Cam chain tensioners

Beth hacktastic at gmail.com
Mon May 18 08:42:15 PDT 2009


On Sun, May 17, 2009 at 7:42 PM, Randy Grein <randygrein at comcast.net> wrote:
> An interesting idea, but consider that there will be an 'optimum' coolant
> velocity through the system beyond which there will be little improvement in
> heat exchange.

Using an electrically-powered pump would assure that you were getting
that optimal coolant velocity at all times. I see.

> Further the power draw from the pump will go up as to what -
> the cube of engine RPM. More, trimmed blades will make a very inefficient
> pump - big loss in flow with just a little reduction in power draw; the rest
> goes into water eddies (heat).

Now we're talking! The OEM water pump is dependent on engine speed.
There is probably a nominal decrease in drag in the coolant from
trimming the blades, which were probably computer-designed to pump
water quite efficiently. (This is starting to sound like the famous
snorkelectomy jetting debacle.) I also consider that the flow of the
coolant would be so affected. Dangit! I did not look at the system as
a whole. I've got some reading to do, it seems. :)

> A variable ratio pump would be a great idea -
> if it were simple and efficient. I do know the electric water pump idea is
> not unique; the idea is common in NASCAR where they actually do experiment
> with such things.

It would be heavy, expensive and silly considering that you can do the
same thing with an electrical pump.

They experiment in NASCAR!?!?!? I thought all they did was sit around
and chew tobacco while the F-1 guys figured everything out.

> Final bit about this is that a really clever racer might configure the
> alternator so that it stopped producing power during full throttle
> application. Even with an SV much of the circuit is run under part-throttle
> operation. Cutting the alternator to run off the battery (temporary total
> loss) might give the best of both worlds for endurance racing - during the
> daytime anyway. (grin)

Clever clever clever.

This is the stuff that makes me happy. :)))

-Beth


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