are pessimistic because you
assumed that all of the extra heat has to be handled
by the oil.

I think a better analysis is to estimate, from
experience, how fast the oil is heating up. Then look
at the amount of oil and the heat capacity of the oil.
That should give you a number in the units of power,
like watts. Then compare that to the heat transfered
to the air by the fins (i.e., 5000 watts) that should
give you an idea of how effective this can be. If the
oil is heating up at less than 5000 watts, we're cool.

I may mess up on the following, so feel free to
correct me.

It looks like the specific heat of oil is about 0.422
KW/lb F.

if 10 qts of oil weighs about 19 lbs (my guess) it
looks like 1 Kw will heat up 10 quarts of oil at a
rate of .022 deg F per second. So we can dump 1.33 deg
F per minute from the oil if the fins loose 1 Kw. If
it's 2 Kw, we loose 2.66 Deg F/ sec. In 20 minutes,
that's 52 deg F. So if it takes 20 minutes for your
oil to go  from 225 deg F to 275 deg F, the loss of 2
Kw would keep the oil at 225 deg F.

I haven't done this kind of stuff since about 1975, so
take it in that context : )

Ken

--- John Bentley <jab@cisco.com> wrote:
> Tomas,
> 
> The pan is aluminum (as would be the fins).  Steel
> is not a very good 
> conductor of heat.  The fins would be attached with
> screws initially for 
> testing and then welded if successful.
> 
> The amount of power transfer is fairly straight
> forward.  It is governed by 
> the surface area, (including the fin area for thick
> fins where there is no 
> temp gradient from the tip to the root of the fin),
> the temperature 
> gradient between the fins and the air, and the
> amount of air flow 
> (including whether its turbulent flow or not).  If
> you moved the stove 
> through the air at 140 MPH and had a large surface
> area on each burner with 
> fins, it would not get red hot with only 1000W
> input!!!  The air would keep 
> it cool.
> 
> In any case, more measurements need to be taken. 
> The bad news is with an 
> engine putting out say 300 HP at 60% efficiency, 
> (300*1.667)*(746W/HP)=373000W, subtracting 5000W
> from the oil pan may not 
> do much!  We'll see.....
> 
> JB
> 
> 
> At 10:55 PM 5/31/2001 +0200, you wrote:
> >John,
> >
> >Are you adding fins to a steel pan? How are they
> being attached? The power
> >transfers you mention sound kind of high. Compare
> it to a stove that has
> >maybe 1 kW or so per pot. The stove gets glowing
> red if there's nothing on
> >it. I'd say 200 W sounds more likely than 2000 W.
> >
> >Tomas
> >
> >----------
> > > Från: John Bentley <jab@cisco.com>
> > > Till: Multiple recipients of list
> <detomaso@realbig.com>
> > > Ämne: Re: Race Oil & coolers
> > > Datum:  den 31 maj 2001 20:10
> > >
> > > I had an ME friend do the back of the envelope
> analysis and if you add 1
> > > inch fins spaced 1 inch apart to the bottom of
> the pan, you would triple
> > > the amount of heat removed from the pan.  That
> would equate to an
> >increase
> > > in power from about 1970 watts to about 5784
> watts.  That is a
> >significant
> > > amount of heat transfer!  His guess is a
> reduction in oil temp of tens of
> >
> > > degrees.
> > >
> > > When I get my new engine, I will run some
> experiments.  I'll collect air
> > > temp, oil temp, vehicle speed and water temp
> data before and after adding
> >
> > > the fins.  More later.......
> > >
> > > JB
> > >
> > >
> > > At 07:37 PM 5/29/2001 -0400, Mr ken green wrote:
> > > >Like a lot of things, it should be a matter of
> degree,
> > > >not a will work or won't work. It sounds like
