I save all of Kas' responses since they comprise a nice library of answers
to tech questions. I just looked up this issue this morning since Peyote
overheated last weekend (first time also). I've pasted Kas' comments at
the end. The fluctuating temperature is almost certainly from surface
boiling on the sleeves--you get a local hot spot that creates a steam
bubble--that bubble reduces the heat transfer capability of the affected
area and it gets even hotter. The bubble grows until turbulence collapses
it, and the rush of water to the hot surface causes a temperature spike.
The cycle can continue until the localized heating causes the piston to
seize and then it all runs away down hill. In nuclear power plants we call
this Departure from Nucleate Boiling (DNB) and the end result if the
critical heat flux is exceeded is called bulk boiling, which is very bad.
Been a long time since I was a nuke--amazing how this stuff sticks around
in the dusty recesses of the gooey computer.
Kas' answer is right on. Increasing the radiator size may not solve the
problem since it may be caused by local flow patterns and/or too low a
pressure within the heat exchanger (the cylinder) or even things like a
big, oily fingerprint on the cylinder wall. I pulled down a TR3 motor once
and found one of the cylinders was PAINTED!! Tell me you didn't do that.
-----Original Message-----
From: Mark J Bradakis [mailto:mjb@autox.team.net]
Sent: Tuesday, June 19, 2001 11:21 AM
To: fot@autox.team.net
Subject: Forwarded note [ames@cmn.net: RE: fot-digest V1 #361]
For some reason, this was sent to me rather than fot@autox.team.net.
mjb.
----
------- Start of forwarded message -------
From: "Robert Ames" <ames@cmn.net>
Subject: RE: fot-digest V1 #361
Date: Mon, 18 Jun 2001 21:27:49 -0600
To Fot, From Robert Ames, rebuilt Ambro Triumph #57.
Question. After a ground up this winter, the Ambro is over heating. Last
year I put in a 6 core radiator and new oil cooler and it ran so cool I
had
to tape it off at most events. This year it overheated once and now the
gauge will move and jump around 10-20 degrees. I replaced the water pump
after the overheating. Any suggestions?? I really want to get this worked
out before pulling it all the way to Mid-Ohio next year.
Thank you in advance for suggestions.
------- End of forwarded message -------
If you area using revs about 6500 or more then I figured that a 3 to 5
speed
was about right. That is 3 for the water pump for 5 at the crank. Work
it
out depending on what pulleys are available.
----- Original Message -----
From: "John Price" <jprice1@txcyber.com>
To: "R. Kastner" <kaskas@earthlink.net>; <WEmery7451@aol.com>;
<mattspit@att.net>; <fot@autox.team.net>
Sent: Saturday, April 21, 2001 3:15 PM
Subject: Re: water pump speeds
> OK. I'm sold. What difference in size pulleys are we talking about? I'm
> looking at replacing my stock TR-6 pulley with an aluminum one anyway.
>
> John Price
> -----Original Message-----
> From: R. Kastner <kaskas@earthlink.net>
> To: WEmery7451@aol.com <WEmery7451@aol.com>; mattspit@att.net
> <mattspit@att.net>; fot@autox.team.net <fot@autox.team.net>
> Date: Saturday, April 21, 2001 10:56 AM
> Subject: Re: water pump speeds
>
>
> >The reason to restrict the flow is to increase or maintain the BLOCK
> >PRESSURE. The block pressure is what eliminates the areas of steam
pockets
> >in the cylinder head that when ignored result in blown head gaskets
etc.
> >Generally about 25 pounds block pressure is a good spot. You will find
> with
> >the TR engines that the block pressure goes down as the revs go over
4000
> >because the system was designed for street use. Therefore the pressure
is
> >going down just when you want it to be working the best. The cure is to
> SLOW
> >down the water pump by reducing the size of the driver pulley or
increasing
> >the size of the water pump pulley. This will stop the pump from
cavitating
> >and thus the pressure will stay constant at higher revs. A simple
pressure
> >gage with a line to the drain cock fitting in the side of the block
will
> >give you a pressure number. While testing this on the dyno you could
watch
> >the pressure go from about 15 pounds right down to zero over the rev
range
> >of 6500. By the way you will also get a nice power increase from this
> little
> >mod. Fitting Gilmer type belts and pulleys and with a GT-6 engine we
had
a
> >power increase of 8 bhp. After that bit of info we did the same thing
to
all
> >the engines.
> >
> >----- Original Message -----
> >From: <WEmery7451@aol.com>
> >To: <mattspit@att.net>; <fot@autox.team.net>
> >Sent: Saturday, April 21, 2001 7:13 AM
> >Subject: Re: water pump speeds
> >
> >
> >> In a message dated 4/20/01 8:22:23 PM Pacific Daylight Time,
> >mattspit@att.net
> >> writes:
> >>
> >> << I remember a discussion on speed of water moving through radiators
and
> >> whether it is better for it to move slow (more time to exchange) or
fast
> >> (higher gradient).
> >> There is an excellent discussion in June 2001 Circle Track. >>
> >>
> >> I will have to look for this article in my June issue.
> >>
> >> There is an optimum flow rate for every radiator -- not too fast and
not
> >too
> >> slow. This rule also holds true for heat exchangers in power plants.
> >>
> >> The ancient practice for TR-3/4's was to install a restrictor washer
in
> >place
> >> of the thermostat (opening, about the size of a quarter), use about a
15
> >psi
> >> cap, and eliminate the bypass flow. All of the open areas around the
> >> radiator are then shrouded off with sheet metal or aluminum. The
> overflow
> >is
> >> then connected by tubing to the top of a gallon lacquer thinner can
> (catch
> >> tank with a small vent hole in the top).
> >>
> >> I am sure that some of the list now have a better system than the one
> >above.
> >> I hope to eventually get an aluminum radiator.
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