[DeTomaso] coolant bypass

Fri Feb 10 19:20:44 EST 2012

Glad I was slow getting around to responding Julian.
Yes to all that and to Larry's point about restriction in a Pantera..
You might also get venturi cavitation in a radiator if you had one 
helluva flow rate
and the cross tube area was a lot less than the minimumm area anywhere 
else in the system.

Not going to happen at 40 gpm or whatever a 55 gpm-rated pump really 
flows though.
Not going to happen with a water-pump that cavitates either, it's a 
perfect low-limiter.
dave

On 10/02/2012 2:40 PM, Julian Kift wrote:
> Just catching up with this thread after a vacation.
> Cavitation can occur at the water pump and is common problem at high 
> rpm wity mechanical water pumps. Other points for cavitation are 
> impingement points or sharp bends etc. so large radius bends are 
> always better, not always possible in the Pantera though.
> However the general statement that increasing coolant veloicty will be 
> negative on cooling is a falsehood, you just need to examine some 
> mass flow and heat transfer equations to see that. It is explained 
> fairly well here;
> http://www.arrowheadradiator.com/14_rules_for_improving_engine_cooling_system_capability_in_high-performance_automobiles.htm
> or the Finched version;
> http://tinyurl.com/3uc3ed3
> Julian
>
> > From: pantera at cox.net
> > Date: Fri, 10 Feb 2012 14:04:04 -0800
> > To: davel at emspace.com
> > CC: cuvee at sbcglobal.net; detomaso at realbig.com; 
> justingreisberg at hotmail.com
> > Subject: Re: [DeTomaso] coolant bypass
> >
> > Hey, guys,
> >
> > Just reading the mail here, allow me add something to the conversation,
> >
> > If the fluid's (unrestricted) velocity it too great, it will 
> cavitate, and
> > its contact with the inner surfaces of the radiator will diminish, 
> as will
> > the heat transfer. Hence the reason for the ring when the thermostat is
> > removed.
> >
> > This is in the short term. Long term, it can cause engine damage.
> >
> > Check out this link, especially the section on "Cavitation in engines",
> > about 1/2 way down that page.
> >
> > http://en.wikipedia.org/wiki/Cavitation
> >
> > FWIW,
> >
> > Al
> > #3915
> >
> > 
> =====================================================================================
> >
> >
> >
> > On Thu, Feb 2, 2012 at 12:20 PM, Dave Londry <davel at emspace.com> wrote:
> >
> > > Just to add to that.
> > > You can take out the thermostat if you're under sustained loading,
> > > which is why a lot of race cars are un-thermostatted.
> > > The cooling system is matched to the load and tweaked with duct tape.
> > > (or whatever magic you're allowed)
> > >
> > > Or for more general use, you can take out the thermostat and 
> control the
> > > water-pump speed.
> > > (using the pump as the thermostat)
> > > dave
> > >
> > > On 02/02/2012 11:58 AM, gow2 at rc-tech.net wrote:
> > > > If you remove the thermostat you remove the function of the 
> thermostat.
> > > > The thermostat is designed to keep the operating temp in range. You
> > > > actually want your engine in the 190-200+/- range. Oil flows 
> good, water
> > > > is largely kept evaporated form oil and metal is at a happy 
> temperature.
> > > >
> > > > G
> > > >
> > > >> If that is the case? Why not just remove the thermostat all 
> together and
> > > >> remove the brass ring under it?
> > > >>
> > > >> --- On Thu, 2/2/12, gow2 at rc-tech.net<gow2 at rc-tech.net> wrote:
> > > >>
> > > >>
> > > >> From: gow2 at rc-tech.net<gow2 at rc-tech.net>
> > > >> Subject: Re: [DeTomaso] coolant bypass
> > > >> To: "Curt Hall"<cuvee at sbcglobal.net>
> > > >> Cc: gow2 at rc-tech.net, "Dave Londry"<davel at emspace.com>, "Justin
> > > >> Greisberg"<justingreisberg at hotmail.com>, detomaso at realbig.com
> > > >> Date: Thursday, February 2, 2012, 11:11 AM
> > > >>
> > > >>
> > > >> It is just the size of the passage through the thermostat. Add 
> 2 and you
> > > >> can get 2x as much water through. Look at a thermostat and see 
> how small
> > > >> the hole is the water passes trough. With long narrow tubes in 
> a Pantera
> > > >> anything to keep the flow going.
> > > >>
> > > >>
> > > >>
> > > >>> Dumb question...if the thermostat restricts flow, how does 
> adding a
> > > >>> second
> > > >>> thermostat help the flow?
> > > >>>
> > > >>> --- On Thu, 2/2/12, Dave Londry<davel at emspace.com> wrote:
> > > >>>
> > > >>>
> > > >>> From: Dave Londry<davel at emspace.com>
> > > >>> Subject: Re: [DeTomaso] coolant bypass
> > > >>> To: gow2 at rc-tech.net
> > > >>> Cc: "Justin Greisberg"<justingreisberg at hotmail.com>,
> > > >>> detomaso at realbig.com
> > > >>> Date: Thursday, February 2, 2012, 9:36 AM
> > > >>>
> > > >>>
> > > >>> I like the 2 thermostats a lot Gary.
> > > >>> The thermostat is the real flow restrictor in the system, even 
> when
> > > it's
> > > >>> open
> > > >>> Getting rid of it or doubling it up makes good sense.
> > > >>> dave
> > > >>>
> > > >>> On 01/02/2012 6:42 PM, gow2 at rc-tech.net wrote:
> > > >>>> I think I would also add,
> > > >>>>
> > > >>>> -Allows more water to circulate during warm up
> > > >>>> -I wanted to try 2 thermostats to increase flow
> > > >>>> -Were Pantera guys, it's what we do.
> > > >>>>
> > > >>>>
> > > >>>>
> > > >>>>> Justin,
> > > >>>>>
> > > >>>>> If you're happy with your car, then stick with it!
> > > >>>>>
> > > >>>>> I wasn't.
> > > >>>>>
> > > >>>>> Since the tank is on the high pressure side of the water 
> pump, I was
> > > >>>>> running a 24lb cap on it and it would still puke coolant when I
> > > backed
> > > >>>>> off
> > > >>>>> the throttle at 7200rpm.
> > > >>>>> It would run kinda' OK in 100F+ temperatures, even with a 
> nice new
> > > >>>>> Pantera
> > > >>>>> Performance aluminum radiator. Kinda' OK wasn't acceptable.
> > > >>>>>
> > > >>>>> After changing the system to a remote thermostat and moving 
> the tank
> > > >>>>> to
> > > >>>>> the low pressure side, using the Mike Trusty/John Taphorn
> > > modification
> > > >>>>> whatever you want to call it, I have none of those problems.
> > > >>>>>
> > > >>>>> Note that these changes make a Pantera cooling system act 
> just like
> > > >>>>> any
> > > >>>>> modern car's cooling system.
> > > >>>>>
> > > >>>>> Works for me. If what you have works for you, then I'd recommend
> > > >>>>> leaving
> > > >>>>> it.
> > > >>>>>
> > > >>>>> Regards,
> > > >>>>> Kirby
> > > >>>>>
> > > >>>>> On Feb 1, 2012, at 6:17 PM, Justin Greisberg wrote:
> > > >>>>>
> > > >>>>>> why are we doing this? why don't we just use a cleveland 
> thermostat
> > > >>>>>> on
> > > >>>>>> a cleveland block? i do, and the car seems to run fine and 
> cool on
> > > >>>>>> the
> > > >>>>>> street. justin
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