[DeTomaso] coolant bypass

Fri Feb 10 17:40:07 EST 2012

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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