> the oil
> > > >is maybe 50 degrees hotter than the coolant. If
> an
> > > >aluminum heat sink is bonded to the side of an
> oil
> > > >pan, and under-car air is vented toward the
> heat sink,
> > > >there has to be some reduction in oil
> temperature. If
> > > >it's 2 degrees, it's not worth the trouble, but
> if it
> > > >will drop the oil temperature from 260 degrees
> F to
> > > >maybe 240, it might be worth looking into.
> There is a
> > > >pretty big temperature gradient to work with
> here, and
> > > >the air will be moving really fast, so maybe
> there is
> > > >a chance to do a back of the envelope analysis?
> > > >
> > > >Ken
> > > >
> > > >
> > > >--- Gray Gregory <rgg@gregorycook.com> wrote:
> > > > > I definitely agree that it's no substitute
> for an
> > > > > oil cooler. the question
> > > > > is would it have any effect at all.
> > > > >
> > > > > Gray
> > > > > ----- Original Message -----
> > > > > From: "Cal Eustaquio"
> <catman351@digitalputty.com>
> > > > > To: "Multiple recipients of list"
> > > > > <detomaso@realbig.com>
> > > > > Sent: Tuesday, May 29, 2001 4:48 PM
> > > > > Subject: Re: Race Oil & coolers
> > > > >
> > > > >
> > > > > > For some reason, I'm a little iffy on the
> > > > > effective surface area a
> > > > > > finned pan would have on the oil temp. You
> take a
> > > > > look at some of the
> > > > > > available oil coolers and their surface
> area seems
> > > > > to be a bit more
> > > > > > significant in terms of the amount of coil
> and
> > > > > fins available to cool
> > > > > > the oil. Cal. #2428.
> > > > > >
> > > > > > ---- Original Message ----
> > > > > > From: rgg@gregorycook.com
> > > > > > To: detomaso@realbig.com
> > > > > > Subject: Re: Race Oil & coolers
> > > > > > Date: Tue, 29 May 2001 17:18:58 -0400
> > > > > >
> > > > > > >Charlie,
> > > > > > >
> > > > > > > my 67 Ferrari has a finned aluminum oil
> pan and
> > > > > I've wondered too
> > > > > > >if that
> > > > > > >would help the Pantera.
> > > > > > >
> > > > > > >Gray
> > > > > > >----- Original Message -----
> > > > > > >From: "Charlie Mccall"
> > > > > <Charlie.Mccall@haworth.com>
> > > > > > >To: "Multiple recipients of list"
> > > > > <detomaso@realbig.com>
> > > > > > >Sent: Saturday, May 26, 2001 5:49 PM
> > > > > > >Subject: Re: Race Oil & coolers
> > > > > > >
> > > > > > >
> > > > > > >> This reminds me of something I've been
> > > > > wondering for a while.
> > > > > > >There are
> > > > > > >many
> > > > > > >>  motorcycle engines, and a few cars,
> that rely
> > > > > only on air
> > > > > > >cooling. As I'm
> > > > > > >sure everyone
> > > > > > >>  knows, they have tons of deep fins to
> give
> > > > > lots of surface area
> > > > > > >to allow
> > > > > > >maximum
> > > > > > >>  cooling. That being so, why aren't oil
> pans
> > > > > finned? It would
> > > > > > >obviously
> > > > > > >not replace an
> > > > > > >>  oil cooler, but a finned oil pan,
> especially
> > > > > if it is getting
> > > > > > >some good
> > > > > > >airflow, ought to
> > > > > > >>  make a measurable difference, with no
> increase
> > > > > in moving parts of
> > > > > > >potential for failure.
> > > > > > >>
> > > > > > >> Could it be because pans are usually
> stamped
> > > > > and not cast, and
> > > > > > >therefore
> > > > > > >it would be
> > > > > > >>  tricky to add the fins? Someone would
> have
> > > > > tried it by now if it
> > > > > > >worked,
> > > > > > >so why won't
> > > > > > >>  it?
> > > > > > >>
> 
=== message truncated ===


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