Cooling water exhaust flow (video examples)

[Kelly]

I was recently inspired by Mo's posting of a video showing flow rates for exhaust cooling water (found here).

Often I would like to compare engine performance (sounds, techniques, tips...) in video form with afourians but video postings are fairly rare although increasing in frequency as of late.

Here is my first contribution in response to Mo's video. I show pretty much the same procedure: cold start, exhaust flow at idle and then again at about 1500 RPM.

[YOUTUBE]umUP2u2hR4E[/YOUTUBE]

Hopefully the comparison will be instructive (it already has been for me) and will inspire others to contribute. We could start other threads for different subjects and perhaps keep "(video examples)" in the thread title to facilitate searching.

[Mo]

Cool. Good show!

[Administrator]

Wish we could put some volumetric #'s on these (gallons/minute).

Bill

[Baltimore Sailor]

Next time I'm at the boat I'll hang a five-gallon bucket over the stern, time it for a minute, and see how many gallons I got.

[Kelly]

...and I will try to do the same.

[pallen58]

Nice video. I just re-built my water pump. The impellar looked like an Oreo that had seen better days, no telling when the PO had changed it, if she ever did, and I'll bet the shaft had a 1/16th groove in it. Thanks to Marthur and all the others on this site who have posted re-build information. It sure made the job easy. The best part of all is that it is back on the boat and working like a champ. No leaks! We where a little surpised at how much water was now coming out. before it would spit perhaps a foot behind the boat and now I'll bet it is hitting the water 2 1/2 feet back. Sure a lot more than in this video. Thanks again. Now on to the new altenator and an engine re-wire. I'll soon have a new engine.

[Carl-T705]

Something to keep in mind is when replacing the suction hose to the pump many people use common automotive heater hose. This is really a mistake, heater/coolant hose is not made to be to be used in suction. If you have ever changed the lower radiator hose on a car you will find a coiled steel wire on the inside ,this is to keep the hose from collapsing. A collapsed suction hose will restrict the flow to the point the engine over heats. The higher the rpm, the greater the suction. This is especially true if you are not running a thermostat. Suction hose is available from any place that makes up hydraulic hose, some NAPA stores as well. Cheers

[Baltimore Sailor]

I finally got around yesterday to measuring the outflow from the exhaust. I stuck a five-gallon bucket under the exhaust and timed it for one minute at 1000 rpm and another at 2000 rpm.

I got about two gallons at 1000 rpm and just a little more at 2000 rpm -- not significantly different, maybe a quart at the most.

I'd think after a new pump installation and complete exhaust/manifold rebuild/replacement, I'd get a bit better than that. I have a valve installed between the T-fitting and the thermostat, and it's completely closed off to send all the water into the head. I run at about 175F with the hot plugs in.

Should I be getting more flow than that? I also get good steam off the water even now, but it is hot water coming out of there. I'd put it at a good 150F at least. (I should take my digital thermometer and see what the temp actually is.)

Well, there's my results. Has anyone else taken a measurement?

[sastanley]

BS, I haven't measured flow directly yet, but I was sucking out of a 5 gallon bucket, roughly 2 gallons per minute when I was using it to winterize.

Recently, my IR laser thermometer was reading about 115-120 F water as it exited the manifold on its way to the water lift muffler & my gauge was reading 160 F. However, at the #1 spark plug the head temp was reading 375 F!

[Administrator]

I found this performance table for the Oberdorfer pump on their website. Seeing little or no change in throughput when doubling RPM's doesn't seem to make much sense unless the head the pump is fighting is really tremendous, and beyond anything you can imagine with this engine.

(I think....) Or maybe the head really is that high....

Bill

[Baltimore Sailor]

This doesn't have anything to do with the pump, but I had an interesting experience the other day. I'd fired up the engine and was idling at the dock when I noticed water coming from the engine compartment. When I took a peek inside I saw that the anti-siphon valve had unscrewed itself, and water was bubbling out of the hole like a school drinking fountain.

I shut it down and screwed it back in place, and I've checked it for tightness before starting ever since.

All I used on the threads was a bit of teflon tape; should I use a bit of Permatex there as well? Has anyone else had this happen?

[Administrator]

Seeing little or no change in throughput when doubling RPM's doesn't seem to make much sense unless the head the pump is fighting is really tremendous, and beyond anything you can imagine with this engine.

(I think....) Or maybe the head really is that high....

Anybody up for plumbing a pressure gauge just downstream of the raw water pump?

Bill

[hanleyclifford]

I found this performance table for the Oberdorfer pump on their website. Seeing little or no change in throughput when doubling RPM's doesn't seem to make much sense unless the head the pump is fighting is really tremendous, and beyond anything you can imagine with this engine.

(I think....) Or maybe the head really is that high....

Bill

It isn't just "head"the pump is fighting; it's the restrictive fittings. The machined brass 90 degree fitting should be eliminated from the repertoire. Remember the testing Tom Thatch did comparing the cast "plumbers" style with the "machined" type.

[Administrator]

Hanley:

I wasn't using "head" in the context of lift. You'll see that the Oberdorfer chart uses "lift" and "psi" interchangeably, though obviously in different units of measurement.

"Head is a measure of energy. The units of energy are expressed in feet or meters. Pressure is a force applied to a unit of area, such as a pound of force applied to a square inch of area, or PSI. For water, we can say that had in feet divided by 2.31 is pressure in PSI, and pressure in PSI multiplied by 2.31 is head in feet. Stated mathematically:

Head (ft.)/2.31 = PSI and PSI x 2.31 = Head (feet)"

Bill

[ndutton]

I'm wondering if a change in flow was difficult to notice due to the batching discharge of the waterlift exhaust. A steady flow is one thing but an intermittent sploosh is another and exhaust system size can dramatically affect its appearance.