In reply to Ed Weldon's interesting and well thought out post. I did not
copy it as I doubt if my answer would go through with his original attached.
The old message size filter would snag it.
1. Can't agree more. All the commonly used clearances are with an assumed
180 to 210 operating temp. Some of the alloy block engines have to be
preheated before starting or even turned over. The main bearing clearance is
zero at room temp.
2. How would you get high velocity and the pressure? I think you have to
trade one for the other at some point. How much velocity can you
realistically get through the rather confined cooling passages commonly
found in most engines. They are not as well designed as a commercial or an
industrial steam plant due to casting considerations. Some engines have some
pretty small passages in sections of the heads. Yes you have to have a good
amount of velocity but you have to have the pressure to go with it. Velocity
beyond what you need to cool the engine is just a waste of energy. If you
need 100 gallons per minute to cool the engine for the sake of a number and
you provide 200 gallons per minute what have you accomplished? As a side
note on Stewart's website the list their stage 4 pump at 160 GPM and their
electric one at 55 GPM and available for drag race use.
3. Sure do have to have a good delta T for a radiator to work. They work
real good in an ice water bath. For LSR use think outside the box a little
many classes do not require the radiator to be in the air stream so why use
an antiquated mode of heat transfer? Also by this method of water to water
you lose the aero loss of the radiator and the hole in the body.
4. Raising the boiling point of the coolant is always a good idea. Even with
the engine at 180 F there are spots that are much hotter than that. You are
measuring the average temperature.
5. High thermal expansion is not your friend. Possibly why ceramics and
other materials have been explored for running an engine hotter than current
practice.
Dave Dahlgren
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