Hello all...
Dave's point is very important when you start to push the envelope.
The only place pressure is needed is at hot spots.
You can get it by having a low volume pump (20), in an unrestricted
sealed system pressurized to 40-50 PSI.
Or you can have an unrestricted system with a 200 GPM pump and restrict
the engine outlet to produce the same 40-50 PSI at the hot spots.
Or a combo of the two.
Like using washers to restrict the flow in a flat head with a 7 PSI
pressure cap.
But until you start having a problem with detonation, which is usually
the first sign of this problem, it's just something to be aware of.
Bryan Savage
dahlgren wrote:
>
> The point that is missed here is the need for a pressure system and the
> more pressure the better. 22 lbs is pretty common. It is not so much to
> raise the boiling point which it does help but to eliminate small air
> pockets that cause localized steam and high temp areas.. I have worked
> on some engines that raised the pressure to 30 psi before even starting
> the engine..some of these ran at 50 psi under a load.
> Dave Dahlgren
>
> ardunbill@webtv.net wrote:
> >
> > Hi Folks. Read the items about cooling with interest. I have a 15 gpm
> > Jabsco 12V marine coolant circulating pump which they tell me is
> > in widespread use for cooling converted auto engines in marine use where
> > sea water is not used, but there is some form of heat exchanger so tap
> > water and antifreeze mix is used in the engine as per car practice.
> >
> > I certainly question the idea that a huge gpm figure is necessary for
> > speed trials engine cooling. You're only running a short while, even at
> > Bonneville, so the practice for decades has been, has it not, electric
> > pumps like mine, and vented systems, so you just run down there, and
> > heat your 10 to 20 or more gallons of water up gradually so that the
> > run's over before boiling point is reached.
> >
> > I do agree that a thermostat makes complete sense, you get your engine
> > hot enough to "go", but your cooling water is not hot, so you have more
> > running time than if you heat the whole system up to some point.
> >
> > I think the expert Keith cited is right that the engine makes best power
> > a little over 200, evidence for it is that the Japanese water-cooled
> > motorcycles commonly use thermostats about 205 degrees. With 50/50
> > antifreeze you have a boiling point way up there, 226 with no pressure,
> > and higher with pressure. So no practical reason why you can't run 205
> > with a speed trials iron.
> >
> > My Ardun worked fine with the 15 gpm pump, 180 degree thermostats, and
> > 10 gallons in the system with a trunk-mounted tank, at Maxton last
> > weekend. This may be a different matter than a SB Chevy with tremendous
> > power output and smallish aluminum heads. The Ardun aluminum heads
> > weigh maybe 50 pounds apiece and are thought to have a lot of
> > AIR-cooling value from their sheer size. The bottom line is, a working
> > system that gives you the endurance and running temperature you want.
> > Cheers from ArdunBill in the Great Dismal Swamp, Chesapeake, VA
> >
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