[Diy_efi] RE: Timing and dyno pulls

Adam Wade espresso_doppio at yahoo.com
Mon Dec 23 23:49:25 GMT 2002


--- Grant Beaty <gbeaty at ufl.edu> wrote:

> Ah, so its all from the better transfer from engine
> -> coolant.

Yeah, as you raise the coolant temp, the pressure
rises (of course), but as you have more heat going
INTO the coolant, you won't be able to get it out as
easily as you get it in (because air is a lot harder
to heat than metal or coolant).  Theoretically, you
want the coolant as hot as possible, since it'll shed
heat more quickly if it is hotter, but then you run
into design issues with the cooling system's pressure,
what to make the hoses from, etc.

> I already knew that heat transfer is proportional to
> delta T ;) I was talking about pressure alone.

I'm not sure what you mean by that...  Again, the
hotter the coolant temp, the more heat will be shed to
air of a given temp, but to get coolant temps higher
without reducing radiator area, you're going to
itroduce heat more quickly than you can shed it (from
additional coolant temp), meaning there's actually a
disadvantge in the real world in most cases.

Particular engines seem to have a coolant temperature
that they "like" best for best power.  I know a little
of the science behind it, but not enough to really
talk about it seriously.  I'd definitely be interested
in knowing more about that.


=====
| Adam Wade                       1990 Kwak Zephyr 550 (Daphne) |
|   http://y42.photos.yahoo.com/bc/espresso_doppio/lst?.dir=/   |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |

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